authorgravatar for luuk@degram.devLuuk de Gram <luuk@degram.dev> 2022-05-23 18:24:03+02:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2022-05-24 15:34:52-07:00
logc90a97f9be9ffef858b0e450de5006f61a12fafd
treec8ba955be7b7cd81230a2e0da39f2c36e73a681e
parent3264abe3d8f658e1b7275d2be80e43eddfc098dc

codegen: Order error union fields per alignment

Based on the size of the payload the native backends will lower the error union with its fields (errorset & payload) in the correct order. e.g. ErrorA!u8 will first lower the error set's value and then the payload. In the event of ErrorA!u32 will lower the payload first.

1 files changed, 41 insertions(+), 7 deletions(-)

src/codegen.zig+41-7
...@@ -702,16 +702,50 @@ pub fn generateSymbol(...@@ -702,16 +702,50 @@ pub fn generateSymbol(
702 .ErrorUnion => {702 .ErrorUnion => {
703 const error_ty = typed_value.ty.errorUnionSet();703 const error_ty = typed_value.ty.errorUnionSet();
704 const payload_ty = typed_value.ty.errorUnionPayload();704 const payload_ty = typed_value.ty.errorUnionPayload();
705
706 if (error_ty.errorSetCardinality() == .zero) {
707 const payload_val = typed_value.val.castTag(.eu_payload).?.data;
708 return generateSymbol(bin_file, src_loc, .{
709 .ty = payload_ty,
710 .val = payload_val,
711 }, code, debug_output, reloc_info);
712 }
713
705 const is_payload = typed_value.val.errorUnionIsPayload();714 const is_payload = typed_value.val.errorUnionIsPayload();
706715
716 if (!payload_ty.hasRuntimeBitsIgnoreComptime()) {
717 const err_val = if (!is_payload) typed_value.val else Value.initTag(.zero);
718 return generateSymbol(bin_file, src_loc, .{
719 .ty = error_ty,
720 .val = err_val,
721 }, code, debug_output, reloc_info);
722 }
723
724 const payload_align = payload_ty.abiAlignment(target);
725 const error_align = Type.anyerror.abiAlignment(target);
707 const abi_align = typed_value.ty.abiAlignment(target);726 const abi_align = typed_value.ty.abiAlignment(target);
708727
728 // error value first when its type is larger than the error union's payload
729 if (error_align > payload_align) {
730 switch (try generateSymbol(bin_file, src_loc, .{
731 .ty = error_ty,
732 .val = if (is_payload) Value.initTag(.zero) else typed_value.val,
733 }, code, debug_output, reloc_info)) {
734 .appended => {},
735 .externally_managed => |external_slice| {
736 code.appendSliceAssumeCapacity(external_slice);
737 },
738 .fail => |em| return Result{ .fail = em },
739 }
740 }
741
742 // emit payload part of the error union
709 {743 {
710 const error_val = if (!is_payload) typed_value.val else Value.initTag(.zero);
711 const begin = code.items.len;744 const begin = code.items.len;
745 const payload_val = if (typed_value.val.castTag(.eu_payload)) |val| val.data else Value.initTag(.undef);
712 switch (try generateSymbol(bin_file, src_loc, .{746 switch (try generateSymbol(bin_file, src_loc, .{
713 .ty = error_ty,747 .ty = payload_ty,
714 .val = error_val,748 .val = payload_val,
715 }, code, debug_output, reloc_info)) {749 }, code, debug_output, reloc_info)) {
716 .appended => {},750 .appended => {},
717 .externally_managed => |external_slice| {751 .externally_managed => |external_slice| {
...@@ -728,12 +762,12 @@ pub fn generateSymbol(...@@ -728,12 +762,12 @@ pub fn generateSymbol(
728 }762 }
729 }763 }
730764
731 if (payload_ty.hasRuntimeBits()) {765 // Payload size is larger than error set, so emit our error set last
766 if (error_align < payload_align) {
732 const begin = code.items.len;767 const begin = code.items.len;
733 const payload_val = if (typed_value.val.castTag(.eu_payload)) |val| val.data else Value.initTag(.undef);
734 switch (try generateSymbol(bin_file, src_loc, .{768 switch (try generateSymbol(bin_file, src_loc, .{
735 .ty = payload_ty,769 .ty = error_ty,
736 .val = payload_val,770 .val = if (is_payload) Value.initTag(.zero) else typed_value.val,
737 }, code, debug_output, reloc_info)) {771 }, code, debug_output, reloc_info)) {
738 .appended => {},772 .appended => {},
739 .externally_managed => |external_slice| {773 .externally_managed => |external_slice| {