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wasm: Implement lowering unions

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This commit is contained in:
Luuk de Gram
2022-01-22 21:23:17 +01:00
parent 288b407fa9
commit e9d122f164
1 changed files with 40 additions and 3 deletions
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43
src/arch/wasm/CodeGen.zig
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@@ -1053,9 +1053,46 @@ pub const DeclGen = struct {
return Result{ .appended = {} };
},
.Union => {
// TODO: Implement Union declarations
try writer.writeByteNTimes(0xaa, @intCast(usize, ty.abiSize(self.target())));
return Result{ .appended = {} };
const union_val = val.castTag(.@"union").?.data;
const layout = ty.unionGetLayout(self.target());
if (layout.payload_size == 0) {
return self.genTypedValue(ty.unionTagType().?, union_val.tag, writer);
}
// Check if we should store the tag first, in which case, do so now:
if (layout.tag_align >= layout.payload_align) {
switch (try self.genTypedValue(ty.unionTagType().?, union_val.tag, writer)) {
.appended => {},
.externally_managed => |payload| try writer.writeAll(payload),
}
}
const union_ty = ty.cast(Type.Payload.Union).?.data;
const field_index = union_ty.tag_ty.enumTagFieldIndex(union_val.tag).?;
assert(union_ty.haveFieldTypes());
const field_ty = union_ty.fields.values()[field_index].ty;
if (!field_ty.hasCodeGenBits()) {
try writer.writeByteNTimes(0xaa, layout.payload_size);
} else {
switch (try self.genTypedValue(field_ty, union_val.val, writer)) {
.appended => {},
.externally_managed => |payload| try writer.writeAll(payload),
}
// Unions have the size of the largest field, so we must pad
// whenever the active field has a smaller size.
const diff = layout.payload_size - field_ty.abiSize(self.target());
if (diff > 0) {
try writer.writeByteNTimes(0xaa, diff);
}
}
if (layout.tag_size == 0) {
return Result{ .appended = {} };
}
return self.genTypedValue(union_ty.tag_ty, union_val.tag, writer);
},
.Pointer => switch (val.tag()) {
.variable => {