Merge remote-tracking branch 'origin/master' into llvm13

Conflicts:
   lib/libcxx/include/__config

d57c0cc3bfeff9af297279759ec2b631e6d95140 added support for DragonFlyBSD
to libc++ by updating some ifdefs. This needed to be synced with llvm13.

30 files changed, 2016 insertions, 887 deletions

diff --git a/src/Air.zig b/src/Air.zig
index 391683afd5..6e4125be44 100644
--- a/src/Air.zig
+++ b/src/Air.zig
@@ -94,6 +94,12 @@ pub const Inst = struct {
         /// Result type is the same as both operands.
         /// Uses the `bin_op` field.
         bit_or,
+        /// Shift right. `>>`
+        /// Uses the `bin_op` field.
+        shr,
+        /// Shift left. `<<`
+        /// Uses the `bin_op` field.
+        shl,
         /// Bitwise XOR. `^`
         /// Uses the `bin_op` field.
         xor,
@@ -258,6 +264,13 @@ pub const Inst = struct {
         /// Given a pointer to a struct and a field index, returns a pointer to the field.
         /// Uses the `ty_pl` field, payload is `StructField`.
         struct_field_ptr,
+        /// Given a pointer to a struct, returns a pointer to the field.
+        /// The field index is the number at the end of the name.
+        /// Uses `ty_op` field.
+        struct_field_ptr_index_0,
+        struct_field_ptr_index_1,
+        struct_field_ptr_index_2,
+        struct_field_ptr_index_3,
         /// Given a byval struct and a field index, returns the field byval.
         /// Uses the `ty_pl` field, payload is `StructField`.
         struct_field_val,
@@ -280,6 +293,10 @@ pub const Inst = struct {
         /// Result type is the element type of the pointer operand.
         /// Uses the `bin_op` field.
         ptr_elem_val,
+        /// Given a pointer value, and element index, return the element pointer at that index.
+        /// Result type is pointer to the element type of the pointer operand.
+        /// Uses the `ty_pl` field with payload `Bin`.
+        ptr_elem_ptr,
         /// Given a pointer to a pointer, and element index, return the element value of the inner
         /// pointer at that index.
         /// Result type is the element type of the inner pointer operand.
@@ -404,6 +421,11 @@ pub const StructField = struct {
     field_index: u32,
 };
 
+pub const Bin = struct {
+    lhs: Inst.Ref,
+    rhs: Inst.Ref,
+};
+
 /// Trailing:
 /// 0. `Inst.Ref` for every outputs_len
 /// 1. `Inst.Ref` for every inputs_len
@@ -445,6 +467,8 @@ pub fn typeOfIndex(air: Air, inst: Air.Inst.Index) Type {
         .xor,
         .ptr_add,
         .ptr_sub,
+        .shr,
+        .shl,
         => return air.typeOf(datas[inst].bin_op.lhs),
 
         .cmp_lt,
@@ -474,6 +498,7 @@ pub fn typeOfIndex(air: Air, inst: Air.Inst.Index) Type {
         .constant,
         .struct_field_ptr,
         .struct_field_val,
+        .ptr_elem_ptr,
         => return air.getRefType(datas[inst].ty_pl.ty),
 
         .not,
@@ -492,6 +517,10 @@ pub fn typeOfIndex(air: Air, inst: Air.Inst.Index) Type {
         .wrap_errunion_payload,
         .wrap_errunion_err,
         .slice_ptr,
+        .struct_field_ptr_index_0,
+        .struct_field_ptr_index_1,
+        .struct_field_ptr_index_2,
+        .struct_field_ptr_index_3,
         => return air.getRefType(datas[inst].ty_op.ty),
 
         .loop,
@@ -519,8 +548,8 @@ pub fn typeOfIndex(air: Air, inst: Air.Inst.Index) Type {
         },
 
         .slice_elem_val, .ptr_elem_val => {
-            const slice_ty = air.typeOf(datas[inst].bin_op.lhs);
-            return slice_ty.elemType();
+            const ptr_ty = air.typeOf(datas[inst].bin_op.lhs);
+            return ptr_ty.elemType();
         },
         .ptr_slice_elem_val, .ptr_ptr_elem_val => {
             const outer_ptr_ty = air.typeOf(datas[inst].bin_op.lhs);
diff --git a/src/AstGen.zig b/src/AstGen.zig
index e3f33ec332..0a34e9a0ca 100644
--- a/src/AstGen.zig
+++ b/src/AstGen.zig
@@ -370,10 +370,6 @@ fn lvalExpr(gz: *GenZir, scope: *Scope, node: ast.Node.Index) InnerError!Zir.Ins
         .bool_not,
         .address_of,
         .float_literal,
-        .undefined_literal,
-        .true_literal,
-        .false_literal,
-        .null_literal,
         .optional_type,
         .block,
         .block_semicolon,
@@ -698,7 +694,13 @@ fn expr(gz: *GenZir, scope: *Scope, rl: ResultLoc, node: ast.Node.Index) InnerEr
                 .lhs = lhs,
                 .start = start,
             });
-            return rvalue(gz, rl, result, node);
+            switch (rl) {
+                .ref, .none_or_ref => return result,
+                else => {
+                    const dereffed = try gz.addUnNode(.load, result, node);
+                    return rvalue(gz, rl, dereffed, node);
+                },
+            }
         },
         .slice => {
             const lhs = try expr(gz, scope, .ref, node_datas[node].lhs);
@@ -710,7 +712,13 @@ fn expr(gz: *GenZir, scope: *Scope, rl: ResultLoc, node: ast.Node.Index) InnerEr
                 .start = start,
                 .end = end,
             });
-            return rvalue(gz, rl, result, node);
+            switch (rl) {
+                .ref, .none_or_ref => return result,
+                else => {
+                    const dereffed = try gz.addUnNode(.load, result, node);
+                    return rvalue(gz, rl, dereffed, node);
+                },
+            }
         },
         .slice_sentinel => {
             const lhs = try expr(gz, scope, .ref, node_datas[node].lhs);
@@ -724,7 +732,13 @@ fn expr(gz: *GenZir, scope: *Scope, rl: ResultLoc, node: ast.Node.Index) InnerEr
                 .end = end,
                 .sentinel = sentinel,
             });
-            return rvalue(gz, rl, result, node);
+            switch (rl) {
+                .ref, .none_or_ref => return result,
+                else => {
+                    const dereffed = try gz.addUnNode(.load, result, node);
+                    return rvalue(gz, rl, dereffed, node);
+                },
+            }
         },
 
         .deref => {
@@ -741,10 +755,6 @@ fn expr(gz: *GenZir, scope: *Scope, rl: ResultLoc, node: ast.Node.Index) InnerEr
             const result = try expr(gz, scope, .ref, node_datas[node].lhs);
             return rvalue(gz, rl, result, node);
         },
-        .undefined_literal => return rvalue(gz, rl, .undef, node),
-        .true_literal => return rvalue(gz, rl, .bool_true, node),
-        .false_literal => return rvalue(gz, rl, .bool_false, node),
-        .null_literal => return rvalue(gz, rl, .null_value, node),
         .optional_type => {
             const operand = try typeExpr(gz, scope, node_datas[node].lhs);
             const result = try gz.addUnNode(.optional_type, operand, node);
@@ -2367,7 +2377,7 @@ fn varDecl(
     }
     const ident_name = try astgen.identAsString(name_token);
 
-    try astgen.detectLocalShadowing(scope, ident_name, name_token);
+    try astgen.detectLocalShadowing(scope, ident_name, name_token, ident_name_raw);
 
     if (var_decl.ast.init_node == 0) {
         return astgen.failNode(node, "variables must be initialized", .{});
@@ -2873,7 +2883,7 @@ fn fnDecl(
     };
     const fn_name_str_index = try astgen.identAsString(fn_name_token);
 
-    try astgen.declareNewName(scope, fn_name_str_index, decl_node);
+    try astgen.declareNewName(scope, fn_name_str_index, decl_node, fn_name_token);
 
     // We insert this at the beginning so that its instruction index marks the
     // start of the top level declaration.
@@ -2934,12 +2944,13 @@ fn fnDecl(
             } else false;
 
             const param_name: u32 = if (param.name_token) |name_token| blk: {
-                if (mem.eql(u8, "_", tree.tokenSlice(name_token)))
+                const name_bytes = tree.tokenSlice(name_token);
+                if (mem.eql(u8, "_", name_bytes))
                     break :blk 0;
 
                 const param_name = try astgen.identAsString(name_token);
                 if (!is_extern) {
-                    try astgen.detectLocalShadowing(params_scope, param_name, name_token);
+                    try astgen.detectLocalShadowing(params_scope, param_name, name_token, name_bytes);
                 }
                 break :blk param_name;
             } else if (!is_extern) {
@@ -3142,7 +3153,7 @@ fn globalVarDecl(
     const name_token = var_decl.ast.mut_token + 1;
     const name_str_index = try astgen.identAsString(name_token);
 
-    try astgen.declareNewName(scope, name_str_index, node);
+    try astgen.declareNewName(scope, name_str_index, node, name_token);
 
     var block_scope: GenZir = .{
         .parent = scope,
@@ -5017,7 +5028,7 @@ fn ifExpr(
                 const token_name_str = tree.tokenSlice(token_name_index);
                 if (mem.eql(u8, "_", token_name_str))
                     break :s &then_scope.base;
-                try astgen.detectLocalShadowing(&then_scope.base, ident_name, token_name_index);
+                try astgen.detectLocalShadowing(&then_scope.base, ident_name, token_name_index, token_name_str);
                 payload_val_scope = .{
                     .parent = &then_scope.base,
                     .gen_zir = &then_scope,
@@ -5036,11 +5047,12 @@ fn ifExpr(
                 .optional_payload_unsafe_ptr
             else
                 .optional_payload_unsafe;
-            if (mem.eql(u8, "_", tree.tokenSlice(ident_token)))
+            const ident_bytes = tree.tokenSlice(ident_token);
+            if (mem.eql(u8, "_", ident_bytes))
                 break :s &then_scope.base;
             const payload_inst = try then_scope.addUnNode(tag, cond.inst, node);
             const ident_name = try astgen.identAsString(ident_token);
-            try astgen.detectLocalShadowing(&then_scope.base, ident_name, ident_token);
+            try astgen.detectLocalShadowing(&then_scope.base, ident_name, ident_token, ident_bytes);
             payload_val_scope = .{
                 .parent = &then_scope.base,
                 .gen_zir = &then_scope,
@@ -5082,7 +5094,7 @@ fn ifExpr(
                 const error_token_str = tree.tokenSlice(error_token);
                 if (mem.eql(u8, "_", error_token_str))
                     break :s &else_scope.base;
-                try astgen.detectLocalShadowing(&else_scope.base, ident_name, error_token);
+                try astgen.detectLocalShadowing(&else_scope.base, ident_name, error_token, error_token_str);
                 payload_val_scope = .{
                     .parent = &else_scope.base,
                     .gen_zir = &else_scope,
@@ -5273,11 +5285,12 @@ fn whileExpr(
                     .err_union_payload_unsafe;
                 const payload_inst = try then_scope.addUnNode(tag, cond.inst, node);
                 const ident_token = if (payload_is_ref) payload_token + 1 else payload_token;
-                if (mem.eql(u8, "_", tree.tokenSlice(ident_token)))
+                const ident_bytes = tree.tokenSlice(ident_token);
+                if (mem.eql(u8, "_", ident_bytes))
                     break :s &then_scope.base;
                 const payload_name_loc = payload_token + @boolToInt(payload_is_ref);
                 const ident_name = try astgen.identAsString(payload_name_loc);
-                try astgen.detectLocalShadowing(&then_scope.base, ident_name, payload_name_loc);
+                try astgen.detectLocalShadowing(&then_scope.base, ident_name, payload_name_loc, ident_bytes);
                 payload_val_scope = .{
                     .parent = &then_scope.base,
                     .gen_zir = &then_scope,
@@ -5298,9 +5311,10 @@ fn whileExpr(
                 .optional_payload_unsafe;
             const payload_inst = try then_scope.addUnNode(tag, cond.inst, node);
             const ident_name = try astgen.identAsString(ident_token);
-            if (mem.eql(u8, "_", tree.tokenSlice(ident_token)))
+            const ident_bytes = tree.tokenSlice(ident_token);
+            if (mem.eql(u8, "_", ident_bytes))
                 break :s &then_scope.base;
-            try astgen.detectLocalShadowing(&then_scope.base, ident_name, ident_token);
+            try astgen.detectLocalShadowing(&then_scope.base, ident_name, ident_token, ident_bytes);
             payload_val_scope = .{
                 .parent = &then_scope.base,
                 .gen_zir = &then_scope,
@@ -5356,9 +5370,10 @@ fn whileExpr(
                     .err_union_code;
                 const payload_inst = try else_scope.addUnNode(tag, cond.inst, node);
                 const ident_name = try astgen.identAsString(error_token);
-                if (mem.eql(u8, tree.tokenSlice(error_token), "_"))
+                const ident_bytes = tree.tokenSlice(error_token);
+                if (mem.eql(u8, ident_bytes, "_"))
                     break :s &else_scope.base;
-                try astgen.detectLocalShadowing(&else_scope.base, ident_name, error_token);
+                try astgen.detectLocalShadowing(&else_scope.base, ident_name, error_token, ident_bytes);
                 payload_val_scope = .{
                     .parent = &else_scope.base,
                     .gen_zir = &else_scope,
@@ -5418,12 +5433,19 @@ fn forExpr(
     if (for_full.label_token) |label_token| {
         try astgen.checkLabelRedefinition(scope, label_token);
     }
+
     // Set up variables and constants.
     const is_inline = parent_gz.force_comptime or for_full.inline_token != null;
     const tree = astgen.tree;
     const token_tags = tree.tokens.items(.tag);
 
-    const array_ptr = try expr(parent_gz, scope, .none_or_ref, for_full.ast.cond_expr);
+    const payload_is_ref = if (for_full.payload_token) |payload_token|
+        token_tags[payload_token] == .asterisk
+    else
+        false;
+
+    const cond_rl: ResultLoc = if (payload_is_ref) .ref else .none;
+    const array_ptr = try expr(parent_gz, scope, cond_rl, for_full.ast.cond_expr);
     const len = try parent_gz.addUnNode(.indexable_ptr_len, array_ptr, for_full.ast.cond_expr);
 
     const index_ptr = blk: {
@@ -5498,7 +5520,7 @@ fn forExpr(
             const name_str_index = try astgen.identAsString(ident);
             const tag: Zir.Inst.Tag = if (is_ptr) .elem_ptr else .elem_val;
             const payload_inst = try then_scope.addBin(tag, array_ptr, index);
-            try astgen.detectLocalShadowing(&then_scope.base, name_str_index, ident);
+            try astgen.detectLocalShadowing(&then_scope.base, name_str_index, ident, value_name);
             payload_val_scope = .{
                 .parent = &then_scope.base,
                 .gen_zir = &then_scope,
@@ -5518,11 +5540,12 @@ fn forExpr(
             ident + 2
         else
             break :blk payload_sub_scope;
-        if (mem.eql(u8, tree.tokenSlice(index_token), "_")) {
+        const token_bytes = tree.tokenSlice(index_token);
+        if (mem.eql(u8, token_bytes, "_")) {
             return astgen.failTok(index_token, "discard of index capture; omit it instead", .{});
         }
         const index_name = try astgen.identAsString(index_token);
-        try astgen.detectLocalShadowing(payload_sub_scope, index_name, index_token);
+        try astgen.detectLocalShadowing(payload_sub_scope, index_name, index_token, token_bytes);
         index_scope = .{
             .parent = payload_sub_scope,
             .gen_zir = &then_scope,
@@ -6294,34 +6317,36 @@ fn identifier(
     }
     const ident_name = try astgen.identifierTokenString(ident_token);
 
-    if (simple_types.get(ident_name)) |zir_const_ref| {
-        return rvalue(gz, rl, zir_const_ref, ident);
-    }
+    if (ident_name_raw[0] != '@') {
+        if (simple_types.get(ident_name)) |zir_const_ref| {
+            return rvalue(gz, rl, zir_const_ref, ident);
+        }
 
-    if (ident_name.len >= 2) integer: {
-        const first_c = ident_name[0];
-        if (first_c == 'i' or first_c == 'u') {
-            const signedness: std.builtin.Signedness = switch (first_c == 'i') {
-                true => .signed,
-                false => .unsigned,
-            };
-            const bit_count = std.fmt.parseInt(u16, ident_name[1..], 10) catch |err| switch (err) {
-                error.Overflow => return astgen.failNode(
-                    ident,
-                    "primitive integer type '{s}' exceeds maximum bit width of 65535",
-                    .{ident_name},
-                ),
-                error.InvalidCharacter => break :integer,
-            };
-            const result = try gz.add(.{
-                .tag = .int_type,
-                .data = .{ .int_type = .{
-                    .src_node = gz.nodeIndexToRelative(ident),
-                    .signedness = signedness,
-                    .bit_count = bit_count,
-                } },
-            });
-            return rvalue(gz, rl, result, ident);
+        if (ident_name.len >= 2) integer: {
+            const first_c = ident_name[0];
+            if (first_c == 'i' or first_c == 'u') {
+                const signedness: std.builtin.Signedness = switch (first_c == 'i') {
+                    true => .signed,
+                    false => .unsigned,
+                };
+                const bit_count = std.fmt.parseInt(u16, ident_name[1..], 10) catch |err| switch (err) {
+                    error.Overflow => return astgen.failNode(
+                        ident,
+                        "primitive integer type '{s}' exceeds maximum bit width of 65535",
+                        .{ident_name},
+                    ),
+                    error.InvalidCharacter => break :integer,
+                };
+                const result = try gz.add(.{
+                    .tag = .int_type,
+                    .data = .{ .int_type = .{
+                        .src_node = gz.nodeIndexToRelative(ident),
+                        .signedness = signedness,
+                        .bit_count = bit_count,
+                    } },
+                });
+                return rvalue(gz, rl, result, ident);
+            }
         }
     }
 
@@ -7102,38 +7127,38 @@ fn builtinCall(
         .bit_size_of => return simpleUnOpType(gz, scope, rl, node, params[0], .bit_size_of),
         .align_of    => return simpleUnOpType(gz, scope, rl, node, params[0], .align_of),
 
-        .ptr_to_int            => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .ptr_to_int),
-        .error_to_int          => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .error_to_int),
-        .int_to_error          => return simpleUnOp(gz, scope, rl, node, .{ .ty = .u16_type },            params[0], .int_to_error),
-        .compile_error         => return simpleUnOp(gz, scope, rl, node, .{ .ty = .const_slice_u8_type }, params[0], .compile_error),
-        .set_eval_branch_quota => return simpleUnOp(gz, scope, rl, node, .{ .ty = .u32_type },            params[0], .set_eval_branch_quota),
-        .enum_to_int           => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .enum_to_int),
-        .bool_to_int           => return simpleUnOp(gz, scope, rl, node, bool_rl,                         params[0], .bool_to_int),
-        .embed_file            => return simpleUnOp(gz, scope, rl, node, .{ .ty = .const_slice_u8_type }, params[0], .embed_file),
-        .error_name            => return simpleUnOp(gz, scope, rl, node, .{ .ty = .anyerror_type },       params[0], .error_name),
-        .panic                 => return simpleUnOp(gz, scope, rl, node, .{ .ty = .const_slice_u8_type }, params[0], .panic),
-        .set_align_stack       => return simpleUnOp(gz, scope, rl, node, align_rl,                        params[0], .set_align_stack),
-        .set_cold              => return simpleUnOp(gz, scope, rl, node, bool_rl,                         params[0], .set_cold),
-        .set_float_mode        => return simpleUnOp(gz, scope, rl, node, .{ .ty = .float_mode_type },     params[0], .set_float_mode),
-        .set_runtime_safety    => return simpleUnOp(gz, scope, rl, node, bool_rl,                         params[0], .set_runtime_safety),
-        .sqrt                  => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .sqrt),
-        .sin                   => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .sin),
-        .cos                   => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .cos),
-        .exp                   => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .exp),
-        .exp2                  => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .exp2),
-        .log                   => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .log),
-        .log2                  => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .log2),
-        .log10                 => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .log10),
-        .fabs                  => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .fabs),
-        .floor                 => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .floor),
-        .ceil                  => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .ceil),
-        .trunc                 => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .trunc),
-        .round                 => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .round),
-        .tag_name              => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .tag_name),
-        .Type                  => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .reify),
-        .type_name             => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .type_name),
-        .Frame                 => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .frame_type),
-        .frame_size            => return simpleUnOp(gz, scope, rl, node, .none,                           params[0], .frame_size),
+        .ptr_to_int            => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .ptr_to_int),
+        .error_to_int          => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .error_to_int),
+        .int_to_error          => return simpleUnOp(gz, scope, rl, node, .{ .ty = .u16_type },                params[0], .int_to_error),
+        .compile_error         => return simpleUnOp(gz, scope, rl, node, .{ .ty = .const_slice_u8_type },     params[0], .compile_error),
+        .set_eval_branch_quota => return simpleUnOp(gz, scope, rl, node, .{ .ty = .u32_type },                params[0], .set_eval_branch_quota),
+        .enum_to_int           => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .enum_to_int),
+        .bool_to_int           => return simpleUnOp(gz, scope, rl, node, bool_rl,                             params[0], .bool_to_int),
+        .embed_file            => return simpleUnOp(gz, scope, rl, node, .{ .ty = .const_slice_u8_type },     params[0], .embed_file),
+        .error_name            => return simpleUnOp(gz, scope, rl, node, .{ .ty = .anyerror_type },           params[0], .error_name),
+        .panic                 => return simpleUnOp(gz, scope, rl, node, .{ .ty = .const_slice_u8_type },     params[0], .panic),
+        .set_align_stack       => return simpleUnOp(gz, scope, rl, node, align_rl,                            params[0], .set_align_stack),
+        .set_cold              => return simpleUnOp(gz, scope, rl, node, bool_rl,                             params[0], .set_cold),
+        .set_float_mode        => return simpleUnOp(gz, scope, rl, node, .{ .coerced_ty = .float_mode_type }, params[0], .set_float_mode),
+        .set_runtime_safety    => return simpleUnOp(gz, scope, rl, node, bool_rl,                             params[0], .set_runtime_safety),
+        .sqrt                  => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .sqrt),
+        .sin                   => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .sin),
+        .cos                   => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .cos),
+        .exp                   => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .exp),
+        .exp2                  => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .exp2),
+        .log                   => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .log),
+        .log2                  => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .log2),
+        .log10                 => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .log10),
+        .fabs                  => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .fabs),
+        .floor                 => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .floor),
+        .ceil                  => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .ceil),
+        .trunc                 => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .trunc),
+        .round                 => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .round),
+        .tag_name              => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .tag_name),
+        .Type                  => return simpleUnOp(gz, scope, rl, node, .{ .coerced_ty = .type_info_type },  params[0], .reify),
+        .type_name             => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .type_name),
+        .Frame                 => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .frame_type),
+        .frame_size            => return simpleUnOp(gz, scope, rl, node, .none,                               params[0], .frame_size),
 
         .float_to_int => return typeCast(gz, scope, rl, node, params[0], params[1], .float_to_int),
         .int_to_float => return typeCast(gz, scope, rl, node, params[0], params[1], .int_to_float),
@@ -7819,10 +7844,6 @@ fn nodeMayNeedMemoryLocation(tree: *const ast.Tree, start_node: ast.Node.Index)
             .string_literal,
             .multiline_string_literal,
             .char_literal,
-            .true_literal,
-            .false_literal,
-            .null_literal,
-            .undefined_literal,
             .unreachable_literal,
             .identifier,
             .error_set_decl,
@@ -8059,10 +8080,6 @@ fn nodeMayEvalToError(tree: *const ast.Tree, start_node: ast.Node.Index) enum {
             .string_literal,
             .multiline_string_literal,
             .char_literal,
-            .true_literal,
-            .false_literal,
-            .null_literal,
-            .undefined_literal,
             .unreachable_literal,
             .error_set_decl,
             .container_decl,
@@ -8232,10 +8249,6 @@ fn nodeImpliesRuntimeBits(tree: *const ast.Tree, start_node: ast.Node.Index) boo
             .string_literal,
             .multiline_string_literal,
             .char_literal,
-            .true_literal,
-            .false_literal,
-            .null_literal,
-            .undefined_literal,
             .unreachable_literal,
             .identifier,
             .error_set_decl,
@@ -10006,8 +10019,21 @@ fn declareNewName(
     start_scope: *Scope,
     name_index: u32,
     node: ast.Node.Index,
+    name_token: ast.TokenIndex,
 ) !void {
     const gpa = astgen.gpa;
+
+    const token_bytes = astgen.tree.tokenSlice(name_token);
+    if (token_bytes[0] != '@' and isPrimitive(token_bytes)) {
+        return astgen.failTokNotes(name_token, "name shadows primitive '{s}'", .{
+            token_bytes,
+        }, &[_]u32{
+            try astgen.errNoteTok(name_token, "consider using @\"{s}\" to disambiguate", .{
+                token_bytes,
+            }),
+        });
+    }
+
     var scope = start_scope;
     while (true) {
         switch (scope.tag) {
@@ -10019,7 +10045,7 @@ fn declareNewName(
                 const ns = scope.cast(Scope.Namespace).?;
                 const gop = try ns.decls.getOrPut(gpa, name_index);
                 if (gop.found_existing) {
-                    const name = try gpa.dupe(u8, mem.spanZ(astgen.nullTerminatedString(name_index)));
+                    const name = try gpa.dupe(u8, mem.span(astgen.nullTerminatedString(name_index)));
                     defer gpa.free(name);
                     return astgen.failNodeNotes(node, "redeclaration of '{s}'", .{
                         name,
@@ -10035,21 +10061,45 @@ fn declareNewName(
     }
 }
 
-/// Local variables shadowing detection, including function parameters.
+fn isPrimitive(name: []const u8) bool {
+    if (simple_types.get(name) != null) return true;
+    if (name.len < 2) return false;
+    const first_c = name[0];
+    if (first_c != 'i' and first_c != 'u') return false;
+    if (std.fmt.parseInt(u16, name[1..], 10)) |_| {
+        return true;
+    } else |err| switch (err) {
+        error.Overflow => return true,
+        error.InvalidCharacter => return false,
+    }
+}
+
+/// Local variables shadowing detection, including function parameters and primitives.
 fn detectLocalShadowing(
     astgen: *AstGen,
     scope: *Scope,
     ident_name: u32,
     name_token: ast.TokenIndex,
+    token_bytes: []const u8,
 ) !void {
     const gpa = astgen.gpa;
+    if (token_bytes[0] != '@' and isPrimitive(token_bytes)) {
+        return astgen.failTokNotes(name_token, "name shadows primitive '{s}'", .{
+            token_bytes,
+        }, &[_]u32{
+            try astgen.errNoteTok(name_token, "consider using @\"{s}\" to disambiguate", .{
+                token_bytes,
+            }),
+        });
+    }
 
     var s = scope;
     while (true) switch (s.tag) {
         .local_val => {
             const local_val = s.cast(Scope.LocalVal).?;
             if (local_val.name == ident_name) {
-                const name = try gpa.dupe(u8, mem.spanZ(astgen.nullTerminatedString(ident_name)));
+                const name_slice = mem.span(astgen.nullTerminatedString(ident_name));
+                const name = try gpa.dupe(u8, name_slice);
                 defer gpa.free(name);
                 return astgen.failTokNotes(name_token, "redeclaration of {s} '{s}'", .{
                     @tagName(local_val.id_cat), name,
@@ -10066,7 +10116,8 @@ fn detectLocalShadowing(
         .local_ptr => {
             const local_ptr = s.cast(Scope.LocalPtr).?;
             if (local_ptr.name == ident_name) {
-                const name = try gpa.dupe(u8, mem.spanZ(astgen.nullTerminatedString(ident_name)));
+                const name_slice = mem.span(astgen.nullTerminatedString(ident_name));
+                const name = try gpa.dupe(u8, name_slice);
                 defer gpa.free(name);
                 return astgen.failTokNotes(name_token, "redeclaration of {s} '{s}'", .{
                     @tagName(local_ptr.id_cat), name,
@@ -10086,7 +10137,8 @@ fn detectLocalShadowing(
                 s = ns.parent;
                 continue;
             };
-            const name = try gpa.dupe(u8, mem.spanZ(astgen.nullTerminatedString(ident_name)));
+            const name_slice = mem.span(astgen.nullTerminatedString(ident_name));
+            const name = try gpa.dupe(u8, name_slice);
             defer gpa.free(name);
             return astgen.failTokNotes(name_token, "local shadows declaration of '{s}'", .{
                 name,
diff --git a/src/Compilation.zig b/src/Compilation.zig
index 63475821ab..b830fdc652 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -2557,6 +2557,7 @@ pub fn cImport(comp: *Compilation, c_src: []const u8) !CImportResult {
         var argv = std.ArrayList([]const u8).init(comp.gpa);
         defer argv.deinit();
 
+        try argv.append(""); // argv[0] is program name, actual args start at [1]
         try comp.addTranslateCCArgs(arena, &argv, .c, out_dep_path);
 
         try argv.append(out_h_path);
diff --git a/src/Liveness.zig b/src/Liveness.zig
index 48603fc7c9..6a47bfe597 100644
--- a/src/Liveness.zig
+++ b/src/Liveness.zig
@@ -249,6 +249,8 @@ fn analyzeInst(
         .ptr_slice_elem_val,
         .ptr_elem_val,
         .ptr_ptr_elem_val,
+        .shl,
+        .shr,
         => {
             const o = inst_datas[inst].bin_op;
             return trackOperands(a, new_set, inst, main_tomb, .{ o.lhs, o.rhs, .none });
@@ -280,6 +282,10 @@ fn analyzeInst(
         .wrap_errunion_err,
         .slice_ptr,
         .slice_len,
+        .struct_field_ptr_index_0,
+        .struct_field_ptr_index_1,
+        .struct_field_ptr_index_2,
+        .struct_field_ptr_index_3,
         => {
             const o = inst_datas[inst].ty_op;
             return trackOperands(a, new_set, inst, main_tomb, .{ o.operand, .none, .none });
@@ -328,6 +334,10 @@ fn analyzeInst(
             const extra = a.air.extraData(Air.StructField, inst_datas[inst].ty_pl.payload).data;
             return trackOperands(a, new_set, inst, main_tomb, .{ extra.struct_operand, .none, .none });
         },
+        .ptr_elem_ptr => {
+            const extra = a.air.extraData(Air.Bin, inst_datas[inst].ty_pl.payload).data;
+            return trackOperands(a, new_set, inst, main_tomb, .{ extra.lhs, extra.rhs, .none });
+        },
         .br => {
             const br = inst_datas[inst].br;
             return trackOperands(a, new_set, inst, main_tomb, .{ br.operand, .none, .none });
diff --git a/src/Module.zig b/src/Module.zig
index 319363e9b8..4ed39c9954 100644
--- a/src/Module.zig
+++ b/src/Module.zig
@@ -66,6 +66,10 @@ import_table: std.StringArrayHashMapUnmanaged(*Scope.File) = .{},
 /// to the same function.
 monomorphed_funcs: MonomorphedFuncsSet = .{},
 
+/// The set of all comptime function calls that have been cached so that future calls
+/// with the same parameters will get the same return value.
+memoized_calls: MemoizedCallSet = .{},
+
 /// We optimize memory usage for a compilation with no compile errors by storing the
 /// error messages and mapping outside of `Decl`.
 /// The ErrorMsg memory is owned by the decl, using Module's general purpose allocator.
@@ -157,6 +161,60 @@ const MonomorphedFuncsContext = struct {
     }
 };
 
+pub const MemoizedCallSet = std.HashMapUnmanaged(
+    MemoizedCall.Key,
+    MemoizedCall.Result,
+    MemoizedCall,
+    std.hash_map.default_max_load_percentage,
+);
+
+pub const MemoizedCall = struct {
+    pub const Key = struct {
+        func: *Fn,
+        args: []TypedValue,
+    };
+
+    pub const Result = struct {
+        val: Value,
+        arena: std.heap.ArenaAllocator.State,
+    };
+
+    pub fn eql(ctx: @This(), a: Key, b: Key) bool {
+        _ = ctx;
+
+        if (a.func != b.func) return false;
+
+        assert(a.args.len == b.args.len);
+        for (a.args) |a_arg, arg_i| {
+            const b_arg = b.args[arg_i];
+            if (!a_arg.eql(b_arg)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /// Must match `Sema.GenericCallAdapter.hash`.
+    pub fn hash(ctx: @This(), key: Key) u64 {
+        _ = ctx;
+
+        var hasher = std.hash.Wyhash.init(0);
+
+        // The generic function Decl is guaranteed to be the first dependency
+        // of each of its instantiations.
+        std.hash.autoHash(&hasher, @ptrToInt(key.func));
+
+        // This logic must be kept in sync with the logic in `analyzeCall` that
+        // computes the hash.
+        for (key.args) |arg| {
+            arg.hash(&hasher);
+        }
+
+        return hasher.final();
+    }
+};
+
 /// A `Module` has zero or one of these depending on whether `-femit-h` is enabled.
 pub const GlobalEmitH = struct {
     /// Where to put the output.
@@ -554,8 +612,8 @@ pub const Decl = struct {
                 assert(struct_obj.owner_decl == decl);
                 return &struct_obj.namespace;
             },
-            .enum_full => {
-                const enum_obj = ty.castTag(.enum_full).?.data;
+            .enum_full, .enum_nonexhaustive => {
+                const enum_obj = ty.cast(Type.Payload.EnumFull).?.data;
                 assert(enum_obj.owner_decl == decl);
                 return &enum_obj.namespace;
             },
@@ -660,6 +718,7 @@ pub const Struct = struct {
     /// is necessary to determine whether it has bits at runtime.
     known_has_bits: bool,
 
+    /// The `Type` and `Value` memory is owned by the arena of the Struct's owner_decl.
     pub const Field = struct {
         /// Uses `noreturn` to indicate `anytype`.
         /// undefined until `status` is `have_field_types` or `have_layout`.
@@ -2254,15 +2313,26 @@ pub fn deinit(mod: *Module) void {
     }
     mod.export_owners.deinit(gpa);
 
-    var it = mod.global_error_set.keyIterator();
-    while (it.next()) |key| {
-        gpa.free(key.*);
+    {
+        var it = mod.global_error_set.keyIterator();
+        while (it.next()) |key| {
+            gpa.free(key.*);
+        }
+        mod.global_error_set.deinit(gpa);
     }
-    mod.global_error_set.deinit(gpa);
 
     mod.error_name_list.deinit(gpa);
     mod.test_functions.deinit(gpa);
     mod.monomorphed_funcs.deinit(gpa);
+
+    {
+        var it = mod.memoized_calls.iterator();
+        while (it.next()) |entry| {
+            gpa.free(entry.key_ptr.args);
+            entry.value_ptr.arena.promote(gpa).deinit();
+        }
+        mod.memoized_calls.deinit(gpa);
+    }
 }
 
 fn freeExportList(gpa: *Allocator, export_list: []*Export) void {
@@ -3091,6 +3161,9 @@ fn semaDecl(mod: *Module, decl: *Decl) !bool {
         if (linksection_ref == .none) break :blk Value.initTag(.null_value);
         break :blk (try sema.resolveInstConst(&block_scope, src, linksection_ref)).val;
     };
+    // Note this resolves the type of the Decl, not the value; if this Decl
+    // is a struct, for example, this resolves `type` (which needs no resolution),
+    // not the struct itself.
     try sema.resolveTypeLayout(&block_scope, src, decl_tv.ty);
 
     // We need the memory for the Type to go into the arena for the Decl
@@ -3193,6 +3266,15 @@ fn semaDecl(mod: *Module, decl: *Decl) !bool {
         if (type_changed and mod.emit_h != null) {
             try mod.comp.work_queue.writeItem(.{ .emit_h_decl = decl });
         }
+    } else if (decl_tv.ty.zigTypeTag() == .Type) {
+        // In case this Decl is a struct or union, we need to resolve the fields
+        // while we still have the `Sema` in scope, so that the field type expressions
+        // can use the resolved AIR instructions that they possibly reference.
+        // We do this after the decl is populated and set to `complete` so that a `Decl`
+        // may reference itself.
+        var buffer: Value.ToTypeBuffer = undefined;
+        const ty = decl.val.toType(&buffer);
+        try sema.resolveDeclFields(&block_scope, src, ty);
     }
 
     if (decl.is_exported) {
@@ -4024,7 +4106,6 @@ pub fn createAnonymousDeclFromDeclNamed(
     new_decl.ty = typed_value.ty;
     new_decl.val = typed_value.val;
     new_decl.has_tv = true;
-    new_decl.owns_tv = true;
     new_decl.analysis = .complete;
     new_decl.generation = mod.generation;
 
@@ -4450,309 +4531,6 @@ pub const PeerTypeCandidateSrc = union(enum) {
     }
 };
 
-pub fn analyzeStructFields(mod: *Module, struct_obj: *Struct) CompileError!void {
-    const tracy = trace(@src());
-    defer tracy.end();
-
-    const gpa = mod.gpa;
-    const zir = struct_obj.owner_decl.namespace.file_scope.zir;
-    const extended = zir.instructions.items(.data)[struct_obj.zir_index].extended;
-    assert(extended.opcode == .struct_decl);
-    const small = @bitCast(Zir.Inst.StructDecl.Small, extended.small);
-    var extra_index: usize = extended.operand;
-
-    const src: LazySrcLoc = .{ .node_offset = struct_obj.node_offset };
-    extra_index += @boolToInt(small.has_src_node);
-
-    const body_len = if (small.has_body_len) blk: {
-        const body_len = zir.extra[extra_index];
-        extra_index += 1;
-        break :blk body_len;
-    } else 0;
-
-    const fields_len = if (small.has_fields_len) blk: {
-        const fields_len = zir.extra[extra_index];
-        extra_index += 1;
-        break :blk fields_len;
-    } else 0;
-
-    const decls_len = if (small.has_decls_len) decls_len: {
-        const decls_len = zir.extra[extra_index];
-        extra_index += 1;
-        break :decls_len decls_len;
-    } else 0;
-
-    // Skip over decls.
-    var decls_it = zir.declIteratorInner(extra_index, decls_len);
-    while (decls_it.next()) |_| {}
-    extra_index = decls_it.extra_index;
-
-    const body = zir.extra[extra_index..][0..body_len];
-    if (fields_len == 0) {
-        assert(body.len == 0);
-        return;
-    }
-    extra_index += body.len;
-
-    var decl_arena = struct_obj.owner_decl.value_arena.?.promote(gpa);
-    defer struct_obj.owner_decl.value_arena.?.* = decl_arena.state;
-
-    try struct_obj.fields.ensureCapacity(&decl_arena.allocator, fields_len);
-
-    // We create a block for the field type instructions because they
-    // may need to reference Decls from inside the struct namespace.
-    // Within the field type, default value, and alignment expressions, the "owner decl"
-    // should be the struct itself. Thus we need a new Sema.
-    var sema: Sema = .{
-        .mod = mod,
-        .gpa = gpa,
-        .arena = &decl_arena.allocator,
-        .code = zir,
-        .owner_decl = struct_obj.owner_decl,
-        .namespace = &struct_obj.namespace,
-        .owner_func = null,
-        .func = null,
-        .fn_ret_ty = Type.initTag(.void),
-    };
-    defer sema.deinit();
-
-    var block: Scope.Block = .{
-        .parent = null,
-        .sema = &sema,
-        .src_decl = struct_obj.owner_decl,
-        .instructions = .{},
-        .inlining = null,
-        .is_comptime = true,
-    };
-    defer assert(block.instructions.items.len == 0); // should all be comptime instructions
-
-    if (body.len != 0) {
-        _ = try sema.analyzeBody(&block, body);
-    }
-
-    const bits_per_field = 4;
-    const fields_per_u32 = 32 / bits_per_field;
-    const bit_bags_count = std.math.divCeil(usize, fields_len, fields_per_u32) catch unreachable;
-    var bit_bag_index: usize = extra_index;
-    extra_index += bit_bags_count;
-    var cur_bit_bag: u32 = undefined;
-    var field_i: u32 = 0;
-    while (field_i < fields_len) : (field_i += 1) {
-        if (field_i % fields_per_u32 == 0) {
-            cur_bit_bag = zir.extra[bit_bag_index];
-            bit_bag_index += 1;
-        }
-        const has_align = @truncate(u1, cur_bit_bag) != 0;
-        cur_bit_bag >>= 1;
-        const has_default = @truncate(u1, cur_bit_bag) != 0;
-        cur_bit_bag >>= 1;
-        const is_comptime = @truncate(u1, cur_bit_bag) != 0;
-        cur_bit_bag >>= 1;
-        const unused = @truncate(u1, cur_bit_bag) != 0;
-        cur_bit_bag >>= 1;
-
-        _ = unused;
-
-        const field_name_zir = zir.nullTerminatedString(zir.extra[extra_index]);
-        extra_index += 1;
-        const field_type_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
-        extra_index += 1;
-
-        // This string needs to outlive the ZIR code.
-        const field_name = try decl_arena.allocator.dupe(u8, field_name_zir);
-        if (field_type_ref == .none) {
-            return mod.fail(&block.base, src, "TODO: implement anytype struct field", .{});
-        }
-        const field_ty: Type = if (field_type_ref == .none)
-            Type.initTag(.noreturn)
-        else
-            // TODO: if we need to report an error here, use a source location
-            // that points to this type expression rather than the struct.
-            // But only resolve the source location if we need to emit a compile error.
-            try sema.resolveType(&block, src, field_type_ref);
-
-        const gop = struct_obj.fields.getOrPutAssumeCapacity(field_name);
-        assert(!gop.found_existing);
-        gop.value_ptr.* = .{
-            .ty = field_ty,
-            .abi_align = Value.initTag(.abi_align_default),
-            .default_val = Value.initTag(.unreachable_value),
-            .is_comptime = is_comptime,
-            .offset = undefined,
-        };
-
-        if (has_align) {
-            const align_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
-            extra_index += 1;
-            // TODO: if we need to report an error here, use a source location
-            // that points to this alignment expression rather than the struct.
-            // But only resolve the source location if we need to emit a compile error.
-            gop.value_ptr.abi_align = (try sema.resolveInstConst(&block, src, align_ref)).val;
-        }
-        if (has_default) {
-            const default_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
-            extra_index += 1;
-            // TODO: if we need to report an error here, use a source location
-            // that points to this default value expression rather than the struct.
-            // But only resolve the source location if we need to emit a compile error.
-            gop.value_ptr.default_val = (try sema.resolveInstConst(&block, src, default_ref)).val;
-        }
-    }
-}
-
-pub fn analyzeUnionFields(mod: *Module, union_obj: *Union) CompileError!void {
-    const tracy = trace(@src());
-    defer tracy.end();
-
-    const gpa = mod.gpa;
-    const zir = union_obj.owner_decl.namespace.file_scope.zir;
-    const extended = zir.instructions.items(.data)[union_obj.zir_index].extended;
-    assert(extended.opcode == .union_decl);
-    const small = @bitCast(Zir.Inst.UnionDecl.Small, extended.small);
-    var extra_index: usize = extended.operand;
-
-    const src: LazySrcLoc = .{ .node_offset = union_obj.node_offset };
-    extra_index += @boolToInt(small.has_src_node);
-
-    if (small.has_tag_type) {
-        extra_index += 1;
-    }
-
-    const body_len = if (small.has_body_len) blk: {
-        const body_len = zir.extra[extra_index];
-        extra_index += 1;
-        break :blk body_len;
-    } else 0;
-
-    const fields_len = if (small.has_fields_len) blk: {
-        const fields_len = zir.extra[extra_index];
-        extra_index += 1;
-        break :blk fields_len;
-    } else 0;
-
-    const decls_len = if (small.has_decls_len) decls_len: {
-        const decls_len = zir.extra[extra_index];
-        extra_index += 1;
-        break :decls_len decls_len;
-    } else 0;
-
-    // Skip over decls.
-    var decls_it = zir.declIteratorInner(extra_index, decls_len);
-    while (decls_it.next()) |_| {}
-    extra_index = decls_it.extra_index;
-
-    const body = zir.extra[extra_index..][0..body_len];
-    if (fields_len == 0) {
-        assert(body.len == 0);
-        return;
-    }
-    extra_index += body.len;
-
-    var decl_arena = union_obj.owner_decl.value_arena.?.promote(gpa);
-    defer union_obj.owner_decl.value_arena.?.* = decl_arena.state;
-
-    try union_obj.fields.ensureCapacity(&decl_arena.allocator, fields_len);
-
-    // We create a block for the field type instructions because they
-    // may need to reference Decls from inside the struct namespace.
-    // Within the field type, default value, and alignment expressions, the "owner decl"
-    // should be the struct itself. Thus we need a new Sema.
-    var sema: Sema = .{
-        .mod = mod,
-        .gpa = gpa,
-        .arena = &decl_arena.allocator,
-        .code = zir,
-        .owner_decl = union_obj.owner_decl,
-        .namespace = &union_obj.namespace,
-        .owner_func = null,
-        .func = null,
-        .fn_ret_ty = Type.initTag(.void),
-    };
-    defer sema.deinit();
-
-    var block: Scope.Block = .{
-        .parent = null,
-        .sema = &sema,
-        .src_decl = union_obj.owner_decl,
-        .instructions = .{},
-        .inlining = null,
-        .is_comptime = true,
-    };
-    defer assert(block.instructions.items.len == 0); // should all be comptime instructions
-
-    if (body.len != 0) {
-        _ = try sema.analyzeBody(&block, body);
-    }
-
-    const bits_per_field = 4;
-    const fields_per_u32 = 32 / bits_per_field;
-    const bit_bags_count = std.math.divCeil(usize, fields_len, fields_per_u32) catch unreachable;
-    var bit_bag_index: usize = extra_index;
-    extra_index += bit_bags_count;
-    var cur_bit_bag: u32 = undefined;
-    var field_i: u32 = 0;
-    while (field_i < fields_len) : (field_i += 1) {
-        if (field_i % fields_per_u32 == 0) {
-            cur_bit_bag = zir.extra[bit_bag_index];
-            bit_bag_index += 1;
-        }
-        const has_type = @truncate(u1, cur_bit_bag) != 0;
-        cur_bit_bag >>= 1;
-        const has_align = @truncate(u1, cur_bit_bag) != 0;
-        cur_bit_bag >>= 1;
-        const has_tag = @truncate(u1, cur_bit_bag) != 0;
-        cur_bit_bag >>= 1;
-        const unused = @truncate(u1, cur_bit_bag) != 0;
-        cur_bit_bag >>= 1;
-        _ = unused;
-
-        const field_name_zir = zir.nullTerminatedString(zir.extra[extra_index]);
-        extra_index += 1;
-
-        const field_type_ref: Zir.Inst.Ref = if (has_type) blk: {
-            const field_type_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
-            extra_index += 1;
-            break :blk field_type_ref;
-        } else .none;
-
-        const align_ref: Zir.Inst.Ref = if (has_align) blk: {
-            const align_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
-            extra_index += 1;
-            break :blk align_ref;
-        } else .none;
-
-        if (has_tag) {
-            extra_index += 1;
-        }
-
-        // This string needs to outlive the ZIR code.
-        const field_name = try decl_arena.allocator.dupe(u8, field_name_zir);
-        const field_ty: Type = if (field_type_ref == .none)
-            Type.initTag(.void)
-        else
-            // TODO: if we need to report an error here, use a source location
-            // that points to this type expression rather than the union.
-            // But only resolve the source location if we need to emit a compile error.
-            try sema.resolveType(&block, src, field_type_ref);
-
-        const gop = union_obj.fields.getOrPutAssumeCapacity(field_name);
-        assert(!gop.found_existing);
-        gop.value_ptr.* = .{
-            .ty = field_ty,
-            .abi_align = Value.initTag(.abi_align_default),
-        };
-
-        if (align_ref != .none) {
-            // TODO: if we need to report an error here, use a source location
-            // that points to this alignment expression rather than the struct.
-            // But only resolve the source location if we need to emit a compile error.
-            gop.value_ptr.abi_align = (try sema.resolveInstConst(&block, src, align_ref)).val;
-        }
-    }
-
-    // TODO resolve the union tag_type_ref
-}
-
 /// Called from `performAllTheWork`, after all AstGen workers have finished,
 /// and before the main semantic analysis loop begins.
 pub fn processOutdatedAndDeletedDecls(mod: *Module) !void {
diff --git a/src/Sema.zig b/src/Sema.zig
index 8b6f6d4a9f..90505c6806 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -649,6 +649,24 @@ fn resolveValue(
     return sema.failWithNeededComptime(block, src);
 }
 
+/// Value Tag `variable` will cause a compile error.
+/// Value Tag `undef` may be returned.
+fn resolveConstMaybeUndefVal(
+    sema: *Sema,
+    block: *Scope.Block,
+    src: LazySrcLoc,
+    inst: Air.Inst.Ref,
+) CompileError!Value {
+    if (try sema.resolveMaybeUndefValAllowVariables(block, src, inst)) |val| {
+        switch (val.tag()) {
+            .variable => return sema.failWithNeededComptime(block, src),
+            .generic_poison => return error.GenericPoison,
+            else => return val,
+        }
+    }
+    return sema.failWithNeededComptime(block, src);
+}
+
 /// Will not return Value Tags: `variable`, `undef`. Instead they will emit compile errors.
 /// See `resolveValue` for an alternative.
 fn resolveConstValue(
@@ -866,6 +884,7 @@ fn zirStructDecl(
         .ty = Type.initTag(.type),
         .val = struct_val,
     }, type_name);
+    new_decl.owns_tv = true;
     errdefer sema.mod.deleteAnonDecl(&block.base, new_decl);
     struct_obj.* = .{
         .owner_decl = new_decl,
@@ -986,6 +1005,7 @@ fn zirEnumDecl(
         .ty = Type.initTag(.type),
         .val = enum_val,
     }, type_name);
+    new_decl.owns_tv = true;
     errdefer sema.mod.deleteAnonDecl(&block.base, new_decl);
 
     enum_obj.* = .{
@@ -1032,25 +1052,27 @@ fn zirEnumDecl(
         // We create a block for the field type instructions because they
         // may need to reference Decls from inside the enum namespace.
         // Within the field type, default value, and alignment expressions, the "owner decl"
-        // should be the enum itself. Thus we need a new Sema.
-        var enum_sema: Sema = .{
-            .mod = mod,
-            .gpa = gpa,
-            .arena = &new_decl_arena.allocator,
-            .code = sema.code,
-            .inst_map = sema.inst_map,
-            .owner_decl = new_decl,
-            .namespace = &enum_obj.namespace,
-            .owner_func = null,
-            .func = null,
-            .fn_ret_ty = Type.initTag(.void),
-            .branch_quota = sema.branch_quota,
-            .branch_count = sema.branch_count,
-        };
+        // should be the enum itself.
+
+        const prev_owner_decl = sema.owner_decl;
+        sema.owner_decl = new_decl;
+        defer sema.owner_decl = prev_owner_decl;
+
+        const prev_namespace = sema.namespace;
+        sema.namespace = &enum_obj.namespace;
+        defer sema.namespace = prev_namespace;
+
+        const prev_owner_func = sema.owner_func;
+        sema.owner_func = null;
+        defer sema.owner_func = prev_owner_func;
+
+        const prev_func = sema.func;
+        sema.func = null;
+        defer sema.func = prev_func;
 
         var enum_block: Scope.Block = .{
             .parent = null,
-            .sema = &enum_sema,
+            .sema = sema,
             .src_decl = new_decl,
             .instructions = .{},
             .inlining = null,
@@ -1059,11 +1081,8 @@ fn zirEnumDecl(
         defer assert(enum_block.instructions.items.len == 0); // should all be comptime instructions
 
         if (body.len != 0) {
-            _ = try enum_sema.analyzeBody(&enum_block, body);
+            _ = try sema.analyzeBody(&enum_block, body);
         }
-
-        sema.branch_count = enum_sema.branch_count;
-        sema.branch_quota = enum_sema.branch_quota;
     }
     var bit_bag_index: usize = body_end;
     var cur_bit_bag: u32 = undefined;
@@ -1153,6 +1172,7 @@ fn zirUnionDecl(
         .ty = Type.initTag(.type),
         .val = union_val,
     }, type_name);
+    new_decl.owns_tv = true;
     errdefer sema.mod.deleteAnonDecl(&block.base, new_decl);
     union_obj.* = .{
         .owner_decl = new_decl,
@@ -1224,6 +1244,7 @@ fn zirErrorSetDecl(
         .ty = Type.initTag(.type),
         .val = error_set_val,
     }, type_name);
+    new_decl.owns_tv = true;
     errdefer sema.mod.deleteAnonDecl(&block.base, new_decl);
     const names = try new_decl_arena.allocator.alloc([]const u8, fields.len);
     for (fields) |str_index, i| {
@@ -1466,8 +1487,7 @@ fn zirResolveInferredAlloc(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Inde
     const ptr = sema.resolveInst(inst_data.operand);
     const ptr_inst = Air.refToIndex(ptr).?;
     assert(sema.air_instructions.items(.tag)[ptr_inst] == .constant);
-    const air_datas = sema.air_instructions.items(.data);
-    const value_index = air_datas[ptr_inst].ty_pl.payload;
+    const value_index = sema.air_instructions.items(.data)[ptr_inst].ty_pl.payload;
     const ptr_val = sema.air_values.items[value_index];
     const var_is_mut = switch (sema.typeOf(ptr).tag()) {
         .inferred_alloc_const => false,
@@ -1481,7 +1501,8 @@ fn zirResolveInferredAlloc(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Inde
 
         const final_elem_ty = try decl.ty.copy(sema.arena);
         const final_ptr_ty = try Module.simplePtrType(sema.arena, final_elem_ty, true, .One);
-        air_datas[ptr_inst].ty_pl.ty = try sema.addType(final_ptr_ty);
+        const final_ptr_ty_inst = try sema.addType(final_ptr_ty);
+        sema.air_instructions.items(.data)[ptr_inst].ty_pl.ty = final_ptr_ty_inst;
 
         if (var_is_mut) {
             sema.air_values.items[value_index] = try Value.Tag.decl_ref_mut.create(sema.arena, .{
@@ -2562,6 +2583,19 @@ fn analyzeCall(
         defer merges.results.deinit(gpa);
         defer merges.br_list.deinit(gpa);
 
+        // If it's a comptime function call, we need to memoize it as long as no external
+        // comptime memory is mutated.
+        var memoized_call_key: Module.MemoizedCall.Key = undefined;
+        var delete_memoized_call_key = false;
+        defer if (delete_memoized_call_key) gpa.free(memoized_call_key.args);
+        if (is_comptime_call) {
+            memoized_call_key = .{
+                .func = module_fn,
+                .args = try gpa.alloc(TypedValue, func_ty_info.param_types.len),
+            };
+            delete_memoized_call_key = true;
+        }
+
         try sema.emitBackwardBranch(&child_block, call_src);
 
         // This will have return instructions analyzed as break instructions to
@@ -2586,12 +2620,32 @@ fn analyzeCall(
                 const arg_src = call_src; // TODO: better source location
                 const casted_arg = try sema.coerce(&child_block, param_ty, uncasted_args[arg_i], arg_src);
                 try sema.inst_map.putNoClobber(gpa, inst, casted_arg);
+
+                if (is_comptime_call) {
+                    const arg_val = try sema.resolveConstMaybeUndefVal(&child_block, arg_src, casted_arg);
+                    memoized_call_key.args[arg_i] = .{
+                        .ty = param_ty,
+                        .val = arg_val,
+                    };
+                }
+
                 arg_i += 1;
                 continue;
             },
             .param_anytype, .param_anytype_comptime => {
                 // No coercion needed.
-                try sema.inst_map.putNoClobber(gpa, inst, uncasted_args[arg_i]);
+                const uncasted_arg = uncasted_args[arg_i];
+                try sema.inst_map.putNoClobber(gpa, inst, uncasted_arg);
+
+                if (is_comptime_call) {
+                    const arg_src = call_src; // TODO: better source location
+                    const arg_val = try sema.resolveConstMaybeUndefVal(&child_block, arg_src, uncasted_arg);
+                    memoized_call_key.args[arg_i] = .{
+                        .ty = sema.typeOf(uncasted_arg),
+                        .val = arg_val,
+                    };
+                }
+
                 arg_i += 1;
                 continue;
             },
@@ -2623,8 +2677,61 @@ fn analyzeCall(
         sema.fn_ret_ty = fn_ret_ty;
         defer sema.fn_ret_ty = parent_fn_ret_ty;
 
-        _ = try sema.analyzeBody(&child_block, fn_info.body);
-        break :res try sema.analyzeBlockBody(block, call_src, &child_block, merges);
+        // This `res2` is here instead of directly breaking from `res` due to a stage1
+        // bug generating invalid LLVM IR.
+        const res2: Air.Inst.Ref = res2: {
+            if (is_comptime_call) {
+                if (mod.memoized_calls.get(memoized_call_key)) |result| {
+                    const ty_inst = try sema.addType(fn_ret_ty);
+                    try sema.air_values.append(gpa, result.val);
+                    sema.air_instructions.set(block_inst, .{
+                        .tag = .constant,
+                        .data = .{ .ty_pl = .{
+                            .ty = ty_inst,
+                            .payload = @intCast(u32, sema.air_values.items.len - 1),
+                        } },
+                    });
+                    break :res2 Air.indexToRef(block_inst);
+                }
+            }
+
+            _ = try sema.analyzeBody(&child_block, fn_info.body);
+            const result = try sema.analyzeBlockBody(block, call_src, &child_block, merges);
+
+            if (is_comptime_call) {
+                const result_val = try sema.resolveConstMaybeUndefVal(block, call_src, result);
+
+                // TODO: check whether any external comptime memory was mutated by the
+                // comptime function call. If so, then do not memoize the call here.
+                {
+                    var arena_allocator = std.heap.ArenaAllocator.init(gpa);
+                    errdefer arena_allocator.deinit();
+                    const arena = &arena_allocator.allocator;
+
+                    for (memoized_call_key.args) |*arg| {
+                        arg.* = try arg.*.copy(arena);
+                    }
+
+                    try mod.memoized_calls.put(gpa, memoized_call_key, .{
+                        .val = result_val,
+                        .arena = arena_allocator.state,
+                    });
+                    delete_memoized_call_key = false;
+                }
+
+                // Much like in `Module.semaDecl`, if the result is a struct or union type,
+                // we need to resolve the field type expressions right here, right now, while
+                // the child `Sema` is still available, with the AIR instruction map intact,
+                // because the field type expressions may reference into it.
+                if (sema.typeOf(result).zigTypeTag() == .Type) {
+                    const ty = try sema.analyzeAsType(&child_block, call_src, result);
+                    try sema.resolveDeclFields(&child_block, call_src, ty);
+                }
+            }
+
+            break :res2 result;
+        };
+        break :res res2;
     } else if (func_ty_info.is_generic) res: {
         const func_val = try sema.resolveConstValue(block, func_src, func);
         const module_fn = func_val.castTag(.function).?.data;
@@ -3291,31 +3398,9 @@ fn zirEnumToInt(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileE
     }
 
     if (try sema.resolveMaybeUndefVal(block, operand_src, enum_tag)) |enum_tag_val| {
-        if (enum_tag_val.castTag(.enum_field_index)) |enum_field_payload| {
-            const field_index = enum_field_payload.data;
-            switch (enum_tag_ty.tag()) {
-                .enum_full => {
-                    const enum_full = enum_tag_ty.castTag(.enum_full).?.data;
-                    if (enum_full.values.count() != 0) {
-                        const val = enum_full.values.keys()[field_index];
-                        return sema.addConstant(int_tag_ty, val);
-                    } else {
-                        // Field index and integer values are the same.
-                        const val = try Value.Tag.int_u64.create(arena, field_index);
-                        return sema.addConstant(int_tag_ty, val);
-                    }
-                },
-                .enum_simple => {
-                    // Field index and integer values are the same.
-                    const val = try Value.Tag.int_u64.create(arena, field_index);
-                    return sema.addConstant(int_tag_ty, val);
-                },
-                else => unreachable,
-            }
-        } else {
-            // Assume it is already an integer and return it directly.
-            return sema.addConstant(int_tag_ty, enum_tag_val);
-        }
+        var buffer: Value.Payload.U64 = undefined;
+        const val = enum_tag_val.enumToInt(enum_tag_ty, &buffer);
+        return sema.addConstant(int_tag_ty, try val.copy(sema.arena));
     }
 
     try sema.requireRuntimeBlock(block, src);
@@ -3400,7 +3485,10 @@ fn zirOptionalPayloadPtr(
                 return sema.mod.fail(&block.base, src, "unable to unwrap null", .{});
             }
             // The same Value represents the pointer to the optional and the payload.
-            return sema.addConstant(child_pointer, pointer_val);
+            return sema.addConstant(
+                child_pointer,
+                try Value.Tag.opt_payload_ptr.create(sema.arena, pointer_val),
+            );
         }
     }
 
@@ -3437,7 +3525,8 @@ fn zirOptionalPayload(
         if (val.isNull()) {
             return sema.mod.fail(&block.base, src, "unable to unwrap null", .{});
         }
-        return sema.addConstant(child_type, val);
+        const sub_val = val.castTag(.opt_payload).?.data;
+        return sema.addConstant(child_type, sub_val);
     }
 
     try sema.requireRuntimeBlock(block, src);
@@ -5294,17 +5383,56 @@ fn zirShl(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileError!A
     const tracy = trace(@src());
     defer tracy.end();
 
-    _ = block;
-    _ = inst;
-    return sema.mod.fail(&block.base, sema.src, "TODO implement zirShl", .{});
+    const inst_data = sema.code.instructions.items(.data)[inst].pl_node;
+    const src: LazySrcLoc = .{ .node_offset_bin_op = inst_data.src_node };
+    const lhs_src: LazySrcLoc = .{ .node_offset_bin_lhs = inst_data.src_node };
+    const rhs_src: LazySrcLoc = .{ .node_offset_bin_rhs = inst_data.src_node };
+    const extra = sema.code.extraData(Zir.Inst.Bin, inst_data.payload_index).data;
+    const lhs = sema.resolveInst(extra.lhs);
+    const rhs = sema.resolveInst(extra.rhs);
+
+    if (try sema.resolveMaybeUndefVal(block, lhs_src, lhs)) |lhs_val| {
+        if (try sema.resolveMaybeUndefVal(block, rhs_src, rhs)) |rhs_val| {
+            if (lhs_val.isUndef() or rhs_val.isUndef()) {
+                return sema.addConstUndef(sema.typeOf(lhs));
+            }
+            return sema.mod.fail(&block.base, src, "TODO implement comptime shl", .{});
+        }
+    }
+
+    try sema.requireRuntimeBlock(block, src);
+    return block.addBinOp(.shl, lhs, rhs);
 }
 
 fn zirShr(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileError!Air.Inst.Ref {
     const tracy = trace(@src());
     defer tracy.end();
 
-    _ = inst;
-    return sema.mod.fail(&block.base, sema.src, "TODO implement zirShr", .{});
+    const inst_data = sema.code.instructions.items(.data)[inst].pl_node;
+    const src: LazySrcLoc = .{ .node_offset_bin_op = inst_data.src_node };
+    const lhs_src: LazySrcLoc = .{ .node_offset_bin_lhs = inst_data.src_node };
+    const rhs_src: LazySrcLoc = .{ .node_offset_bin_rhs = inst_data.src_node };
+    const extra = sema.code.extraData(Zir.Inst.Bin, inst_data.payload_index).data;
+    const lhs = sema.resolveInst(extra.lhs);
+    const rhs = sema.resolveInst(extra.rhs);
+
+    if (try sema.resolveMaybeUndefVal(block, lhs_src, lhs)) |lhs_val| {
+        if (try sema.resolveMaybeUndefVal(block, rhs_src, rhs)) |rhs_val| {
+            const lhs_ty = sema.typeOf(lhs);
+            if (lhs_val.isUndef() or rhs_val.isUndef()) {
+                return sema.addConstUndef(lhs_ty);
+            }
+            // If rhs is 0, return lhs without doing any calculations.
+            if (rhs_val.compareWithZero(.eq)) {
+                return sema.addConstant(lhs_ty, lhs_val);
+            }
+            const val = try lhs_val.shr(rhs_val, sema.arena);
+            return sema.addConstant(lhs_ty, val);
+        }
+    }
+
+    try sema.requireRuntimeBlock(block, src);
+    return block.addBinOp(.shr, lhs, rhs);
 }
 
 fn zirBitwise(
@@ -5975,6 +6103,28 @@ fn zirTypeInfo(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileEr
                 }),
             );
         },
+        .Int => {
+            const info = ty.intInfo(target);
+            const field_values = try sema.arena.alloc(Value, 2);
+            // signedness: Signedness,
+            field_values[0] = try Value.Tag.enum_field_index.create(
+                sema.arena,
+                @enumToInt(info.signedness),
+            );
+            // bits: comptime_int,
+            field_values[1] = try Value.Tag.int_u64.create(sema.arena, info.bits);
+
+            return sema.addConstant(
+                type_info_ty,
+                try Value.Tag.@"union".create(sema.arena, .{
+                    .tag = try Value.Tag.enum_field_index.create(
+                        sema.arena,
+                        @enumToInt(@typeInfo(std.builtin.TypeInfo).Union.tag_type.?.Int),
+                    ),
+                    .val = try Value.Tag.@"struct".create(sema.arena, field_values.ptr),
+                }),
+            );
+        },
         else => |t| return sema.mod.fail(&block.base, src, "TODO: implement zirTypeInfo for {s}", .{
             @tagName(t),
         }),
@@ -6001,13 +6151,37 @@ fn zirTypeofElem(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) Compile
 fn zirTypeofLog2IntType(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileError!Air.Inst.Ref {
     const inst_data = sema.code.instructions.items(.data)[inst].un_node;
     const src = inst_data.src();
-    return sema.mod.fail(&block.base, src, "TODO: implement Sema.zirTypeofLog2IntType", .{});
+    const operand = sema.resolveInst(inst_data.operand);
+    const operand_ty = sema.typeOf(operand);
+    return sema.log2IntType(block, operand_ty, src);
 }
 
 fn zirLog2IntType(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileError!Air.Inst.Ref {
     const inst_data = sema.code.instructions.items(.data)[inst].un_node;
     const src = inst_data.src();
-    return sema.mod.fail(&block.base, src, "TODO: implement Sema.zirLog2IntType", .{});
+    const operand = try sema.resolveType(block, src, inst_data.operand);
+    return sema.log2IntType(block, operand, src);
+}
+
+fn log2IntType(sema: *Sema, block: *Scope.Block, operand: Type, src: LazySrcLoc) CompileError!Air.Inst.Ref {
+    switch (operand.zigTypeTag()) {
+        .ComptimeInt => return Air.Inst.Ref.comptime_int_type,
+        .Int => {
+            var count: u16 = 0;
+            var s = operand.bitSize(sema.mod.getTarget()) - 1;
+            while (s != 0) : (s >>= 1) {
+                count += 1;
+            }
+            const res = try Module.makeIntType(sema.arena, .unsigned, count);
+            return sema.addType(res);
+        },
+        else => return sema.mod.fail(
+            &block.base,
+            src,
+            "bit shifting operation expected integer type, found '{}'",
+            .{operand},
+        ),
+    }
 }
 
 fn zirTypeofPeer(
@@ -6464,99 +6638,134 @@ fn zirStructInit(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index, is_ref:
     const first_field_type_data = zir_datas[first_item.field_type].pl_node;
     const first_field_type_extra = sema.code.extraData(Zir.Inst.FieldType, first_field_type_data.payload_index).data;
     const unresolved_struct_type = try sema.resolveType(block, src, first_field_type_extra.container_type);
-    const struct_ty = try sema.resolveTypeFields(block, src, unresolved_struct_type);
-    const struct_obj = struct_ty.castTag(.@"struct").?.data;
-
-    // Maps field index to field_type index of where it was already initialized.
-    // For making sure all fields are accounted for and no fields are duplicated.
-    const found_fields = try gpa.alloc(Zir.Inst.Index, struct_obj.fields.count());
-    defer gpa.free(found_fields);
-    mem.set(Zir.Inst.Index, found_fields, 0);
+    const resolved_ty = try sema.resolveTypeFields(block, src, unresolved_struct_type);
+
+    if (resolved_ty.castTag(.@"struct")) |struct_payload| {
+        const struct_obj = struct_payload.data;
+
+        // Maps field index to field_type index of where it was already initialized.
+        // For making sure all fields are accounted for and no fields are duplicated.
+        const found_fields = try gpa.alloc(Zir.Inst.Index, struct_obj.fields.count());
+        defer gpa.free(found_fields);
+        mem.set(Zir.Inst.Index, found_fields, 0);
+
+        // The init values to use for the struct instance.
+        const field_inits = try gpa.alloc(Air.Inst.Ref, struct_obj.fields.count());
+        defer gpa.free(field_inits);
+
+        var field_i: u32 = 0;
+        var extra_index = extra.end;
+
+        while (field_i < extra.data.fields_len) : (field_i += 1) {
+            const item = sema.code.extraData(Zir.Inst.StructInit.Item, extra_index);
+            extra_index = item.end;
+
+            const field_type_data = zir_datas[item.data.field_type].pl_node;
+            const field_src: LazySrcLoc = .{ .node_offset_back2tok = field_type_data.src_node };
+            const field_type_extra = sema.code.extraData(Zir.Inst.FieldType, field_type_data.payload_index).data;
+            const field_name = sema.code.nullTerminatedString(field_type_extra.name_start);
+            const field_index = struct_obj.fields.getIndex(field_name) orelse
+                return sema.failWithBadFieldAccess(block, struct_obj, field_src, field_name);
+            if (found_fields[field_index] != 0) {
+                const other_field_type = found_fields[field_index];
+                const other_field_type_data = zir_datas[other_field_type].pl_node;
+                const other_field_src: LazySrcLoc = .{ .node_offset_back2tok = other_field_type_data.src_node };
+                const msg = msg: {
+                    const msg = try mod.errMsg(&block.base, field_src, "duplicate field", .{});
+                    errdefer msg.destroy(gpa);
+                    try mod.errNote(&block.base, other_field_src, msg, "other field here", .{});
+                    break :msg msg;
+                };
+                return mod.failWithOwnedErrorMsg(&block.base, msg);
+            }
+            found_fields[field_index] = item.data.field_type;
+            field_inits[field_index] = sema.resolveInst(item.data.init);
+        }
 
-    // The init values to use for the struct instance.
-    const field_inits = try gpa.alloc(Air.Inst.Ref, struct_obj.fields.count());
-    defer gpa.free(field_inits);
+        var root_msg: ?*Module.ErrorMsg = null;
 
-    var field_i: u32 = 0;
-    var extra_index = extra.end;
-
-    while (field_i < extra.data.fields_len) : (field_i += 1) {
-        const item = sema.code.extraData(Zir.Inst.StructInit.Item, extra_index);
-        extra_index = item.end;
+        for (found_fields) |field_type_inst, i| {
+            if (field_type_inst != 0) continue;
 
-        const field_type_data = zir_datas[item.data.field_type].pl_node;
-        const field_src: LazySrcLoc = .{ .node_offset_back2tok = field_type_data.src_node };
-        const field_type_extra = sema.code.extraData(Zir.Inst.FieldType, field_type_data.payload_index).data;
-        const field_name = sema.code.nullTerminatedString(field_type_extra.name_start);
-        const field_index = struct_obj.fields.getIndex(field_name) orelse
-            return sema.failWithBadFieldAccess(block, struct_obj, field_src, field_name);
-        if (found_fields[field_index] != 0) {
-            const other_field_type = found_fields[field_index];
-            const other_field_type_data = zir_datas[other_field_type].pl_node;
-            const other_field_src: LazySrcLoc = .{ .node_offset_back2tok = other_field_type_data.src_node };
-            const msg = msg: {
-                const msg = try mod.errMsg(&block.base, field_src, "duplicate field", .{});
-                errdefer msg.destroy(gpa);
-                try mod.errNote(&block.base, other_field_src, msg, "other field here", .{});
-                break :msg msg;
-            };
+            // Check if the field has a default init.
+            const field = struct_obj.fields.values()[i];
+            if (field.default_val.tag() == .unreachable_value) {
+                const field_name = struct_obj.fields.keys()[i];
+                const template = "missing struct field: {s}";
+                const args = .{field_name};
+                if (root_msg) |msg| {
+                    try mod.errNote(&block.base, src, msg, template, args);
+                } else {
+                    root_msg = try mod.errMsg(&block.base, src, template, args);
+                }
+            } else {
+                field_inits[i] = try sema.addConstant(field.ty, field.default_val);
+            }
+        }
+        if (root_msg) |msg| {
+            const fqn = try struct_obj.getFullyQualifiedName(gpa);
+            defer gpa.free(fqn);
+            try mod.errNoteNonLazy(
+                struct_obj.srcLoc(),
+                msg,
+                "struct '{s}' declared here",
+                .{fqn},
+            );
             return mod.failWithOwnedErrorMsg(&block.base, msg);
         }
-        found_fields[field_index] = item.data.field_type;
-        field_inits[field_index] = sema.resolveInst(item.data.init);
-    }
 
-    var root_msg: ?*Module.ErrorMsg = null;
+        if (is_ref) {
+            return mod.fail(&block.base, src, "TODO: Sema.zirStructInit is_ref=true", .{});
+        }
 
-    for (found_fields) |field_type_inst, i| {
-        if (field_type_inst != 0) continue;
-
-        // Check if the field has a default init.
-        const field = struct_obj.fields.values()[i];
-        if (field.default_val.tag() == .unreachable_value) {
-            const field_name = struct_obj.fields.keys()[i];
-            const template = "missing struct field: {s}";
-            const args = .{field_name};
-            if (root_msg) |msg| {
-                try mod.errNote(&block.base, src, msg, template, args);
-            } else {
-                root_msg = try mod.errMsg(&block.base, src, template, args);
+        const is_comptime = for (field_inits) |field_init| {
+            if (!(try sema.isComptimeKnown(block, src, field_init))) {
+                break false;
             }
-        } else {
-            field_inits[i] = try sema.addConstant(field.ty, field.default_val);
+        } else true;
+
+        if (is_comptime) {
+            const values = try sema.arena.alloc(Value, field_inits.len);
+            for (field_inits) |field_init, i| {
+                values[i] = (sema.resolveMaybeUndefVal(block, src, field_init) catch unreachable).?;
+            }
+            return sema.addConstant(resolved_ty, try Value.Tag.@"struct".create(sema.arena, values.ptr));
         }
-    }
-    if (root_msg) |msg| {
-        const fqn = try struct_obj.getFullyQualifiedName(gpa);
-        defer gpa.free(fqn);
-        try mod.errNoteNonLazy(
-            struct_obj.srcLoc(),
-            msg,
-            "struct '{s}' declared here",
-            .{fqn},
-        );
-        return mod.failWithOwnedErrorMsg(&block.base, msg);
-    }
 
-    if (is_ref) {
-        return mod.fail(&block.base, src, "TODO: Sema.zirStructInit is_ref=true", .{});
-    }
+        return mod.fail(&block.base, src, "TODO: Sema.zirStructInit for runtime-known struct values", .{});
+    } else if (resolved_ty.cast(Type.Payload.Union)) |union_payload| {
+        const union_obj = union_payload.data;
+
+        if (extra.data.fields_len != 1) {
+            return sema.mod.fail(&block.base, src, "union initialization expects exactly one field", .{});
+        }
 
-    const is_comptime = for (field_inits) |field_init| {
-        if (!(try sema.isComptimeKnown(block, src, field_init))) {
-            break false;
+        const item = sema.code.extraData(Zir.Inst.StructInit.Item, extra.end);
+
+        const field_type_data = zir_datas[item.data.field_type].pl_node;
+        const field_src: LazySrcLoc = .{ .node_offset_back2tok = field_type_data.src_node };
+        const field_type_extra = sema.code.extraData(Zir.Inst.FieldType, field_type_data.payload_index).data;
+        const field_name = sema.code.nullTerminatedString(field_type_extra.name_start);
+        const field_index = union_obj.fields.getIndex(field_name) orelse
+            return sema.failWithBadUnionFieldAccess(block, union_obj, field_src, field_name);
+
+        if (is_ref) {
+            return mod.fail(&block.base, src, "TODO: Sema.zirStructInit is_ref=true union", .{});
         }
-    } else true;
 
-    if (is_comptime) {
-        const values = try sema.arena.alloc(Value, field_inits.len);
-        for (field_inits) |field_init, i| {
-            values[i] = (sema.resolveMaybeUndefVal(block, src, field_init) catch unreachable).?;
+        const init_inst = sema.resolveInst(item.data.init);
+        if (try sema.resolveMaybeUndefVal(block, field_src, init_inst)) |val| {
+            return sema.addConstant(
+                resolved_ty,
+                try Value.Tag.@"union".create(sema.arena, .{
+                    .tag = try Value.Tag.int_u64.create(sema.arena, field_index),
+                    .val = val,
+                }),
+            );
         }
-        return sema.addConstant(struct_ty, try Value.Tag.@"struct".create(sema.arena, values.ptr));
+        return mod.fail(&block.base, src, "TODO: Sema.zirStructInit for runtime-known union values", .{});
     }
-
-    return mod.fail(&block.base, src, "TODO: Sema.zirStructInit for runtime-known struct values", .{});
+    unreachable;
 }
 
 fn zirStructInitAnon(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index, is_ref: bool) CompileError!Air.Inst.Ref {
@@ -6594,17 +6803,25 @@ fn zirFieldType(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileE
     const extra = sema.code.extraData(Zir.Inst.FieldType, inst_data.payload_index).data;
     const src = inst_data.src();
     const field_name = sema.code.nullTerminatedString(extra.name_start);
-    const unresolved_struct_type = try sema.resolveType(block, src, extra.container_type);
-    if (unresolved_struct_type.zigTypeTag() != .Struct) {
-        return sema.mod.fail(&block.base, src, "expected struct; found '{}'", .{
-            unresolved_struct_type,
-        });
+    const unresolved_ty = try sema.resolveType(block, src, extra.container_type);
+    const resolved_ty = try sema.resolveTypeFields(block, src, unresolved_ty);
+    switch (resolved_ty.zigTypeTag()) {
+        .Struct => {
+            const struct_obj = resolved_ty.castTag(.@"struct").?.data;
+            const field = struct_obj.fields.get(field_name) orelse
+                return sema.failWithBadFieldAccess(block, struct_obj, src, field_name);
+            return sema.addType(field.ty);
+        },
+        .Union => {
+            const union_obj = resolved_ty.cast(Type.Payload.Union).?.data;
+            const field = union_obj.fields.get(field_name) orelse
+                return sema.failWithBadUnionFieldAccess(block, union_obj, src, field_name);
+            return sema.addType(field.ty);
+        },
+        else => return sema.mod.fail(&block.base, src, "expected struct or union; found '{}'", .{
+            resolved_ty,
+        }),
     }
-    const struct_ty = try sema.resolveTypeFields(block, src, unresolved_struct_type);
-    const struct_obj = struct_ty.castTag(.@"struct").?.data;
-    const field = struct_obj.fields.get(field_name) orelse
-        return sema.failWithBadFieldAccess(block, struct_obj, src, field_name);
-    return sema.addType(field.ty);
 }
 
 fn zirErrorReturnTrace(
@@ -6679,7 +6896,54 @@ fn zirTagName(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileErr
 fn zirReify(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileError!Air.Inst.Ref {
     const inst_data = sema.code.instructions.items(.data)[inst].un_node;
     const src = inst_data.src();
-    return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify", .{});
+    const type_info_ty = try sema.getBuiltinType(block, src, "TypeInfo");
+    const uncasted_operand = sema.resolveInst(inst_data.operand);
+    const operand_src: LazySrcLoc = .{ .node_offset_builtin_call_arg0 = inst_data.src_node };
+    const type_info = try sema.coerce(block, type_info_ty, uncasted_operand, operand_src);
+    const val = try sema.resolveConstValue(block, operand_src, type_info);
+    const union_val = val.cast(Value.Payload.Union).?.data;
+    const TypeInfoTag = std.meta.Tag(std.builtin.TypeInfo);
+    const tag_index = @intCast(std.meta.Tag(TypeInfoTag), union_val.tag.toUnsignedInt());
+    switch (@intToEnum(std.builtin.TypeId, tag_index)) {
+        .Type => return Air.Inst.Ref.type_type,
+        .Void => return Air.Inst.Ref.void_type,
+        .Bool => return Air.Inst.Ref.bool_type,
+        .NoReturn => return Air.Inst.Ref.noreturn_type,
+        .Int => {
+            const struct_val = union_val.val.castTag(.@"struct").?.data;
+            // TODO use reflection instead of magic numbers here
+            const signedness_val = struct_val[0];
+            const bits_val = struct_val[1];
+
+            const signedness = signedness_val.toEnum(std.builtin.Signedness);
+            const bits = @intCast(u16, bits_val.toUnsignedInt());
+            const ty = switch (signedness) {
+                .signed => try Type.Tag.int_signed.create(sema.arena, bits),
+                .unsigned => try Type.Tag.int_unsigned.create(sema.arena, bits),
+            };
+            return sema.addType(ty);
+        },
+        .Float => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Float", .{}),
+        .Pointer => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Pointer", .{}),
+        .Array => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Array", .{}),
+        .Struct => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Struct", .{}),
+        .ComptimeFloat => return Air.Inst.Ref.comptime_float_type,
+        .ComptimeInt => return Air.Inst.Ref.comptime_int_type,
+        .Undefined => return Air.Inst.Ref.undefined_type,
+        .Null => return Air.Inst.Ref.null_type,
+        .Optional => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Optional", .{}),
+        .ErrorUnion => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for ErrorUnion", .{}),
+        .ErrorSet => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for ErrorSet", .{}),
+        .Enum => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Enum", .{}),
+        .Union => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Union", .{}),
+        .Fn => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Fn", .{}),
+        .BoundFn => @panic("TODO delete BoundFn from the language"),
+        .Opaque => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Opaque", .{}),
+        .Frame => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Frame", .{}),
+        .AnyFrame => return Air.Inst.Ref.anyframe_type,
+        .Vector => return sema.mod.fail(&block.base, src, "TODO: Sema.zirReify for Vector", .{}),
+        .EnumLiteral => return Air.Inst.Ref.enum_literal_type,
+    }
 }
 
 fn zirTypeName(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileError!Air.Inst.Ref {
@@ -7855,14 +8119,29 @@ fn structFieldPtr(
     }
 
     try sema.requireRuntimeBlock(block, src);
+    const tag: Air.Inst.Tag = switch (field_index) {
+        0 => .struct_field_ptr_index_0,
+        1 => .struct_field_ptr_index_1,
+        2 => .struct_field_ptr_index_2,
+        3 => .struct_field_ptr_index_3,
+        else => {
+            return block.addInst(.{
+                .tag = .struct_field_ptr,
+                .data = .{ .ty_pl = .{
+                    .ty = try sema.addType(ptr_field_ty),
+                    .payload = try sema.addExtra(Air.StructField{
+                        .struct_operand = struct_ptr,
+                        .field_index = @intCast(u32, field_index),
+                    }),
+                } },
+            });
+        },
+    };
     return block.addInst(.{
-        .tag = .struct_field_ptr,
-        .data = .{ .ty_pl = .{
+        .tag = tag,
+        .data = .{ .ty_op = .{
             .ty = try sema.addType(ptr_field_ty),
-            .payload = try sema.addExtra(Air.StructField{
-                .struct_operand = struct_ptr,
-                .field_index = @intCast(u32, field_index),
-            }),
+            .operand = struct_ptr,
         } },
     });
 }
@@ -8099,24 +8378,35 @@ fn elemPtrArray(
     elem_index: Air.Inst.Ref,
     elem_index_src: LazySrcLoc,
 ) CompileError!Air.Inst.Ref {
+    const array_ptr_ty = sema.typeOf(array_ptr);
+    const pointee_type = array_ptr_ty.elemType().elemType();
+    const result_ty = if (array_ptr_ty.ptrIsMutable())
+        try Type.Tag.single_mut_pointer.create(sema.arena, pointee_type)
+    else
+        try Type.Tag.single_const_pointer.create(sema.arena, pointee_type);
+
     if (try sema.resolveDefinedValue(block, src, array_ptr)) |array_ptr_val| {
-        if (try sema.resolveDefinedValue(block, src, elem_index)) |index_val| {
+        if (try sema.resolveDefinedValue(block, elem_index_src, elem_index)) |index_val| {
             // Both array pointer and index are compile-time known.
             const index_u64 = index_val.toUnsignedInt();
             // @intCast here because it would have been impossible to construct a value that
             // required a larger index.
             const elem_ptr = try array_ptr_val.elemPtr(sema.arena, @intCast(usize, index_u64));
-            const pointee_type = sema.typeOf(array_ptr).elemType().elemType();
-
-            return sema.addConstant(
-                try Type.Tag.single_const_pointer.create(sema.arena, pointee_type),
-                elem_ptr,
-            );
+            return sema.addConstant(result_ty, elem_ptr);
         }
     }
-    _ = elem_index;
-    _ = elem_index_src;
-    return sema.mod.fail(&block.base, src, "TODO implement more analyze elemptr for arrays", .{});
+    // TODO safety check for array bounds
+    try sema.requireRuntimeBlock(block, src);
+    return block.addInst(.{
+        .tag = .ptr_elem_ptr,
+        .data = .{ .ty_pl = .{
+            .ty = try sema.addType(result_ty),
+            .payload = try sema.addExtra(Air.Bin{
+                .lhs = array_ptr,
+                .rhs = elem_index,
+            }),
+        } },
+    });
 }
 
 fn coerce(
@@ -8528,9 +8818,12 @@ fn analyzeRef(
 
     try sema.requireRuntimeBlock(block, src);
     const ptr_type = try Module.simplePtrType(sema.arena, operand_ty, false, .One);
-    const alloc = try block.addTy(.alloc, ptr_type);
+    const mut_ptr_type = try Module.simplePtrType(sema.arena, operand_ty, true, .One);
+    const alloc = try block.addTy(.alloc, mut_ptr_type);
     try sema.storePtr(block, src, alloc, operand);
-    return alloc;
+
+    // TODO: Replace with sema.coerce when that supports adding pointer constness.
+    return sema.bitcast(block, ptr_type, alloc, src);
 }
 
 fn analyzeLoad(
@@ -8895,7 +9188,7 @@ fn wrapOptional(
     inst_src: LazySrcLoc,
 ) !Air.Inst.Ref {
     if (try sema.resolveMaybeUndefVal(block, inst_src, inst)) |val| {
-        return sema.addConstant(dest_type, val);
+        return sema.addConstant(dest_type, try Value.Tag.opt_payload.create(sema.arena, val));
     }
 
     try sema.requireRuntimeBlock(block, inst_src);
@@ -9124,22 +9417,62 @@ pub fn resolveTypeLayout(
     }
 }
 
-fn resolveTypeFields(sema: *Sema, block: *Scope.Block, src: LazySrcLoc, ty: Type) CompileError!Type {
+/// `sema` and `block` are expected to be the same ones used for the `Decl`.
+pub fn resolveDeclFields(sema: *Sema, block: *Scope.Block, src: LazySrcLoc, ty: Type) !void {
     switch (ty.tag()) {
         .@"struct" => {
             const struct_obj = ty.castTag(.@"struct").?.data;
+            if (struct_obj.owner_decl.namespace != sema.owner_decl.namespace) return;
             switch (struct_obj.status) {
                 .none => {},
                 .field_types_wip => {
                     return sema.mod.fail(&block.base, src, "struct {} depends on itself", .{ty});
                 },
-                .have_field_types, .have_layout, .layout_wip => return ty,
+                .have_field_types, .have_layout, .layout_wip => return,
             }
+            const prev_namespace = sema.namespace;
+            sema.namespace = &struct_obj.namespace;
+            defer sema.namespace = prev_namespace;
+
             struct_obj.status = .field_types_wip;
-            try sema.mod.analyzeStructFields(struct_obj);
+            try sema.analyzeStructFields(block, struct_obj);
             struct_obj.status = .have_field_types;
-            return ty;
         },
+        .@"union", .union_tagged => {
+            const union_obj = ty.cast(Type.Payload.Union).?.data;
+            if (union_obj.owner_decl.namespace != sema.owner_decl.namespace) return;
+            switch (union_obj.status) {
+                .none => {},
+                .field_types_wip => {
+                    return sema.mod.fail(&block.base, src, "union {} depends on itself", .{ty});
+                },
+                .have_field_types, .have_layout, .layout_wip => return,
+            }
+            const prev_namespace = sema.namespace;
+            sema.namespace = &union_obj.namespace;
+            defer sema.namespace = prev_namespace;
+
+            union_obj.status = .field_types_wip;
+            try sema.analyzeUnionFields(block, union_obj);
+            union_obj.status = .have_field_types;
+        },
+        else => return,
+    }
+}
+
+fn resolveTypeFields(sema: *Sema, block: *Scope.Block, src: LazySrcLoc, ty: Type) CompileError!Type {
+    switch (ty.tag()) {
+        .@"struct" => {
+            const struct_obj = ty.castTag(.@"struct").?.data;
+            switch (struct_obj.status) {
+                .none => unreachable,
+                .field_types_wip => {
+                    return sema.mod.fail(&block.base, src, "struct {} depends on itself", .{ty});
+                },
+                .have_field_types, .have_layout, .layout_wip => return ty,
+            }
+        },
+        .type_info => return sema.resolveBuiltinTypeFields(block, src, "TypeInfo"),
         .extern_options => return sema.resolveBuiltinTypeFields(block, src, "ExternOptions"),
         .export_options => return sema.resolveBuiltinTypeFields(block, src, "ExportOptions"),
         .atomic_ordering => return sema.resolveBuiltinTypeFields(block, src, "AtomicOrdering"),
@@ -9152,18 +9485,12 @@ fn resolveTypeFields(sema: *Sema, block: *Scope.Block, src: LazySrcLoc, ty: Type
         .@"union", .union_tagged => {
             const union_obj = ty.cast(Type.Payload.Union).?.data;
             switch (union_obj.status) {
-                .none => {},
+                .none => unreachable,
                 .field_types_wip => {
-                    return sema.mod.fail(&block.base, src, "union {} depends on itself", .{
-                        ty,
-                    });
+                    return sema.mod.fail(&block.base, src, "union {} depends on itself", .{ty});
                 },
                 .have_field_types, .have_layout, .layout_wip => return ty,
             }
-            union_obj.status = .field_types_wip;
-            try sema.mod.analyzeUnionFields(union_obj);
-            union_obj.status = .have_field_types;
-            return ty;
         },
         else => return ty,
     }
@@ -9179,6 +9506,265 @@ fn resolveBuiltinTypeFields(
     return sema.resolveTypeFields(block, src, resolved_ty);
 }
 
+fn analyzeStructFields(
+    sema: *Sema,
+    block: *Scope.Block,
+    struct_obj: *Module.Struct,
+) CompileError!void {
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    const gpa = sema.gpa;
+    const zir = sema.code;
+    const extended = zir.instructions.items(.data)[struct_obj.zir_index].extended;
+    assert(extended.opcode == .struct_decl);
+    const small = @bitCast(Zir.Inst.StructDecl.Small, extended.small);
+    var extra_index: usize = extended.operand;
+
+    const src: LazySrcLoc = .{ .node_offset = struct_obj.node_offset };
+    extra_index += @boolToInt(small.has_src_node);
+
+    const body_len = if (small.has_body_len) blk: {
+        const body_len = zir.extra[extra_index];
+        extra_index += 1;
+        break :blk body_len;
+    } else 0;
+
+    const fields_len = if (small.has_fields_len) blk: {
+        const fields_len = zir.extra[extra_index];
+        extra_index += 1;
+        break :blk fields_len;
+    } else 0;
+
+    const decls_len = if (small.has_decls_len) decls_len: {
+        const decls_len = zir.extra[extra_index];
+        extra_index += 1;
+        break :decls_len decls_len;
+    } else 0;
+
+    // Skip over decls.
+    var decls_it = zir.declIteratorInner(extra_index, decls_len);
+    while (decls_it.next()) |_| {}
+    extra_index = decls_it.extra_index;
+
+    const body = zir.extra[extra_index..][0..body_len];
+    if (fields_len == 0) {
+        assert(body.len == 0);
+        return;
+    }
+    extra_index += body.len;
+
+    var decl_arena = struct_obj.owner_decl.value_arena.?.promote(gpa);
+    defer struct_obj.owner_decl.value_arena.?.* = decl_arena.state;
+
+    try struct_obj.fields.ensureTotalCapacity(&decl_arena.allocator, fields_len);
+
+    if (body.len != 0) {
+        _ = try sema.analyzeBody(block, body);
+    }
+
+    const bits_per_field = 4;
+    const fields_per_u32 = 32 / bits_per_field;
+    const bit_bags_count = std.math.divCeil(usize, fields_len, fields_per_u32) catch unreachable;
+    var bit_bag_index: usize = extra_index;
+    extra_index += bit_bags_count;
+    var cur_bit_bag: u32 = undefined;
+    var field_i: u32 = 0;
+    while (field_i < fields_len) : (field_i += 1) {
+        if (field_i % fields_per_u32 == 0) {
+            cur_bit_bag = zir.extra[bit_bag_index];
+            bit_bag_index += 1;
+        }
+        const has_align = @truncate(u1, cur_bit_bag) != 0;
+        cur_bit_bag >>= 1;
+        const has_default = @truncate(u1, cur_bit_bag) != 0;
+        cur_bit_bag >>= 1;
+        const is_comptime = @truncate(u1, cur_bit_bag) != 0;
+        cur_bit_bag >>= 1;
+        const unused = @truncate(u1, cur_bit_bag) != 0;
+        cur_bit_bag >>= 1;
+
+        _ = unused;
+
+        const field_name_zir = zir.nullTerminatedString(zir.extra[extra_index]);
+        extra_index += 1;
+        const field_type_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
+        extra_index += 1;
+
+        // This string needs to outlive the ZIR code.
+        const field_name = try decl_arena.allocator.dupe(u8, field_name_zir);
+        const field_ty: Type = if (field_type_ref == .none)
+            Type.initTag(.noreturn)
+        else
+            // TODO: if we need to report an error here, use a source location
+            // that points to this type expression rather than the struct.
+            // But only resolve the source location if we need to emit a compile error.
+            try sema.resolveType(block, src, field_type_ref);
+
+        const gop = struct_obj.fields.getOrPutAssumeCapacity(field_name);
+        assert(!gop.found_existing);
+        gop.value_ptr.* = .{
+            .ty = try field_ty.copy(&decl_arena.allocator),
+            .abi_align = Value.initTag(.abi_align_default),
+            .default_val = Value.initTag(.unreachable_value),
+            .is_comptime = is_comptime,
+            .offset = undefined,
+        };
+
+        if (has_align) {
+            const align_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
+            extra_index += 1;
+            // TODO: if we need to report an error here, use a source location
+            // that points to this alignment expression rather than the struct.
+            // But only resolve the source location if we need to emit a compile error.
+            const abi_align_val = (try sema.resolveInstConst(block, src, align_ref)).val;
+            gop.value_ptr.abi_align = try abi_align_val.copy(&decl_arena.allocator);
+        }
+        if (has_default) {
+            const default_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
+            extra_index += 1;
+            const default_inst = sema.resolveInst(default_ref);
+            // TODO: if we need to report an error here, use a source location
+            // that points to this default value expression rather than the struct.
+            // But only resolve the source location if we need to emit a compile error.
+            const default_val = (try sema.resolveMaybeUndefVal(block, src, default_inst)) orelse
+                return sema.failWithNeededComptime(block, src);
+            gop.value_ptr.default_val = try default_val.copy(&decl_arena.allocator);
+        }
+    }
+}
+
+fn analyzeUnionFields(
+    sema: *Sema,
+    block: *Scope.Block,
+    union_obj: *Module.Union,
+) CompileError!void {
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    const gpa = sema.gpa;
+    const zir = sema.code;
+    const extended = zir.instructions.items(.data)[union_obj.zir_index].extended;
+    assert(extended.opcode == .union_decl);
+    const small = @bitCast(Zir.Inst.UnionDecl.Small, extended.small);
+    var extra_index: usize = extended.operand;
+
+    const src: LazySrcLoc = .{ .node_offset = union_obj.node_offset };
+    extra_index += @boolToInt(small.has_src_node);
+
+    if (small.has_tag_type) {
+        extra_index += 1;
+    }
+
+    const body_len = if (small.has_body_len) blk: {
+        const body_len = zir.extra[extra_index];
+        extra_index += 1;
+        break :blk body_len;
+    } else 0;
+
+    const fields_len = if (small.has_fields_len) blk: {
+        const fields_len = zir.extra[extra_index];
+        extra_index += 1;
+        break :blk fields_len;
+    } else 0;
+
+    const decls_len = if (small.has_decls_len) decls_len: {
+        const decls_len = zir.extra[extra_index];
+        extra_index += 1;
+        break :decls_len decls_len;
+    } else 0;
+
+    // Skip over decls.
+    var decls_it = zir.declIteratorInner(extra_index, decls_len);
+    while (decls_it.next()) |_| {}
+    extra_index = decls_it.extra_index;
+
+    const body = zir.extra[extra_index..][0..body_len];
+    if (fields_len == 0) {
+        assert(body.len == 0);
+        return;
+    }
+    extra_index += body.len;
+
+    var decl_arena = union_obj.owner_decl.value_arena.?.promote(gpa);
+    defer union_obj.owner_decl.value_arena.?.* = decl_arena.state;
+
+    try union_obj.fields.ensureCapacity(&decl_arena.allocator, fields_len);
+
+    if (body.len != 0) {
+        _ = try sema.analyzeBody(block, body);
+    }
+
+    const bits_per_field = 4;
+    const fields_per_u32 = 32 / bits_per_field;
+    const bit_bags_count = std.math.divCeil(usize, fields_len, fields_per_u32) catch unreachable;
+    var bit_bag_index: usize = extra_index;
+    extra_index += bit_bags_count;
+    var cur_bit_bag: u32 = undefined;
+    var field_i: u32 = 0;
+    while (field_i < fields_len) : (field_i += 1) {
+        if (field_i % fields_per_u32 == 0) {
+            cur_bit_bag = zir.extra[bit_bag_index];
+            bit_bag_index += 1;
+        }
+        const has_type = @truncate(u1, cur_bit_bag) != 0;
+        cur_bit_bag >>= 1;
+        const has_align = @truncate(u1, cur_bit_bag) != 0;
+        cur_bit_bag >>= 1;
+        const has_tag = @truncate(u1, cur_bit_bag) != 0;
+        cur_bit_bag >>= 1;
+        const unused = @truncate(u1, cur_bit_bag) != 0;
+        cur_bit_bag >>= 1;
+        _ = unused;
+
+        const field_name_zir = zir.nullTerminatedString(zir.extra[extra_index]);
+        extra_index += 1;
+
+        const field_type_ref: Zir.Inst.Ref = if (has_type) blk: {
+            const field_type_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
+            extra_index += 1;
+            break :blk field_type_ref;
+        } else .none;
+
+        const align_ref: Zir.Inst.Ref = if (has_align) blk: {
+            const align_ref = @intToEnum(Zir.Inst.Ref, zir.extra[extra_index]);
+            extra_index += 1;
+            break :blk align_ref;
+        } else .none;
+
+        if (has_tag) {
+            extra_index += 1;
+        }
+
+        // This string needs to outlive the ZIR code.
+        const field_name = try decl_arena.allocator.dupe(u8, field_name_zir);
+        const field_ty: Type = if (field_type_ref == .none)
+            Type.initTag(.void)
+        else
+            // TODO: if we need to report an error here, use a source location
+            // that points to this type expression rather than the union.
+            // But only resolve the source location if we need to emit a compile error.
+            try sema.resolveType(block, src, field_type_ref);
+
+        const gop = union_obj.fields.getOrPutAssumeCapacity(field_name);
+        assert(!gop.found_existing);
+        gop.value_ptr.* = .{
+            .ty = try field_ty.copy(&decl_arena.allocator),
+            .abi_align = Value.initTag(.abi_align_default),
+        };
+
+        if (align_ref != .none) {
+            // TODO: if we need to report an error here, use a source location
+            // that points to this alignment expression rather than the struct.
+            // But only resolve the source location if we need to emit a compile error.
+            const abi_align_val = (try sema.resolveInstConst(block, src, align_ref)).val;
+            gop.value_ptr.abi_align = try abi_align_val.copy(&decl_arena.allocator);
+        }
+    }
+
+    // TODO resolve the union tag_type_ref
+}
+
 fn getBuiltin(
     sema: *Sema,
     block: *Scope.Block,
@@ -9291,6 +9877,7 @@ fn typeHasOnePossibleValue(
         .call_options,
         .export_options,
         .extern_options,
+        .type_info,
         .@"anyframe",
         .anyframe_T,
         .many_const_pointer,
@@ -9475,6 +10062,7 @@ pub fn addType(sema: *Sema, ty: Type) !Air.Inst.Ref {
         .call_options => return .call_options_type,
         .export_options => return .export_options_type,
         .extern_options => return .extern_options_type,
+        .type_info => return .type_info_type,
         .manyptr_u8 => return .manyptr_u8_type,
         .manyptr_const_u8 => return .manyptr_const_u8_type,
         .fn_noreturn_no_args => return .fn_noreturn_no_args_type,
diff --git a/src/TypedValue.zig b/src/TypedValue.zig
index 48b2c04970..83242b5329 100644
--- a/src/TypedValue.zig
+++ b/src/TypedValue.zig
@@ -23,9 +23,18 @@ pub const Managed = struct {
 };
 
 /// Assumes arena allocation. Does a recursive copy.
-pub fn copy(self: TypedValue, allocator: *Allocator) error{OutOfMemory}!TypedValue {
+pub fn copy(self: TypedValue, arena: *Allocator) error{OutOfMemory}!TypedValue {
     return TypedValue{
-        .ty = try self.ty.copy(allocator),
-        .val = try self.val.copy(allocator),
+        .ty = try self.ty.copy(arena),
+        .val = try self.val.copy(arena),
     };
 }
+
+pub fn eql(a: TypedValue, b: TypedValue) bool {
+    if (!a.ty.eql(b.ty)) return false;
+    return a.val.eql(b.val, a.ty);
+}
+
+pub fn hash(tv: TypedValue, hasher: *std.hash.Wyhash) void {
+    return tv.val.hash(tv.ty, hasher);
+}
diff --git a/src/Zir.zig b/src/Zir.zig
index 1aed609de9..2092a7b5e4 100644
--- a/src/Zir.zig
+++ b/src/Zir.zig
@@ -495,12 +495,15 @@ pub const Inst = struct {
         /// Uses the `ptr_type` union field.
         ptr_type,
         /// Slice operation `lhs[rhs..]`. No sentinel and no end offset.
+        /// Returns a pointer to the subslice.
         /// Uses the `pl_node` field. AST node is the slice syntax. Payload is `SliceStart`.
         slice_start,
         /// Slice operation `array_ptr[start..end]`. No sentinel.
+        /// Returns a pointer to the subslice.
         /// Uses the `pl_node` field. AST node is the slice syntax. Payload is `SliceEnd`.
         slice_end,
         /// Slice operation `array_ptr[start..end:sentinel]`.
+        /// Returns a pointer to the subslice.
         /// Uses the `pl_node` field. AST node is the slice syntax. Payload is `SliceSentinel`.
         slice_sentinel,
         /// Write a value to a pointer. For loading, see `load`.
@@ -687,14 +690,14 @@ pub const Inst = struct {
         /// A struct literal with a specified type, with no fields.
         /// Uses the `un_node` field.
         struct_init_empty,
-        /// Given a struct, union, or enum, and a field name as a string index,
+        /// Given a struct or union, and a field name as a string index,
         /// returns the field type. Uses the `pl_node` field. Payload is `FieldType`.
         field_type,
-        /// Given a struct, union, or enum, and a field name as a Ref,
+        /// Given a struct or union, and a field name as a Ref,
         /// returns the field type. Uses the `pl_node` field. Payload is `FieldTypeRef`.
         field_type_ref,
-        /// Finalizes a typed struct initialization, performs validation, and returns the
-        /// struct value.
+        /// Finalizes a typed struct or union initialization, performs validation, and returns the
+        /// struct or union value.
         /// Uses the `pl_node` field. Payload is `StructInit`.
         struct_init,
         /// Struct initialization syntax, make the result a pointer.
@@ -1703,6 +1706,7 @@ pub const Inst = struct {
         call_options_type,
         export_options_type,
         extern_options_type,
+        type_info_type,
         manyptr_u8_type,
         manyptr_const_u8_type,
         fn_noreturn_no_args_type,
@@ -1973,6 +1977,10 @@ pub const Inst = struct {
                 .ty = Type.initTag(.type),
                 .val = Value.initTag(.extern_options_type),
             },
+            .type_info_type = .{
+                .ty = Type.initTag(.type),
+                .val = Value.initTag(.type_info_type),
+            },
 
             .undef = .{
                 .ty = Type.initTag(.@"undefined"),
diff --git a/src/codegen.zig b/src/codegen.zig
index 11c007dbed..9103c7ad17 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -822,6 +822,8 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                     .bit_and  => try self.airBitAnd(inst),
                     .bit_or   => try self.airBitOr(inst),
                     .xor      => try self.airXor(inst),
+                    .shr      => try self.airShr(inst),
+                    .shl      => try self.airShl(inst),
 
                     .alloc           => try self.airAlloc(inst),
                     .arg             => try self.airArg(inst),
@@ -853,6 +855,12 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                     .store           => try self.airStore(inst),
                     .struct_field_ptr=> try self.airStructFieldPtr(inst),
                     .struct_field_val=> try self.airStructFieldVal(inst),
+
+                    .struct_field_ptr_index_0 => try self.airStructFieldPtrIndex(inst, 0),
+                    .struct_field_ptr_index_1 => try self.airStructFieldPtrIndex(inst, 1),
+                    .struct_field_ptr_index_2 => try self.airStructFieldPtrIndex(inst, 2),
+                    .struct_field_ptr_index_3 => try self.airStructFieldPtrIndex(inst, 3),
+
                     .switch_br       => try self.airSwitch(inst),
                     .slice_ptr       => try self.airSlicePtr(inst),
                     .slice_len       => try self.airSliceLen(inst),
@@ -860,6 +868,7 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                     .slice_elem_val      => try self.airSliceElemVal(inst),
                     .ptr_slice_elem_val  => try self.airPtrSliceElemVal(inst),
                     .ptr_elem_val        => try self.airPtrElemVal(inst),
+                    .ptr_elem_ptr        => try self.airPtrElemPtr(inst),
                     .ptr_ptr_elem_val    => try self.airPtrPtrElemVal(inst),
 
                     .constant => unreachable, // excluded from function bodies
@@ -970,6 +979,20 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                 log.debug("%{d} => {}", .{ inst, result });
                 const branch = &self.branch_stack.items[self.branch_stack.items.len - 1];
                 branch.inst_table.putAssumeCapacityNoClobber(inst, result);
+
+                switch (result) {
+                    .register => |reg| {
+                        // In some cases (such as bitcast), an operand
+                        // may be the same MCValue as the result. If
+                        // that operand died and was a register, it
+                        // was freed by processDeath. We have to
+                        // "re-allocate" the register.
+                        if (self.register_manager.isRegFree(reg)) {
+                            self.register_manager.getRegAssumeFree(reg, inst);
+                        }
+                    },
+                    else => {},
+                }
             }
             self.finishAirBookkeeping();
         }
@@ -1272,6 +1295,24 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
             return self.finishAir(inst, result, .{ bin_op.lhs, bin_op.rhs, .none });
         }
 
+        fn airShl(self: *Self, inst: Air.Inst.Index) !void {
+            const bin_op = self.air.instructions.items(.data)[inst].bin_op;
+            const result: MCValue = if (self.liveness.isUnused(inst)) .dead else switch (arch) {
+                .arm, .armeb => try self.genArmBinOp(inst, bin_op.lhs, bin_op.rhs, .shl),
+                else => return self.fail("TODO implement shl for {}", .{self.target.cpu.arch}),
+            };
+            return self.finishAir(inst, result, .{ bin_op.lhs, bin_op.rhs, .none });
+        }
+
+        fn airShr(self: *Self, inst: Air.Inst.Index) !void {
+            const bin_op = self.air.instructions.items(.data)[inst].bin_op;
+            const result: MCValue = if (self.liveness.isUnused(inst)) .dead else switch (arch) {
+                .arm, .armeb => try self.genArmBinOp(inst, bin_op.lhs, bin_op.rhs, .shr),
+                else => return self.fail("TODO implement shr for {}", .{self.target.cpu.arch}),
+            };
+            return self.finishAir(inst, result, .{ bin_op.lhs, bin_op.rhs, .none });
+        }
+
         fn airOptionalPayload(self: *Self, inst: Air.Inst.Index) !void {
             const ty_op = self.air.instructions.items(.data)[inst].ty_op;
             const result: MCValue = if (self.liveness.isUnused(inst)) .dead else switch (arch) {
@@ -1399,6 +1440,15 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
             return self.finishAir(inst, result, .{ bin_op.lhs, bin_op.rhs, .none });
         }
 
+        fn airPtrElemPtr(self: *Self, inst: Air.Inst.Index) !void {
+            const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
+            const extra = self.air.extraData(Air.Bin, ty_pl.payload).data;
+            const result: MCValue = if (self.liveness.isUnused(inst)) .dead else switch (arch) {
+                else => return self.fail("TODO implement ptr_elem_ptr for {}", .{self.target.cpu.arch}),
+            };
+            return self.finishAir(inst, result, .{ extra.lhs, extra.rhs, .none });
+        }
+
         fn airPtrPtrElemVal(self: *Self, inst: Air.Inst.Index) !void {
             const is_volatile = false; // TODO
             const bin_op = self.air.instructions.items(.data)[inst].bin_op;
@@ -1439,7 +1489,7 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
             return true;
         }
 
-        fn load(self: *Self, dst_mcv: MCValue, ptr: MCValue, ptr_ty: Type) !void {
+        fn load(self: *Self, dst_mcv: MCValue, ptr: MCValue, ptr_ty: Type) InnerError!void {
             const elem_ty = ptr_ty.elemType();
             switch (ptr) {
                 .none => unreachable,
@@ -1456,11 +1506,25 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                 .embedded_in_code => {
                     return self.fail("TODO implement loading from MCValue.embedded_in_code", .{});
                 },
-                .register => {
-                    return self.fail("TODO implement loading from MCValue.register", .{});
+                .register => |reg| {
+                    switch (arch) {
+                        .arm, .armeb => switch (dst_mcv) {
+                            .dead => unreachable,
+                            .undef => unreachable,
+                            .compare_flags_signed, .compare_flags_unsigned => unreachable,
+                            .embedded_in_code => unreachable,
+                            .register => |dst_reg| {
+                                writeInt(u32, try self.code.addManyAsArray(4), Instruction.ldr(.al, dst_reg, reg, .{ .offset = Instruction.Offset.none }).toU32());
+                            },
+                            else => return self.fail("TODO load from register into {}", .{dst_mcv}),
+                        },
+                        else => return self.fail("TODO implement loading from MCValue.register for {}", .{arch}),
+                    }
                 },
-                .memory => {
-                    return self.fail("TODO implement loading from MCValue.memory", .{});
+                .memory => |addr| {
+                    const reg = try self.register_manager.allocReg(null, &.{});
+                    try self.genSetReg(ptr_ty, reg, .{ .memory = addr });
+                    try self.load(dst_mcv, .{ .register = reg }, ptr_ty);
                 },
                 .stack_offset => {
                     return self.fail("TODO implement loading from MCValue.stack_offset", .{});
@@ -1534,7 +1598,18 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
         fn airStructFieldPtr(self: *Self, inst: Air.Inst.Index) !void {
             const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
             const extra = self.air.extraData(Air.StructField, ty_pl.payload).data;
-            _ = extra;
+            return self.structFieldPtr(extra.struct_operand, ty_pl.ty, extra.field_index);
+        }
+
+        fn airStructFieldPtrIndex(self: *Self, inst: Air.Inst.Index, index: u8) !void {
+            const ty_op = self.air.instructions.items(.data)[inst].ty_op;
+            return self.structFieldPtr(ty_op.operand, ty_op.ty, index);
+        }
+        fn structFieldPtr(self: *Self, operand: Air.Inst.Ref, ty: Air.Inst.Ref, index: u32) !void {
+            _ = self;
+            _ = operand;
+            _ = ty;
+            _ = index;
             return self.fail("TODO implement codegen struct_field_ptr", .{});
             //return self.finishAir(inst, result, .{ extra.struct_ptr, .none, .none });
         }
@@ -1572,15 +1647,53 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
         }
 
         fn genArmBinOp(self: *Self, inst: Air.Inst.Index, op_lhs: Air.Inst.Ref, op_rhs: Air.Inst.Ref, op: Air.Inst.Tag) !MCValue {
+            // In the case of bitshifts, the type of rhs is different
+            // from the resulting type
+            const ty = self.air.typeOf(op_lhs);
+
+            switch (ty.zigTypeTag()) {
+                .Float => return self.fail("TODO ARM binary operations on floats", .{}),
+                .Vector => return self.fail("TODO ARM binary operations on vectors", .{}),
+                .Bool => {
+                    return self.genArmBinIntOp(inst, op_lhs, op_rhs, op, 1, .unsigned);
+                },
+                .Int => {
+                    const int_info = ty.intInfo(self.target.*);
+                    return self.genArmBinIntOp(inst, op_lhs, op_rhs, op, int_info.bits, int_info.signedness);
+                },
+                else => unreachable,
+            }
+        }
+
+        fn genArmBinIntOp(
+            self: *Self,
+            inst: Air.Inst.Index,
+            op_lhs: Air.Inst.Ref,
+            op_rhs: Air.Inst.Ref,
+            op: Air.Inst.Tag,
+            bits: u16,
+            signedness: std.builtin.Signedness,
+        ) !MCValue {
+            if (bits > 32) {
+                return self.fail("TODO ARM binary operations on integers > u32/i32", .{});
+            }
+
             const lhs = try self.resolveInst(op_lhs);
             const rhs = try self.resolveInst(op_rhs);
 
             const lhs_is_register = lhs == .register;
             const rhs_is_register = rhs == .register;
-            const lhs_should_be_register = try self.armOperandShouldBeRegister(lhs);
+            const lhs_should_be_register = switch (op) {
+                .shr, .shl => true,
+                else => try self.armOperandShouldBeRegister(lhs),
+            };
             const rhs_should_be_register = try self.armOperandShouldBeRegister(rhs);
             const reuse_lhs = lhs_is_register and self.reuseOperand(inst, op_lhs, 0, lhs);
             const reuse_rhs = !reuse_lhs and rhs_is_register and self.reuseOperand(inst, op_rhs, 1, rhs);
+            const can_swap_lhs_and_rhs = switch (op) {
+                .shr, .shl => false,
+                else => true,
+            };
 
             // Destination must be a register
             var dst_mcv: MCValue = undefined;
@@ -1597,7 +1710,7 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                     branch.inst_table.putAssumeCapacity(Air.refToIndex(op_rhs).?, rhs_mcv);
                 }
                 dst_mcv = lhs;
-            } else if (reuse_rhs) {
+            } else if (reuse_rhs and can_swap_lhs_and_rhs) {
                 // Allocate 0 or 1 registers
                 if (!lhs_is_register and lhs_should_be_register) {
                     lhs_mcv = MCValue{ .register = try self.register_manager.allocReg(Air.refToIndex(op_lhs).?, &.{rhs.register}) };
@@ -1636,7 +1749,7 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                         dst_mcv = MCValue{ .register = try self.register_manager.allocReg(inst, &.{}) };
                         lhs_mcv = dst_mcv;
                     }
-                } else if (rhs_should_be_register) {
+                } else if (rhs_should_be_register and can_swap_lhs_and_rhs) {
                     // LHS is immediate
                     if (rhs_is_register) {
                         dst_mcv = MCValue{ .register = try self.register_manager.allocReg(inst, &.{rhs.register}) };
@@ -1663,6 +1776,7 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                 rhs_mcv,
                 swap_lhs_and_rhs,
                 op,
+                signedness,
             );
             return dst_mcv;
         }
@@ -1674,6 +1788,7 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
             rhs_mcv: MCValue,
             swap_lhs_and_rhs: bool,
             op: Air.Inst.Tag,
+            signedness: std.builtin.Signedness,
         ) !void {
             assert(lhs_mcv == .register or rhs_mcv == .register);
 
@@ -1719,6 +1834,27 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                 .cmp_eq => {
                     writeInt(u32, try self.code.addManyAsArray(4), Instruction.cmp(.al, op1, operand).toU32());
                 },
+                .shl => {
+                    assert(!swap_lhs_and_rhs);
+                    const shift_amout = switch (operand) {
+                        .Register => |reg_op| Instruction.ShiftAmount.reg(@intToEnum(Register, reg_op.rm)),
+                        .Immediate => |imm_op| Instruction.ShiftAmount.imm(@intCast(u5, imm_op.imm)),
+                    };
+                    writeInt(u32, try self.code.addManyAsArray(4), Instruction.lsl(.al, dst_reg, op1, shift_amout).toU32());
+                },
+                .shr => {
+                    assert(!swap_lhs_and_rhs);
+                    const shift_amout = switch (operand) {
+                        .Register => |reg_op| Instruction.ShiftAmount.reg(@intToEnum(Register, reg_op.rm)),
+                        .Immediate => |imm_op| Instruction.ShiftAmount.imm(@intCast(u5, imm_op.imm)),
+                    };
+
+                    const shr = switch (signedness) {
+                        .signed => Instruction.asr,
+                        .unsigned => Instruction.lsr,
+                    };
+                    writeInt(u32, try self.code.addManyAsArray(4), shr(.al, dst_reg, op1, shift_amout).toU32());
+                },
                 else => unreachable, // not a binary instruction
             }
         }
@@ -2969,7 +3105,8 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                     }
 
                     // The destination register is not present in the cmp instruction
-                    try self.genArmBinOpCode(undefined, lhs_mcv, rhs_mcv, false, .cmp_eq);
+                    // The signedness of the integer does not matter for the cmp instruction
+                    try self.genArmBinOpCode(undefined, lhs_mcv, rhs_mcv, false, .cmp_eq, undefined);
 
                     break :result switch (ty.isSignedInt()) {
                         true => MCValue{ .compare_flags_signed = op },
@@ -3792,15 +3929,10 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                             else => return self.fail("TODO implement memset", .{}),
                         }
                     },
-                    .compare_flags_unsigned => |op| {
-                        _ = op;
-                        return self.fail("TODO implement set stack variable with compare flags value (unsigned)", .{});
-                    },
-                    .compare_flags_signed => |op| {
-                        _ = op;
-                        return self.fail("TODO implement set stack variable with compare flags value (signed)", .{});
-                    },
-                    .immediate => {
+                    .compare_flags_unsigned,
+                    .compare_flags_signed,
+                    .immediate,
+                    => {
                         const reg = try self.copyToTmpRegister(ty, mcv);
                         return self.genSetStack(ty, stack_offset, MCValue{ .register = reg });
                     },
@@ -3968,15 +4100,10 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                             else => return self.fail("TODO implement memset", .{}),
                         }
                     },
-                    .compare_flags_unsigned => |op| {
-                        _ = op;
-                        return self.fail("TODO implement set stack variable with compare flags value (unsigned)", .{});
-                    },
-                    .compare_flags_signed => |op| {
-                        _ = op;
-                        return self.fail("TODO implement set stack variable with compare flags value (signed)", .{});
-                    },
-                    .immediate => {
+                    .compare_flags_unsigned,
+                    .compare_flags_signed,
+                    .immediate,
+                    => {
                         const reg = try self.copyToTmpRegister(ty, mcv);
                         return self.genSetStack(ty, stack_offset, MCValue{ .register = reg });
                     },
diff --git a/src/codegen/arm.zig b/src/codegen/arm.zig
index 891a9e100b..3743afd50f 100644
--- a/src/codegen/arm.zig
+++ b/src/codegen/arm.zig
@@ -192,7 +192,7 @@ pub const c_abi_int_return_regs = [_]Register{ .r0, .r1 };
 
 /// Represents an instruction in the ARM instruction set architecture
 pub const Instruction = union(enum) {
-    DataProcessing: packed struct {
+    data_processing: packed struct {
         // Note to self: The order of the fields top-to-bottom is
         // right-to-left in the actual 32-bit int representation
         op2: u12,
@@ -204,7 +204,7 @@ pub const Instruction = union(enum) {
         fixed: u2 = 0b00,
         cond: u4,
     },
-    Multiply: packed struct {
+    multiply: packed struct {
         rn: u4,
         fixed_1: u4 = 0b1001,
         rm: u4,
@@ -215,7 +215,7 @@ pub const Instruction = union(enum) {
         fixed_2: u6 = 0b000000,
         cond: u4,
     },
-    MultiplyLong: packed struct {
+    multiply_long: packed struct {
         rn: u4,
         fixed_1: u4 = 0b1001,
         rm: u4,
@@ -227,7 +227,17 @@ pub const Instruction = union(enum) {
         fixed_2: u5 = 0b00001,
         cond: u4,
     },
-    SingleDataTransfer: packed struct {
+    integer_saturating_arithmetic: packed struct {
+        rm: u4,
+        fixed_1: u8 = 0b0000_0101,
+        rd: u4,
+        rn: u4,
+        fixed_2: u1 = 0b0,
+        opc: u2,
+        fixed_3: u5 = 0b00010,
+        cond: u4,
+    },
+    single_data_transfer: packed struct {
         offset: u12,
         rd: u4,
         rn: u4,
@@ -240,7 +250,7 @@ pub const Instruction = union(enum) {
         fixed: u2 = 0b01,
         cond: u4,
     },
-    ExtraLoadStore: packed struct {
+    extra_load_store: packed struct {
         imm4l: u4,
         fixed_1: u1 = 0b1,
         op2: u2,
@@ -256,7 +266,7 @@ pub const Instruction = union(enum) {
         fixed_3: u3 = 0b000,
         cond: u4,
     },
-    BlockDataTransfer: packed struct {
+    block_data_transfer: packed struct {
         register_list: u16,
         rn: u4,
         load_store: u1,
@@ -267,25 +277,25 @@ pub const Instruction = union(enum) {
         fixed: u3 = 0b100,
         cond: u4,
     },
-    Branch: packed struct {
+    branch: packed struct {
         offset: u24,
         link: u1,
         fixed: u3 = 0b101,
         cond: u4,
     },
-    BranchExchange: packed struct {
+    branch_exchange: packed struct {
         rn: u4,
         fixed_1: u1 = 0b1,
         link: u1,
         fixed_2: u22 = 0b0001_0010_1111_1111_1111_00,
         cond: u4,
     },
-    SupervisorCall: packed struct {
+    supervisor_call: packed struct {
         comment: u24,
         fixed: u4 = 0b1111,
         cond: u4,
     },
-    Breakpoint: packed struct {
+    breakpoint: packed struct {
         imm4: u4,
         fixed_1: u4 = 0b0111,
         imm12: u12,
@@ -293,7 +303,7 @@ pub const Instruction = union(enum) {
     },
 
     /// Represents the possible operations which can be performed by a
-    /// DataProcessing instruction
+    /// Data Processing instruction
     const Opcode = enum(u4) {
         // Rd := Op1 AND Op2
         @"and",
@@ -530,16 +540,17 @@ pub const Instruction = union(enum) {
 
     pub fn toU32(self: Instruction) u32 {
         return switch (self) {
-            .DataProcessing => |v| @bitCast(u32, v),
-            .Multiply => |v| @bitCast(u32, v),
-            .MultiplyLong => |v| @bitCast(u32, v),
-            .SingleDataTransfer => |v| @bitCast(u32, v),
-            .ExtraLoadStore => |v| @bitCast(u32, v),
-            .BlockDataTransfer => |v| @bitCast(u32, v),
-            .Branch => |v| @bitCast(u32, v),
-            .BranchExchange => |v| @bitCast(u32, v),
-            .SupervisorCall => |v| @bitCast(u32, v),
-            .Breakpoint => |v| @intCast(u32, v.imm4) | (@intCast(u32, v.fixed_1) << 4) | (@intCast(u32, v.imm12) << 8) | (@intCast(u32, v.fixed_2_and_cond) << 20),
+            .data_processing => |v| @bitCast(u32, v),
+            .multiply => |v| @bitCast(u32, v),
+            .multiply_long => |v| @bitCast(u32, v),
+            .integer_saturating_arithmetic => |v| @bitCast(u32, v),
+            .single_data_transfer => |v| @bitCast(u32, v),
+            .extra_load_store => |v| @bitCast(u32, v),
+            .block_data_transfer => |v| @bitCast(u32, v),
+            .branch => |v| @bitCast(u32, v),
+            .branch_exchange => |v| @bitCast(u32, v),
+            .supervisor_call => |v| @bitCast(u32, v),
+            .breakpoint => |v| @intCast(u32, v.imm4) | (@intCast(u32, v.fixed_1) << 4) | (@intCast(u32, v.imm12) << 8) | (@intCast(u32, v.fixed_2_and_cond) << 20),
         };
     }
 
@@ -554,7 +565,7 @@ pub const Instruction = union(enum) {
         op2: Operand,
     ) Instruction {
         return Instruction{
-            .DataProcessing = .{
+            .data_processing = .{
                 .cond = @enumToInt(cond),
                 .i = @boolToInt(op2 == .Immediate),
                 .opcode = @enumToInt(opcode),
@@ -573,7 +584,7 @@ pub const Instruction = union(enum) {
         top: bool,
     ) Instruction {
         return Instruction{
-            .DataProcessing = .{
+            .data_processing = .{
                 .cond = @enumToInt(cond),
                 .i = 1,
                 .opcode = if (top) 0b1010 else 0b1000,
@@ -594,7 +605,7 @@ pub const Instruction = union(enum) {
         ra: ?Register,
     ) Instruction {
         return Instruction{
-            .Multiply = .{
+            .multiply = .{
                 .cond = @enumToInt(cond),
                 .accumulate = @boolToInt(ra != null),
                 .set_cond = set_cond,
@@ -617,7 +628,7 @@ pub const Instruction = union(enum) {
         rn: Register,
     ) Instruction {
         return Instruction{
-            .MultiplyLong = .{
+            .multiply_long = .{
                 .cond = @enumToInt(cond),
                 .unsigned = signed,
                 .accumulate = accumulate,
@@ -630,6 +641,24 @@ pub const Instruction = union(enum) {
         };
     }
 
+    fn integerSaturationArithmetic(
+        cond: Condition,
+        rd: Register,
+        rm: Register,
+        rn: Register,
+        opc: u2,
+    ) Instruction {
+        return Instruction{
+            .integer_saturating_arithmetic = .{
+                .rm = rm.id(),
+                .rd = rd.id(),
+                .rn = rn.id(),
+                .opc = opc,
+                .cond = @enumToInt(cond),
+            },
+        };
+    }
+
     fn singleDataTransfer(
         cond: Condition,
         rd: Register,
@@ -642,7 +671,7 @@ pub const Instruction = union(enum) {
         load_store: u1,
     ) Instruction {
         return Instruction{
-            .SingleDataTransfer = .{
+            .single_data_transfer = .{
                 .cond = @enumToInt(cond),
                 .rn = rn.id(),
                 .rd = rd.id(),
@@ -678,7 +707,7 @@ pub const Instruction = union(enum) {
         };
 
         return Instruction{
-            .ExtraLoadStore = .{
+            .extra_load_store = .{
                 .imm4l = imm4l,
                 .op2 = op2,
                 .imm4h = imm4h,
@@ -705,7 +734,7 @@ pub const Instruction = union(enum) {
         load_store: u1,
     ) Instruction {
         return Instruction{
-            .BlockDataTransfer = .{
+            .block_data_transfer = .{
                 .register_list = @bitCast(u16, reg_list),
                 .rn = rn.id(),
                 .load_store = load_store,
@@ -720,7 +749,7 @@ pub const Instruction = union(enum) {
 
     fn branch(cond: Condition, offset: i26, link: u1) Instruction {
         return Instruction{
-            .Branch = .{
+            .branch = .{
                 .cond = @enumToInt(cond),
                 .link = link,
                 .offset = @bitCast(u24, @intCast(i24, offset >> 2)),
@@ -730,7 +759,7 @@ pub const Instruction = union(enum) {
 
     fn branchExchange(cond: Condition, rn: Register, link: u1) Instruction {
         return Instruction{
-            .BranchExchange = .{
+            .branch_exchange = .{
                 .cond = @enumToInt(cond),
                 .link = link,
                 .rn = rn.id(),
@@ -740,7 +769,7 @@ pub const Instruction = union(enum) {
 
     fn supervisorCall(cond: Condition, comment: u24) Instruction {
         return Instruction{
-            .SupervisorCall = .{
+            .supervisor_call = .{
                 .cond = @enumToInt(cond),
                 .comment = comment,
             },
@@ -749,7 +778,7 @@ pub const Instruction = union(enum) {
 
     fn breakpoint(imm: u16) Instruction {
         return Instruction{
-            .Breakpoint = .{
+            .breakpoint = .{
                 .imm12 = @truncate(u12, imm >> 4),
                 .imm4 = @truncate(u4, imm),
             },
@@ -873,6 +902,24 @@ pub const Instruction = union(enum) {
         return dataProcessing(cond, .mvn, 1, rd, .r0, op2);
     }
 
+    // Integer Saturating Arithmetic
+
+    pub fn qadd(cond: Condition, rd: Register, rm: Register, rn: Register) Instruction {
+        return integerSaturationArithmetic(cond, rd, rm, rn, 0b00);
+    }
+
+    pub fn qsub(cond: Condition, rd: Register, rm: Register, rn: Register) Instruction {
+        return integerSaturationArithmetic(cond, rd, rm, rn, 0b01);
+    }
+
+    pub fn qdadd(cond: Condition, rd: Register, rm: Register, rn: Register) Instruction {
+        return integerSaturationArithmetic(cond, rd, rm, rn, 0b10);
+    }
+
+    pub fn qdsub(cond: Condition, rd: Register, rm: Register, rn: Register) Instruction {
+        return integerSaturationArithmetic(cond, rd, rm, rn, 0b11);
+    }
+
     // movw and movt
 
     pub fn movw(cond: Condition, rd: Register, imm: u16) Instruction {
@@ -887,7 +934,7 @@ pub const Instruction = union(enum) {
 
     pub fn mrs(cond: Condition, rd: Register, psr: Psr) Instruction {
         return Instruction{
-            .DataProcessing = .{
+            .data_processing = .{
                 .cond = @enumToInt(cond),
                 .i = 0,
                 .opcode = if (psr == .spsr) 0b1010 else 0b1000,
@@ -901,7 +948,7 @@ pub const Instruction = union(enum) {
 
     pub fn msr(cond: Condition, psr: Psr, op: Operand) Instruction {
         return Instruction{
-            .DataProcessing = .{
+            .data_processing = .{
                 .cond = @enumToInt(cond),
                 .i = 0,
                 .opcode = if (psr == .spsr) 0b1011 else 0b1001,
@@ -1142,6 +1189,79 @@ pub const Instruction = union(enum) {
             return stmdb(cond, .sp, true, @bitCast(RegisterList, register_list));
         }
     }
+
+    pub const ShiftAmount = union(enum) {
+        immediate: u5,
+        register: Register,
+
+        pub fn imm(immediate: u5) ShiftAmount {
+            return .{
+                .immediate = immediate,
+            };
+        }
+
+        pub fn reg(register: Register) ShiftAmount {
+            return .{
+                .register = register,
+            };
+        }
+    };
+
+    pub fn lsl(cond: Condition, rd: Register, rm: Register, shift: ShiftAmount) Instruction {
+        return switch (shift) {
+            .immediate => |imm| mov(cond, rd, Operand.reg(rm, Operand.Shift.imm(imm, .logical_left))),
+            .register => |reg| mov(cond, rd, Operand.reg(rm, Operand.Shift.reg(reg, .logical_left))),
+        };
+    }
+
+    pub fn lsr(cond: Condition, rd: Register, rm: Register, shift: ShiftAmount) Instruction {
+        return switch (shift) {
+            .immediate => |imm| mov(cond, rd, Operand.reg(rm, Operand.Shift.imm(imm, .logical_right))),
+            .register => |reg| mov(cond, rd, Operand.reg(rm, Operand.Shift.reg(reg, .logical_right))),
+        };
+    }
+
+    pub fn asr(cond: Condition, rd: Register, rm: Register, shift: ShiftAmount) Instruction {
+        return switch (shift) {
+            .immediate => |imm| mov(cond, rd, Operand.reg(rm, Operand.Shift.imm(imm, .arithmetic_right))),
+            .register => |reg| mov(cond, rd, Operand.reg(rm, Operand.Shift.reg(reg, .arithmetic_right))),
+        };
+    }
+
+    pub fn ror(cond: Condition, rd: Register, rm: Register, shift: ShiftAmount) Instruction {
+        return switch (shift) {
+            .immediate => |imm| mov(cond, rd, Operand.reg(rm, Operand.Shift.imm(imm, .rotate_right))),
+            .register => |reg| mov(cond, rd, Operand.reg(rm, Operand.Shift.reg(reg, .rotate_right))),
+        };
+    }
+
+    pub fn lsls(cond: Condition, rd: Register, rm: Register, shift: ShiftAmount) Instruction {
+        return switch (shift) {
+            .immediate => |imm| movs(cond, rd, Operand.reg(rm, Operand.Shift.imm(imm, .logical_left))),
+            .register => |reg| movs(cond, rd, Operand.reg(rm, Operand.Shift.reg(reg, .logical_left))),
+        };
+    }
+
+    pub fn lsrs(cond: Condition, rd: Register, rm: Register, shift: ShiftAmount) Instruction {
+        return switch (shift) {
+            .immediate => |imm| movs(cond, rd, Operand.reg(rm, Operand.Shift.imm(imm, .logical_right))),
+            .register => |reg| movs(cond, rd, Operand.reg(rm, Operand.Shift.reg(reg, .logical_right))),
+        };
+    }
+
+    pub fn asrs(cond: Condition, rd: Register, rm: Register, shift: ShiftAmount) Instruction {
+        return switch (shift) {
+            .immediate => |imm| movs(cond, rd, Operand.reg(rm, Operand.Shift.imm(imm, .arithmetic_right))),
+            .register => |reg| movs(cond, rd, Operand.reg(rm, Operand.Shift.reg(reg, .arithmetic_right))),
+        };
+    }
+
+    pub fn rors(cond: Condition, rd: Register, rm: Register, shift: ShiftAmount) Instruction {
+        return switch (shift) {
+            .immediate => |imm| movs(cond, rd, Operand.reg(rm, Operand.Shift.imm(imm, .rotate_right))),
+            .register => |reg| movs(cond, rd, Operand.reg(rm, Operand.Shift.reg(reg, .rotate_right))),
+        };
+    }
 };
 
 test "serialize instructions" {
@@ -1221,6 +1341,10 @@ test "serialize instructions" {
             .inst = Instruction.ldmea(.al, .r4, true, .{ .r2 = true, .r5 = true }),
             .expected = 0b1110_100_1_0_0_1_1_0100_0000000000100100,
         },
+        .{ // qadd r0, r7, r8
+            .inst = Instruction.qadd(.al, .r0, .r7, .r8),
+            .expected = 0b1110_00010_00_0_1000_0000_0000_0101_0111,
+        },
     };
 
     for (testcases) |case| {
@@ -1262,6 +1386,20 @@ test "aliases" {
             .actual = Instruction.push(.al, .{ .r0, .r2 }),
             .expected = Instruction.stmdb(.al, .sp, true, .{ .r0 = true, .r2 = true }),
         },
+        .{ // lsl r4, r5, #5
+            .actual = Instruction.lsl(.al, .r4, .r5, Instruction.ShiftAmount.imm(5)),
+            .expected = Instruction.mov(.al, .r4, Instruction.Operand.reg(
+                .r5,
+                Instruction.Operand.Shift.imm(5, .logical_left),
+            )),
+        },
+        .{ // asrs r1, r1, r3
+            .actual = Instruction.asrs(.al, .r1, .r1, Instruction.ShiftAmount.reg(.r3)),
+            .expected = Instruction.movs(.al, .r1, Instruction.Operand.reg(
+                .r1,
+                Instruction.Operand.Shift.reg(.r3, .arithmetic_right),
+            )),
+        },
     };
 
     for (testcases) |case| {
diff --git a/src/codegen/c.zig b/src/codegen/c.zig
index a67e2438c2..2084b1e1ce 100644
--- a/src/codegen/c.zig
+++ b/src/codegen/c.zig
@@ -319,18 +319,20 @@ pub const DeclGen = struct {
             .Bool => return writer.print("{}", .{val.toBool()}),
             .Optional => {
                 var opt_buf: Type.Payload.ElemType = undefined;
-                const child_type = t.optionalChild(&opt_buf);
+                const payload_type = t.optionalChild(&opt_buf);
                 if (t.isPtrLikeOptional()) {
-                    return dg.renderValue(writer, child_type, val);
+                    return dg.renderValue(writer, payload_type, val);
                 }
                 try writer.writeByte('(');
                 try dg.renderType(writer, t);
-                if (val.tag() == .null_value) {
-                    try writer.writeAll("){ .is_null = true }");
-                } else {
-                    try writer.writeAll("){ .is_null = false, .payload = ");
-                    try dg.renderValue(writer, child_type, val);
+                try writer.writeAll("){");
+                if (val.castTag(.opt_payload)) |pl| {
+                    const payload_val = pl.data;
+                    try writer.writeAll(" .is_null = false, .payload = ");
+                    try dg.renderValue(writer, payload_type, payload_val);
                     try writer.writeAll(" }");
+                } else {
+                    try writer.writeAll(" .is_null = true }");
                 }
             },
             .ErrorSet => {
@@ -871,6 +873,9 @@ fn genBody(o: *Object, body: []const Air.Inst.Index) error{ AnalysisFail, OutOfM
             .bit_or     => try airBinOp(o, inst, " | "),
             .xor        => try airBinOp(o, inst, " ^ "),
 
+            .shr        => try airBinOp(o, inst, " >> "),
+            .shl        => try airBinOp(o, inst, " << "),
+
             .not        => try airNot(  o, inst),
 
             .optional_payload     => try airOptionalPayload(o, inst),
@@ -904,12 +909,19 @@ fn genBody(o: *Object, body: []const Air.Inst.Index) error{ AnalysisFail, OutOfM
             .switch_br        => try airSwitchBr(o, inst),
             .wrap_optional    => try airWrapOptional(o, inst),
             .struct_field_ptr => try airStructFieldPtr(o, inst),
+
+            .struct_field_ptr_index_0 => try airStructFieldPtrIndex(o, inst, 0),
+            .struct_field_ptr_index_1 => try airStructFieldPtrIndex(o, inst, 1),
+            .struct_field_ptr_index_2 => try airStructFieldPtrIndex(o, inst, 2),
+            .struct_field_ptr_index_3 => try airStructFieldPtrIndex(o, inst, 3),
+
             .struct_field_val => try airStructFieldVal(o, inst),
             .slice_ptr        => try airSliceField(o, inst, ".ptr;\n"),
             .slice_len        => try airSliceField(o, inst, ".len;\n"),
 
             .ptr_elem_val       => try airPtrElemVal(o, inst, "["),
             .ptr_ptr_elem_val   => try airPtrElemVal(o, inst, "[0]["),
+            .ptr_elem_ptr       => try airPtrElemPtr(o, inst),
             .slice_elem_val     => try airSliceElemVal(o, inst, "["),
             .ptr_slice_elem_val => try airSliceElemVal(o, inst, "[0]["),
 
@@ -957,6 +969,13 @@ fn airPtrElemVal(o: *Object, inst: Air.Inst.Index, prefix: []const u8) !CValue {
     return o.dg.fail("TODO: C backend: airPtrElemVal", .{});
 }
 
+fn airPtrElemPtr(o: *Object, inst: Air.Inst.Index) !CValue {
+    if (o.liveness.isUnused(inst))
+        return CValue.none;
+
+    return o.dg.fail("TODO: C backend: airPtrElemPtr", .{});
+}
+
 fn airSliceElemVal(o: *Object, inst: Air.Inst.Index, prefix: []const u8) !CValue {
     const is_volatile = false; // TODO
     if (!is_volatile and o.liveness.isUnused(inst))
@@ -1638,15 +1657,31 @@ fn airOptionalPayload(o: *Object, inst: Air.Inst.Index) !CValue {
 
 fn airStructFieldPtr(o: *Object, inst: Air.Inst.Index) !CValue {
     if (o.liveness.isUnused(inst))
-        return CValue.none;
+        // TODO this @as is needed because of a stage1 bug
+        return @as(CValue, CValue.none);
 
     const ty_pl = o.air.instructions.items(.data)[inst].ty_pl;
     const extra = o.air.extraData(Air.StructField, ty_pl.payload).data;
-    const writer = o.writer();
     const struct_ptr = try o.resolveInst(extra.struct_operand);
     const struct_ptr_ty = o.air.typeOf(extra.struct_operand);
+    return structFieldPtr(o, inst, struct_ptr_ty, struct_ptr, extra.field_index);
+}
+
+fn airStructFieldPtrIndex(o: *Object, inst: Air.Inst.Index, index: u8) !CValue {
+    if (o.liveness.isUnused(inst))
+        // TODO this @as is needed because of a stage1 bug
+        return @as(CValue, CValue.none);
+
+    const ty_op = o.air.instructions.items(.data)[inst].ty_op;
+    const struct_ptr = try o.resolveInst(ty_op.operand);
+    const struct_ptr_ty = o.air.typeOf(ty_op.operand);
+    return structFieldPtr(o, inst, struct_ptr_ty, struct_ptr, index);
+}
+
+fn structFieldPtr(o: *Object, inst: Air.Inst.Index, struct_ptr_ty: Type, struct_ptr: CValue, index: u32) !CValue {
+    const writer = o.writer();
     const struct_obj = struct_ptr_ty.elemType().castTag(.@"struct").?.data;
-    const field_name = struct_obj.fields.keys()[extra.field_index];
+    const field_name = struct_obj.fields.keys()[index];
 
     const inst_ty = o.air.typeOfIndex(inst);
     const local = try o.allocLocal(inst_ty, .Const);
diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
index 2b678b0a69..0a715edbfd 100644
--- a/src/codegen/llvm.zig
+++ b/src/codegen/llvm.zig
@@ -434,6 +434,8 @@ pub const Object = struct {
             },
             else => |e| return e,
         };
+        const decl_exports = module.decl_exports.get(decl) orelse &[0]*Module.Export{};
+        try self.updateDeclExports(module, decl, decl_exports);
     }
 
     pub fn updateDeclExports(
@@ -442,7 +444,9 @@ pub const Object = struct {
         decl: *const Module.Decl,
         exports: []const *Module.Export,
     ) !void {
-        const llvm_fn = self.llvm_module.getNamedFunction(decl.name).?;
+        // If the module does not already have the function, we ignore this function call
+        // because we call `updateDeclExports` at the end of `updateFunc` and `updateDecl`.
+        const llvm_fn = self.llvm_module.getNamedFunction(decl.name) orelse return;
         const is_extern = decl.val.tag() == .extern_fn;
         if (is_extern or exports.len != 0) {
             llvm_fn.setLinkage(.External);
@@ -808,27 +812,22 @@ pub const DeclGen = struct {
                 return self.todo("handle more array values", .{});
             },
             .Optional => {
-                if (!tv.ty.isPtrLikeOptional()) {
-                    var buf: Type.Payload.ElemType = undefined;
-                    const child_type = tv.ty.optionalChild(&buf);
-                    const llvm_child_type = try self.llvmType(child_type);
-
-                    if (tv.val.tag() == .null_value) {
-                        var optional_values: [2]*const llvm.Value = .{
-                            llvm_child_type.constNull(),
-                            self.context.intType(1).constNull(),
-                        };
-                        return self.context.constStruct(&optional_values, optional_values.len, .False);
-                    } else {
-                        var optional_values: [2]*const llvm.Value = .{
-                            try self.genTypedValue(.{ .ty = child_type, .val = tv.val }),
-                            self.context.intType(1).constAllOnes(),
-                        };
-                        return self.context.constStruct(&optional_values, optional_values.len, .False);
-                    }
-                } else {
+                if (tv.ty.isPtrLikeOptional()) {
                     return self.todo("implement const of optional pointer", .{});
                 }
+                var buf: Type.Payload.ElemType = undefined;
+                const payload_type = tv.ty.optionalChild(&buf);
+                const is_pl = !tv.val.isNull();
+                const llvm_i1 = self.context.intType(1);
+
+                const fields: [2]*const llvm.Value = .{
+                    try self.genTypedValue(.{
+                        .ty = payload_type,
+                        .val = if (tv.val.castTag(.opt_payload)) |pl| pl.data else Value.initTag(.undef),
+                    }),
+                    if (is_pl) llvm_i1.constAllOnes() else llvm_i1.constNull(),
+                };
+                return self.context.constStruct(&fields, fields.len, .False);
             },
             .Fn => {
                 const fn_decl = switch (tv.val.tag()) {
@@ -995,6 +994,9 @@ pub const FuncGen = struct {
                 .bit_or, .bool_or   => try self.airOr(inst),
                 .xor                => try self.airXor(inst),
 
+                .shl                => try self.airShl(inst),
+                .shr                => try self.airShr(inst),
+
                 .cmp_eq  => try self.airCmp(inst, .eq),
                 .cmp_gt  => try self.airCmp(inst, .gt),
                 .cmp_gte => try self.airCmp(inst, .gte),
@@ -1037,9 +1039,15 @@ pub const FuncGen = struct {
                 .struct_field_ptr => try self.airStructFieldPtr(inst),
                 .struct_field_val => try self.airStructFieldVal(inst),
 
+                .struct_field_ptr_index_0 => try self.airStructFieldPtrIndex(inst, 0),
+                .struct_field_ptr_index_1 => try self.airStructFieldPtrIndex(inst, 1),
+                .struct_field_ptr_index_2 => try self.airStructFieldPtrIndex(inst, 2),
+                .struct_field_ptr_index_3 => try self.airStructFieldPtrIndex(inst, 3),
+
                 .slice_elem_val     => try self.airSliceElemVal(inst),
                 .ptr_slice_elem_val => try self.airPtrSliceElemVal(inst),
                 .ptr_elem_val       => try self.airPtrElemVal(inst),
+                .ptr_elem_ptr       => try self.airPtrElemPtr(inst),
                 .ptr_ptr_elem_val   => try self.airPtrPtrElemVal(inst),
 
                 .optional_payload     => try self.airOptionalPayload(inst, false),
@@ -1295,11 +1303,35 @@ pub const FuncGen = struct {
         const bin_op = self.air.instructions.items(.data)[inst].bin_op;
         const base_ptr = try self.resolveInst(bin_op.lhs);
         const rhs = try self.resolveInst(bin_op.rhs);
-        const indices: [1]*const llvm.Value = .{rhs};
-        const ptr = self.builder.buildInBoundsGEP(base_ptr, &indices, indices.len, "");
+        const ptr = if (self.air.typeOf(bin_op.lhs).isSinglePointer()) ptr: {
+            // If this is a single-item pointer to an array, we need another index in the GEP.
+            const indices: [2]*const llvm.Value = .{ self.context.intType(32).constNull(), rhs };
+            break :ptr self.builder.buildInBoundsGEP(base_ptr, &indices, indices.len, "");
+        } else ptr: {
+            const indices: [1]*const llvm.Value = .{rhs};
+            break :ptr self.builder.buildInBoundsGEP(base_ptr, &indices, indices.len, "");
+        };
         return self.builder.buildLoad(ptr, "");
     }
 
+    fn airPtrElemPtr(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
+        if (self.liveness.isUnused(inst))
+            return null;
+
+        const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
+        const bin_op = self.air.extraData(Air.Bin, ty_pl.payload).data;
+        const base_ptr = try self.resolveInst(bin_op.lhs);
+        const rhs = try self.resolveInst(bin_op.rhs);
+        if (self.air.typeOf(bin_op.lhs).isSinglePointer()) {
+            // If this is a single-item pointer to an array, we need another index in the GEP.
+            const indices: [2]*const llvm.Value = .{ self.context.intType(32).constNull(), rhs };
+            return self.builder.buildInBoundsGEP(base_ptr, &indices, indices.len, "");
+        } else {
+            const indices: [1]*const llvm.Value = .{rhs};
+            return self.builder.buildInBoundsGEP(base_ptr, &indices, indices.len, "");
+        }
+    }
+
     fn airPtrPtrElemVal(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
         const is_volatile = false; // TODO
         if (!is_volatile and self.liveness.isUnused(inst))
@@ -1325,6 +1357,15 @@ pub const FuncGen = struct {
         return self.builder.buildStructGEP(struct_ptr, field_index, "");
     }
 
+    fn airStructFieldPtrIndex(self: *FuncGen, inst: Air.Inst.Index, field_index: c_uint) !?*const llvm.Value {
+        if (self.liveness.isUnused(inst))
+            return null;
+
+        const ty_op = self.air.instructions.items(.data)[inst].ty_op;
+        const struct_ptr = try self.resolveInst(ty_op.operand);
+        return self.builder.buildStructGEP(struct_ptr, field_index, "");
+    }
+
     fn airStructFieldVal(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
         if (self.liveness.isUnused(inst))
             return null;
@@ -1739,6 +1780,41 @@ pub const FuncGen = struct {
         return self.builder.buildXor(lhs, rhs, "");
     }
 
+    fn airShl(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
+        if (self.liveness.isUnused(inst))
+            return null;
+        const bin_op = self.air.instructions.items(.data)[inst].bin_op;
+        const lhs = try self.resolveInst(bin_op.lhs);
+        const rhs = try self.resolveInst(bin_op.rhs);
+        const lhs_type = self.air.typeOf(bin_op.lhs);
+        const tg = self.dg.module.getTarget();
+        const casted_rhs = if (self.air.typeOf(bin_op.rhs).bitSize(tg) < lhs_type.bitSize(tg))
+            self.builder.buildZExt(rhs, try self.dg.llvmType(lhs_type), "")
+        else
+            rhs;
+        return self.builder.buildShl(lhs, casted_rhs, "");
+    }
+
+    fn airShr(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
+        if (self.liveness.isUnused(inst))
+            return null;
+        const bin_op = self.air.instructions.items(.data)[inst].bin_op;
+        const lhs = try self.resolveInst(bin_op.lhs);
+        const rhs = try self.resolveInst(bin_op.rhs);
+        const lhs_type = self.air.typeOf(bin_op.lhs);
+        const tg = self.dg.module.getTarget();
+        const casted_rhs = if (self.air.typeOf(bin_op.rhs).bitSize(tg) < lhs_type.bitSize(tg))
+            self.builder.buildZExt(rhs, try self.dg.llvmType(lhs_type), "")
+        else
+            rhs;
+
+        if (self.air.typeOfIndex(inst).isSignedInt()) {
+            return self.builder.buildAShr(lhs, casted_rhs, "");
+        } else {
+            return self.builder.buildLShr(lhs, casted_rhs, "");
+        }
+    }
+
     fn airIntCast(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
         if (self.liveness.isUnused(inst))
             return null;
diff --git a/src/codegen/llvm/bindings.zig b/src/codegen/llvm/bindings.zig
index fc97dfb81f..fe0c211df3 100644
--- a/src/codegen/llvm/bindings.zig
+++ b/src/codegen/llvm/bindings.zig
@@ -291,6 +291,14 @@ pub const Builder = opaque {
     pub const getInsertBlock = LLVMGetInsertBlock;
     extern fn LLVMGetInsertBlock(Builder: *const Builder) *const BasicBlock;
 
+    pub const buildZExt = LLVMBuildZExt;
+    extern fn LLVMBuildZExt(
+        *const Builder,
+        Value: *const Value,
+        DestTy: *const Type,
+        Name: [*:0]const u8,
+    ) *const Value;
+
     pub const buildCall = LLVMBuildCall;
     extern fn LLVMBuildCall(
         *const Builder,
@@ -382,6 +390,15 @@ pub const Builder = opaque {
     pub const buildAnd = LLVMBuildAnd;
     extern fn LLVMBuildAnd(*const Builder, LHS: *const Value, RHS: *const Value, Name: [*:0]const u8) *const Value;
 
+    pub const buildLShr = LLVMBuildLShr;
+    extern fn LLVMBuildLShr(*const Builder, LHS: *const Value, RHS: *const Value, Name: [*:0]const u8) *const Value;
+
+    pub const buildAShr = LLVMBuildAShr;
+    extern fn LLVMBuildAShr(*const Builder, LHS: *const Value, RHS: *const Value, Name: [*:0]const u8) *const Value;
+
+    pub const buildShl = LLVMBuildShl;
+    extern fn LLVMBuildShl(*const Builder, LHS: *const Value, RHS: *const Value, Name: [*:0]const u8) *const Value;
+
     pub const buildOr = LLVMBuildOr;
     extern fn LLVMBuildOr(*const Builder, LHS: *const Value, RHS: *const Value, Name: [*:0]const u8) *const Value;
 
diff --git a/src/codegen/wasm.zig b/src/codegen/wasm.zig
index 4814ba0b55..bb05567236 100644
--- a/src/codegen/wasm.zig
+++ b/src/codegen/wasm.zig
@@ -862,6 +862,10 @@ pub const Context = struct {
             .ret => self.airRet(inst),
             .store => self.airStore(inst),
             .struct_field_ptr => self.airStructFieldPtr(inst),
+            .struct_field_ptr_index_0 => self.airStructFieldPtrIndex(inst, 0),
+            .struct_field_ptr_index_1 => self.airStructFieldPtrIndex(inst, 1),
+            .struct_field_ptr_index_2 => self.airStructFieldPtrIndex(inst, 2),
+            .struct_field_ptr_index_3 => self.airStructFieldPtrIndex(inst, 3),
             .switch_br => self.airSwitchBr(inst),
             .unreach => self.airUnreachable(inst),
             .wrap_optional => self.airWrapOptional(inst),
@@ -1198,7 +1202,12 @@ pub const Context = struct {
 
                 // When constant has value 'null', set is_null local to '1'
                 // and payload to '0'
-                if (val.tag() == .null_value) {
+                if (val.castTag(.opt_payload)) |pl| {
+                    const payload_val = pl.data;
+                    try writer.writeByte(wasm.opcode(.i32_const));
+                    try leb.writeILEB128(writer, @as(i32, 0));
+                    try self.emitConstant(payload_val, payload_type);
+                } else {
                     try writer.writeByte(wasm.opcode(.i32_const));
                     try leb.writeILEB128(writer, @as(i32, 1));
 
@@ -1208,10 +1217,6 @@ pub const Context = struct {
                     });
                     try writer.writeByte(wasm.opcode(opcode));
                     try leb.writeULEB128(writer, @as(u32, 0));
-                } else {
-                    try writer.writeByte(wasm.opcode(.i32_const));
-                    try leb.writeILEB128(writer, @as(i32, 0));
-                    try self.emitConstant(val, payload_type);
                 }
             },
             else => |zig_type| return self.fail("Wasm TODO: emitConstant for zigTypeTag {s}", .{zig_type}),
@@ -1440,8 +1445,15 @@ pub const Context = struct {
         const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
         const extra = self.air.extraData(Air.StructField, ty_pl.payload);
         const struct_ptr = self.resolveInst(extra.data.struct_operand);
-
-        return WValue{ .local = struct_ptr.multi_value.index + @intCast(u32, extra.data.field_index) };
+        return structFieldPtr(struct_ptr, extra.data.field_index);
+    }
+    fn airStructFieldPtrIndex(self: *Context, inst: Air.Inst.Index, index: u32) InnerError!WValue {
+        const ty_op = self.air.instructions.items(.data)[inst].ty_op;
+        const struct_ptr = self.resolveInst(ty_op.operand);
+        return structFieldPtr(struct_ptr, index);
+    }
+    fn structFieldPtr(struct_ptr: WValue, index: u32) InnerError!WValue {
+        return WValue{ .local = struct_ptr.multi_value.index + index };
     }
 
     fn airSwitchBr(self: *Context, inst: Air.Inst.Index) InnerError!WValue {
diff --git a/src/link/Wasm.zig b/src/link/Wasm.zig
index 3c3cd4eef3..fc559948c4 100644
--- a/src/link/Wasm.zig
+++ b/src/link/Wasm.zig
@@ -765,12 +765,8 @@ fn linkWithLLD(self: *Wasm, comp: *Compilation) !void {
             if (self.base.options.wasi_exec_model == .reactor) {
                 // Reactor execution model does not have _start so lld doesn't look for it.
                 try argv.append("--no-entry");
-                // Make sure "_initialize" is exported even if this is pure Zig WASI reactor
-                // where WASM_SYMBOL_EXPORTED flag in LLVM is not set on _initialize.
-                try argv.appendSlice(&[_][]const u8{
-                    "--export",
-                    "_initialize",
-                });
+                // Make sure "_initialize" and other used-defined functions are exported if this is WASI reactor.
+                try argv.append("--export-dynamic");
             }
         } else {
             try argv.append("--no-entry"); // So lld doesn't look for _start.
diff --git a/src/main.zig b/src/main.zig
index 285b6d2316..44b3a0515c 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -2492,6 +2492,7 @@ fn cmdTranslateC(comp: *Compilation, arena: *Allocator, enable_cache: bool) !voi
 
     const digest = if (try man.hit()) man.final() else digest: {
         var argv = std.ArrayList([]const u8).init(arena);
+        try argv.append(""); // argv[0] is program name, actual args start at [1]
 
         var zig_cache_tmp_dir = try comp.local_cache_directory.handle.makeOpenPath("tmp", .{});
         defer zig_cache_tmp_dir.close();
diff --git a/src/mingw.zig b/src/mingw.zig
index 42d1ac47db..529025c517 100644
--- a/src/mingw.zig
+++ b/src/mingw.zig
@@ -187,27 +187,25 @@ pub fn buildCRTFile(comp: *Compilation, crt_file: CRTFile) !void {
                     };
                 }
             } else if (target.cpu.arch.isARM()) {
-                if (target.cpu.arch.ptrBitWidth() == 32) {
-                    for (mingwex_arm32_src) |dep| {
-                        (try c_source_files.addOne()).* = .{
-                            .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{
-                                "libc", "mingw", dep,
-                            }),
-                            .extra_flags = extra_flags,
-                        };
-                    }
-                } else {
-                    for (mingwex_arm64_src) |dep| {
-                        (try c_source_files.addOne()).* = .{
-                            .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{
-                                "libc", "mingw", dep,
-                            }),
-                            .extra_flags = extra_flags,
-                        };
-                    }
+                for (mingwex_arm32_src) |dep| {
+                    (try c_source_files.addOne()).* = .{
+                        .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{
+                            "libc", "mingw", dep,
+                        }),
+                        .extra_flags = extra_flags,
+                    };
+                }
+            } else if (target.cpu.arch.isAARCH64()) {
+                for (mingwex_arm64_src) |dep| {
+                    (try c_source_files.addOne()).* = .{
+                        .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{
+                            "libc", "mingw", dep,
+                        }),
+                        .extra_flags = extra_flags,
+                    };
                 }
             } else {
-                unreachable;
+                @panic("unsupported arch");
             }
             return comp.build_crt_file("mingwex", .Lib, c_source_files.items);
         },
diff --git a/src/print_air.zig b/src/print_air.zig
index 66490b6512..276158f720 100644
--- a/src/print_air.zig
+++ b/src/print_air.zig
@@ -127,6 +127,8 @@ const Writer = struct {
             .ptr_slice_elem_val,
             .ptr_elem_val,
             .ptr_ptr_elem_val,
+            .shl,
+            .shr,
             => try w.writeBinOp(s, inst),
 
             .is_null,
@@ -167,12 +169,17 @@ const Writer = struct {
             .wrap_errunion_err,
             .slice_ptr,
             .slice_len,
+            .struct_field_ptr_index_0,
+            .struct_field_ptr_index_1,
+            .struct_field_ptr_index_2,
+            .struct_field_ptr_index_3,
             => try w.writeTyOp(s, inst),
 
             .block,
             .loop,
             => try w.writeBlock(s, inst),
 
+            .ptr_elem_ptr => try w.writePtrElemPtr(s, inst),
             .struct_field_ptr => try w.writeStructField(s, inst),
             .struct_field_val => try w.writeStructField(s, inst),
             .constant => try w.writeConstant(s, inst),
@@ -237,10 +244,19 @@ const Writer = struct {
 
     fn writeStructField(w: *Writer, s: anytype, inst: Air.Inst.Index) @TypeOf(s).Error!void {
         const ty_pl = w.air.instructions.items(.data)[inst].ty_pl;
-        const extra = w.air.extraData(Air.StructField, ty_pl.payload);
+        const extra = w.air.extraData(Air.StructField, ty_pl.payload).data;
 
-        try w.writeOperand(s, inst, 0, extra.data.struct_operand);
-        try s.print(", {d}", .{extra.data.field_index});
+        try w.writeOperand(s, inst, 0, extra.struct_operand);
+        try s.print(", {d}", .{extra.field_index});
+    }
+
+    fn writePtrElemPtr(w: *Writer, s: anytype, inst: Air.Inst.Index) @TypeOf(s).Error!void {
+        const ty_pl = w.air.instructions.items(.data)[inst].ty_pl;
+        const extra = w.air.extraData(Air.Bin, ty_pl.payload).data;
+
+        try w.writeOperand(s, inst, 0, extra.lhs);
+        try s.writeAll(", ");
+        try w.writeOperand(s, inst, 0, extra.rhs);
     }
 
     fn writeConstant(w: *Writer, s: anytype, inst: Air.Inst.Index) @TypeOf(s).Error!void {
diff --git a/src/stage1/all_types.hpp b/src/stage1/all_types.hpp
index dfebc66cfd..fc3b00d6db 100644
--- a/src/stage1/all_types.hpp
+++ b/src/stage1/all_types.hpp
@@ -1125,6 +1125,7 @@ struct AstNodeContainerInitExpr {
 
 struct AstNodeIdentifier {
     Buf *name;
+    bool is_at_syntax;
 };
 
 struct AstNodeEnumLiteral {
diff --git a/src/stage1/analyze.cpp b/src/stage1/analyze.cpp
index cf61bf79b7..2eb609ef1a 100644
--- a/src/stage1/analyze.cpp
+++ b/src/stage1/analyze.cpp
@@ -3918,12 +3918,6 @@ static void add_top_level_decl(CodeGen *g, ScopeDecls *decls_scope, Tld *tld) {
             add_error_note(g, msg, other_tld->source_node, buf_sprintf("previous definition here"));
             return;
         }
-
-        ZigType *type;
-        if (get_primitive_type(g, tld->name, &type) != ErrorPrimitiveTypeNotFound) {
-            add_node_error(g, tld->source_node,
-                buf_sprintf("declaration shadows primitive type '%s'", buf_ptr(tld->name)));
-        }
     }
 }
 
@@ -4170,48 +4164,6 @@ ZigVar *add_variable(CodeGen *g, AstNode *source_node, Scope *parent_scope, Buf
         variable_entry->var_type = g->builtin_types.entry_invalid;
     } else {
         variable_entry->align_bytes = get_abi_alignment(g, var_type);
-
-        ZigVar *existing_var = find_variable(g, parent_scope, name, nullptr);
-        if (existing_var && !existing_var->shadowable) {
-            if (existing_var->var_type == nullptr || !type_is_invalid(existing_var->var_type)) {
-                ErrorMsg *msg = add_node_error(g, source_node,
-                        buf_sprintf("redeclaration of variable '%s'", buf_ptr(name)));
-                add_error_note(g, msg, existing_var->decl_node, buf_sprintf("previous declaration here"));
-            }
-            variable_entry->var_type = g->builtin_types.entry_invalid;
-        } else {
-            ZigType *type;
-            if (get_primitive_type(g, name, &type) != ErrorPrimitiveTypeNotFound) {
-                add_node_error(g, source_node,
-                        buf_sprintf("variable shadows primitive type '%s'", buf_ptr(name)));
-                variable_entry->var_type = g->builtin_types.entry_invalid;
-            } else {
-                Scope *search_scope = nullptr;
-                if (src_tld == nullptr) {
-                    search_scope = parent_scope;
-                } else if (src_tld->parent_scope != nullptr && src_tld->parent_scope->parent != nullptr) {
-                    search_scope = src_tld->parent_scope->parent;
-                }
-                if (search_scope != nullptr) {
-                    Tld *tld = find_decl(g, search_scope, name);
-                    if (tld != nullptr && tld != src_tld) {
-                        bool want_err_msg = true;
-                        if (tld->id == TldIdVar) {
-                            ZigVar *var = reinterpret_cast<TldVar *>(tld)->var;
-                            if (var != nullptr && var->var_type != nullptr && type_is_invalid(var->var_type)) {
-                                want_err_msg = false;
-                            }
-                        }
-                        if (want_err_msg) {
-                            ErrorMsg *msg = add_node_error(g, source_node,
-                                    buf_sprintf("redefinition of '%s'", buf_ptr(name)));
-                            add_error_note(g, msg, tld->source_node, buf_sprintf("previous definition here"));
-                        }
-                        variable_entry->var_type = g->builtin_types.entry_invalid;
-                    }
-                }
-            }
-        }
     }
 
     Scope *child_scope;
diff --git a/src/stage1/astgen.cpp b/src/stage1/astgen.cpp
index 44dc1080c2..367fd8ac08 100644
--- a/src/stage1/astgen.cpp
+++ b/src/stage1/astgen.cpp
@@ -3194,30 +3194,6 @@ ZigVar *create_local_var(CodeGen *codegen, AstNode *node, Scope *parent_scope,
                     add_error_note(codegen, msg, existing_var->decl_node, buf_sprintf("previous declaration here"));
                 }
                 variable_entry->var_type = codegen->builtin_types.entry_invalid;
-            } else {
-                ZigType *type;
-                if (get_primitive_type(codegen, name, &type) != ErrorPrimitiveTypeNotFound) {
-                    add_node_error(codegen, node,
-                            buf_sprintf("variable shadows primitive type '%s'", buf_ptr(name)));
-                    variable_entry->var_type = codegen->builtin_types.entry_invalid;
-                } else {
-                    Tld *tld = find_decl(codegen, parent_scope, name);
-                    if (tld != nullptr) {
-                        bool want_err_msg = true;
-                        if (tld->id == TldIdVar) {
-                            ZigVar *var = reinterpret_cast<TldVar *>(tld)->var;
-                            if (var != nullptr && var->var_type != nullptr && type_is_invalid(var->var_type)) {
-                                want_err_msg = false;
-                            }
-                        }
-                        if (want_err_msg) {
-                            ErrorMsg *msg = add_node_error(codegen, node,
-                                    buf_sprintf("redefinition of '%s'", buf_ptr(name)));
-                            add_error_note(codegen, msg, tld->source_node, buf_sprintf("previous definition here"));
-                        }
-                        variable_entry->var_type = codegen->builtin_types.entry_invalid;
-                    }
-                }
             }
         }
     } else {
@@ -3832,35 +3808,38 @@ static Stage1ZirInst *astgen_identifier(Stage1AstGen *ag, Scope *scope, AstNode
     Error err;
     assert(node->type == NodeTypeIdentifier);
 
-    Buf *variable_name = node_identifier_buf(node);
-
-    if (buf_eql_str(variable_name, "_")) {
-        if (lval == LValAssign) {
-            Stage1ZirInstConst *const_instruction = ir_build_instruction<Stage1ZirInstConst>(ag, scope, node);
-            const_instruction->value = ag->codegen->pass1_arena->create<ZigValue>();
-            const_instruction->value->type = get_pointer_to_type(ag->codegen,
-                    ag->codegen->builtin_types.entry_void, false);
-            const_instruction->value->special = ConstValSpecialStatic;
-            const_instruction->value->data.x_ptr.special = ConstPtrSpecialDiscard;
-            return &const_instruction->base;
+    bool is_at_syntax;
+    Buf *variable_name = node_identifier_buf2(node, &is_at_syntax);
+
+    if (!is_at_syntax) {
+        if (buf_eql_str(variable_name, "_")) {
+            if (lval == LValAssign) {
+                Stage1ZirInstConst *const_instruction = ir_build_instruction<Stage1ZirInstConst>(ag, scope, node);
+                const_instruction->value = ag->codegen->pass1_arena->create<ZigValue>();
+                const_instruction->value->type = get_pointer_to_type(ag->codegen,
+                        ag->codegen->builtin_types.entry_void, false);
+                const_instruction->value->special = ConstValSpecialStatic;
+                const_instruction->value->data.x_ptr.special = ConstPtrSpecialDiscard;
+                return &const_instruction->base;
+            }
         }
-    }
 
-    ZigType *primitive_type;
-    if ((err = get_primitive_type(ag->codegen, variable_name, &primitive_type))) {
-        if (err == ErrorOverflow) {
-            add_node_error(ag->codegen, node,
-                buf_sprintf("primitive integer type '%s' exceeds maximum bit width of 65535",
-                    buf_ptr(variable_name)));
-            return ag->codegen->invalid_inst_src;
-        }
-        assert(err == ErrorPrimitiveTypeNotFound);
-    } else {
-        Stage1ZirInst *value = ir_build_const_type(ag, scope, node, primitive_type);
-        if (lval == LValPtr || lval == LValAssign) {
-            return ir_build_ref_src(ag, scope, node, value);
+        ZigType *primitive_type;
+        if ((err = get_primitive_type(ag->codegen, variable_name, &primitive_type))) {
+            if (err == ErrorOverflow) {
+                add_node_error(ag->codegen, node,
+                    buf_sprintf("primitive integer type '%s' exceeds maximum bit width of 65535",
+                        buf_ptr(variable_name)));
+                return ag->codegen->invalid_inst_src;
+            }
+            assert(err == ErrorPrimitiveTypeNotFound);
         } else {
-            return ir_expr_wrap(ag, scope, value, result_loc);
+            Stage1ZirInst *value = ir_build_const_type(ag, scope, node, primitive_type);
+            if (lval == LValPtr || lval == LValAssign) {
+                return ir_build_ref_src(ag, scope, node, value);
+            } else {
+                return ir_expr_wrap(ag, scope, value, result_loc);
+            }
         }
     }
 
@@ -3875,7 +3854,31 @@ static Stage1ZirInst *astgen_identifier(Stage1AstGen *ag, Scope *scope, AstNode
         }
     }
 
-    Tld *tld = find_decl(ag->codegen, scope, variable_name);
+    Tld *tld = nullptr;
+    {
+        Scope *s = scope;
+        while (s) {
+            if (s->id == ScopeIdDecls) {
+                ScopeDecls *decls_scope = (ScopeDecls *)s;
+
+                Tld *result = find_container_decl(ag->codegen, decls_scope, variable_name);
+                if (result != nullptr) {
+                    if (tld != nullptr && tld != result) {
+                        ErrorMsg *msg = add_node_error(ag->codegen, node,
+                                buf_sprintf("ambiguous reference"));
+                        add_error_note(ag->codegen, msg, tld->source_node,
+                                buf_sprintf("declared here"));
+                        add_error_note(ag->codegen, msg, result->source_node,
+                                buf_sprintf("also declared here"));
+                        return ag->codegen->invalid_inst_src;
+                    }
+                    tld = result;
+                }
+            }
+            s = s->parent;
+        }
+    }
+
     if (tld) {
         Stage1ZirInst *decl_ref = ir_build_decl_ref(ag, scope, node, tld, lval);
         if (lval == LValPtr || lval == LValAssign) {
@@ -4653,17 +4656,17 @@ static Stage1ZirInst *astgen_builtin_fn_call(Stage1AstGen *ag, Scope *scope, Ast
 
                 AstNode *arg1_node = node->data.fn_call_expr.params.at(1);
                 Stage1ZirInst *arg1_value = astgen_node(ag, arg1_node, scope);
-                if (arg0_value == ag->codegen->invalid_inst_src)
+                if (arg1_value == ag->codegen->invalid_inst_src)
                     return arg1_value;
 
                 AstNode *arg2_node = node->data.fn_call_expr.params.at(2);
                 Stage1ZirInst *arg2_value = astgen_node(ag, arg2_node, scope);
-                if (arg1_value == ag->codegen->invalid_inst_src)
+                if (arg2_value == ag->codegen->invalid_inst_src)
                     return arg2_value;
 
                 AstNode *arg3_node = node->data.fn_call_expr.params.at(3);
                 Stage1ZirInst *arg3_value = astgen_node(ag, arg3_node, scope);
-                if (arg2_value == ag->codegen->invalid_inst_src)
+                if (arg3_value == ag->codegen->invalid_inst_src)
                     return arg3_value;
 
                 Stage1ZirInst *select = ir_build_select(ag, scope, node,
diff --git a/src/stage1/ir.cpp b/src/stage1/ir.cpp
index b1583cc6b4..830ce76708 100644
--- a/src/stage1/ir.cpp
+++ b/src/stage1/ir.cpp
@@ -20007,29 +20007,24 @@ static Stage1AirInst *ir_analyze_instruction_truncate(IrAnalyze *ira, Stage1ZirI
     return ir_build_truncate_gen(ira, instruction->base.scope, instruction->base.source_node, dest_type, target);
 }
 
-static Stage1AirInst *ir_analyze_instruction_int_cast(IrAnalyze *ira, Stage1ZirInstIntCast *instruction) {
-    ZigType *dest_type = ir_resolve_type(ira, instruction->dest_type->child);
-    if (type_is_invalid(dest_type))
-        return ira->codegen->invalid_inst_gen;
-
+static Stage1AirInst *ir_analyze_int_cast(IrAnalyze *ira, Scope *scope, AstNode *source_node,
+    ZigType *dest_type, AstNode *dest_type_src_node,
+    Stage1AirInst *target, AstNode *target_src_node)
+{
     ZigType *scalar_dest_type = (dest_type->id == ZigTypeIdVector) ?
         dest_type->data.vector.elem_type : dest_type;
 
     if (scalar_dest_type->id != ZigTypeIdInt && scalar_dest_type->id != ZigTypeIdComptimeInt) {
-        ir_add_error_node(ira, instruction->dest_type->source_node,
+        ir_add_error_node(ira, dest_type_src_node,
                 buf_sprintf("expected integer type, found '%s'", buf_ptr(&scalar_dest_type->name)));
         return ira->codegen->invalid_inst_gen;
     }
 
-    Stage1AirInst *target = instruction->target->child;
-    if (type_is_invalid(target->value->type))
-        return ira->codegen->invalid_inst_gen;
-
     ZigType *scalar_target_type = (target->value->type->id == ZigTypeIdVector) ?
         target->value->type->data.vector.elem_type : target->value->type;
 
     if (scalar_target_type->id != ZigTypeIdInt && scalar_target_type->id != ZigTypeIdComptimeInt) {
-        ir_add_error_node(ira, instruction->target->source_node, buf_sprintf("expected integer type, found '%s'",
+        ir_add_error_node(ira, target_src_node, buf_sprintf("expected integer type, found '%s'",
                     buf_ptr(&scalar_target_type->name)));
         return ira->codegen->invalid_inst_gen;
     }
@@ -20039,10 +20034,24 @@ static Stage1AirInst *ir_analyze_instruction_int_cast(IrAnalyze *ira, Stage1ZirI
         if (val == nullptr)
             return ira->codegen->invalid_inst_gen;
 
-        return ir_implicit_cast2(ira, instruction->target->scope, instruction->target->source_node, target, dest_type);
+        return ir_implicit_cast2(ira, scope, target_src_node, target, dest_type);
     }
 
-    return ir_analyze_widen_or_shorten(ira, instruction->base.scope, instruction->base.source_node, target, dest_type);
+    return ir_analyze_widen_or_shorten(ira, scope, source_node, target, dest_type);
+}
+
+static Stage1AirInst *ir_analyze_instruction_int_cast(IrAnalyze *ira, Stage1ZirInstIntCast *instruction) {
+    ZigType *dest_type = ir_resolve_type(ira, instruction->dest_type->child);
+    if (type_is_invalid(dest_type))
+        return ira->codegen->invalid_inst_gen;
+
+    Stage1AirInst *target = instruction->target->child;
+    if (type_is_invalid(target->value->type))
+        return ira->codegen->invalid_inst_gen;
+
+    return ir_analyze_int_cast(ira, instruction->base.scope, instruction->base.source_node,
+            dest_type, instruction->dest_type->source_node,
+            target, instruction->target->source_node);
 }
 
 static Stage1AirInst *ir_analyze_instruction_float_cast(IrAnalyze *ira, Stage1ZirInstFloatCast *instruction) {
@@ -24282,7 +24291,9 @@ static Stage1AirInst *ir_analyze_instruction_int_to_enum(IrAnalyze *ira, Stage1Z
     if (type_is_invalid(target->value->type))
         return ira->codegen->invalid_inst_gen;
 
-    Stage1AirInst *casted_target = ir_implicit_cast(ira, target, tag_type);
+    Stage1AirInst *casted_target = ir_analyze_int_cast(ira, instruction->base.scope,
+            instruction->base.source_node, tag_type, instruction->dest_type->source_node,
+            target, instruction->target->source_node);
     if (type_is_invalid(casted_target->value->type))
         return ira->codegen->invalid_inst_gen;
 
diff --git a/src/stage1/parser.cpp b/src/stage1/parser.cpp
index 9a429364b1..b06a944172 100644
--- a/src/stage1/parser.cpp
+++ b/src/stage1/parser.cpp
@@ -3482,8 +3482,7 @@ Error source_char_literal(const char *source, uint32_t *result, size_t *bad_inde
     }
 }
 
-
-Buf *token_identifier_buf(RootStruct *root_struct, TokenIndex token) {
+static Buf *token_identifier_buf2(RootStruct *root_struct, TokenIndex token, bool *is_at_syntax) {
     Error err;
     const char *source = buf_ptr(root_struct->source_code);
     size_t byte_offset = root_struct->token_locs[token].offset;
@@ -3495,6 +3494,7 @@ Buf *token_identifier_buf(RootStruct *root_struct, TokenIndex token) {
     assert(source[byte_offset] != '.'); // wrong token index
 
     if (source[byte_offset] == '@') {
+        *is_at_syntax = true;
         size_t bad_index;
         Buf *str = buf_alloc();
         if ((err = source_string_literal_buf(source + byte_offset + 1, str, &bad_index))) {
@@ -3503,6 +3503,7 @@ Buf *token_identifier_buf(RootStruct *root_struct, TokenIndex token) {
         }
         return str;
     } else {
+        *is_at_syntax = false;
         size_t start = byte_offset;
         for (;; byte_offset += 1) {
             if (source[byte_offset] == 0) break;
@@ -3519,7 +3520,17 @@ Buf *token_identifier_buf(RootStruct *root_struct, TokenIndex token) {
     }
 }
 
+Buf *token_identifier_buf(RootStruct *root_struct, TokenIndex token) {
+    bool trash;
+    return token_identifier_buf2(root_struct, token, &trash);
+}
+
 Buf *node_identifier_buf(AstNode *node) {
+    bool trash;
+    return node_identifier_buf2(node, &trash);
+}
+
+Buf *node_identifier_buf2(AstNode *node, bool *is_at_syntax) {
     assert(node->type == NodeTypeIdentifier);
     // Currently, stage1 runs astgen for every comptime function call,
     // resulting the allocation here wasting memory. As a workaround until
@@ -3527,8 +3538,10 @@ Buf *node_identifier_buf(AstNode *node) {
     // we memoize the result into the AST here.
     if (node->data.identifier.name == nullptr) {
         RootStruct *root_struct = node->owner->data.structure.root_struct;
-        node->data.identifier.name = token_identifier_buf(root_struct, node->main_token);
+        node->data.identifier.name = token_identifier_buf2(root_struct, node->main_token,
+                &node->data.identifier.is_at_syntax);
     }
+    *is_at_syntax = node->data.identifier.is_at_syntax;
     return node->data.identifier.name;
 }
 
diff --git a/src/stage1/parser.hpp b/src/stage1/parser.hpp
index 9f73444cb8..8ac8ce6de1 100644
--- a/src/stage1/parser.hpp
+++ b/src/stage1/parser.hpp
@@ -19,6 +19,7 @@ void ast_print(AstNode *node, int indent);
 void ast_visit_node_children(AstNode *node, void (*visit)(AstNode **, void *context), void *context);
 
 Buf *node_identifier_buf(AstNode *node);
+Buf *node_identifier_buf2(AstNode *node, bool *is_at_syntax);
 
 Buf *token_identifier_buf(RootStruct *root_struct, TokenIndex token);
 
diff --git a/src/stage1/target.cpp b/src/stage1/target.cpp
index 9c95be3d5a..85ea2f1d3d 100644
--- a/src/stage1/target.cpp
+++ b/src/stage1/target.cpp
@@ -925,7 +925,7 @@ bool target_has_valgrind_support(const ZigTarget *target) {
         case ZigLLVM_UnknownArch:
             zig_unreachable();
         case ZigLLVM_x86_64:
-            return (target->os == OsLinux || target_os_is_darwin(target->os) || target->os == OsSolaris ||
+            return (target->os == OsLinux || target->os == OsSolaris ||
                 (target->os == OsWindows && target->abi != ZigLLVM_MSVC));
         default:
             return false;
diff --git a/src/target.zig b/src/target.zig
index 0958f1d00f..6f50c8d5e9 100644
--- a/src/target.zig
+++ b/src/target.zig
@@ -166,7 +166,7 @@ pub fn isSingleThreaded(target: std.Target) bool {
 pub fn hasValgrindSupport(target: std.Target) bool {
     switch (target.cpu.arch) {
         .x86_64 => {
-            return target.os.tag == .linux or target.isDarwin() or target.os.tag == .solaris or
+            return target.os.tag == .linux or target.os.tag == .solaris or
                 (target.os.tag == .windows and target.abi != .msvc);
         },
         else => return false,
diff --git a/src/translate_c.zig b/src/translate_c.zig
index e11fc5b736..0cc40cdfd4 100644
--- a/src/translate_c.zig
+++ b/src/translate_c.zig
@@ -719,6 +719,30 @@ fn transQualTypeMaybeInitialized(c: *Context, scope: *Scope, qt: clang.QualType,
         transQualType(c, scope, qt, loc);
 }
 
+/// This is used in global scope to convert a string literal `S` to [*c]u8:
+/// &(struct {
+///     var static = S.*;
+/// }).static;
+fn stringLiteralToCharStar(c: *Context, str: Node) Error!Node {
+    const var_name = Scope.Block.StaticInnerName;
+
+    const variables = try c.arena.alloc(Node, 1);
+    variables[0] = try Tag.mut_str.create(c.arena, .{ .name = var_name, .init = str });
+
+    const anon_struct = try Tag.@"struct".create(c.arena, .{
+        .layout = .none,
+        .fields = &.{},
+        .functions = &.{},
+        .variables = variables,
+    });
+
+    const member_access = try Tag.field_access.create(c.arena, .{
+        .lhs = anon_struct,
+        .field_name = var_name,
+    });
+    return Tag.address_of.create(c.arena, member_access);
+}
+
 /// if mangled_name is not null, this var decl was declared in a block scope.
 fn visitVarDecl(c: *Context, var_decl: *const clang.VarDecl, mangled_name: ?[]const u8) Error!void {
     const var_name = mangled_name orelse try c.str(@ptrCast(*const clang.NamedDecl, var_decl).getName_bytes_begin());
@@ -779,6 +803,8 @@ fn visitVarDecl(c: *Context, var_decl: *const clang.VarDecl, mangled_name: ?[]co
             };
             if (!qualTypeIsBoolean(qual_type) and isBoolRes(init_node.?)) {
                 init_node = try Tag.bool_to_int.create(c.arena, init_node.?);
+            } else if (init_node.?.tag() == .string_literal and qualTypeIsCharStar(qual_type)) {
+                init_node = try stringLiteralToCharStar(c, init_node.?);
             }
         } else {
             init_node = Tag.undefined_literal.init();
@@ -1101,9 +1127,10 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
         record_payload.* = .{
             .base = .{ .tag = ([2]Tag{ .@"struct", .@"union" })[@boolToInt(is_union)] },
             .data = .{
-                .is_packed = is_packed,
+                .layout = if (is_packed) .@"packed" else .@"extern",
                 .fields = try c.arena.dupe(ast.Payload.Record.Field, fields.items),
                 .functions = try c.arena.dupe(Node, functions.items),
+                .variables = &.{},
             },
         };
         break :blk Node.initPayload(&record_payload.base);
@@ -1805,6 +1832,9 @@ fn transDeclStmtOne(
                 Tag.undefined_literal.init();
             if (!qualTypeIsBoolean(qual_type) and isBoolRes(init_node)) {
                 init_node = try Tag.bool_to_int.create(c.arena, init_node);
+            } else if (init_node.tag() == .string_literal and qualTypeIsCharStar(qual_type)) {
+                const dst_type_node = try transQualType(c, scope, qual_type, loc);
+                init_node = try removeCVQualifiers(c, dst_type_node, init_node);
             }
 
             const var_name: []const u8 = if (is_static_local) Scope.Block.StaticInnerName else mangled_name;
@@ -2522,9 +2552,19 @@ fn transInitListExprRecord(
             raw_name = try mem.dupe(c.arena, u8, name);
         }
 
+        var init_expr = try transExpr(c, scope, elem_expr, .used);
+        const field_qt = field_decl.getType();
+        if (init_expr.tag() == .string_literal and qualTypeIsCharStar(field_qt)) {
+            if (scope.id == .root) {
+                init_expr = try stringLiteralToCharStar(c, init_expr);
+            } else {
+                const dst_type_node = try transQualType(c, scope, field_qt, loc);
+                init_expr = try removeCVQualifiers(c, dst_type_node, init_expr);
+            }
+        }
         try field_inits.append(.{
             .name = raw_name,
-            .value = try transExpr(c, scope, elem_expr, .used),
+            .value = init_expr,
         });
     }
     if (ty_node.castTag(.identifier)) |ident_node| {
@@ -3459,6 +3499,10 @@ fn transCallExpr(c: *Context, scope: *Scope, stmt: *const clang.CallExpr, result
                         const param_qt = fn_proto.getParamType(@intCast(c_uint, i));
                         if (isBoolRes(arg) and cIsNativeInt(param_qt)) {
                             arg = try Tag.bool_to_int.create(c.arena, arg);
+                        } else if (arg.tag() == .string_literal and qualTypeIsCharStar(param_qt)) {
+                            const loc = @ptrCast(*const clang.Stmt, stmt).getBeginLoc();
+                            const dst_type_node = try transQualType(c, scope, param_qt, loc);
+                            arg = try removeCVQualifiers(c, dst_type_node, arg);
                         }
                     }
                 },
@@ -3835,6 +3879,12 @@ fn transCreateCompoundAssign(
     return block_scope.complete(c);
 }
 
+// Casting away const or volatile requires us to use @intToPtr
+fn removeCVQualifiers(c: *Context, dst_type_node: Node, expr: Node) Error!Node {
+    const ptr_to_int = try Tag.ptr_to_int.create(c.arena, expr);
+    return Tag.int_to_ptr.create(c.arena, .{ .lhs = dst_type_node, .rhs = ptr_to_int });
+}
+
 fn transCPtrCast(
     c: *Context,
     scope: *Scope,
@@ -3854,10 +3904,7 @@ fn transCPtrCast(
         (src_child_type.isVolatileQualified() and
         !child_type.isVolatileQualified())))
     {
-        // Casting away const or volatile requires us to use @intToPtr
-        const ptr_to_int = try Tag.ptr_to_int.create(c.arena, expr);
-        const int_to_ptr = try Tag.int_to_ptr.create(c.arena, .{ .lhs = dst_type_node, .rhs = ptr_to_int });
-        return int_to_ptr;
+        return removeCVQualifiers(c, dst_type_node, expr);
     } else {
         // Implicit downcasting from higher to lower alignment values is forbidden,
         // use @alignCast to side-step this problem
@@ -4217,6 +4264,26 @@ fn typeIsOpaque(c: *Context, ty: *const clang.Type, loc: clang.SourceLocation) b
     }
 }
 
+/// plain `char *` (not const; not explicitly signed or unsigned)
+fn qualTypeIsCharStar(qt: clang.QualType) bool {
+    if (qualTypeIsPtr(qt)) {
+        const child_qt = qualTypeCanon(qt).getPointeeType();
+        return cIsUnqualifiedChar(child_qt) and !child_qt.isConstQualified();
+    }
+    return false;
+}
+
+/// C `char` without explicit signed or unsigned qualifier
+fn cIsUnqualifiedChar(qt: clang.QualType) bool {
+    const c_type = qualTypeCanon(qt);
+    if (c_type.getTypeClass() != .Builtin) return false;
+    const builtin_ty = @ptrCast(*const clang.BuiltinType, c_type);
+    return switch (builtin_ty.getKind()) {
+        .Char_S, .Char_U => true,
+        else => false,
+    };
+}
+
 fn cIsInteger(qt: clang.QualType) bool {
     return cIsSignedInteger(qt) or cIsUnsignedInteger(qt);
 }
diff --git a/src/translate_c/ast.zig b/src/translate_c/ast.zig
index fa6b749589..1058936191 100644
--- a/src/translate_c/ast.zig
+++ b/src/translate_c/ast.zig
@@ -62,6 +62,8 @@ pub const Node = extern union {
         var_decl,
         /// const name = struct { init }
         static_local_var,
+        /// var name = init.*
+        mut_str,
         func,
         warning,
         @"struct",
@@ -361,7 +363,7 @@ pub const Node = extern union {
                 .array_type, .null_sentinel_array_type => Payload.Array,
                 .arg_redecl, .alias, .fail_decl => Payload.ArgRedecl,
                 .log2_int_type => Payload.Log2IntType,
-                .var_simple, .pub_var_simple, .static_local_var => Payload.SimpleVarDecl,
+                .var_simple, .pub_var_simple, .static_local_var, .mut_str => Payload.SimpleVarDecl,
                 .enum_constant => Payload.EnumConstant,
                 .array_filler => Payload.ArrayFiller,
                 .pub_inline_fn => Payload.PubInlineFn,
@@ -558,9 +560,10 @@ pub const Payload = struct {
     pub const Record = struct {
         base: Payload,
         data: struct {
-            is_packed: bool,
+            layout: enum { @"packed", @"extern", none },
             fields: []Field,
             functions: []Node,
+            variables: []Node,
         },
 
         pub const Field = struct {
@@ -925,23 +928,23 @@ fn renderNode(c: *Context, node: Node) Allocator.Error!NodeIndex {
             return renderCall(c, lhs, payload.args);
         },
         .null_literal => return c.addNode(.{
-            .tag = .null_literal,
-            .main_token = try c.addToken(.keyword_null, "null"),
+            .tag = .identifier,
+            .main_token = try c.addToken(.identifier, "null"),
             .data = undefined,
         }),
         .undefined_literal => return c.addNode(.{
-            .tag = .undefined_literal,
-            .main_token = try c.addToken(.keyword_undefined, "undefined"),
+            .tag = .identifier,
+            .main_token = try c.addToken(.identifier, "undefined"),
             .data = undefined,
         }),
         .true_literal => return c.addNode(.{
-            .tag = .true_literal,
-            .main_token = try c.addToken(.keyword_true, "true"),
+            .tag = .identifier,
+            .main_token = try c.addToken(.identifier, "true"),
             .data = undefined,
         }),
         .false_literal => return c.addNode(.{
-            .tag = .false_literal,
-            .main_token = try c.addToken(.keyword_false, "false"),
+            .tag = .identifier,
+            .main_token = try c.addToken(.identifier, "false"),
             .data = undefined,
         }),
         .zero_literal => return c.addNode(.{
@@ -1229,6 +1232,7 @@ fn renderNode(c: *Context, node: Node) Allocator.Error!NodeIndex {
                 },
             });
             _ = try c.addToken(.r_brace, "}");
+            _ = try c.addToken(.semicolon, ";");
 
             return c.addNode(.{
                 .tag = .simple_var_decl,
@@ -1239,6 +1243,29 @@ fn renderNode(c: *Context, node: Node) Allocator.Error!NodeIndex {
                 },
             });
         },
+        .mut_str => {
+            const payload = node.castTag(.mut_str).?.data;
+
+            const var_tok = try c.addToken(.keyword_var, "var");
+            _ = try c.addIdentifier(payload.name);
+            _ = try c.addToken(.equal, "=");
+
+            const deref = try c.addNode(.{
+                .tag = .deref,
+                .data = .{
+                    .lhs = try renderNodeGrouped(c, payload.init),
+                    .rhs = undefined,
+                },
+                .main_token = try c.addToken(.period_asterisk, ".*"),
+            });
+            _ = try c.addToken(.semicolon, ";");
+
+            return c.addNode(.{
+                .tag = .simple_var_decl,
+                .main_token = var_tok,
+                .data = .{ .lhs = 0, .rhs = deref },
+            });
+        },
         .var_decl => return renderVar(c, node),
         .arg_redecl, .alias => {
             const payload = @fieldParentPtr(Payload.ArgRedecl, "base", node.ptr_otherwise).data;
@@ -1572,8 +1599,8 @@ fn renderNode(c: *Context, node: Node) Allocator.Error!NodeIndex {
             const while_tok = try c.addToken(.keyword_while, "while");
             _ = try c.addToken(.l_paren, "(");
             const cond = try c.addNode(.{
-                .tag = .true_literal,
-                .main_token = try c.addToken(.keyword_true, "true"),
+                .tag = .identifier,
+                .main_token = try c.addToken(.identifier, "true"),
                 .data = undefined,
             });
             _ = try c.addToken(.r_paren, ")");
@@ -1952,9 +1979,9 @@ fn renderNode(c: *Context, node: Node) Allocator.Error!NodeIndex {
 
 fn renderRecord(c: *Context, node: Node) !NodeIndex {
     const payload = @fieldParentPtr(Payload.Record, "base", node.ptr_otherwise).data;
-    if (payload.is_packed)
+    if (payload.layout == .@"packed")
         _ = try c.addToken(.keyword_packed, "packed")
-    else
+    else if (payload.layout == .@"extern")
         _ = try c.addToken(.keyword_extern, "extern");
     const kind_tok = if (node.tag() == .@"struct")
         try c.addToken(.keyword_struct, "struct")
@@ -1963,8 +1990,9 @@ fn renderRecord(c: *Context, node: Node) !NodeIndex {
 
     _ = try c.addToken(.l_brace, "{");
 
+    const num_vars = payload.variables.len;
     const num_funcs = payload.functions.len;
-    const total_members = payload.fields.len + num_funcs;
+    const total_members = payload.fields.len + num_vars + num_funcs;
     const members = try c.gpa.alloc(NodeIndex, std.math.max(total_members, 2));
     defer c.gpa.free(members);
     members[0] = 0;
@@ -2006,8 +2034,11 @@ fn renderRecord(c: *Context, node: Node) !NodeIndex {
         });
         _ = try c.addToken(.comma, ",");
     }
+    for (payload.variables) |variable, i| {
+        members[payload.fields.len + i] = try renderNode(c, variable);
+    }
     for (payload.functions) |function, i| {
-        members[payload.fields.len + i] = try renderNode(c, function);
+        members[payload.fields.len + num_vars + i] = try renderNode(c, function);
     }
     _ = try c.addToken(.r_brace, "}");
 
@@ -2140,7 +2171,7 @@ fn renderNullSentinelArrayType(c: *Context, len: usize, elem_type: Node) !NodeIn
 fn addSemicolonIfNeeded(c: *Context, node: Node) !void {
     switch (node.tag()) {
         .warning => unreachable,
-        .var_decl, .var_simple, .arg_redecl, .alias, .block, .empty_block, .block_single, .@"switch" => {},
+        .var_decl, .var_simple, .arg_redecl, .alias, .block, .empty_block, .block_single, .@"switch", .static_local_var, .mut_str => {},
         .while_true => {
             const payload = node.castTag(.while_true).?.data;
             return addSemicolonIfNotBlock(c, payload);
@@ -2235,6 +2266,7 @@ fn renderNodeGrouped(c: *Context, node: Node) !NodeIndex {
         .offset_of,
         .shuffle,
         .static_local_var,
+        .mut_str,
         => {
             // no grouping needed
             return renderNode(c, node);
diff --git a/src/type.zig b/src/type.zig
index 41f392c04a..467e9c931b 100644
--- a/src/type.zig
+++ b/src/type.zig
@@ -133,6 +133,7 @@ pub const Type = extern union {
 
             .@"union",
             .union_tagged,
+            .type_info,
             => return .Union,
 
             .var_args_param => unreachable, // can be any type
@@ -248,6 +249,30 @@ pub const Type = extern union {
         };
     }
 
+    pub fn ptrIsMutable(ty: Type) bool {
+        return switch (ty.tag()) {
+            .single_const_pointer_to_comptime_int,
+            .const_slice_u8,
+            .single_const_pointer,
+            .many_const_pointer,
+            .manyptr_const_u8,
+            .c_const_pointer,
+            .const_slice,
+            => false,
+
+            .single_mut_pointer,
+            .many_mut_pointer,
+            .manyptr_u8,
+            .c_mut_pointer,
+            .mut_slice,
+            => true,
+
+            .pointer => ty.castTag(.pointer).?.data.mutable,
+
+            else => unreachable,
+        };
+    }
+
     pub fn ptrInfo(self: Type) Payload.Pointer {
         switch (self.tag()) {
             .single_const_pointer_to_comptime_int => return .{ .data = .{
@@ -717,6 +742,7 @@ pub const Type = extern union {
             .call_options,
             .export_options,
             .extern_options,
+            .type_info,
             .@"anyframe",
             .generic_poison,
             => unreachable,
@@ -928,6 +954,7 @@ pub const Type = extern union {
                 .call_options => return writer.writeAll("std.builtin.CallOptions"),
                 .export_options => return writer.writeAll("std.builtin.ExportOptions"),
                 .extern_options => return writer.writeAll("std.builtin.ExternOptions"),
+                .type_info => return writer.writeAll("std.builtin.TypeInfo"),
                 .function => {
                     const payload = ty.castTag(.function).?.data;
                     try writer.writeAll("fn(");
@@ -1178,6 +1205,7 @@ pub const Type = extern union {
             .comptime_int,
             .comptime_float,
             .enum_literal,
+            .type_info,
             => true,
 
             .var_args_param => unreachable,
@@ -1269,6 +1297,7 @@ pub const Type = extern union {
             .call_options => return Value.initTag(.call_options_type),
             .export_options => return Value.initTag(.export_options_type),
             .extern_options => return Value.initTag(.extern_options_type),
+            .type_info => return Value.initTag(.type_info_type),
             .inferred_alloc_const => unreachable,
             .inferred_alloc_mut => unreachable,
             else => return Value.Tag.ty.create(allocator, self),
@@ -1409,6 +1438,7 @@ pub const Type = extern union {
             .empty_struct,
             .empty_struct_literal,
             .@"opaque",
+            .type_info,
             => false,
 
             .inferred_alloc_const => unreachable,
@@ -1636,6 +1666,7 @@ pub const Type = extern union {
             .inferred_alloc_mut,
             .@"opaque",
             .var_args_param,
+            .type_info,
             => unreachable,
 
             .generic_poison => unreachable,
@@ -1667,6 +1698,7 @@ pub const Type = extern union {
             .@"opaque" => unreachable,
             .var_args_param => unreachable,
             .generic_poison => unreachable,
+            .type_info => unreachable,
 
             .@"struct" => {
                 const s = self.castTag(.@"struct").?.data;
@@ -1978,6 +2010,7 @@ pub const Type = extern union {
             .call_options,
             .export_options,
             .extern_options,
+            .type_info,
             => @panic("TODO at some point we gotta resolve builtin types"),
         };
     }
@@ -2691,6 +2724,7 @@ pub const Type = extern union {
             .call_options,
             .export_options,
             .extern_options,
+            .type_info,
             .@"anyframe",
             .anyframe_T,
             .many_const_pointer,
@@ -2778,6 +2812,7 @@ pub const Type = extern union {
         return switch (self.tag()) {
             .@"struct" => &self.castTag(.@"struct").?.data.namespace,
             .enum_full => &self.castTag(.enum_full).?.data.namespace,
+            .enum_nonexhaustive => &self.castTag(.enum_nonexhaustive).?.data.namespace,
             .empty_struct => self.castTag(.empty_struct).?.data,
             .@"opaque" => &self.castTag(.@"opaque").?.data,
             .@"union" => &self.castTag(.@"union").?.data.namespace,
@@ -3022,6 +3057,7 @@ pub const Type = extern union {
             .call_options,
             .export_options,
             .extern_options,
+            .type_info,
             => @panic("TODO resolve std.builtin types"),
             else => unreachable,
         }
@@ -3058,6 +3094,7 @@ pub const Type = extern union {
             .call_options,
             .export_options,
             .extern_options,
+            .type_info,
             => @panic("TODO resolve std.builtin types"),
             else => unreachable,
         }
@@ -3167,6 +3204,7 @@ pub const Type = extern union {
         call_options,
         export_options,
         extern_options,
+        type_info,
         manyptr_u8,
         manyptr_const_u8,
         fn_noreturn_no_args,
@@ -3289,6 +3327,7 @@ pub const Type = extern union {
                 .call_options,
                 .export_options,
                 .extern_options,
+                .type_info,
                 .@"anyframe",
                 => @compileError("Type Tag " ++ @tagName(t) ++ " has no payload"),
 
diff --git a/src/value.zig b/src/value.zig
index 562d7171e8..5ac9f142c4 100644
--- a/src/value.zig
+++ b/src/value.zig
@@ -68,6 +68,7 @@ pub const Value = extern union {
         call_options_type,
         export_options_type,
         extern_options_type,
+        type_info_type,
         manyptr_u8_type,
         manyptr_const_u8_type,
         fn_noreturn_no_args_type,
@@ -132,12 +133,21 @@ pub const Value = extern union {
         /// When the type is error union:
         /// * If the tag is `.@"error"`, the error union is an error.
         /// * If the tag is `.eu_payload`, the error union is a payload.
-        /// * A nested error such as `((anyerror!T1)!T2)` in which the the outer error union
+        /// * A nested error such as `anyerror!(anyerror!T)` in which the the outer error union
         ///   is non-error, but the inner error union is an error, is represented as
         ///   a tag of `.eu_payload`, with a sub-tag of `.@"error"`.
         eu_payload,
         /// A pointer to the payload of an error union, based on a pointer to an error union.
         eu_payload_ptr,
+        /// When the type is optional:
+        /// * If the tag is `.null_value`, the optional is null.
+        /// * If the tag is `.opt_payload`, the optional is a payload.
+        /// * A nested optional such as `??T` in which the the outer optional
+        ///   is non-null, but the inner optional is null, is represented as
+        ///   a tag of `.opt_payload`, with a sub-tag of `.null_value`.
+        opt_payload,
+        /// A pointer to the payload of an optional, based on a pointer to an optional.
+        opt_payload_ptr,
         /// An instance of a struct.
         @"struct",
         /// An instance of a union.
@@ -221,6 +231,7 @@ pub const Value = extern union {
                 .call_options_type,
                 .export_options_type,
                 .extern_options_type,
+                .type_info_type,
                 .generic_poison,
                 => @compileError("Value Tag " ++ @tagName(t) ++ " has no payload"),
 
@@ -236,6 +247,8 @@ pub const Value = extern union {
                 .repeated,
                 .eu_payload,
                 .eu_payload_ptr,
+                .opt_payload,
+                .opt_payload_ptr,
                 => Payload.SubValue,
 
                 .bytes,
@@ -402,6 +415,7 @@ pub const Value = extern union {
             .call_options_type,
             .export_options_type,
             .extern_options_type,
+            .type_info_type,
             .generic_poison,
             => unreachable,
 
@@ -456,7 +470,12 @@ pub const Value = extern union {
                 return Value{ .ptr_otherwise = &new_payload.base };
             },
             .bytes => return self.copyPayloadShallow(allocator, Payload.Bytes),
-            .repeated, .eu_payload, .eu_payload_ptr => {
+            .repeated,
+            .eu_payload,
+            .eu_payload_ptr,
+            .opt_payload,
+            .opt_payload_ptr,
+            => {
                 const payload = self.cast(Payload.SubValue).?;
                 const new_payload = try allocator.create(Payload.SubValue);
                 new_payload.* = .{
@@ -585,6 +604,7 @@ pub const Value = extern union {
             .call_options_type => return out_stream.writeAll("std.builtin.CallOptions"),
             .export_options_type => return out_stream.writeAll("std.builtin.ExportOptions"),
             .extern_options_type => return out_stream.writeAll("std.builtin.ExternOptions"),
+            .type_info_type => return out_stream.writeAll("std.builtin.TypeInfo"),
             .abi_align_default => return out_stream.writeAll("(default ABI alignment)"),
 
             .empty_struct_value => return out_stream.writeAll("struct {}{}"),
@@ -652,12 +672,20 @@ pub const Value = extern union {
                 try out_stream.writeAll("(eu_payload) ");
                 val = val.castTag(.eu_payload).?.data;
             },
+            .opt_payload => {
+                try out_stream.writeAll("(opt_payload) ");
+                val = val.castTag(.opt_payload).?.data;
+            },
             .inferred_alloc => return out_stream.writeAll("(inferred allocation value)"),
             .inferred_alloc_comptime => return out_stream.writeAll("(inferred comptime allocation value)"),
             .eu_payload_ptr => {
                 try out_stream.writeAll("(eu_payload_ptr)");
                 val = val.castTag(.eu_payload_ptr).?.data;
             },
+            .opt_payload_ptr => {
+                try out_stream.writeAll("(opt_payload_ptr)");
+                val = val.castTag(.opt_payload_ptr).?.data;
+            },
         };
     }
 
@@ -743,6 +771,7 @@ pub const Value = extern union {
             .call_options_type => Type.initTag(.call_options),
             .export_options_type => Type.initTag(.export_options),
             .extern_options_type => Type.initTag(.extern_options),
+            .type_info_type => Type.initTag(.type_info),
 
             .int_type => {
                 const payload = self.castTag(.int_type).?.data;
@@ -771,6 +800,38 @@ pub const Value = extern union {
         }
     }
 
+    pub fn enumToInt(val: Value, ty: Type, buffer: *Payload.U64) Value {
+        if (val.castTag(.enum_field_index)) |enum_field_payload| {
+            const field_index = enum_field_payload.data;
+            switch (ty.tag()) {
+                .enum_full, .enum_nonexhaustive => {
+                    const enum_full = ty.cast(Type.Payload.EnumFull).?.data;
+                    if (enum_full.values.count() != 0) {
+                        return enum_full.values.keys()[field_index];
+                    } else {
+                        // Field index and integer values are the same.
+                        buffer.* = .{
+                            .base = .{ .tag = .int_u64 },
+                            .data = field_index,
+                        };
+                        return Value.initPayload(&buffer.base);
+                    }
+                },
+                .enum_simple => {
+                    // Field index and integer values are the same.
+                    buffer.* = .{
+                        .base = .{ .tag = .int_u64 },
+                        .data = field_index,
+                    };
+                    return Value.initPayload(&buffer.base);
+                },
+                else => unreachable,
+            }
+        }
+        // Assume it is already an integer and return it directly.
+        return val;
+    }
+
     /// Asserts the value is an integer.
     pub fn toBigInt(self: Value, space: *BigIntSpace) BigIntConst {
         switch (self.tag()) {
@@ -1127,7 +1188,10 @@ pub const Value = extern union {
     }
 
     pub fn hash(val: Value, ty: Type, hasher: *std.hash.Wyhash) void {
-        switch (ty.zigTypeTag()) {
+        const zig_ty_tag = ty.zigTypeTag();
+        std.hash.autoHash(hasher, zig_ty_tag);
+
+        switch (zig_ty_tag) {
             .BoundFn => unreachable, // TODO remove this from the language
 
             .Void,
@@ -1152,7 +1216,10 @@ pub const Value = extern union {
                 }
             },
             .Float, .ComptimeFloat => {
-                @panic("TODO implement hashing float values");
+                // TODO double check the lang spec. should we to bitwise hashing here,
+                // or a hash that normalizes the float value?
+                const float = val.toFloat(f128);
+                std.hash.autoHash(hasher, @bitCast(u128, float));
             },
             .Pointer => {
                 @panic("TODO implement hashing pointer values");
@@ -1164,7 +1231,15 @@ pub const Value = extern union {
                 @panic("TODO implement hashing struct values");
             },
             .Optional => {
-                @panic("TODO implement hashing optional values");
+                if (val.castTag(.opt_payload)) |payload| {
+                    std.hash.autoHash(hasher, true); // non-null
+                    const sub_val = payload.data;
+                    var buffer: Type.Payload.ElemType = undefined;
+                    const sub_ty = ty.optionalChild(&buffer);
+                    sub_val.hash(sub_ty, hasher);
+                } else {
+                    std.hash.autoHash(hasher, false); // non-null
+                }
             },
             .ErrorUnion => {
                 @panic("TODO implement hashing error union values");
@@ -1173,7 +1248,16 @@ pub const Value = extern union {
                 @panic("TODO implement hashing error set values");
             },
             .Enum => {
-                @panic("TODO implement hashing enum values");
+                var enum_space: Payload.U64 = undefined;
+                const int_val = val.enumToInt(ty, &enum_space);
+
+                var space: BigIntSpace = undefined;
+                const big = int_val.toBigInt(&space);
+
+                std.hash.autoHash(hasher, big.positive);
+                for (big.limbs) |limb| {
+                    std.hash.autoHash(hasher, limb);
+                }
             },
             .Union => {
                 @panic("TODO implement hashing union values");
@@ -1252,6 +1336,11 @@ pub const Value = extern union {
                 const err_union_val = (try err_union_ptr.pointerDeref(allocator)) orelse return null;
                 break :blk err_union_val.castTag(.eu_payload).?.data;
             },
+            .opt_payload_ptr => blk: {
+                const opt_ptr = self.castTag(.opt_payload_ptr).?.data;
+                const opt_val = (try opt_ptr.pointerDeref(allocator)) orelse return null;
+                break :blk opt_val.castTag(.opt_payload).?.data;
+            },
 
             .zero,
             .one,
@@ -1349,13 +1438,14 @@ pub const Value = extern union {
     /// Valid for all types. Asserts the value is not undefined and not unreachable.
     pub fn isNull(self: Value) bool {
         return switch (self.tag()) {
+            .null_value => true,
+            .opt_payload => false,
+
             .undef => unreachable,
             .unreachable_value => unreachable,
             .inferred_alloc => unreachable,
             .inferred_alloc_comptime => unreachable,
-            .null_value => true,
-
-            else => false,
+            else => unreachable,
         };
     }
 
@@ -1385,6 +1475,10 @@ pub const Value = extern union {
         return switch (val.tag()) {
             .eu_payload => true,
             else => false,
+
+            .undef => unreachable,
+            .inferred_alloc => unreachable,
+            .inferred_alloc_comptime => unreachable,
         };
     }
 
@@ -1514,6 +1608,31 @@ pub const Value = extern union {
         return Tag.int_u64.create(arena, truncated);
     }
 
+    pub fn shr(lhs: Value, rhs: Value, allocator: *Allocator) !Value {
+        // TODO is this a performance issue? maybe we should try the operation without
+        // resorting to BigInt first.
+        var lhs_space: Value.BigIntSpace = undefined;
+        const lhs_bigint = lhs.toBigInt(&lhs_space);
+        const shift = rhs.toUnsignedInt();
+        const limbs = try allocator.alloc(
+            std.math.big.Limb,
+            lhs_bigint.limbs.len - (shift / (@sizeOf(std.math.big.Limb) * 8)),
+        );
+        var result_bigint = BigIntMutable{
+            .limbs = limbs,
+            .positive = undefined,
+            .len = undefined,
+        };
+        result_bigint.shiftRight(lhs_bigint, shift);
+        const result_limbs = result_bigint.limbs[0..result_bigint.len];
+
+        if (result_bigint.positive) {
+            return Value.Tag.int_big_positive.create(allocator, result_limbs);
+        } else {
+            return Value.Tag.int_big_negative.create(allocator, result_limbs);
+        }
+    }
+
     pub fn floatAdd(
         lhs: Value,
         rhs: Value,