Merge pull request #5583 from ziglang/zig-ast-to-zir

self-hosted: hook up Zig AST to ZIR

1 files changed, 1452 insertions, 455 deletions

diff --git a/src-self-hosted/Module.zig b/src-self-hosted/Module.zig
index 4bcc30a65e..89dcac3f41 100644
--- a/src-self-hosted/Module.zig
+++ b/src-self-hosted/Module.zig
@@ -15,13 +15,16 @@ const ir = @import("ir.zig");
 const zir = @import("zir.zig");
 const Module = @This();
 const Inst = ir.Inst;
+const ast = std.zig.ast;
+const trace = @import("tracy.zig").trace;
 
 /// General-purpose allocator.
 allocator: *Allocator,
 /// Pointer to externally managed resource.
 root_pkg: *Package,
 /// Module owns this resource.
-root_scope: *Scope.ZIRModule,
+/// The `Scope` is either a `Scope.ZIRModule` or `Scope.File`.
+root_scope: *Scope,
 bin_file: link.ElfFile,
 bin_file_dir: std.fs.Dir,
 bin_file_path: []const u8,
@@ -35,10 +38,10 @@ decl_exports: std.AutoHashMap(*Decl, []*Export),
 /// This table owns the Export memory.
 export_owners: std.AutoHashMap(*Decl, []*Export),
 /// Maps fully qualified namespaced names to the Decl struct for them.
-decl_table: std.AutoHashMap(Decl.Hash, *Decl),
+decl_table: DeclTable,
 
 optimize_mode: std.builtin.Mode,
-link_error_flags: link.ElfFile.ErrorFlags = link.ElfFile.ErrorFlags{},
+link_error_flags: link.ElfFile.ErrorFlags = .{},
 
 work_queue: std.fifo.LinearFifo(WorkItem, .Dynamic),
 
@@ -49,8 +52,8 @@ work_queue: std.fifo.LinearFifo(WorkItem, .Dynamic),
 /// a Decl can have a failed_decls entry but have analysis status of success.
 failed_decls: std.AutoHashMap(*Decl, *ErrorMsg),
 /// Using a map here for consistency with the other fields here.
-/// The ErrorMsg memory is owned by the `Scope.ZIRModule`, using Module's allocator.
-failed_files: std.AutoHashMap(*Scope.ZIRModule, *ErrorMsg),
+/// The ErrorMsg memory is owned by the `Scope`, using Module's allocator.
+failed_files: std.AutoHashMap(*Scope, *ErrorMsg),
 /// Using a map here for consistency with the other fields here.
 /// The ErrorMsg memory is owned by the `Export`, using Module's allocator.
 failed_exports: std.AutoHashMap(*Export, *ErrorMsg),
@@ -60,15 +63,23 @@ failed_exports: std.AutoHashMap(*Export, *ErrorMsg),
 /// previous analysis.
 generation: u32 = 0,
 
+next_anon_name_index: usize = 0,
+
 /// Candidates for deletion. After a semantic analysis update completes, this list
 /// contains Decls that need to be deleted if they end up having no references to them.
-deletion_set: std.ArrayListUnmanaged(*Decl) = std.ArrayListUnmanaged(*Decl){},
+deletion_set: std.ArrayListUnmanaged(*Decl) = .{},
+
+keep_source_files_loaded: bool,
+
+const DeclTable = std.HashMap(Scope.NameHash, *Decl, Scope.name_hash_hash, Scope.name_hash_eql);
 
-pub const WorkItem = union(enum) {
+const WorkItem = union(enum) {
     /// Write the machine code for a Decl to the output file.
     codegen_decl: *Decl,
-    /// Decl has been determined to be outdated; perform semantic analysis again.
-    re_analyze_decl: *Decl,
+    /// The Decl needs to be analyzed and possibly export itself.
+    /// It may have already be analyzed, or it may have been determined
+    /// to be outdated; in this case perform semantic analysis again.
+    analyze_decl: *Decl,
 };
 
 pub const Export = struct {
@@ -99,13 +110,12 @@ pub const Decl = struct {
     /// mapping them to an address in the output file.
     /// Memory owned by this decl, using Module's allocator.
     name: [*:0]const u8,
-    /// The direct parent container of the Decl. This field will need to get more fleshed out when
-    /// self-hosted supports proper struct types and Zig AST => ZIR.
+    /// The direct parent container of the Decl. This is either a `Scope.File` or `Scope.ZIRModule`.
     /// Reference to externally owned memory.
-    scope: *Scope.ZIRModule,
-    /// Byte offset into the source file that contains this declaration.
-    /// This is the base offset that src offsets within this Decl are relative to.
-    src: usize,
+    scope: *Scope,
+    /// The AST Node decl index or ZIR Inst index that contains this declaration.
+    /// Must be recomputed when the corresponding source file is modified.
+    src_index: usize,
     /// The most recent value of the Decl after a successful semantic analysis.
     typed_value: union(enum) {
         never_succeeded: void,
@@ -116,6 +126,9 @@ pub const Decl = struct {
     /// analysis of the function body is performed with this value set to `success`. Functions
     /// have their own analysis status field.
     analysis: enum {
+        /// This Decl corresponds to an AST Node that has not been referenced yet, and therefore
+        /// because of Zig's lazy declaration analysis, it will remain unanalyzed until referenced.
+        unreferenced,
         /// Semantic analysis for this Decl is running right now. This state detects dependency loops.
         in_progress,
         /// This Decl might be OK but it depends on another one which did not successfully complete
@@ -125,6 +138,10 @@ pub const Decl = struct {
         /// There will be a corresponding ErrorMsg in Module.failed_decls.
         sema_failure,
         /// There will be a corresponding ErrorMsg in Module.failed_decls.
+        /// This indicates the failure was something like running out of disk space,
+        /// and attempting semantic analysis again may succeed.
+        sema_failure_retryable,
+        /// There will be a corresponding ErrorMsg in Module.failed_decls.
         codegen_failure,
         /// There will be a corresponding ErrorMsg in Module.failed_decls.
         /// This indicates the failure was something like running out of disk space,
@@ -150,7 +167,7 @@ pub const Decl = struct {
     /// This is populated regardless of semantic analysis and code generation.
     link: link.ElfFile.TextBlock = link.ElfFile.TextBlock.empty,
 
-    contents_hash: Hash,
+    contents_hash: std.zig.SrcHash,
 
     /// The shallow set of other decls whose typed_value could possibly change if this Decl's
     /// typed_value is modified.
@@ -169,28 +186,28 @@ pub const Decl = struct {
         allocator.destroy(self);
     }
 
-    pub const Hash = [16]u8;
-
-    /// If the name is small enough, it is used directly as the hash.
-    /// If it is long, blake3 hash is computed.
-    pub fn hashSimpleName(name: []const u8) Hash {
-        var out: Hash = undefined;
-        if (name.len <= Hash.len) {
-            mem.copy(u8, &out, name);
-            mem.set(u8, out[name.len..], 0);
-        } else {
-            std.crypto.Blake3.hash(name, &out);
+    pub fn src(self: Decl) usize {
+        switch (self.scope.tag) {
+            .file => {
+                const file = @fieldParentPtr(Scope.File, "base", self.scope);
+                const tree = file.contents.tree;
+                const decl_node = tree.root_node.decls()[self.src_index];
+                return tree.token_locs[decl_node.firstToken()].start;
+            },
+            .zir_module => {
+                const zir_module = @fieldParentPtr(Scope.ZIRModule, "base", self.scope);
+                const module = zir_module.contents.module;
+                const src_decl = module.decls[self.src_index];
+                return src_decl.inst.src;
+            },
+            .block => unreachable,
+            .gen_zir => unreachable,
+            .decl => unreachable,
         }
-        return out;
     }
 
-    /// Must generate unique bytes with no collisions with other decls.
-    /// The point of hashing here is only to limit the number of bytes of
-    /// the unique identifier to a fixed size (16 bytes).
-    pub fn fullyQualifiedNameHash(self: Decl) Hash {
-        // Right now we only have ZIRModule as the source. So this is simply the
-        // relative name of the decl.
-        return hashSimpleName(mem.spanZ(self.name));
+    pub fn fullyQualifiedNameHash(self: Decl) Scope.NameHash {
+        return self.scope.fullyQualifiedNameHash(mem.spanZ(self.name));
     }
 
     pub fn typedValue(self: *Decl) error{AnalysisFail}!TypedValue {
@@ -248,11 +265,9 @@ pub const Decl = struct {
 /// Fn struct memory is owned by the Decl's TypedValue.Managed arena allocator.
 pub const Fn = struct {
     /// This memory owned by the Decl's TypedValue.Managed arena allocator.
-    fn_type: Type,
     analysis: union(enum) {
-        /// The value is the source instruction.
-        queued: *zir.Inst.Fn,
-        in_progress: *Analysis,
+        queued: *ZIR,
+        in_progress,
         /// There will be a corresponding ErrorMsg in Module.failed_decls
         sema_failure,
         /// This Fn might be OK but it depends on another Decl which did not successfully complete
@@ -266,16 +281,20 @@ pub const Fn = struct {
     /// of Fn analysis.
     pub const Analysis = struct {
         inner_block: Scope.Block,
-        /// TODO Performance optimization idea: instead of this inst_table,
-        /// use a field in the zir.Inst instead to track corresponding instructions
-        inst_table: std.AutoHashMap(*zir.Inst, *Inst),
-        needed_inst_capacity: usize,
+    };
+
+    /// Contains un-analyzed ZIR instructions generated from Zig source AST.
+    pub const ZIR = struct {
+        body: zir.Module.Body,
+        arena: std.heap.ArenaAllocator.State,
     };
 };
 
 pub const Scope = struct {
     tag: Tag,
 
+    pub const NameHash = [16]u8;
+
     pub fn cast(base: *Scope, comptime T: type) ?*T {
         if (base.tag != T.base_tag)
             return null;
@@ -289,7 +308,9 @@ pub const Scope = struct {
         switch (self.tag) {
             .block => return self.cast(Block).?.arena,
             .decl => return &self.cast(DeclAnalysis).?.arena.allocator,
+            .gen_zir => return &self.cast(GenZIR).?.arena.allocator,
             .zir_module => return &self.cast(ZIRModule).?.contents.module.arena.allocator,
+            .file => unreachable,
         }
     }
 
@@ -298,18 +319,45 @@ pub const Scope = struct {
     pub fn decl(self: *Scope) ?*Decl {
         return switch (self.tag) {
             .block => self.cast(Block).?.decl,
+            .gen_zir => self.cast(GenZIR).?.decl,
             .decl => self.cast(DeclAnalysis).?.decl,
             .zir_module => null,
+            .file => null,
         };
     }
 
-    /// Asserts the scope has a parent which is a ZIRModule and
+    /// Asserts the scope has a parent which is a ZIRModule or File and
     /// returns it.
-    pub fn namespace(self: *Scope) *ZIRModule {
+    pub fn namespace(self: *Scope) *Scope {
         switch (self.tag) {
             .block => return self.cast(Block).?.decl.scope,
+            .gen_zir => return self.cast(GenZIR).?.decl.scope,
             .decl => return self.cast(DeclAnalysis).?.decl.scope,
-            .zir_module => return self.cast(ZIRModule).?,
+            .zir_module, .file => return self,
+        }
+    }
+
+    /// Must generate unique bytes with no collisions with other decls.
+    /// The point of hashing here is only to limit the number of bytes of
+    /// the unique identifier to a fixed size (16 bytes).
+    pub fn fullyQualifiedNameHash(self: *Scope, name: []const u8) NameHash {
+        switch (self.tag) {
+            .block => unreachable,
+            .gen_zir => unreachable,
+            .decl => unreachable,
+            .zir_module => return self.cast(ZIRModule).?.fullyQualifiedNameHash(name),
+            .file => return self.cast(File).?.fullyQualifiedNameHash(name),
+        }
+    }
+
+    /// Asserts the scope is a child of a File and has an AST tree and returns the tree.
+    pub fn tree(self: *Scope) *ast.Tree {
+        switch (self.tag) {
+            .file => return self.cast(File).?.contents.tree,
+            .zir_module => unreachable,
+            .decl => return self.cast(DeclAnalysis).?.decl.scope.cast(File).?.contents.tree,
+            .block => return self.cast(Block).?.decl.scope.cast(File).?.contents.tree,
+            .gen_zir => return self.cast(GenZIR).?.decl.scope.cast(File).?.contents.tree,
         }
     }
 
@@ -325,10 +373,173 @@ pub const Scope = struct {
         });
     }
 
+    /// Asserts the scope has a parent which is a ZIRModule or File and
+    /// returns the sub_file_path field.
+    pub fn subFilePath(base: *Scope) []const u8 {
+        switch (base.tag) {
+            .file => return @fieldParentPtr(File, "base", base).sub_file_path,
+            .zir_module => return @fieldParentPtr(ZIRModule, "base", base).sub_file_path,
+            .block => unreachable,
+            .gen_zir => unreachable,
+            .decl => unreachable,
+        }
+    }
+
+    pub fn unload(base: *Scope, allocator: *Allocator) void {
+        switch (base.tag) {
+            .file => return @fieldParentPtr(File, "base", base).unload(allocator),
+            .zir_module => return @fieldParentPtr(ZIRModule, "base", base).unload(allocator),
+            .block => unreachable,
+            .gen_zir => unreachable,
+            .decl => unreachable,
+        }
+    }
+
+    pub fn getSource(base: *Scope, module: *Module) ![:0]const u8 {
+        switch (base.tag) {
+            .file => return @fieldParentPtr(File, "base", base).getSource(module),
+            .zir_module => return @fieldParentPtr(ZIRModule, "base", base).getSource(module),
+            .gen_zir => unreachable,
+            .block => unreachable,
+            .decl => unreachable,
+        }
+    }
+
+    /// Asserts the scope is a namespace Scope and removes the Decl from the namespace.
+    pub fn removeDecl(base: *Scope, child: *Decl) void {
+        switch (base.tag) {
+            .file => return @fieldParentPtr(File, "base", base).removeDecl(child),
+            .zir_module => return @fieldParentPtr(ZIRModule, "base", base).removeDecl(child),
+            .block => unreachable,
+            .gen_zir => unreachable,
+            .decl => unreachable,
+        }
+    }
+
+    /// Asserts the scope is a File or ZIRModule and deinitializes it, then deallocates it.
+    pub fn destroy(base: *Scope, allocator: *Allocator) void {
+        switch (base.tag) {
+            .file => {
+                const scope_file = @fieldParentPtr(File, "base", base);
+                scope_file.deinit(allocator);
+                allocator.destroy(scope_file);
+            },
+            .zir_module => {
+                const scope_zir_module = @fieldParentPtr(ZIRModule, "base", base);
+                scope_zir_module.deinit(allocator);
+                allocator.destroy(scope_zir_module);
+            },
+            .block => unreachable,
+            .gen_zir => unreachable,
+            .decl => unreachable,
+        }
+    }
+
+    fn name_hash_hash(x: NameHash) u32 {
+        return @truncate(u32, @bitCast(u128, x));
+    }
+
+    fn name_hash_eql(a: NameHash, b: NameHash) bool {
+        return @bitCast(u128, a) == @bitCast(u128, b);
+    }
+
     pub const Tag = enum {
+        /// .zir source code.
         zir_module,
+        /// .zig source code.
+        file,
         block,
         decl,
+        gen_zir,
+    };
+
+    pub const File = struct {
+        pub const base_tag: Tag = .file;
+        base: Scope = Scope{ .tag = base_tag },
+
+        /// Relative to the owning package's root_src_dir.
+        /// Reference to external memory, not owned by File.
+        sub_file_path: []const u8,
+        source: union(enum) {
+            unloaded: void,
+            bytes: [:0]const u8,
+        },
+        contents: union {
+            not_available: void,
+            tree: *ast.Tree,
+        },
+        status: enum {
+            never_loaded,
+            unloaded_success,
+            unloaded_parse_failure,
+            loaded_success,
+        },
+
+        /// Direct children of the file.
+        decls: ArrayListUnmanaged(*Decl),
+
+        pub fn unload(self: *File, allocator: *Allocator) void {
+            switch (self.status) {
+                .never_loaded,
+                .unloaded_parse_failure,
+                .unloaded_success,
+                => {},
+
+                .loaded_success => {
+                    self.contents.tree.deinit();
+                    self.status = .unloaded_success;
+                },
+            }
+            switch (self.source) {
+                .bytes => |bytes| {
+                    allocator.free(bytes);
+                    self.source = .{ .unloaded = {} };
+                },
+                .unloaded => {},
+            }
+        }
+
+        pub fn deinit(self: *File, allocator: *Allocator) void {
+            self.decls.deinit(allocator);
+            self.unload(allocator);
+            self.* = undefined;
+        }
+
+        pub fn removeDecl(self: *File, child: *Decl) void {
+            for (self.decls.items) |item, i| {
+                if (item == child) {
+                    _ = self.decls.swapRemove(i);
+                    return;
+                }
+            }
+        }
+
+        pub fn dumpSrc(self: *File, src: usize) void {
+            const loc = std.zig.findLineColumn(self.source.bytes, src);
+            std.debug.warn("{}:{}:{}\n", .{ self.sub_file_path, loc.line + 1, loc.column + 1 });
+        }
+
+        pub fn getSource(self: *File, module: *Module) ![:0]const u8 {
+            switch (self.source) {
+                .unloaded => {
+                    const source = try module.root_pkg.root_src_dir.readFileAllocOptions(
+                        module.allocator,
+                        self.sub_file_path,
+                        std.math.maxInt(u32),
+                        1,
+                        0,
+                    );
+                    self.source = .{ .bytes = source };
+                    return source;
+                },
+                .bytes => |bytes| return bytes,
+            }
+        }
+
+        pub fn fullyQualifiedNameHash(self: *File, name: []const u8) NameHash {
+            // We don't have struct scopes yet so this is currently just a simple name hash.
+            return std.zig.hashSrc(name);
+        }
     };
 
     pub const ZIRModule = struct {
@@ -355,6 +566,11 @@ pub const Scope = struct {
             loaded_success,
         },
 
+        /// Even though .zir files only have 1 module, this set is still needed
+        /// because of anonymous Decls, which can exist in the global set, but
+        /// not this one.
+        decls: ArrayListUnmanaged(*Decl),
+
         pub fn unload(self: *ZIRModule, allocator: *Allocator) void {
             switch (self.status) {
                 .never_loaded,
@@ -366,11 +582,13 @@ pub const Scope = struct {
                 .loaded_success => {
                     self.contents.module.deinit(allocator);
                     allocator.destroy(self.contents.module);
+                    self.contents = .{ .not_available = {} };
                     self.status = .unloaded_success;
                 },
                 .loaded_sema_failure => {
                     self.contents.module.deinit(allocator);
                     allocator.destroy(self.contents.module);
+                    self.contents = .{ .not_available = {} };
                     self.status = .unloaded_sema_failure;
                 },
             }
@@ -384,14 +602,46 @@ pub const Scope = struct {
         }
 
         pub fn deinit(self: *ZIRModule, allocator: *Allocator) void {
+            self.decls.deinit(allocator);
             self.unload(allocator);
             self.* = undefined;
         }
 
+        pub fn removeDecl(self: *ZIRModule, child: *Decl) void {
+            for (self.decls.items) |item, i| {
+                if (item == child) {
+                    _ = self.decls.swapRemove(i);
+                    return;
+                }
+            }
+        }
+
         pub fn dumpSrc(self: *ZIRModule, src: usize) void {
             const loc = std.zig.findLineColumn(self.source.bytes, src);
             std.debug.warn("{}:{}:{}\n", .{ self.sub_file_path, loc.line + 1, loc.column + 1 });
         }
+
+        pub fn getSource(self: *ZIRModule, module: *Module) ![:0]const u8 {
+            switch (self.source) {
+                .unloaded => {
+                    const source = try module.root_pkg.root_src_dir.readFileAllocOptions(
+                        module.allocator,
+                        self.sub_file_path,
+                        std.math.maxInt(u32),
+                        1,
+                        0,
+                    );
+                    self.source = .{ .bytes = source };
+                    return source;
+                },
+                .bytes => |bytes| return bytes,
+            }
+        }
+
+        pub fn fullyQualifiedNameHash(self: *ZIRModule, name: []const u8) NameHash {
+            // ZIR modules only have 1 file with all decls global in the same namespace.
+            return std.zig.hashSrc(name);
+        }
     };
 
     /// This is a temporary structure, references to it are valid only
@@ -399,7 +649,7 @@ pub const Scope = struct {
     pub const Block = struct {
         pub const base_tag: Tag = .block;
         base: Scope = Scope{ .tag = base_tag },
-        func: *Fn,
+        func: ?*Fn,
         decl: *Decl,
         instructions: ArrayListUnmanaged(*Inst),
         /// Points to the arena allocator of DeclAnalysis
@@ -414,6 +664,16 @@ pub const Scope = struct {
         decl: *Decl,
         arena: std.heap.ArenaAllocator,
     };
+
+    /// This is a temporary structure, references to it are valid only
+    /// during semantic analysis of the decl.
+    pub const GenZIR = struct {
+        pub const base_tag: Tag = .gen_zir;
+        base: Scope = Scope{ .tag = base_tag },
+        decl: *Decl,
+        arena: std.heap.ArenaAllocator,
+        instructions: std.ArrayList(*zir.Inst),
+    };
 };
 
 pub const Body = struct {
@@ -463,19 +723,10 @@ pub const InitOptions = struct {
     link_mode: ?std.builtin.LinkMode = null,
     object_format: ?std.builtin.ObjectFormat = null,
     optimize_mode: std.builtin.Mode = .Debug,
+    keep_source_files_loaded: bool = false,
 };
 
 pub fn init(gpa: *Allocator, options: InitOptions) !Module {
-    const root_scope = try gpa.create(Scope.ZIRModule);
-    errdefer gpa.destroy(root_scope);
-
-    root_scope.* = .{
-        .sub_file_path = options.root_pkg.root_src_path,
-        .source = .{ .unloaded = {} },
-        .contents = .{ .not_available = {} },
-        .status = .never_loaded,
-    };
-
     const bin_file_dir = options.bin_file_dir orelse std.fs.cwd();
     var bin_file = try link.openBinFilePath(gpa, bin_file_dir, options.bin_file_path, .{
         .target = options.target,
@@ -485,6 +736,32 @@ pub fn init(gpa: *Allocator, options: InitOptions) !Module {
     });
     errdefer bin_file.deinit();
 
+    const root_scope = blk: {
+        if (mem.endsWith(u8, options.root_pkg.root_src_path, ".zig")) {
+            const root_scope = try gpa.create(Scope.File);
+            root_scope.* = .{
+                .sub_file_path = options.root_pkg.root_src_path,
+                .source = .{ .unloaded = {} },
+                .contents = .{ .not_available = {} },
+                .status = .never_loaded,
+                .decls = .{},
+            };
+            break :blk &root_scope.base;
+        } else if (mem.endsWith(u8, options.root_pkg.root_src_path, ".zir")) {
+            const root_scope = try gpa.create(Scope.ZIRModule);
+            root_scope.* = .{
+                .sub_file_path = options.root_pkg.root_src_path,
+                .source = .{ .unloaded = {} },
+                .contents = .{ .not_available = {} },
+                .status = .never_loaded,
+                .decls = .{},
+            };
+            break :blk &root_scope.base;
+        } else {
+            unreachable;
+        }
+    };
+
     return Module{
         .allocator = gpa,
         .root_pkg = options.root_pkg,
@@ -493,13 +770,14 @@ pub fn init(gpa: *Allocator, options: InitOptions) !Module {
         .bin_file_path = options.bin_file_path,
         .bin_file = bin_file,
         .optimize_mode = options.optimize_mode,
-        .decl_table = std.AutoHashMap(Decl.Hash, *Decl).init(gpa),
+        .decl_table = DeclTable.init(gpa),
         .decl_exports = std.AutoHashMap(*Decl, []*Export).init(gpa),
         .export_owners = std.AutoHashMap(*Decl, []*Export).init(gpa),
         .failed_decls = std.AutoHashMap(*Decl, *ErrorMsg).init(gpa),
-        .failed_files = std.AutoHashMap(*Scope.ZIRModule, *ErrorMsg).init(gpa),
+        .failed_files = std.AutoHashMap(*Scope, *ErrorMsg).init(gpa),
         .failed_exports = std.AutoHashMap(*Export, *ErrorMsg).init(gpa),
         .work_queue = std.fifo.LinearFifo(WorkItem, .Dynamic).init(gpa),
+        .keep_source_files_loaded = options.keep_source_files_loaded,
     };
 }
 
@@ -551,10 +829,7 @@ pub fn deinit(self: *Module) void {
         }
         self.export_owners.deinit();
     }
-    {
-        self.root_scope.deinit(allocator);
-        allocator.destroy(self.root_scope);
-    }
+    self.root_scope.destroy(allocator);
     self.* = undefined;
 }
 
@@ -571,19 +846,31 @@ pub fn target(self: Module) std.Target {
 
 /// Detect changes to source files, perform semantic analysis, and update the output files.
 pub fn update(self: *Module) !void {
+    const tracy = trace(@src());
+    defer tracy.end();
+
     self.generation += 1;
 
     // TODO Use the cache hash file system to detect which source files changed.
-    // Here we simulate a full cache miss.
-    // Analyze the root source file now.
-    // Source files could have been loaded for any reason; to force a refresh we unload now.
-    self.root_scope.unload(self.allocator);
-    self.analyzeRoot(self.root_scope) catch |err| switch (err) {
-        error.AnalysisFail => {
-            assert(self.totalErrorCount() != 0);
-        },
-        else => |e| return e,
-    };
+    // Until then we simulate a full cache miss. Source files could have been loaded for any reason;
+    // to force a refresh we unload now.
+    if (self.root_scope.cast(Scope.File)) |zig_file| {
+        zig_file.unload(self.allocator);
+        self.analyzeRootSrcFile(zig_file) catch |err| switch (err) {
+            error.AnalysisFail => {
+                assert(self.totalErrorCount() != 0);
+            },
+            else => |e| return e,
+        };
+    } else if (self.root_scope.cast(Scope.ZIRModule)) |zir_module| {
+        zir_module.unload(self.allocator);
+        self.analyzeRootZIRModule(zir_module) catch |err| switch (err) {
+            error.AnalysisFail => {
+                assert(self.totalErrorCount() != 0);
+            },
+            else => |e| return e,
+        };
+    }
 
     try self.performAllTheWork();
 
@@ -596,14 +883,16 @@ pub fn update(self: *Module) !void {
         try self.deleteDecl(decl);
     }
 
+    self.link_error_flags = self.bin_file.error_flags;
+
     // If there are any errors, we anticipate the source files being loaded
     // to report error messages. Otherwise we unload all source files to save memory.
     if (self.totalErrorCount() == 0) {
-        self.root_scope.unload(self.allocator);
+        if (!self.keep_source_files_loaded) {
+            self.root_scope.unload(self.allocator);
+        }
+        try self.bin_file.flush();
     }
-
-    try self.bin_file.flush();
-    self.link_error_flags = self.bin_file.error_flags;
 }
 
 /// Having the file open for writing is problematic as far as executing the
@@ -619,10 +908,10 @@ pub fn makeBinFileWritable(self: *Module) !void {
 }
 
 pub fn totalErrorCount(self: *Module) usize {
-    return self.failed_decls.size +
+    const total = self.failed_decls.size +
         self.failed_files.size +
-        self.failed_exports.size +
-        @boolToInt(self.link_error_flags.no_entry_point_found);
+        self.failed_exports.size;
+    return if (total == 0) @boolToInt(self.link_error_flags.no_entry_point_found) else total;
 }
 
 pub fn getAllErrorsAlloc(self: *Module) !AllErrors {
@@ -637,8 +926,8 @@ pub fn getAllErrorsAlloc(self: *Module) !AllErrors {
         while (it.next()) |kv| {
             const scope = kv.key;
             const err_msg = kv.value;
-            const source = try self.getSource(scope);
-            try AllErrors.add(&arena, &errors, scope.sub_file_path, source, err_msg.*);
+            const source = try scope.getSource(self);
+            try AllErrors.add(&arena, &errors, scope.subFilePath(), source, err_msg.*);
         }
     }
     {
@@ -646,8 +935,8 @@ pub fn getAllErrorsAlloc(self: *Module) !AllErrors {
         while (it.next()) |kv| {
             const decl = kv.key;
             const err_msg = kv.value;
-            const source = try self.getSource(decl.scope);
-            try AllErrors.add(&arena, &errors, decl.scope.sub_file_path, source, err_msg.*);
+            const source = try decl.scope.getSource(self);
+            try AllErrors.add(&arena, &errors, decl.scope.subFilePath(), source, err_msg.*);
         }
     }
     {
@@ -655,12 +944,12 @@ pub fn getAllErrorsAlloc(self: *Module) !AllErrors {
         while (it.next()) |kv| {
             const decl = kv.key.owner_decl;
             const err_msg = kv.value;
-            const source = try self.getSource(decl.scope);
-            try AllErrors.add(&arena, &errors, decl.scope.sub_file_path, source, err_msg.*);
+            const source = try decl.scope.getSource(self);
+            try AllErrors.add(&arena, &errors, decl.scope.subFilePath(), source, err_msg.*);
         }
     }
 
-    if (self.link_error_flags.no_entry_point_found) {
+    if (errors.items.len == 0 and self.link_error_flags.no_entry_point_found) {
         try errors.append(.{
             .src_path = self.root_pkg.root_src_path,
             .line = 0,
@@ -683,12 +972,14 @@ const InnerError = error{ OutOfMemory, AnalysisFail };
 pub fn performAllTheWork(self: *Module) error{OutOfMemory}!void {
     while (self.work_queue.readItem()) |work_item| switch (work_item) {
         .codegen_decl => |decl| switch (decl.analysis) {
+            .unreferenced => unreachable,
             .in_progress => unreachable,
             .outdated => unreachable,
 
             .sema_failure,
             .codegen_failure,
             .dependency_failure,
+            .sema_failure_retryable,
             => continue,
 
             .complete, .codegen_failure_retryable => {
@@ -696,12 +987,10 @@ pub fn performAllTheWork(self: *Module) error{OutOfMemory}!void {
                     switch (payload.func.analysis) {
                         .queued => self.analyzeFnBody(decl, payload.func) catch |err| switch (err) {
                             error.AnalysisFail => {
-                                if (payload.func.analysis == .queued) {
-                                    payload.func.analysis = .dependency_failure;
-                                }
+                                assert(payload.func.analysis != .in_progress);
                                 continue;
                             },
-                            else => |e| return e,
+                            error.OutOfMemory => return error.OutOfMemory,
                         },
                         .in_progress => unreachable,
                         .sema_failure, .dependency_failure => continue,
@@ -720,7 +1009,7 @@ pub fn performAllTheWork(self: *Module) error{OutOfMemory}!void {
                         try self.failed_decls.ensureCapacity(self.failed_decls.size + 1);
                         self.failed_decls.putAssumeCapacityNoClobber(decl, try ErrorMsg.create(
                             self.allocator,
-                            decl.src,
+                            decl.src(),
                             "unable to codegen: {}",
                             .{@errorName(err)},
                         ));
@@ -729,41 +1018,560 @@ pub fn performAllTheWork(self: *Module) error{OutOfMemory}!void {
                 };
             },
         },
-        .re_analyze_decl => |decl| switch (decl.analysis) {
-            .in_progress => unreachable,
+        .analyze_decl => |decl| {
+            self.ensureDeclAnalyzed(decl) catch |err| switch (err) {
+                error.OutOfMemory => return error.OutOfMemory,
+                error.AnalysisFail => continue,
+            };
+        },
+    };
+}
 
-            .sema_failure,
-            .codegen_failure,
-            .dependency_failure,
-            .complete,
-            .codegen_failure_retryable,
-            => continue,
+fn ensureDeclAnalyzed(self: *Module, decl: *Decl) InnerError!void {
+    const tracy = trace(@src());
+    defer tracy.end();
 
-            .outdated => {
-                const zir_module = self.getSrcModule(decl.scope) catch |err| switch (err) {
-                    error.OutOfMemory => return error.OutOfMemory,
-                    else => {
-                        try self.failed_decls.ensureCapacity(self.failed_decls.size + 1);
-                        self.failed_decls.putAssumeCapacityNoClobber(decl, try ErrorMsg.create(
-                            self.allocator,
-                            decl.src,
-                            "unable to load source file '{}': {}",
-                            .{ decl.scope.sub_file_path, @errorName(err) },
-                        ));
-                        decl.analysis = .codegen_failure_retryable;
-                        continue;
+    const subsequent_analysis = switch (decl.analysis) {
+        .in_progress => unreachable,
+
+        .sema_failure,
+        .sema_failure_retryable,
+        .codegen_failure,
+        .dependency_failure,
+        .codegen_failure_retryable,
+        => return error.AnalysisFail,
+
+        .complete, .outdated => blk: {
+            if (decl.generation == self.generation) {
+                assert(decl.analysis == .complete);
+                return;
+            }
+            //std.debug.warn("re-analyzing {}\n", .{decl.name});
+
+            // The exports this Decl performs will be re-discovered, so we remove them here
+            // prior to re-analysis.
+            self.deleteDeclExports(decl);
+            // Dependencies will be re-discovered, so we remove them here prior to re-analysis.
+            for (decl.dependencies.items) |dep| {
+                dep.removeDependant(decl);
+                if (dep.dependants.items.len == 0 and !dep.deletion_flag) {
+                    // We don't perform a deletion here, because this Decl or another one
+                    // may end up referencing it before the update is complete.
+                    dep.deletion_flag = true;
+                    try self.deletion_set.append(self.allocator, dep);
+                }
+            }
+            decl.dependencies.shrink(self.allocator, 0);
+
+            break :blk true;
+        },
+
+        .unreferenced => false,
+    };
+
+    const type_changed = if (self.root_scope.cast(Scope.ZIRModule)) |zir_module|
+        try self.analyzeZirDecl(decl, zir_module.contents.module.decls[decl.src_index])
+    else
+        self.astGenAndAnalyzeDecl(decl) catch |err| switch (err) {
+            error.OutOfMemory => return error.OutOfMemory,
+            error.AnalysisFail => return error.AnalysisFail,
+            else => {
+                try self.failed_decls.ensureCapacity(self.failed_decls.size + 1);
+                self.failed_decls.putAssumeCapacityNoClobber(decl, try ErrorMsg.create(
+                    self.allocator,
+                    decl.src(),
+                    "unable to analyze: {}",
+                    .{@errorName(err)},
+                ));
+                decl.analysis = .sema_failure_retryable;
+                return error.AnalysisFail;
+            },
+        };
+
+    if (subsequent_analysis) {
+        // We may need to chase the dependants and re-analyze them.
+        // However, if the decl is a function, and the type is the same, we do not need to.
+        if (type_changed or decl.typed_value.most_recent.typed_value.val.tag() != .function) {
+            for (decl.dependants.items) |dep| {
+                switch (dep.analysis) {
+                    .unreferenced => unreachable,
+                    .in_progress => unreachable,
+                    .outdated => continue, // already queued for update
+
+                    .dependency_failure,
+                    .sema_failure,
+                    .sema_failure_retryable,
+                    .codegen_failure,
+                    .codegen_failure_retryable,
+                    .complete,
+                    => if (dep.generation != self.generation) {
+                        try self.markOutdatedDecl(dep);
                     },
+                }
+            }
+        }
+    }
+}
+
+fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    const file_scope = decl.scope.cast(Scope.File).?;
+    const tree = try self.getAstTree(file_scope);
+    const ast_node = tree.root_node.decls()[decl.src_index];
+    switch (ast_node.id) {
+        .FnProto => {
+            const fn_proto = @fieldParentPtr(ast.Node.FnProto, "base", ast_node);
+
+            decl.analysis = .in_progress;
+
+            // This arena allocator's memory is discarded at the end of this function. It is used
+            // to determine the type of the function, and hence the type of the decl, which is needed
+            // to complete the Decl analysis.
+            var fn_type_scope: Scope.GenZIR = .{
+                .decl = decl,
+                .arena = std.heap.ArenaAllocator.init(self.allocator),
+                .instructions = std.ArrayList(*zir.Inst).init(self.allocator),
+            };
+            defer fn_type_scope.arena.deinit();
+            defer fn_type_scope.instructions.deinit();
+
+            const body_node = fn_proto.body_node orelse
+                return self.failTok(&fn_type_scope.base, fn_proto.fn_token, "TODO implement extern functions", .{});
+            if (fn_proto.params_len != 0) {
+                return self.failTok(
+                    &fn_type_scope.base,
+                    fn_proto.params()[0].name_token.?,
+                    "TODO implement function parameters",
+                    .{},
+                );
+            }
+            if (fn_proto.lib_name) |lib_name| {
+                return self.failNode(&fn_type_scope.base, lib_name, "TODO implement function library name", .{});
+            }
+            if (fn_proto.align_expr) |align_expr| {
+                return self.failNode(&fn_type_scope.base, align_expr, "TODO implement function align expression", .{});
+            }
+            if (fn_proto.section_expr) |sect_expr| {
+                return self.failNode(&fn_type_scope.base, sect_expr, "TODO implement function section expression", .{});
+            }
+            if (fn_proto.callconv_expr) |callconv_expr| {
+                return self.failNode(
+                    &fn_type_scope.base,
+                    callconv_expr,
+                    "TODO implement function calling convention expression",
+                    .{},
+                );
+            }
+            const return_type_expr = switch (fn_proto.return_type) {
+                .Explicit => |node| node,
+                .InferErrorSet => |node| return self.failNode(&fn_type_scope.base, node, "TODO implement inferred error sets", .{}),
+                .Invalid => |tok| return self.failTok(&fn_type_scope.base, tok, "unable to parse return type", .{}),
+            };
+
+            const return_type_inst = try self.astGenExpr(&fn_type_scope.base, return_type_expr);
+            const fn_src = tree.token_locs[fn_proto.fn_token].start;
+            const fn_type_inst = try self.addZIRInst(&fn_type_scope.base, fn_src, zir.Inst.FnType, .{
+                .return_type = return_type_inst,
+                .param_types = &[0]*zir.Inst{},
+            }, .{});
+            _ = try self.addZIRInst(&fn_type_scope.base, fn_src, zir.Inst.Return, .{ .operand = fn_type_inst }, .{});
+
+            // We need the memory for the Type to go into the arena for the Decl
+            var decl_arena = std.heap.ArenaAllocator.init(self.allocator);
+            errdefer decl_arena.deinit();
+            const decl_arena_state = try decl_arena.allocator.create(std.heap.ArenaAllocator.State);
+
+            var block_scope: Scope.Block = .{
+                .func = null,
+                .decl = decl,
+                .instructions = .{},
+                .arena = &decl_arena.allocator,
+            };
+            defer block_scope.instructions.deinit(self.allocator);
+
+            const fn_type = try self.analyzeBodyValueAsType(&block_scope, .{
+                .instructions = fn_type_scope.instructions.items,
+            });
+            const new_func = try decl_arena.allocator.create(Fn);
+            const fn_payload = try decl_arena.allocator.create(Value.Payload.Function);
+
+            const fn_zir = blk: {
+                // This scope's arena memory is discarded after the ZIR generation
+                // pass completes, and semantic analysis of it completes.
+                var gen_scope: Scope.GenZIR = .{
+                    .decl = decl,
+                    .arena = std.heap.ArenaAllocator.init(self.allocator),
+                    .instructions = std.ArrayList(*zir.Inst).init(self.allocator),
                 };
-                const decl_name = mem.spanZ(decl.name);
-                // We already detected deletions, so we know this will be found.
-                const src_decl = zir_module.findDecl(decl_name).?;
-                self.reAnalyzeDecl(decl, src_decl) catch |err| switch (err) {
-                    error.OutOfMemory => return error.OutOfMemory,
-                    error.AnalysisFail => continue,
+                errdefer gen_scope.arena.deinit();
+                defer gen_scope.instructions.deinit();
+
+                const body_block = body_node.cast(ast.Node.Block).?;
+
+                try self.astGenBlock(&gen_scope.base, body_block);
+
+                const fn_zir = try gen_scope.arena.allocator.create(Fn.ZIR);
+                fn_zir.* = .{
+                    .body = .{
+                        .instructions = try gen_scope.arena.allocator.dupe(*zir.Inst, gen_scope.instructions.items),
+                    },
+                    .arena = gen_scope.arena.state,
                 };
-            },
+                break :blk fn_zir;
+            };
+
+            new_func.* = .{
+                .analysis = .{ .queued = fn_zir },
+                .owner_decl = decl,
+            };
+            fn_payload.* = .{ .func = new_func };
+
+            var prev_type_has_bits = false;
+            var type_changed = true;
+
+            if (decl.typedValueManaged()) |tvm| {
+                prev_type_has_bits = tvm.typed_value.ty.hasCodeGenBits();
+                type_changed = !tvm.typed_value.ty.eql(fn_type);
+
+                tvm.deinit(self.allocator);
+            }
+
+            decl_arena_state.* = decl_arena.state;
+            decl.typed_value = .{
+                .most_recent = .{
+                    .typed_value = .{
+                        .ty = fn_type,
+                        .val = Value.initPayload(&fn_payload.base),
+                    },
+                    .arena = decl_arena_state,
+                },
+            };
+            decl.analysis = .complete;
+            decl.generation = self.generation;
+
+            if (fn_type.hasCodeGenBits()) {
+                // We don't fully codegen the decl until later, but we do need to reserve a global
+                // offset table index for it. This allows us to codegen decls out of dependency order,
+                // increasing how many computations can be done in parallel.
+                try self.bin_file.allocateDeclIndexes(decl);
+                try self.work_queue.writeItem(.{ .codegen_decl = decl });
+            } else if (prev_type_has_bits) {
+                self.bin_file.freeDecl(decl);
+            }
+
+            if (fn_proto.extern_export_inline_token) |maybe_export_token| {
+                if (tree.token_ids[maybe_export_token] == .Keyword_export) {
+                    const export_src = tree.token_locs[maybe_export_token].start;
+                    const name_loc = tree.token_locs[fn_proto.name_token.?];
+                    const name = tree.tokenSliceLoc(name_loc);
+                    // The scope needs to have the decl in it.
+                    try self.analyzeExport(&block_scope.base, export_src, name, decl);
+                }
+            }
+            return type_changed;
         },
+        .VarDecl => @panic("TODO var decl"),
+        .Comptime => @panic("TODO comptime decl"),
+        .Use => @panic("TODO usingnamespace decl"),
+        else => unreachable,
+    }
+}
+
+fn analyzeBodyValueAsType(self: *Module, block_scope: *Scope.Block, body: zir.Module.Body) !Type {
+    try self.analyzeBody(&block_scope.base, body);
+    for (block_scope.instructions.items) |inst| {
+        if (inst.cast(Inst.Ret)) |ret| {
+            const val = try self.resolveConstValue(&block_scope.base, ret.args.operand);
+            return val.toType();
+        } else {
+            return self.fail(&block_scope.base, inst.src, "unable to resolve comptime value", .{});
+        }
+    }
+    unreachable;
+}
+
+fn astGenExpr(self: *Module, scope: *Scope, ast_node: *ast.Node) InnerError!*zir.Inst {
+    switch (ast_node.id) {
+        .Identifier => return self.astGenIdent(scope, @fieldParentPtr(ast.Node.Identifier, "base", ast_node)),
+        .Asm => return self.astGenAsm(scope, @fieldParentPtr(ast.Node.Asm, "base", ast_node)),
+        .StringLiteral => return self.astGenStringLiteral(scope, @fieldParentPtr(ast.Node.StringLiteral, "base", ast_node)),
+        .IntegerLiteral => return self.astGenIntegerLiteral(scope, @fieldParentPtr(ast.Node.IntegerLiteral, "base", ast_node)),
+        .BuiltinCall => return self.astGenBuiltinCall(scope, @fieldParentPtr(ast.Node.BuiltinCall, "base", ast_node)),
+        .Call => return self.astGenCall(scope, @fieldParentPtr(ast.Node.Call, "base", ast_node)),
+        .Unreachable => return self.astGenUnreachable(scope, @fieldParentPtr(ast.Node.Unreachable, "base", ast_node)),
+        .ControlFlowExpression => return self.astGenControlFlowExpression(scope, @fieldParentPtr(ast.Node.ControlFlowExpression, "base", ast_node)),
+        else => return self.failNode(scope, ast_node, "TODO implement astGenExpr for {}", .{@tagName(ast_node.id)}),
+    }
+}
+
+fn astGenControlFlowExpression(
+    self: *Module,
+    scope: *Scope,
+    cfe: *ast.Node.ControlFlowExpression,
+) InnerError!*zir.Inst {
+    switch (cfe.kind) {
+        .Break => return self.failNode(scope, &cfe.base, "TODO implement astGenExpr for Break", .{}),
+        .Continue => return self.failNode(scope, &cfe.base, "TODO implement astGenExpr for Continue", .{}),
+        .Return => {},
+    }
+    const tree = scope.tree();
+    const src = tree.token_locs[cfe.ltoken].start;
+    if (cfe.rhs) |rhs_node| {
+        const operand = try self.astGenExpr(scope, rhs_node);
+        return self.addZIRInst(scope, src, zir.Inst.Return, .{ .operand = operand }, .{});
+    } else {
+        return self.addZIRInst(scope, src, zir.Inst.ReturnVoid, .{}, .{});
+    }
+}
+
+fn astGenIdent(self: *Module, scope: *Scope, ident: *ast.Node.Identifier) InnerError!*zir.Inst {
+    const tree = scope.tree();
+    const ident_name = tree.tokenSlice(ident.token);
+    if (mem.eql(u8, ident_name, "_")) {
+        return self.failNode(scope, &ident.base, "TODO implement '_' identifier", .{});
+    }
+
+    if (getSimplePrimitiveValue(ident_name)) |typed_value| {
+        const src = tree.token_locs[ident.token].start;
+        return self.addZIRInstConst(scope, src, typed_value);
+    }
+
+    if (ident_name.len >= 2) integer: {
+        const first_c = ident_name[0];
+        if (first_c == 'i' or first_c == 'u') {
+            const is_signed = first_c == 'i';
+            const bit_count = std.fmt.parseInt(u16, ident_name[1..], 10) catch |err| switch (err) {
+                error.Overflow => return self.failNode(
+                    scope,
+                    &ident.base,
+                    "primitive integer type '{}' exceeds maximum bit width of 65535",
+                    .{ident_name},
+                ),
+                error.InvalidCharacter => break :integer,
+            };
+            return self.failNode(scope, &ident.base, "TODO implement arbitrary integer bitwidth types", .{});
+        }
+    }
+
+    if (self.lookupDeclName(scope, ident_name)) |decl| {
+        const src = tree.token_locs[ident.token].start;
+        return try self.addZIRInst(scope, src, zir.Inst.DeclValInModule, .{ .decl = decl }, .{});
+    }
+
+    return self.failNode(scope, &ident.base, "TODO implement local variable identifier lookup", .{});
+}
+
+fn astGenStringLiteral(self: *Module, scope: *Scope, str_lit: *ast.Node.StringLiteral) InnerError!*zir.Inst {
+    const tree = scope.tree();
+    const unparsed_bytes = tree.tokenSlice(str_lit.token);
+    const arena = scope.arena();
+
+    var bad_index: usize = undefined;
+    const bytes = std.zig.parseStringLiteral(arena, unparsed_bytes, &bad_index) catch |err| switch (err) {
+        error.InvalidCharacter => {
+            const bad_byte = unparsed_bytes[bad_index];
+            const src = tree.token_locs[str_lit.token].start;
+            return self.fail(scope, src + bad_index, "invalid string literal character: '{c}'\n", .{bad_byte});
+        },
+        else => |e| return e,
     };
+
+    const src = tree.token_locs[str_lit.token].start;
+    return self.addZIRInst(scope, src, zir.Inst.Str, .{ .bytes = bytes }, .{});
+}
+
+fn astGenIntegerLiteral(self: *Module, scope: *Scope, int_lit: *ast.Node.IntegerLiteral) InnerError!*zir.Inst {
+    const arena = scope.arena();
+    const tree = scope.tree();
+    const prefixed_bytes = tree.tokenSlice(int_lit.token);
+    const base = if (mem.startsWith(u8, prefixed_bytes, "0x"))
+        16
+    else if (mem.startsWith(u8, prefixed_bytes, "0o"))
+        8
+    else if (mem.startsWith(u8, prefixed_bytes, "0b"))
+        2
+    else
+        @as(u8, 10);
+
+    const bytes = if (base == 10)
+        prefixed_bytes
+    else
+        prefixed_bytes[2..];
+
+    if (std.fmt.parseInt(u64, bytes, base)) |small_int| {
+        const int_payload = try arena.create(Value.Payload.Int_u64);
+        int_payload.* = .{ .int = small_int };
+        const src = tree.token_locs[int_lit.token].start;
+        return self.addZIRInstConst(scope, src, .{
+            .ty = Type.initTag(.comptime_int),
+            .val = Value.initPayload(&int_payload.base),
+        });
+    } else |err| {
+        return self.failTok(scope, int_lit.token, "TODO implement int literals that don't fit in a u64", .{});
+    }
+}
+
+fn astGenBlock(self: *Module, scope: *Scope, block_node: *ast.Node.Block) !void {
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    if (block_node.label) |label| {
+        return self.failTok(scope, label, "TODO implement labeled blocks", .{});
+    }
+    for (block_node.statements()) |statement| {
+        _ = try self.astGenExpr(scope, statement);
+    }
+}
+
+fn astGenAsm(self: *Module, scope: *Scope, asm_node: *ast.Node.Asm) InnerError!*zir.Inst {
+    if (asm_node.outputs.len != 0) {
+        return self.failNode(scope, &asm_node.base, "TODO implement asm with an output", .{});
+    }
+    const arena = scope.arena();
+    const tree = scope.tree();
+
+    const inputs = try arena.alloc(*zir.Inst, asm_node.inputs.len);
+    const args = try arena.alloc(*zir.Inst, asm_node.inputs.len);
+
+    for (asm_node.inputs) |input, i| {
+        // TODO semantically analyze constraints
+        inputs[i] = try self.astGenExpr(scope, input.constraint);
+        args[i] = try self.astGenExpr(scope, input.expr);
+    }
+
+    const src = tree.token_locs[asm_node.asm_token].start;
+    const return_type = try self.addZIRInstConst(scope, src, .{
+        .ty = Type.initTag(.type),
+        .val = Value.initTag(.void_type),
+    });
+    const asm_inst = try self.addZIRInst(scope, src, zir.Inst.Asm, .{
+        .asm_source = try self.astGenExpr(scope, asm_node.template),
+        .return_type = return_type,
+    }, .{
+        .@"volatile" = asm_node.volatile_token != null,
+        //.clobbers =  TODO handle clobbers
+        .inputs = inputs,
+        .args = args,
+    });
+    return asm_inst;
+}
+
+fn astGenBuiltinCall(self: *Module, scope: *Scope, call: *ast.Node.BuiltinCall) InnerError!*zir.Inst {
+    const tree = scope.tree();
+    const builtin_name = tree.tokenSlice(call.builtin_token);
+    const src = tree.token_locs[call.builtin_token].start;
+
+    inline for (std.meta.declarations(zir.Inst)) |inst| {
+        if (inst.data != .Type) continue;
+        const T = inst.data.Type;
+        if (!@hasDecl(T, "builtin_name")) continue;
+        if (std.mem.eql(u8, builtin_name, T.builtin_name)) {
+            var value: T = undefined;
+            const positionals = @typeInfo(std.meta.fieldInfo(T, "positionals").field_type).Struct;
+            if (positionals.fields.len == 0) {
+                return self.addZIRInst(scope, src, T, value.positionals, value.kw_args);
+            }
+            const arg_count: ?usize = if (positionals.fields[0].field_type == []*zir.Inst) null else positionals.fields.len;
+            if (arg_count) |some| {
+                if (call.params_len != some) {
+                    return self.failTok(scope, call.builtin_token, "expected {} parameter, found {}", .{ some, call.params_len });
+                }
+                const params = call.params();
+                inline for (positionals.fields) |p, i| {
+                    @field(value.positionals, p.name) = try self.astGenExpr(scope, params[i]);
+                }
+            } else {
+                return self.failTok(scope, call.builtin_token, "TODO var args builtin '{}'", .{builtin_name});
+            }
+
+            return self.addZIRInst(scope, src, T, value.positionals, .{});
+        }
+    }
+    return self.failTok(scope, call.builtin_token, "TODO implement builtin call for '{}'", .{builtin_name});
+}
+
+fn astGenCall(self: *Module, scope: *Scope, call: *ast.Node.Call) InnerError!*zir.Inst {
+    const tree = scope.tree();
+
+    if (call.params_len != 0) {
+        return self.failNode(scope, &call.base, "TODO implement fn calls with parameters", .{});
+    }
+    const lhs = try self.astGenExpr(scope, call.lhs);
+
+    const src = tree.token_locs[call.lhs.firstToken()].start;
+    return self.addZIRInst(scope, src, zir.Inst.Call, .{
+        .func = lhs,
+        .args = &[0]*zir.Inst{},
+    }, .{});
+}
+
+fn astGenUnreachable(self: *Module, scope: *Scope, unreach_node: *ast.Node.Unreachable) InnerError!*zir.Inst {
+    const tree = scope.tree();
+    const src = tree.token_locs[unreach_node.token].start;
+    return self.addZIRInst(scope, src, zir.Inst.Unreachable, .{}, .{});
+}
+
+fn getSimplePrimitiveValue(name: []const u8) ?TypedValue {
+    const simple_types = std.ComptimeStringMap(Value.Tag, .{
+        .{ "u8", .u8_type },
+        .{ "i8", .i8_type },
+        .{ "isize", .isize_type },
+        .{ "usize", .usize_type },
+        .{ "c_short", .c_short_type },
+        .{ "c_ushort", .c_ushort_type },
+        .{ "c_int", .c_int_type },
+        .{ "c_uint", .c_uint_type },
+        .{ "c_long", .c_long_type },
+        .{ "c_ulong", .c_ulong_type },
+        .{ "c_longlong", .c_longlong_type },
+        .{ "c_ulonglong", .c_ulonglong_type },
+        .{ "c_longdouble", .c_longdouble_type },
+        .{ "f16", .f16_type },
+        .{ "f32", .f32_type },
+        .{ "f64", .f64_type },
+        .{ "f128", .f128_type },
+        .{ "c_void", .c_void_type },
+        .{ "bool", .bool_type },
+        .{ "void", .void_type },
+        .{ "type", .type_type },
+        .{ "anyerror", .anyerror_type },
+        .{ "comptime_int", .comptime_int_type },
+        .{ "comptime_float", .comptime_float_type },
+        .{ "noreturn", .noreturn_type },
+    });
+    if (simple_types.get(name)) |tag| {
+        return TypedValue{
+            .ty = Type.initTag(.type),
+            .val = Value.initTag(tag),
+        };
+    }
+    if (mem.eql(u8, name, "null")) {
+        return TypedValue{
+            .ty = Type.initTag(.@"null"),
+            .val = Value.initTag(.null_value),
+        };
+    }
+    if (mem.eql(u8, name, "undefined")) {
+        return TypedValue{
+            .ty = Type.initTag(.@"undefined"),
+            .val = Value.initTag(.undef),
+        };
+    }
+    if (mem.eql(u8, name, "true")) {
+        return TypedValue{
+            .ty = Type.initTag(.bool),
+            .val = Value.initTag(.bool_true),
+        };
+    }
+    if (mem.eql(u8, name, "false")) {
+        return TypedValue{
+            .ty = Type.initTag(.bool),
+            .val = Value.initTag(.bool_false),
+        };
+    }
+    return null;
 }
 
 fn declareDeclDependency(self: *Module, depender: *Decl, dependee: *Decl) !void {
@@ -783,29 +1591,12 @@ fn declareDeclDependency(self: *Module, depender: *Decl, dependee: *Decl) !void
     }
 }
 
-fn getSource(self: *Module, root_scope: *Scope.ZIRModule) ![:0]const u8 {
-    switch (root_scope.source) {
-        .unloaded => {
-            const source = try self.root_pkg.root_src_dir.readFileAllocOptions(
-                self.allocator,
-                root_scope.sub_file_path,
-                std.math.maxInt(u32),
-                1,
-                0,
-            );
-            root_scope.source = .{ .bytes = source };
-            return source;
-        },
-        .bytes => |bytes| return bytes,
-    }
-}
-
 fn getSrcModule(self: *Module, root_scope: *Scope.ZIRModule) !*zir.Module {
     switch (root_scope.status) {
         .never_loaded, .unloaded_success => {
             try self.failed_files.ensureCapacity(self.failed_files.size + 1);
 
-            const source = try self.getSource(root_scope);
+            const source = try root_scope.getSource(self);
 
             var keep_zir_module = false;
             const zir_module = try self.allocator.create(zir.Module);
@@ -816,7 +1607,7 @@ fn getSrcModule(self: *Module, root_scope: *Scope.ZIRModule) !*zir.Module {
 
             if (zir_module.error_msg) |src_err_msg| {
                 self.failed_files.putAssumeCapacityNoClobber(
-                    root_scope,
+                    &root_scope.base,
                     try ErrorMsg.create(self.allocator, src_err_msg.byte_offset, "{}", .{src_err_msg.msg}),
                 );
                 root_scope.status = .unloaded_parse_failure;
@@ -838,90 +1629,189 @@ fn getSrcModule(self: *Module, root_scope: *Scope.ZIRModule) !*zir.Module {
     }
 }
 
-fn analyzeRoot(self: *Module, root_scope: *Scope.ZIRModule) !void {
+fn getAstTree(self: *Module, root_scope: *Scope.File) !*ast.Tree {
+    const tracy = trace(@src());
+    defer tracy.end();
+
     switch (root_scope.status) {
-        .never_loaded => {
-            const src_module = try self.getSrcModule(root_scope);
+        .never_loaded, .unloaded_success => {
+            try self.failed_files.ensureCapacity(self.failed_files.size + 1);
 
-            // Here we ensure enough queue capacity to store all the decls, so that later we can use
-            // appendAssumeCapacity.
-            try self.work_queue.ensureUnusedCapacity(src_module.decls.len);
+            const source = try root_scope.getSource(self);
 
-            for (src_module.decls) |decl| {
-                if (decl.cast(zir.Inst.Export)) |export_inst| {
-                    _ = try self.resolveDecl(&root_scope.base, &export_inst.base);
-                }
+            var keep_tree = false;
+            const tree = try std.zig.parse(self.allocator, source);
+            defer if (!keep_tree) tree.deinit();
+
+            if (tree.errors.len != 0) {
+                const parse_err = tree.errors[0];
+
+                var msg = std.ArrayList(u8).init(self.allocator);
+                defer msg.deinit();
+
+                try parse_err.render(tree.token_ids, msg.outStream());
+                const err_msg = try self.allocator.create(ErrorMsg);
+                err_msg.* = .{
+                    .msg = msg.toOwnedSlice(),
+                    .byte_offset = tree.token_locs[parse_err.loc()].start,
+                };
+
+                self.failed_files.putAssumeCapacityNoClobber(&root_scope.base, err_msg);
+                root_scope.status = .unloaded_parse_failure;
+                return error.AnalysisFail;
             }
+
+            root_scope.status = .loaded_success;
+            root_scope.contents = .{ .tree = tree };
+            keep_tree = true;
+
+            return tree;
         },
 
-        .unloaded_parse_failure,
-        .unloaded_sema_failure,
-        .unloaded_success,
-        .loaded_sema_failure,
-        .loaded_success,
-        => {
-            const src_module = try self.getSrcModule(root_scope);
-
-            var exports_to_resolve = std.ArrayList(*zir.Inst).init(self.allocator);
-            defer exports_to_resolve.deinit();
-
-            // Keep track of the decls that we expect to see in this file so that
-            // we know which ones have been deleted.
-            var deleted_decls = std.AutoHashMap(*Decl, void).init(self.allocator);
-            defer deleted_decls.deinit();
-            try deleted_decls.ensureCapacity(self.decl_table.size);
-            {
-                var it = self.decl_table.iterator();
-                while (it.next()) |kv| {
-                    deleted_decls.putAssumeCapacityNoClobber(kv.value, {});
+        .unloaded_parse_failure => return error.AnalysisFail,
+
+        .loaded_success => return root_scope.contents.tree,
+    }
+}
+
+fn analyzeRootSrcFile(self: *Module, root_scope: *Scope.File) !void {
+    // We may be analyzing it for the first time, or this may be
+    // an incremental update. This code handles both cases.
+    const tree = try self.getAstTree(root_scope);
+    const decls = tree.root_node.decls();
+
+    try self.work_queue.ensureUnusedCapacity(decls.len);
+    try root_scope.decls.ensureCapacity(self.allocator, decls.len);
+
+    // Keep track of the decls that we expect to see in this file so that
+    // we know which ones have been deleted.
+    var deleted_decls = std.AutoHashMap(*Decl, void).init(self.allocator);
+    defer deleted_decls.deinit();
+    try deleted_decls.ensureCapacity(root_scope.decls.items.len);
+    for (root_scope.decls.items) |file_decl| {
+        deleted_decls.putAssumeCapacityNoClobber(file_decl, {});
+    }
+
+    for (decls) |src_decl, decl_i| {
+        if (src_decl.cast(ast.Node.FnProto)) |fn_proto| {
+            // We will create a Decl for it regardless of analysis status.
+            const name_tok = fn_proto.name_token orelse
+                @panic("TODO handle missing function name in the parser");
+            const name_loc = tree.token_locs[name_tok];
+            const name = tree.tokenSliceLoc(name_loc);
+            const name_hash = root_scope.fullyQualifiedNameHash(name);
+            const contents_hash = std.zig.hashSrc(tree.getNodeSource(src_decl));
+            if (self.decl_table.get(name_hash)) |kv| {
+                const decl = kv.value;
+                // Update the AST Node index of the decl, even if its contents are unchanged, it may
+                // have been re-ordered.
+                decl.src_index = decl_i;
+                deleted_decls.removeAssertDiscard(decl);
+                if (!srcHashEql(decl.contents_hash, contents_hash)) {
+                    try self.markOutdatedDecl(decl);
+                    decl.contents_hash = contents_hash;
                 }
-            }
-
-            for (src_module.decls) |src_decl| {
-                const name_hash = Decl.hashSimpleName(src_decl.name);
-                if (self.decl_table.get(name_hash)) |kv| {
-                    const decl = kv.value;
-                    deleted_decls.removeAssertDiscard(decl);
-                    const new_contents_hash = Decl.hashSimpleName(src_decl.contents);
-                    //std.debug.warn("'{}' contents: '{}'\n", .{ src_decl.name, src_decl.contents });
-                    if (!mem.eql(u8, &new_contents_hash, &decl.contents_hash)) {
-                        //std.debug.warn("'{}' {x} => {x}\n", .{ src_decl.name, decl.contents_hash, new_contents_hash });
-                        try self.markOutdatedDecl(decl);
-                        decl.contents_hash = new_contents_hash;
+            } else {
+                const new_decl = try self.createNewDecl(&root_scope.base, name, decl_i, name_hash, contents_hash);
+                root_scope.decls.appendAssumeCapacity(new_decl);
+                if (fn_proto.extern_export_inline_token) |maybe_export_token| {
+                    if (tree.token_ids[maybe_export_token] == .Keyword_export) {
+                        self.work_queue.writeItemAssumeCapacity(.{ .analyze_decl = new_decl });
                     }
-                } else if (src_decl.cast(zir.Inst.Export)) |export_inst| {
-                    try exports_to_resolve.append(&export_inst.base);
                 }
             }
-            {
-                // Handle explicitly deleted decls from the source code. Not to be confused
-                // with when we delete decls because they are no longer referenced.
-                var it = deleted_decls.iterator();
-                while (it.next()) |kv| {
-                    //std.debug.warn("noticed '{}' deleted from source\n", .{kv.key.name});
-                    try self.deleteDecl(kv.key);
-                }
+        }
+        // TODO also look for global variable declarations
+        // TODO also look for comptime blocks and exported globals
+    }
+    {
+        // Handle explicitly deleted decls from the source code. Not to be confused
+        // with when we delete decls because they are no longer referenced.
+        var it = deleted_decls.iterator();
+        while (it.next()) |kv| {
+            //std.debug.warn("noticed '{}' deleted from source\n", .{kv.key.name});
+            try self.deleteDecl(kv.key);
+        }
+    }
+}
+
+fn analyzeRootZIRModule(self: *Module, root_scope: *Scope.ZIRModule) !void {
+    // We may be analyzing it for the first time, or this may be
+    // an incremental update. This code handles both cases.
+    const src_module = try self.getSrcModule(root_scope);
+
+    try self.work_queue.ensureUnusedCapacity(src_module.decls.len);
+    try root_scope.decls.ensureCapacity(self.allocator, src_module.decls.len);
+
+    var exports_to_resolve = std.ArrayList(*zir.Decl).init(self.allocator);
+    defer exports_to_resolve.deinit();
+
+    // Keep track of the decls that we expect to see in this file so that
+    // we know which ones have been deleted.
+    var deleted_decls = std.AutoHashMap(*Decl, void).init(self.allocator);
+    defer deleted_decls.deinit();
+    try deleted_decls.ensureCapacity(self.decl_table.size);
+    {
+        var it = self.decl_table.iterator();
+        while (it.next()) |kv| {
+            deleted_decls.putAssumeCapacityNoClobber(kv.value, {});
+        }
+    }
+
+    for (src_module.decls) |src_decl, decl_i| {
+        const name_hash = root_scope.fullyQualifiedNameHash(src_decl.name);
+        if (self.decl_table.get(name_hash)) |kv| {
+            const decl = kv.value;
+            deleted_decls.removeAssertDiscard(decl);
+            //std.debug.warn("'{}' contents: '{}'\n", .{ src_decl.name, src_decl.contents });
+            if (!srcHashEql(src_decl.contents_hash, decl.contents_hash)) {
+                try self.markOutdatedDecl(decl);
+                decl.contents_hash = src_decl.contents_hash;
             }
-            for (exports_to_resolve.items) |export_inst| {
-                _ = try self.resolveDecl(&root_scope.base, export_inst);
+        } else {
+            const new_decl = try self.createNewDecl(
+                &root_scope.base,
+                src_decl.name,
+                decl_i,
+                name_hash,
+                src_decl.contents_hash,
+            );
+            root_scope.decls.appendAssumeCapacity(new_decl);
+            if (src_decl.inst.cast(zir.Inst.Export)) |export_inst| {
+                try exports_to_resolve.append(src_decl);
             }
-        },
+        }
+    }
+    for (exports_to_resolve.items) |export_decl| {
+        _ = try self.resolveZirDecl(&root_scope.base, export_decl);
+    }
+    {
+        // Handle explicitly deleted decls from the source code. Not to be confused
+        // with when we delete decls because they are no longer referenced.
+        var it = deleted_decls.iterator();
+        while (it.next()) |kv| {
+            //std.debug.warn("noticed '{}' deleted from source\n", .{kv.key.name});
+            try self.deleteDecl(kv.key);
+        }
     }
 }
 
 fn deleteDecl(self: *Module, decl: *Decl) !void {
     try self.deletion_set.ensureCapacity(self.allocator, self.deletion_set.items.len + decl.dependencies.items.len);
 
+    // Remove from the namespace it resides in. In the case of an anonymous Decl it will
+    // not be present in the set, and this does nothing.
+    decl.scope.removeDecl(decl);
+
     //std.debug.warn("deleting decl '{}'\n", .{decl.name});
     const name_hash = decl.fullyQualifiedNameHash();
     self.decl_table.removeAssertDiscard(name_hash);
     // Remove itself from its dependencies, because we are about to destroy the decl pointer.
     for (decl.dependencies.items) |dep| {
         dep.removeDependant(decl);
-        if (dep.dependants.items.len == 0) {
+        if (dep.dependants.items.len == 0 and !dep.deletion_flag) {
             // We don't recursively perform a deletion here, because during the update,
             // another reference to it may turn up.
-            assert(!dep.deletion_flag);
             dep.deletion_flag = true;
             self.deletion_set.appendAssumeCapacity(dep);
         }
@@ -974,83 +1864,89 @@ fn deleteDeclExports(self: *Module, decl: *Decl) void {
 }
 
 fn analyzeFnBody(self: *Module, decl: *Decl, func: *Fn) !void {
+    const tracy = trace(@src());
+    defer tracy.end();
+
     // Use the Decl's arena for function memory.
     var arena = decl.typed_value.most_recent.arena.?.promote(self.allocator);
     defer decl.typed_value.most_recent.arena.?.* = arena.state;
-    var analysis: Fn.Analysis = .{
-        .inner_block = .{
-            .func = func,
-            .decl = decl,
-            .instructions = .{},
-            .arena = &arena.allocator,
-        },
-        .needed_inst_capacity = 0,
-        .inst_table = std.AutoHashMap(*zir.Inst, *Inst).init(self.allocator),
+    var inner_block: Scope.Block = .{
+        .func = func,
+        .decl = decl,
+        .instructions = .{},
+        .arena = &arena.allocator,
     };
-    defer analysis.inner_block.instructions.deinit(self.allocator);
-    defer analysis.inst_table.deinit();
+    defer inner_block.instructions.deinit(self.allocator);
 
-    const fn_inst = func.analysis.queued;
-    func.analysis = .{ .in_progress = &analysis };
+    const fn_zir = func.analysis.queued;
+    defer fn_zir.arena.promote(self.allocator).deinit();
+    func.analysis = .{ .in_progress = {} };
+    //std.debug.warn("set {} to in_progress\n", .{decl.name});
 
-    try self.analyzeBody(&analysis.inner_block.base, fn_inst.positionals.body);
+    try self.analyzeBody(&inner_block.base, fn_zir.body);
 
-    func.analysis = .{
-        .success = .{
-            .instructions = try arena.allocator.dupe(*Inst, analysis.inner_block.instructions.items),
-        },
-    };
+    const instructions = try arena.allocator.dupe(*Inst, inner_block.instructions.items);
+    func.analysis = .{ .success = .{ .instructions = instructions } };
+    //std.debug.warn("set {} to success\n", .{decl.name});
 }
 
-fn reAnalyzeDecl(self: *Module, decl: *Decl, old_inst: *zir.Inst) InnerError!void {
-    switch (decl.analysis) {
-        .in_progress => unreachable,
-        .dependency_failure,
-        .sema_failure,
-        .codegen_failure,
-        .codegen_failure_retryable,
-        .complete,
-        => return,
-
-        .outdated => {}, // Decl re-analysis
+fn markOutdatedDecl(self: *Module, decl: *Decl) !void {
+    //std.debug.warn("mark {} outdated\n", .{decl.name});
+    try self.work_queue.writeItem(.{ .analyze_decl = decl });
+    if (self.failed_decls.remove(decl)) |entry| {
+        entry.value.destroy(self.allocator);
     }
-    //std.debug.warn("re-analyzing {}\n", .{decl.name});
-    decl.src = old_inst.src;
+    decl.analysis = .outdated;
+}
 
-    // The exports this Decl performs will be re-discovered, so we remove them here
-    // prior to re-analysis.
-    self.deleteDeclExports(decl);
-    // Dependencies will be re-discovered, so we remove them here prior to re-analysis.
-    for (decl.dependencies.items) |dep| {
-        dep.removeDependant(decl);
-        if (dep.dependants.items.len == 0) {
-            // We don't perform a deletion here, because this Decl or another one
-            // may end up referencing it before the update is complete.
-            assert(!dep.deletion_flag);
-            dep.deletion_flag = true;
-            try self.deletion_set.append(self.allocator, dep);
-        }
-    }
-    decl.dependencies.shrink(self.allocator, 0);
+fn allocateNewDecl(
+    self: *Module,
+    scope: *Scope,
+    src_index: usize,
+    contents_hash: std.zig.SrcHash,
+) !*Decl {
+    const new_decl = try self.allocator.create(Decl);
+    new_decl.* = .{
+        .name = "",
+        .scope = scope.namespace(),
+        .src_index = src_index,
+        .typed_value = .{ .never_succeeded = {} },
+        .analysis = .unreferenced,
+        .deletion_flag = false,
+        .contents_hash = contents_hash,
+        .link = link.ElfFile.TextBlock.empty,
+        .generation = 0,
+    };
+    return new_decl;
+}
+
+fn createNewDecl(
+    self: *Module,
+    scope: *Scope,
+    decl_name: []const u8,
+    src_index: usize,
+    name_hash: Scope.NameHash,
+    contents_hash: std.zig.SrcHash,
+) !*Decl {
+    try self.decl_table.ensureCapacity(self.decl_table.size + 1);
+    const new_decl = try self.allocateNewDecl(scope, src_index, contents_hash);
+    errdefer self.allocator.destroy(new_decl);
+    new_decl.name = try mem.dupeZ(self.allocator, u8, decl_name);
+    self.decl_table.putAssumeCapacityNoClobber(name_hash, new_decl);
+    return new_decl;
+}
+
+fn analyzeZirDecl(self: *Module, decl: *Decl, src_decl: *zir.Decl) InnerError!bool {
     var decl_scope: Scope.DeclAnalysis = .{
         .decl = decl,
         .arena = std.heap.ArenaAllocator.init(self.allocator),
     };
     errdefer decl_scope.arena.deinit();
 
-    const typed_value = self.analyzeInstConst(&decl_scope.base, old_inst) catch |err| switch (err) {
-        error.OutOfMemory => return error.OutOfMemory,
-        error.AnalysisFail => {
-            switch (decl.analysis) {
-                .in_progress => decl.analysis = .dependency_failure,
-                else => {},
-            }
-            decl.generation = self.generation;
-            return error.AnalysisFail;
-        },
-    };
+    decl.analysis = .in_progress;
+
+    const typed_value = try self.analyzeConstInst(&decl_scope.base, src_decl.inst);
     const arena_state = try decl_scope.arena.allocator.create(std.heap.ArenaAllocator.State);
-    arena_state.* = decl_scope.arena.state;
 
     var prev_type_has_bits = false;
     var type_changed = true;
@@ -1061,6 +1957,8 @@ fn reAnalyzeDecl(self: *Module, decl: *Decl, old_inst: *zir.Inst) InnerError!voi
 
         tvm.deinit(self.allocator);
     }
+
+    arena_state.* = decl_scope.arena.state;
     decl.typed_value = .{
         .most_recent = .{
             .typed_value = typed_value,
@@ -1079,137 +1977,66 @@ fn reAnalyzeDecl(self: *Module, decl: *Decl, old_inst: *zir.Inst) InnerError!voi
         self.bin_file.freeDecl(decl);
     }
 
-    // If the decl is a function, and the type is the same, we do not need
-    // to chase the dependants.
-    if (type_changed or typed_value.val.tag() != .function) {
-        for (decl.dependants.items) |dep| {
-            switch (dep.analysis) {
-                .in_progress => unreachable,
-                .outdated => continue, // already queued for update
-
-                .dependency_failure,
-                .sema_failure,
-                .codegen_failure,
-                .codegen_failure_retryable,
-                .complete,
-                => if (dep.generation != self.generation) {
-                    try self.markOutdatedDecl(dep);
-                },
-            }
-        }
-    }
+    return type_changed;
 }
 
-fn markOutdatedDecl(self: *Module, decl: *Decl) !void {
-    //std.debug.warn("mark {} outdated\n", .{decl.name});
-    try self.work_queue.writeItem(.{ .re_analyze_decl = decl });
-    if (self.failed_decls.remove(decl)) |entry| {
-        entry.value.destroy(self.allocator);
-    }
-    decl.analysis = .outdated;
+fn resolveZirDecl(self: *Module, scope: *Scope, src_decl: *zir.Decl) InnerError!*Decl {
+    const zir_module = self.root_scope.cast(Scope.ZIRModule).?;
+    const entry = zir_module.contents.module.findDecl(src_decl.name).?;
+    return self.resolveZirDeclHavingIndex(scope, src_decl, entry.index);
 }
 
-fn resolveDecl(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!*Decl {
-    const hash = Decl.hashSimpleName(old_inst.name);
-    if (self.decl_table.get(hash)) |kv| {
-        const decl = kv.value;
-        try self.reAnalyzeDecl(decl, old_inst);
-        return decl;
-    } else if (old_inst.cast(zir.Inst.DeclVal)) |decl_val| {
-        // This is just a named reference to another decl.
-        return self.analyzeDeclVal(scope, decl_val);
-    } else {
-        const new_decl = blk: {
-            try self.decl_table.ensureCapacity(self.decl_table.size + 1);
-            const new_decl = try self.allocator.create(Decl);
-            errdefer self.allocator.destroy(new_decl);
-            const name = try mem.dupeZ(self.allocator, u8, old_inst.name);
-            errdefer self.allocator.free(name);
-            new_decl.* = .{
-                .name = name,
-                .scope = scope.namespace(),
-                .src = old_inst.src,
-                .typed_value = .{ .never_succeeded = {} },
-                .analysis = .in_progress,
-                .deletion_flag = false,
-                .contents_hash = Decl.hashSimpleName(old_inst.contents),
-                .link = link.ElfFile.TextBlock.empty,
-                .generation = 0,
-            };
-            self.decl_table.putAssumeCapacityNoClobber(hash, new_decl);
-            break :blk new_decl;
-        };
-
-        var decl_scope: Scope.DeclAnalysis = .{
-            .decl = new_decl,
-            .arena = std.heap.ArenaAllocator.init(self.allocator),
-        };
-        errdefer decl_scope.arena.deinit();
-
-        const typed_value = self.analyzeInstConst(&decl_scope.base, old_inst) catch |err| switch (err) {
-            error.OutOfMemory => return error.OutOfMemory,
-            error.AnalysisFail => {
-                switch (new_decl.analysis) {
-                    .in_progress => new_decl.analysis = .dependency_failure,
-                    else => {},
-                }
-                new_decl.generation = self.generation;
-                return error.AnalysisFail;
-            },
-        };
-        const arena_state = try decl_scope.arena.allocator.create(std.heap.ArenaAllocator.State);
-
-        arena_state.* = decl_scope.arena.state;
-
-        new_decl.typed_value = .{
-            .most_recent = .{
-                .typed_value = typed_value,
-                .arena = arena_state,
-            },
-        };
-        new_decl.analysis = .complete;
-        new_decl.generation = self.generation;
-        if (typed_value.ty.hasCodeGenBits()) {
-            // We don't fully codegen the decl until later, but we do need to reserve a global
-            // offset table index for it. This allows us to codegen decls out of dependency order,
-            // increasing how many computations can be done in parallel.
-            try self.bin_file.allocateDeclIndexes(new_decl);
-            try self.work_queue.writeItem(.{ .codegen_decl = new_decl });
-        }
-        return new_decl;
-    }
+fn resolveZirDeclHavingIndex(self: *Module, scope: *Scope, src_decl: *zir.Decl, src_index: usize) InnerError!*Decl {
+    const name_hash = scope.namespace().fullyQualifiedNameHash(src_decl.name);
+    const decl = self.decl_table.getValue(name_hash).?;
+    decl.src_index = src_index;
+    try self.ensureDeclAnalyzed(decl);
+    return decl;
 }
 
 /// Declares a dependency on the decl.
-fn resolveCompleteDecl(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!*Decl {
-    const decl = try self.resolveDecl(scope, old_inst);
+fn resolveCompleteZirDecl(self: *Module, scope: *Scope, src_decl: *zir.Decl) InnerError!*Decl {
+    const decl = try self.resolveZirDecl(scope, src_decl);
     switch (decl.analysis) {
+        .unreferenced => unreachable,
         .in_progress => unreachable,
         .outdated => unreachable,
 
         .dependency_failure,
         .sema_failure,
+        .sema_failure_retryable,
         .codegen_failure,
         .codegen_failure_retryable,
         => return error.AnalysisFail,
 
         .complete => {},
     }
-    if (scope.decl()) |scope_decl| {
-        try self.declareDeclDependency(scope_decl, decl);
-    }
     return decl;
 }
 
+/// TODO Look into removing this function. The body is only needed for .zir files, not .zig files.
 fn resolveInst(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!*Inst {
-    if (scope.cast(Scope.Block)) |block| {
-        if (block.func.analysis.in_progress.inst_table.get(old_inst)) |kv| {
-            return kv.value;
-        }
-    }
-
-    const decl = try self.resolveCompleteDecl(scope, old_inst);
+    if (old_inst.analyzed_inst) |inst| return inst;
+
+    // If this assert trips, the instruction that was referenced did not get properly
+    // analyzed before it was referenced.
+    const zir_module = scope.namespace().cast(Scope.ZIRModule).?;
+    const entry = if (old_inst.cast(zir.Inst.DeclVal)) |declval| blk: {
+        const decl_name = declval.positionals.name;
+        const entry = zir_module.contents.module.findDecl(decl_name) orelse
+            return self.fail(scope, old_inst.src, "decl '{}' not found", .{decl_name});
+        break :blk entry;
+    } else blk: {
+        // If this assert trips, the instruction that was referenced did not get
+        // properly analyzed by a previous instruction analysis before it was
+        // referenced by the current one.
+        break :blk zir_module.contents.module.findInstDecl(old_inst).?;
+    };
+    const decl = try self.resolveCompleteZirDecl(scope, entry.decl);
     const decl_ref = try self.analyzeDeclRef(scope, old_inst.src, decl);
+    // Note: it would be tempting here to store the result into old_inst.analyzed_inst field,
+    // but this would prevent the analyzeDeclRef from happening, which is needed to properly
+    // detect Decl dependencies and dependency failures on updates.
     return self.analyzeDeref(scope, old_inst.src, decl_ref, old_inst.src);
 }
 
@@ -1258,21 +2085,16 @@ fn resolveType(self: *Module, scope: *Scope, old_inst: *zir.Inst) !Type {
     return val.toType();
 }
 
-fn analyzeExport(self: *Module, scope: *Scope, export_inst: *zir.Inst.Export) InnerError!void {
-    try self.decl_exports.ensureCapacity(self.decl_exports.size + 1);
-    try self.export_owners.ensureCapacity(self.export_owners.size + 1);
-    const symbol_name = try self.resolveConstString(scope, export_inst.positionals.symbol_name);
-    const exported_decl = try self.resolveCompleteDecl(scope, export_inst.positionals.value);
+fn analyzeExport(self: *Module, scope: *Scope, src: usize, symbol_name: []const u8, exported_decl: *Decl) !void {
+    try self.ensureDeclAnalyzed(exported_decl);
     const typed_value = exported_decl.typed_value.most_recent.typed_value;
     switch (typed_value.ty.zigTypeTag()) {
         .Fn => {},
-        else => return self.fail(
-            scope,
-            export_inst.positionals.value.src,
-            "unable to export type '{}'",
-            .{typed_value.ty},
-        ),
+        else => return self.fail(scope, src, "unable to export type '{}'", .{typed_value.ty}),
     }
+    try self.decl_exports.ensureCapacity(self.decl_exports.size + 1);
+    try self.export_owners.ensureCapacity(self.export_owners.size + 1);
+
     const new_export = try self.allocator.create(Export);
     errdefer self.allocator.destroy(new_export);
 
@@ -1280,7 +2102,7 @@ fn analyzeExport(self: *Module, scope: *Scope, export_inst: *zir.Inst.Export) In
 
     new_export.* = .{
         .options = .{ .name = symbol_name },
-        .src = export_inst.base.src,
+        .src = src,
         .link = .{},
         .owner_decl = owner_decl,
         .exported_decl = exported_decl,
@@ -1311,7 +2133,7 @@ fn analyzeExport(self: *Module, scope: *Scope, export_inst: *zir.Inst.Export) In
             try self.failed_exports.ensureCapacity(self.failed_exports.size + 1);
             self.failed_exports.putAssumeCapacityNoClobber(new_export, try ErrorMsg.create(
                 self.allocator,
-                export_inst.base.src,
+                src,
                 "unable to export: {}",
                 .{@errorName(err)},
             ));
@@ -1320,7 +2142,6 @@ fn analyzeExport(self: *Module, scope: *Scope, export_inst: *zir.Inst.Export) In
     };
 }
 
-/// TODO should not need the cast on the last parameter at the callsites
 fn addNewInstArgs(
     self: *Module,
     block: *Scope.Block,
@@ -1334,6 +2155,46 @@ fn addNewInstArgs(
     return &inst.base;
 }
 
+fn newZIRInst(
+    allocator: *Allocator,
+    src: usize,
+    comptime T: type,
+    positionals: std.meta.fieldInfo(T, "positionals").field_type,
+    kw_args: std.meta.fieldInfo(T, "kw_args").field_type,
+) !*zir.Inst {
+    const inst = try allocator.create(T);
+    inst.* = .{
+        .base = .{
+            .tag = T.base_tag,
+            .src = src,
+        },
+        .positionals = positionals,
+        .kw_args = kw_args,
+    };
+    return &inst.base;
+}
+
+fn addZIRInst(
+    self: *Module,
+    scope: *Scope,
+    src: usize,
+    comptime T: type,
+    positionals: std.meta.fieldInfo(T, "positionals").field_type,
+    kw_args: std.meta.fieldInfo(T, "kw_args").field_type,
+) !*zir.Inst {
+    const gen_zir = scope.cast(Scope.GenZIR).?;
+    try gen_zir.instructions.ensureCapacity(gen_zir.instructions.items.len + 1);
+    const inst = try newZIRInst(&gen_zir.arena.allocator, src, T, positionals, kw_args);
+    gen_zir.instructions.appendAssumeCapacity(inst);
+    return inst;
+}
+
+/// TODO The existence of this function is a workaround for a bug in stage1.
+fn addZIRInstConst(self: *Module, scope: *Scope, src: usize, typed_value: TypedValue) !*zir.Inst {
+    const P = std.meta.fieldInfo(zir.Inst.Const, "positionals").field_type;
+    return self.addZIRInst(scope, src, zir.Inst.Const, P{ .typed_value = typed_value }, .{});
+}
+
 fn addNewInst(self: *Module, block: *Scope.Block, src: usize, ty: Type, comptime T: type) !*T {
     const inst = try block.arena.create(T);
     inst.* = .{
@@ -1361,19 +2222,6 @@ fn constInst(self: *Module, scope: *Scope, src: usize, typed_value: TypedValue)
     return &const_inst.base;
 }
 
-fn constStr(self: *Module, scope: *Scope, src: usize, str: []const u8) !*Inst {
-    const ty_payload = try scope.arena().create(Type.Payload.Array_u8_Sentinel0);
-    ty_payload.* = .{ .len = str.len };
-
-    const bytes_payload = try scope.arena().create(Value.Payload.Bytes);
-    bytes_payload.* = .{ .data = str };
-
-    return self.constInst(scope, src, .{
-        .ty = Type.initPayload(&ty_payload.base),
-        .val = Value.initPayload(&bytes_payload.base),
-    });
-}
-
 fn constType(self: *Module, scope: *Scope, src: usize, ty: Type) !*Inst {
     return self.constInst(scope, src, .{
         .ty = Type.initTag(.type),
@@ -1388,6 +2236,13 @@ fn constVoid(self: *Module, scope: *Scope, src: usize) !*Inst {
     });
 }
 
+fn constNoReturn(self: *Module, scope: *Scope, src: usize) !*Inst {
+    return self.constInst(scope, src, .{
+        .ty = Type.initTag(.noreturn),
+        .val = Value.initTag(.the_one_possible_value),
+    });
+}
+
 fn constUndef(self: *Module, scope: *Scope, src: usize, ty: Type) !*Inst {
     return self.constInst(scope, src, .{
         .ty = ty,
@@ -1451,7 +2306,7 @@ fn constIntBig(self: *Module, scope: *Scope, src: usize, ty: Type, big_int: BigI
     });
 }
 
-fn analyzeInstConst(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!TypedValue {
+fn analyzeConstInst(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!TypedValue {
     const new_inst = try self.analyzeInst(scope, old_inst);
     return TypedValue{
         .ty = new_inst.ty,
@@ -1459,20 +2314,24 @@ fn analyzeInstConst(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerErro
     };
 }
 
+fn analyzeInstConst(self: *Module, scope: *Scope, const_inst: *zir.Inst.Const) InnerError!*Inst {
+    // Move the TypedValue from old memory to new memory. This allows freeing the ZIR instructions
+    // after analysis.
+    const typed_value_copy = try const_inst.positionals.typed_value.copy(scope.arena());
+    return self.constInst(scope, const_inst.base.src, typed_value_copy);
+}
+
 fn analyzeInst(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!*Inst {
     switch (old_inst.tag) {
         .breakpoint => return self.analyzeInstBreakpoint(scope, old_inst.cast(zir.Inst.Breakpoint).?),
         .call => return self.analyzeInstCall(scope, old_inst.cast(zir.Inst.Call).?),
         .compileerror => return self.analyzeInstCompileError(scope, old_inst.cast(zir.Inst.CompileError).?),
+        .@"const" => return self.analyzeInstConst(scope, old_inst.cast(zir.Inst.Const).?),
         .declref => return self.analyzeInstDeclRef(scope, old_inst.cast(zir.Inst.DeclRef).?),
+        .declref_str => return self.analyzeInstDeclRefStr(scope, old_inst.cast(zir.Inst.DeclRefStr).?),
         .declval => return self.analyzeInstDeclVal(scope, old_inst.cast(zir.Inst.DeclVal).?),
-        .str => {
-            const bytes = old_inst.cast(zir.Inst.Str).?.positionals.bytes;
-            // The bytes references memory inside the ZIR module, which can get deallocated
-            // after semantic analysis is complete. We need the memory to be in the Decl's arena.
-            const arena_bytes = try scope.arena().dupe(u8, bytes);
-            return self.constStr(scope, old_inst.src, arena_bytes);
-        },
+        .declval_in_module => return self.analyzeInstDeclValInModule(scope, old_inst.cast(zir.Inst.DeclValInModule).?),
+        .str => return self.analyzeInstStr(scope, old_inst.cast(zir.Inst.Str).?),
         .int => {
             const big_int = old_inst.cast(zir.Inst.Int).?.positionals.int;
             return self.constIntBig(scope, old_inst.src, Type.initTag(.comptime_int), big_int);
@@ -1484,13 +2343,10 @@ fn analyzeInst(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!*In
         .@"asm" => return self.analyzeInstAsm(scope, old_inst.cast(zir.Inst.Asm).?),
         .@"unreachable" => return self.analyzeInstUnreachable(scope, old_inst.cast(zir.Inst.Unreachable).?),
         .@"return" => return self.analyzeInstRet(scope, old_inst.cast(zir.Inst.Return).?),
+        .returnvoid => return self.analyzeInstRetVoid(scope, old_inst.cast(zir.Inst.ReturnVoid).?),
         .@"fn" => return self.analyzeInstFn(scope, old_inst.cast(zir.Inst.Fn).?),
-        .@"export" => {
-            try self.analyzeExport(scope, old_inst.cast(zir.Inst.Export).?);
-            return self.constVoid(scope, old_inst.src);
-        },
+        .@"export" => return self.analyzeInstExport(scope, old_inst.cast(zir.Inst.Export).?),
         .primitive => return self.analyzeInstPrimitive(scope, old_inst.cast(zir.Inst.Primitive).?),
-        .ref => return self.analyzeInstRef(scope, old_inst.cast(zir.Inst.Ref).?),
         .fntype => return self.analyzeInstFnType(scope, old_inst.cast(zir.Inst.FnType).?),
         .intcast => return self.analyzeInstIntCast(scope, old_inst.cast(zir.Inst.IntCast).?),
         .bitcast => return self.analyzeInstBitCast(scope, old_inst.cast(zir.Inst.BitCast).?),
@@ -1503,39 +2359,104 @@ fn analyzeInst(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!*In
     }
 }
 
+fn analyzeInstStr(self: *Module, scope: *Scope, str_inst: *zir.Inst.Str) InnerError!*Inst {
+    // The bytes references memory inside the ZIR module, which can get deallocated
+    // after semantic analysis is complete. We need the memory to be in the new anonymous Decl's arena.
+    var new_decl_arena = std.heap.ArenaAllocator.init(self.allocator);
+    const arena_bytes = try new_decl_arena.allocator.dupe(u8, str_inst.positionals.bytes);
+
+    const ty_payload = try scope.arena().create(Type.Payload.Array_u8_Sentinel0);
+    ty_payload.* = .{ .len = arena_bytes.len };
+
+    const bytes_payload = try scope.arena().create(Value.Payload.Bytes);
+    bytes_payload.* = .{ .data = arena_bytes };
+
+    const new_decl = try self.createAnonymousDecl(scope, &new_decl_arena, .{
+        .ty = Type.initPayload(&ty_payload.base),
+        .val = Value.initPayload(&bytes_payload.base),
+    });
+    return self.analyzeDeclRef(scope, str_inst.base.src, new_decl);
+}
+
+fn createAnonymousDecl(
+    self: *Module,
+    scope: *Scope,
+    decl_arena: *std.heap.ArenaAllocator,
+    typed_value: TypedValue,
+) !*Decl {
+    const name_index = self.getNextAnonNameIndex();
+    const scope_decl = scope.decl().?;
+    const name = try std.fmt.allocPrint(self.allocator, "{}${}", .{ scope_decl.name, name_index });
+    defer self.allocator.free(name);
+    const name_hash = scope.namespace().fullyQualifiedNameHash(name);
+    const src_hash: std.zig.SrcHash = undefined;
+    const new_decl = try self.createNewDecl(scope, name, scope_decl.src_index, name_hash, src_hash);
+    const decl_arena_state = try decl_arena.allocator.create(std.heap.ArenaAllocator.State);
+
+    decl_arena_state.* = decl_arena.state;
+    new_decl.typed_value = .{
+        .most_recent = .{
+            .typed_value = typed_value,
+            .arena = decl_arena_state,
+        },
+    };
+    new_decl.analysis = .complete;
+    new_decl.generation = self.generation;
+
+    // TODO: This generates the Decl into the machine code file if it is of a type that is non-zero size.
+    // We should be able to further improve the compiler to not omit Decls which are only referenced at
+    // compile-time and not runtime.
+    if (typed_value.ty.hasCodeGenBits()) {
+        try self.bin_file.allocateDeclIndexes(new_decl);
+        try self.work_queue.writeItem(.{ .codegen_decl = new_decl });
+    }
+
+    return new_decl;
+}
+
+fn getNextAnonNameIndex(self: *Module) usize {
+    return @atomicRmw(usize, &self.next_anon_name_index, .Add, 1, .Monotonic);
+}
+
+fn lookupDeclName(self: *Module, scope: *Scope, ident_name: []const u8) ?*Decl {
+    const namespace = scope.namespace();
+    const name_hash = namespace.fullyQualifiedNameHash(ident_name);
+    return self.decl_table.getValue(name_hash);
+}
+
+fn analyzeInstExport(self: *Module, scope: *Scope, export_inst: *zir.Inst.Export) InnerError!*Inst {
+    const symbol_name = try self.resolveConstString(scope, export_inst.positionals.symbol_name);
+    const exported_decl = self.lookupDeclName(scope, export_inst.positionals.decl_name) orelse
+        return self.fail(scope, export_inst.base.src, "decl '{}' not found", .{export_inst.positionals.decl_name});
+    try self.analyzeExport(scope, export_inst.base.src, symbol_name, exported_decl);
+    return self.constVoid(scope, export_inst.base.src);
+}
+
 fn analyzeInstCompileError(self: *Module, scope: *Scope, inst: *zir.Inst.CompileError) InnerError!*Inst {
     return self.fail(scope, inst.base.src, "{}", .{inst.positionals.msg});
 }
 
 fn analyzeInstBreakpoint(self: *Module, scope: *Scope, inst: *zir.Inst.Breakpoint) InnerError!*Inst {
     const b = try self.requireRuntimeBlock(scope, inst.base.src);
-    return self.addNewInstArgs(b, inst.base.src, Type.initTag(.void), Inst.Breakpoint, Inst.Args(Inst.Breakpoint){});
+    return self.addNewInstArgs(b, inst.base.src, Type.initTag(.void), Inst.Breakpoint, {});
 }
 
-fn analyzeInstRef(self: *Module, scope: *Scope, inst: *zir.Inst.Ref) InnerError!*Inst {
-    const decl = try self.resolveCompleteDecl(scope, inst.positionals.operand);
-    return self.analyzeDeclRef(scope, inst.base.src, decl);
+fn analyzeInstDeclRefStr(self: *Module, scope: *Scope, inst: *zir.Inst.DeclRefStr) InnerError!*Inst {
+    const decl_name = try self.resolveConstString(scope, inst.positionals.name);
+    return self.analyzeDeclRefByName(scope, inst.base.src, decl_name);
 }
 
 fn analyzeInstDeclRef(self: *Module, scope: *Scope, inst: *zir.Inst.DeclRef) InnerError!*Inst {
-    const decl_name = try self.resolveConstString(scope, inst.positionals.name);
-    // This will need to get more fleshed out when there are proper structs & namespaces.
-    const zir_module = scope.namespace();
-    const src_decl = zir_module.contents.module.findDecl(decl_name) orelse
-        return self.fail(scope, inst.positionals.name.src, "use of undeclared identifier '{}'", .{decl_name});
-
-    const decl = try self.resolveCompleteDecl(scope, src_decl);
-    return self.analyzeDeclRef(scope, inst.base.src, decl);
+    return self.analyzeDeclRefByName(scope, inst.base.src, inst.positionals.name);
 }
 
 fn analyzeDeclVal(self: *Module, scope: *Scope, inst: *zir.Inst.DeclVal) InnerError!*Decl {
     const decl_name = inst.positionals.name;
-    // This will need to get more fleshed out when there are proper structs & namespaces.
-    const zir_module = scope.namespace();
+    const zir_module = scope.namespace().cast(Scope.ZIRModule).?;
     const src_decl = zir_module.contents.module.findDecl(decl_name) orelse
         return self.fail(scope, inst.base.src, "use of undeclared identifier '{}'", .{decl_name});
 
-    const decl = try self.resolveCompleteDecl(scope, src_decl);
+    const decl = try self.resolveCompleteZirDecl(scope, src_decl.decl);
 
     return decl;
 }
@@ -1546,18 +2467,46 @@ fn analyzeInstDeclVal(self: *Module, scope: *Scope, inst: *zir.Inst.DeclVal) Inn
     return self.analyzeDeref(scope, inst.base.src, ptr, inst.base.src);
 }
 
+fn analyzeInstDeclValInModule(self: *Module, scope: *Scope, inst: *zir.Inst.DeclValInModule) InnerError!*Inst {
+    const decl = inst.positionals.decl;
+    const ptr = try self.analyzeDeclRef(scope, inst.base.src, decl);
+    return self.analyzeDeref(scope, inst.base.src, ptr, inst.base.src);
+}
+
 fn analyzeDeclRef(self: *Module, scope: *Scope, src: usize, decl: *Decl) InnerError!*Inst {
+    const scope_decl = scope.decl().?;
+    try self.declareDeclDependency(scope_decl, decl);
+    self.ensureDeclAnalyzed(decl) catch |err| {
+        if (scope.cast(Scope.Block)) |block| {
+            if (block.func) |func| {
+                func.analysis = .dependency_failure;
+            } else {
+                block.decl.analysis = .dependency_failure;
+            }
+        } else {
+            scope_decl.analysis = .dependency_failure;
+        }
+        return err;
+    };
+
     const decl_tv = try decl.typedValue();
     const ty_payload = try scope.arena().create(Type.Payload.SingleConstPointer);
     ty_payload.* = .{ .pointee_type = decl_tv.ty };
     const val_payload = try scope.arena().create(Value.Payload.DeclRef);
     val_payload.* = .{ .decl = decl };
+
     return self.constInst(scope, src, .{
         .ty = Type.initPayload(&ty_payload.base),
         .val = Value.initPayload(&val_payload.base),
     });
 }
 
+fn analyzeDeclRefByName(self: *Module, scope: *Scope, src: usize, decl_name: []const u8) InnerError!*Inst {
+    const decl = self.lookupDeclName(scope, decl_name) orelse
+        return self.fail(scope, src, "decl '{}' not found", .{decl_name});
+    return self.analyzeDeclRef(scope, src, decl);
+}
+
 fn analyzeInstCall(self: *Module, scope: *Scope, inst: *zir.Inst.Call) InnerError!*Inst {
     const func = try self.resolveInst(scope, inst.positionals.func);
     if (func.ty.zigTypeTag() != .Fn)
@@ -1616,7 +2565,7 @@ fn analyzeInstCall(self: *Module, scope: *Scope, inst: *zir.Inst.Call) InnerErro
     }
 
     const b = try self.requireRuntimeBlock(scope, inst.base.src);
-    return self.addNewInstArgs(b, inst.base.src, Type.initTag(.void), Inst.Call, Inst.Args(Inst.Call){
+    return self.addNewInstArgs(b, inst.base.src, Type.initTag(.void), Inst.Call, .{
         .func = func,
         .args = casted_args,
     });
@@ -1624,10 +2573,22 @@ fn analyzeInstCall(self: *Module, scope: *Scope, inst: *zir.Inst.Call) InnerErro
 
 fn analyzeInstFn(self: *Module, scope: *Scope, fn_inst: *zir.Inst.Fn) InnerError!*Inst {
     const fn_type = try self.resolveType(scope, fn_inst.positionals.fn_type);
+    const fn_zir = blk: {
+        var fn_arena = std.heap.ArenaAllocator.init(self.allocator);
+        errdefer fn_arena.deinit();
+
+        const fn_zir = try scope.arena().create(Fn.ZIR);
+        fn_zir.* = .{
+            .body = .{
+                .instructions = fn_inst.positionals.body.instructions,
+            },
+            .arena = fn_arena.state,
+        };
+        break :blk fn_zir;
+    };
     const new_func = try scope.arena().create(Fn);
     new_func.* = .{
-        .fn_type = fn_type,
-        .analysis = .{ .queued = fn_inst },
+        .analysis = .{ .queued = fn_zir },
         .owner_decl = scope.decl().?,
     };
     const fn_payload = try scope.arena().create(Value.Payload.Function);
@@ -1648,6 +2609,13 @@ fn analyzeInstFnType(self: *Module, scope: *Scope, fntype: *zir.Inst.FnType) Inn
         return self.constType(scope, fntype.base.src, Type.initTag(.fn_noreturn_no_args));
     }
 
+    if (return_type.zigTypeTag() == .Void and
+        fntype.positionals.param_types.len == 0 and
+        fntype.kw_args.cc == .Unspecified)
+    {
+        return self.constType(scope, fntype.base.src, Type.initTag(.fn_void_no_args));
+    }
+
     if (return_type.zigTypeTag() == .NoReturn and
         fntype.positionals.param_types.len == 0 and
         fntype.kw_args.cc == .Naked)
@@ -1683,7 +2651,7 @@ fn analyzeInstPtrToInt(self: *Module, scope: *Scope, ptrtoint: *zir.Inst.PtrToIn
     // TODO handle known-pointer-address
     const b = try self.requireRuntimeBlock(scope, ptrtoint.base.src);
     const ty = Type.initTag(.usize);
-    return self.addNewInstArgs(b, ptrtoint.base.src, ty, Inst.PtrToInt, Inst.Args(Inst.PtrToInt){ .ptr = ptr });
+    return self.addNewInstArgs(b, ptrtoint.base.src, ty, Inst.PtrToInt, .{ .ptr = ptr });
 }
 
 fn analyzeInstFieldPtr(self: *Module, scope: *Scope, fieldptr: *zir.Inst.FieldPtr) InnerError!*Inst {
@@ -1875,7 +2843,7 @@ fn analyzeInstAsm(self: *Module, scope: *Scope, assembly: *zir.Inst.Asm) InnerEr
     }
 
     const b = try self.requireRuntimeBlock(scope, assembly.base.src);
-    return self.addNewInstArgs(b, assembly.base.src, return_type, Inst.Assembly, Inst.Args(Inst.Assembly){
+    return self.addNewInstArgs(b, assembly.base.src, return_type, Inst.Assembly, .{
         .asm_source = asm_source,
         .is_volatile = assembly.kw_args.@"volatile",
         .output = output,
@@ -1911,20 +2879,12 @@ fn analyzeInstCmp(self: *Module, scope: *Scope, inst: *zir.Inst.Cmp) InnerError!
         }
         const b = try self.requireRuntimeBlock(scope, inst.base.src);
         switch (op) {
-            .eq => return self.addNewInstArgs(
-                b,
-                inst.base.src,
-                Type.initTag(.bool),
-                Inst.IsNull,
-                Inst.Args(Inst.IsNull){ .operand = opt_operand },
-            ),
-            .neq => return self.addNewInstArgs(
-                b,
-                inst.base.src,
-                Type.initTag(.bool),
-                Inst.IsNonNull,
-                Inst.Args(Inst.IsNonNull){ .operand = opt_operand },
-            ),
+            .eq => return self.addNewInstArgs(b, inst.base.src, Type.initTag(.bool), Inst.IsNull, .{
+                .operand = opt_operand,
+            }),
+            .neq => return self.addNewInstArgs(b, inst.base.src, Type.initTag(.bool), Inst.IsNonNull, .{
+                .operand = opt_operand,
+            }),
             else => unreachable,
         }
     } else if (is_equality_cmp and
@@ -2019,23 +2979,19 @@ fn analyzeInstUnreachable(self: *Module, scope: *Scope, unreach: *zir.Inst.Unrea
 }
 
 fn analyzeInstRet(self: *Module, scope: *Scope, inst: *zir.Inst.Return) InnerError!*Inst {
+    const operand = try self.resolveInst(scope, inst.positionals.operand);
     const b = try self.requireRuntimeBlock(scope, inst.base.src);
-    return self.addNewInstArgs(b, inst.base.src, Type.initTag(.noreturn), Inst.Ret, {});
+    return self.addNewInstArgs(b, inst.base.src, Type.initTag(.noreturn), Inst.Ret, .{ .operand = operand });
+}
+
+fn analyzeInstRetVoid(self: *Module, scope: *Scope, inst: *zir.Inst.ReturnVoid) InnerError!*Inst {
+    const b = try self.requireRuntimeBlock(scope, inst.base.src);
+    return self.addNewInstArgs(b, inst.base.src, Type.initTag(.noreturn), Inst.RetVoid, {});
 }
 
 fn analyzeBody(self: *Module, scope: *Scope, body: zir.Module.Body) !void {
-    if (scope.cast(Scope.Block)) |b| {
-        const analysis = b.func.analysis.in_progress;
-        analysis.needed_inst_capacity += body.instructions.len;
-        try analysis.inst_table.ensureCapacity(analysis.needed_inst_capacity);
-        for (body.instructions) |src_inst| {
-            const new_inst = try self.analyzeInst(scope, src_inst);
-            analysis.inst_table.putAssumeCapacityNoClobber(src_inst, new_inst);
-        }
-    } else {
-        for (body.instructions) |src_inst| {
-            _ = try self.analyzeInst(scope, src_inst);
-        }
+    for (body.instructions) |src_inst| {
+        src_inst.analyzed_inst = try self.analyzeInst(scope, src_inst);
     }
 }
 
@@ -2118,7 +3074,7 @@ fn cmpNumeric(
         };
         const casted_lhs = try self.coerce(scope, dest_type, lhs);
         const casted_rhs = try self.coerce(scope, dest_type, rhs);
-        return self.addNewInstArgs(b, src, dest_type, Inst.Cmp, Inst.Args(Inst.Cmp){
+        return self.addNewInstArgs(b, src, dest_type, Inst.Cmp, .{
             .lhs = casted_lhs,
             .rhs = casted_rhs,
             .op = op,
@@ -2222,7 +3178,7 @@ fn cmpNumeric(
     const casted_lhs = try self.coerce(scope, dest_type, lhs);
     const casted_rhs = try self.coerce(scope, dest_type, lhs);
 
-    return self.addNewInstArgs(b, src, dest_type, Inst.Cmp, Inst.Args(Inst.Cmp){
+    return self.addNewInstArgs(b, src, dest_type, Inst.Cmp, .{
         .lhs = casted_lhs,
         .rhs = casted_rhs,
         .op = op,
@@ -2299,7 +3255,7 @@ fn bitcast(self: *Module, scope: *Scope, dest_type: Type, inst: *Inst) !*Inst {
     }
     // TODO validate the type size and other compile errors
     const b = try self.requireRuntimeBlock(scope, inst.src);
-    return self.addNewInstArgs(b, inst.src, dest_type, Inst.BitCast, Inst.Args(Inst.BitCast){ .operand = inst });
+    return self.addNewInstArgs(b, inst.src, dest_type, Inst.BitCast, .{ .operand = inst });
 }
 
 fn coerceArrayPtrToSlice(self: *Module, scope: *Scope, dest_type: Type, inst: *Inst) !*Inst {
@@ -2316,6 +3272,30 @@ fn fail(self: *Module, scope: *Scope, src: usize, comptime format: []const u8, a
     return self.failWithOwnedErrorMsg(scope, src, err_msg);
 }
 
+fn failTok(
+    self: *Module,
+    scope: *Scope,
+    token_index: ast.TokenIndex,
+    comptime format: []const u8,
+    args: var,
+) InnerError {
+    @setCold(true);
+    const src = scope.tree().token_locs[token_index].start;
+    return self.fail(scope, src, format, args);
+}
+
+fn failNode(
+    self: *Module,
+    scope: *Scope,
+    ast_node: *ast.Node,
+    comptime format: []const u8,
+    args: var,
+) InnerError {
+    @setCold(true);
+    const src = scope.tree().token_locs[ast_node.firstToken()].start;
+    return self.fail(scope, src, format, args);
+}
+
 fn failWithOwnedErrorMsg(self: *Module, scope: *Scope, src: usize, err_msg: *ErrorMsg) InnerError {
     {
         errdefer err_msg.destroy(self.allocator);
@@ -2326,18 +3306,31 @@ fn failWithOwnedErrorMsg(self: *Module, scope: *Scope, src: usize, err_msg: *Err
         .decl => {
             const decl = scope.cast(Scope.DeclAnalysis).?.decl;
             decl.analysis = .sema_failure;
+            decl.generation = self.generation;
             self.failed_decls.putAssumeCapacityNoClobber(decl, err_msg);
         },
         .block => {
             const block = scope.cast(Scope.Block).?;
-            block.func.analysis = .sema_failure;
+            if (block.func) |func| {
+                func.analysis = .sema_failure;
+            } else {
+                block.decl.analysis = .sema_failure;
+                block.decl.generation = self.generation;
+            }
             self.failed_decls.putAssumeCapacityNoClobber(block.decl, err_msg);
         },
+        .gen_zir => {
+            const gen_zir = scope.cast(Scope.GenZIR).?;
+            gen_zir.decl.analysis = .sema_failure;
+            gen_zir.decl.generation = self.generation;
+            self.failed_decls.putAssumeCapacityNoClobber(gen_zir.decl, err_msg);
+        },
         .zir_module => {
             const zir_module = scope.cast(Scope.ZIRModule).?;
             zir_module.status = .loaded_sema_failure;
-            self.failed_files.putAssumeCapacityNoClobber(zir_module, err_msg);
+            self.failed_files.putAssumeCapacityNoClobber(scope, err_msg);
         },
+        .file => unreachable,
     }
     return error.AnalysisFail;
 }
@@ -2385,3 +3378,7 @@ pub const ErrorMsg = struct {
         self.* = undefined;
     }
 };
+
+fn srcHashEql(a: std.zig.SrcHash, b: std.zig.SrcHash) bool {
+    return @bitCast(u128, a) == @bitCast(u128, b);
+}