stage2: implement `@prefetch`

This reverts commit f423b5949b8722d4b290f57c3d06d015e39217b0,
re-instating commit d48e4245b68bf25c7f41804a5012ac157a5ee546.

5 files changed, 87 insertions, 4 deletions

diff --git a/src/arch/aarch64/CodeGen.zig b/src/arch/aarch64/CodeGen.zig
index f8a774af3b..d5993ea5d7 100644
--- a/src/arch/aarch64/CodeGen.zig
+++ b/src/arch/aarch64/CodeGen.zig
@@ -595,6 +595,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .error_name      => try self.airErrorName(inst),
             .splat           => try self.airSplat(inst),
             .vector_init     => try self.airVectorInit(inst),
+            .prefetch        => try self.airPrefetch(inst),
 
             .atomic_store_unordered => try self.airAtomicStore(inst, .Unordered),
             .atomic_store_monotonic => try self.airAtomicStore(inst, .Monotonic),
@@ -2597,6 +2598,11 @@ fn airVectorInit(self: *Self, inst: Air.Inst.Index) !void {
     return bt.finishAir(result);
 }
 
+fn airPrefetch(self: *Self, inst: Air.Inst.Index) !void {
+    const prefetch = self.air.instructions.items(.data)[inst].prefetch;
+    return self.finishAir(inst, MCValue.dead, .{ prefetch.ptr, .none, .none });
+}
+
 fn resolveInst(self: *Self, inst: Air.Inst.Ref) InnerError!MCValue {
     // First section of indexes correspond to a set number of constant values.
     const ref_int = @enumToInt(inst);
diff --git a/src/arch/arm/CodeGen.zig b/src/arch/arm/CodeGen.zig
index cae5164491..66c5a7a429 100644
--- a/src/arch/arm/CodeGen.zig
+++ b/src/arch/arm/CodeGen.zig
@@ -586,6 +586,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .error_name      => try self.airErrorName(inst),
             .splat           => try self.airSplat(inst),
             .vector_init     => try self.airVectorInit(inst),
+            .prefetch        => try self.airPrefetch(inst),
 
             .atomic_store_unordered => try self.airAtomicStore(inst, .Unordered),
             .atomic_store_monotonic => try self.airAtomicStore(inst, .Monotonic),
@@ -3693,6 +3694,11 @@ fn airVectorInit(self: *Self, inst: Air.Inst.Index) !void {
     return bt.finishAir(result);
 }
 
+fn airPrefetch(self: *Self, inst: Air.Inst.Index) !void {
+    const prefetch = self.air.instructions.items(.data)[inst].prefetch;
+    return self.finishAir(inst, MCValue.dead, .{ prefetch.ptr, .none, .none });
+}
+
 fn resolveInst(self: *Self, inst: Air.Inst.Ref) InnerError!MCValue {
     // First section of indexes correspond to a set number of constant values.
     const ref_int = @enumToInt(inst);
diff --git a/src/arch/riscv64/CodeGen.zig b/src/arch/riscv64/CodeGen.zig
index c5f0d4fb25..0c310d5680 100644
--- a/src/arch/riscv64/CodeGen.zig
+++ b/src/arch/riscv64/CodeGen.zig
@@ -574,6 +574,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .error_name      => try self.airErrorName(inst),
             .splat           => try self.airSplat(inst),
             .vector_init     => try self.airVectorInit(inst),
+            .prefetch        => try self.airPrefetch(inst),
 
             .atomic_store_unordered => try self.airAtomicStore(inst, .Unordered),
             .atomic_store_monotonic => try self.airAtomicStore(inst, .Monotonic),
@@ -2096,6 +2097,11 @@ fn airVectorInit(self: *Self, inst: Air.Inst.Index) !void {
     return bt.finishAir(result);
 }
 
+fn airPrefetch(self: *Self, inst: Air.Inst.Index) !void {
+    const prefetch = self.air.instructions.items(.data)[inst].prefetch;
+    return self.finishAir(inst, MCValue.dead, .{ prefetch.ptr, .none, .none });
+}
+
 fn resolveInst(self: *Self, inst: Air.Inst.Ref) InnerError!MCValue {
     // First section of indexes correspond to a set number of constant values.
     const ref_int = @enumToInt(inst);
diff --git a/src/arch/wasm/CodeGen.zig b/src/arch/wasm/CodeGen.zig
index 7a8efdfcc2..46a8e114e6 100644
--- a/src/arch/wasm/CodeGen.zig
+++ b/src/arch/wasm/CodeGen.zig
@@ -1297,6 +1297,9 @@ fn copyLocal(self: *Self, value: WValue, ty: Type) InnerError!WValue {
 fn genInst(self: *Self, inst: Air.Inst.Index) !WValue {
     const air_tags = self.air.instructions.items(.tag);
     return switch (air_tags[inst]) {
+        .constant => unreachable,
+        .const_ty => unreachable,
+
         .add => self.airBinOp(inst, .add),
         .addwrap => self.airWrapBinOp(inst, .add),
         .sub => self.airBinOp(inst, .sub),
@@ -1330,7 +1333,6 @@ fn genInst(self: *Self, inst: Air.Inst.Index) !WValue {
         .bool_to_int => self.airBoolToInt(inst),
         .call => self.airCall(inst),
         .cond_br => self.airCondBr(inst),
-        .constant => unreachable,
         .dbg_stmt => WValue.none,
         .intcast => self.airIntcast(inst),
         .float_to_int => self.airFloatToInt(inst),
@@ -1358,6 +1360,9 @@ fn genInst(self: *Self, inst: Air.Inst.Index) !WValue {
         .ret => self.airRet(inst),
         .ret_ptr => self.airRetPtr(inst),
         .ret_load => self.airRetLoad(inst),
+        .splat => self.airSplat(inst),
+        .vector_init => self.airVectorInit(inst),
+        .prefetch => self.airPrefetch(inst),
 
         .slice => self.airSlice(inst),
         .slice_len => self.airSliceLen(inst),
@@ -1382,7 +1387,55 @@ fn genInst(self: *Self, inst: Air.Inst.Index) !WValue {
         .unwrap_errunion_err => self.airUnwrapErrUnionError(inst),
         .wrap_errunion_payload => self.airWrapErrUnionPayload(inst),
         .wrap_errunion_err => self.airWrapErrUnionErr(inst),
-        else => |tag| self.fail("TODO: Implement wasm inst: {s}", .{@tagName(tag)}),
+
+        .add_sat,
+        .sub_sat,
+        .mul_sat,
+        .div_float,
+        .div_floor,
+        .div_exact,
+        .rem,
+        .mod,
+        .max,
+        .min,
+        .assembly,
+        .shl_exact,
+        .shl_sat,
+        .ret_addr,
+        .clz,
+        .ctz,
+        .popcount,
+        .is_err_ptr,
+        .is_non_err_ptr,
+        .fptrunc,
+        .fpext,
+        .unwrap_errunion_payload_ptr,
+        .unwrap_errunion_err_ptr,
+        .set_union_tag,
+        .get_union_tag,
+        .ptr_slice_len_ptr,
+        .ptr_slice_ptr_ptr,
+        .int_to_float,
+        .memcpy,
+        .cmpxchg_weak,
+        .cmpxchg_strong,
+        .fence,
+        .atomic_load,
+        .atomic_store_unordered,
+        .atomic_store_monotonic,
+        .atomic_store_release,
+        .atomic_store_seq_cst,
+        .atomic_rmw,
+        .tag_name,
+        .error_name,
+
+        // For these 4, probably best to wait until https://github.com/ziglang/zig/issues/10248
+        // is implemented in the frontend before implementing them here in the wasm backend.
+        .add_with_overflow,
+        .sub_with_overflow,
+        .mul_with_overflow,
+        .shl_with_overflow,
+        => |tag| self.fail("TODO: Implement wasm inst: {s}", .{@tagName(tag)}),
     };
 }
 
@@ -3211,7 +3264,7 @@ fn airFloatToInt(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     return result;
 }
 
-fn airSplat(self: *Self, inst: Air.Inst.Index) !void {
+fn airSplat(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     if (self.liveness.isUnused(inst)) return WValue{ .none = {} };
 
     const ty_op = self.air.instructions.items(.data)[inst].ty_op;
@@ -3222,7 +3275,7 @@ fn airSplat(self: *Self, inst: Air.Inst.Index) !void {
     return self.fail("TODO: Implement wasm airSplat", .{});
 }
 
-fn airVectorInit(self: *Self, inst: Air.Inst.Index) !void {
+fn airVectorInit(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     if (self.liveness.isUnused(inst)) return WValue{ .none = {} };
 
     const vector_ty = self.air.typeOfIndex(inst);
@@ -3234,6 +3287,12 @@ fn airVectorInit(self: *Self, inst: Air.Inst.Index) !void {
     return self.fail("TODO: Wasm backend: implement airVectorInit", .{});
 }
 
+fn airPrefetch(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
+    const prefetch = self.air.instructions.items(.data)[inst].prefetch;
+    _ = prefetch;
+    return WValue{ .none = {} };
+}
+
 fn cmpOptionals(self: *Self, lhs: WValue, rhs: WValue, operand_ty: Type, op: std.math.CompareOperator) InnerError!WValue {
     assert(operand_ty.hasCodeGenBits());
     assert(op == .eq or op == .neq);
diff --git a/src/arch/x86_64/CodeGen.zig b/src/arch/x86_64/CodeGen.zig
index a68674501c..2cf585fe4e 100644
--- a/src/arch/x86_64/CodeGen.zig
+++ b/src/arch/x86_64/CodeGen.zig
@@ -638,6 +638,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .error_name      => try self.airErrorName(inst),
             .splat           => try self.airSplat(inst),
             .vector_init     => try self.airVectorInit(inst),
+            .prefetch        => try self.airPrefetch(inst),
 
             .atomic_store_unordered => try self.airAtomicStore(inst, .Unordered),
             .atomic_store_monotonic => try self.airAtomicStore(inst, .Monotonic),
@@ -3746,6 +3747,11 @@ fn airVectorInit(self: *Self, inst: Air.Inst.Index) !void {
     return bt.finishAir(result);
 }
 
+fn airPrefetch(self: *Self, inst: Air.Inst.Index) !void {
+    const prefetch = self.air.instructions.items(.data)[inst].prefetch;
+    return self.finishAir(inst, MCValue.dead, .{ prefetch.ptr, .none, .none });
+}
+
 fn resolveInst(self: *Self, inst: Air.Inst.Ref) InnerError!MCValue {
     // First section of indexes correspond to a set number of constant values.
     const ref_int = @enumToInt(inst);