authorgravatar for luuk@degram.devLuuk de Gram <luuk@degram.dev> 2022-03-06 15:57:28+01:00
committergravatar for luuk@degram.devLuuk de Gram <luuk@degram.dev> 2022-03-06 16:04:15+01:00
log23e2368ac339842b907ccc36580c3a471bb26d43
tree1522a9e220c037f9a019335b212e1901e6801102
parentbf972e44d5d0ce704cae99957d565c55ea16335d
signaturelock-open Commit is signed but in an unrecognized format.

stage2: Fix codegen for unions and error unions

When an union had a zero-sized payload type, we would lower the tag twice. This is fixed by exiting early when `payload_size` is 0. With regards to error unions, we were only accounting for padding for the payload field. However, the errorset value can have a smaller alignment than the payload as well, i.e. error!usize. We fix this by also accounting for padding/alignment of the error set tag of an error union.

1 files changed, 29 insertions(+), 26 deletions(-)

src/codegen.zig+29-26
......@@ -573,16 +573,10 @@ pub fn generateSymbol(
573573 const layout = typed_value.ty.unionGetLayout(target);
574574
575575 if (layout.payload_size == 0) {
576 switch (try generateSymbol(bin_file, src_loc, .{
576 return generateSymbol(bin_file, src_loc, .{
577577 .ty = typed_value.ty.unionTagType().?,
578578 .val = union_obj.tag,
579 }, code, debug_output, reloc_info)) {
580 .appended => {},
581 .externally_managed => |external_slice| {
582 code.appendSliceAssumeCapacity(external_slice);
583 },
584 .fail => |em| return Result{ .fail = em },
585 }
579 }, code, debug_output, reloc_info);
586580 }
587581
588582 // Check if we should store the tag first.
......@@ -703,20 +697,30 @@ pub fn generateSymbol(
703697
704698 const abi_align = typed_value.ty.abiAlignment(target);
705699
706 const error_val = if (!is_payload) typed_value.val else Value.initTag(.zero);
707 const begin = code.items.len;
708 switch (try generateSymbol(bin_file, src_loc, .{
709 .ty = error_ty,
710 .val = error_val,
711 }, code, debug_output, reloc_info)) {
712 .appended => {},
713 .externally_managed => |external_slice| {
714 code.appendSliceAssumeCapacity(external_slice);
715 },
716 .fail => |em| return Result{ .fail = em },
700 {
701 const error_val = if (!is_payload) typed_value.val else Value.initTag(.zero);
702 const begin = code.items.len;
703 switch (try generateSymbol(bin_file, src_loc, .{
704 .ty = error_ty,
705 .val = error_val,
706 }, code, debug_output, reloc_info)) {
707 .appended => {},
708 .externally_managed => |external_slice| {
709 code.appendSliceAssumeCapacity(external_slice);
710 },
711 .fail => |em| return Result{ .fail = em },
712 }
713 const unpadded_end = code.items.len - begin;
714 const padded_end = mem.alignForwardGeneric(u64, unpadded_end, abi_align);
715 const padding = try math.cast(usize, padded_end - unpadded_end);
716
717 if (padding > 0) {
718 try code.writer().writeByteNTimes(0, padding);
719 }
717720 }
718721
719722 if (payload_ty.hasRuntimeBits()) {
723 const begin = code.items.len;
720724 const payload_val = if (typed_value.val.castTag(.eu_payload)) |val| val.data else Value.initTag(.undef);
721725 switch (try generateSymbol(bin_file, src_loc, .{
722726 .ty = payload_ty,
......@@ -728,14 +732,13 @@ pub fn generateSymbol(
728732 },
729733 .fail => |em| return Result{ .fail = em },
730734 }
731 }
735 const unpadded_end = code.items.len - begin;
736 const padded_end = mem.alignForwardGeneric(u64, unpadded_end, abi_align);
737 const padding = try math.cast(usize, padded_end - unpadded_end);
732738
733 const unpadded_end = code.items.len - begin;
734 const padded_end = mem.alignForwardGeneric(u64, unpadded_end, abi_align);
735 const padding = try math.cast(usize, padded_end - unpadded_end);
736
737 if (padding > 0) {
738 try code.writer().writeByteNTimes(0, padding);
739 if (padding > 0) {
740 try code.writer().writeByteNTimes(0, padding);
741 }
739742 }
740743
741744 return Result{ .appended = {} };