diff --git a/src/codegen.zig b/src/codegen.zig index bd556baa5e..81b303ab82 100644 --- a/src/codegen.zig +++ b/src/codegen.zig @@ -702,16 +702,50 @@ pub fn generateSymbol( .ErrorUnion => { const error_ty = typed_value.ty.errorUnionSet(); const payload_ty = typed_value.ty.errorUnionPayload(); + + if (error_ty.errorSetCardinality() == .zero) { + const payload_val = typed_value.val.castTag(.eu_payload).?.data; + return generateSymbol(bin_file, src_loc, .{ + .ty = payload_ty, + .val = payload_val, + }, code, debug_output, reloc_info); + } + const is_payload = typed_value.val.errorUnionIsPayload(); + if (!payload_ty.hasRuntimeBitsIgnoreComptime()) { + const err_val = if (!is_payload) typed_value.val else Value.initTag(.zero); + return generateSymbol(bin_file, src_loc, .{ + .ty = error_ty, + .val = err_val, + }, code, debug_output, reloc_info); + } + + const payload_align = payload_ty.abiAlignment(target); + const error_align = Type.anyerror.abiAlignment(target); const abi_align = typed_value.ty.abiAlignment(target); - { - const error_val = if (!is_payload) typed_value.val else Value.initTag(.zero); - const begin = code.items.len; + // error value first when its type is larger than the error union's payload + if (error_align > payload_align) { switch (try generateSymbol(bin_file, src_loc, .{ .ty = error_ty, - .val = error_val, + .val = if (is_payload) Value.initTag(.zero) else typed_value.val, + }, code, debug_output, reloc_info)) { + .appended => {}, + .externally_managed => |external_slice| { + code.appendSliceAssumeCapacity(external_slice); + }, + .fail => |em| return Result{ .fail = em }, + } + } + + // emit payload part of the error union + { + const begin = code.items.len; + const payload_val = if (typed_value.val.castTag(.eu_payload)) |val| val.data else Value.initTag(.undef); + switch (try generateSymbol(bin_file, src_loc, .{ + .ty = payload_ty, + .val = payload_val, }, code, debug_output, reloc_info)) { .appended => {}, .externally_managed => |external_slice| { @@ -728,12 +762,12 @@ pub fn generateSymbol( } } - if (payload_ty.hasRuntimeBits()) { + // Payload size is larger than error set, so emit our error set last + if (error_align < payload_align) { const begin = code.items.len; - const payload_val = if (typed_value.val.castTag(.eu_payload)) |val| val.data else Value.initTag(.undef); switch (try generateSymbol(bin_file, src_loc, .{ - .ty = payload_ty, - .val = payload_val, + .ty = error_ty, + .val = if (is_payload) Value.initTag(.zero) else typed_value.val, }, code, debug_output, reloc_info)) { .appended => {}, .externally_managed => |external_slice| {