Commit `7cfc44d86f`

Luuk de Gram <luuk@degram.dev>

2023-05-23 19:55:33

wasm: implement `struct_field_val` for packed unions

We currently have `isRef` return true for any type of union, including packed unions. This means we can simply load it from the data section to the exact type we want. In the future we can optimize it so it works similarly to packed structs below 64 bits which do not get stored in the data section and are not passed by ref.

master

1 parent 49fddbf

Changed files (1)

src

arch

wasm

CodeGen.zig

@@ -3617,7 +3617,6 @@ fn airStructFieldVal(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
         .Packed => switch (struct_ty.zigTypeTag()) {
             .Struct => result: {
                 const struct_obj = struct_ty.castTag(.@"struct").?.data;
-                assert(struct_obj.layout == .Packed);
                 const offset = struct_obj.packedFieldBitOffset(func.target, field_index);
                 const backing_ty = struct_obj.backing_int_ty;
                 const wasm_bits = toWasmBits(backing_ty.intInfo(func.target).bits) orelse {
@@ -3661,7 +3660,10 @@ fn airStructFieldVal(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
                 const truncated = try func.trunc(shifted_value, field_ty, backing_ty);
                 break :result try truncated.toLocal(func, field_ty);
             },
-            .Union => return func.fail("TODO: airStructFieldVal for packed unions", .{}),
+            .Union => result: {
+                const val = try func.load(operand, field_ty, 0);
+                break :result try val.toLocal(func, field_ty);
+            },
             else => unreachable,
         },
         else => result: {
@@ -5032,7 +5034,7 @@ fn airUnionInit(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
         break :result result_ptr;
     };
 
-    func.finishAir(inst, result, &.{extra.init});
+    return func.finishAir(inst, result, &.{extra.init});
 }
 
 fn airPrefetch(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {

Commit 7cfc44d86f

Commit `7cfc44d86f`