| author |  Pavel Verigo <paul.verigo@gmail.com> 2026-10-20 06:00:00+02:00 |
| committer |  Alex Rønne Petersen <alex@alexrp.com> 2026-10-21 00:47:14+02:00 |
| log | 427ddef0e84384c075dd01e8f1b512922c814a1c |
| tree | 554d2309ba5436d392bd25a2245bf015d3a5eae1 |
| parent | c8bb44618a9c3c7bfff4a9f672a451fdeda1bb02 |
llvm: fix lowerType bug on struct/union with under aligned field
2 files changed, 48 insertions(+), 4 deletions(-)
src/codegen/llvm.zig+12-4
| ... | ... | @@ -2893,8 +2893,8 @@ pub const Object = struct { |
| 2893 | 2893 | o.gpa, |
| 2894 | 2894 | try o.builder.arrayType(padding_len, .i8), |
| 2895 | 2895 | ); |
| 2896 | if (@ctz(offset) < max_field_ty_align.toLog2Units()) { | |
| 2897 | struct_kind = .@"packed"; // prevent unexpected trailing padding | |
| 2896 | if (struct_type.alignment.compareStrict(.lt, max_field_ty_align)) { | |
| 2897 | struct_kind = .@"packed"; // prevent wrong alignment | |
| 2898 | 2898 | } |
| 2899 | 2899 | } |
| 2900 | 2900 | |
| ... | ... | @@ -2973,6 +2973,14 @@ pub const Object = struct { |
| 2973 | 2973 | const aligned_field_ty = Type.fromInterned(union_obj.field_types.get(ip)[layout.most_aligned_field]); |
| 2974 | 2974 | const aligned_field_llvm_ty = try o.lowerType(aligned_field_ty, repr); |
| 2975 | 2975 | |
| 2976 | const struct_kind: Builder.Type.Structure.Kind = for (union_obj.field_types.get(ip)) |field_ty_ip| { | |
| 2977 | const field_ty = Type.fromInterned(field_ty_ip); | |
| 2978 | if (!field_ty.hasRuntimeBits(zcu)) continue; | |
| 2979 | if (layout.payload_align.compareStrict(.lt, field_ty.abiAlignment(zcu))) { | |
| 2980 | break .@"packed"; // prevent wrong alignment | |
| 2981 | } | |
| 2982 | } else .normal; | |
| 2983 | ||
| 2976 | 2984 | const payload_ty = ty: { |
| 2977 | 2985 | if (layout.most_aligned_field_size == layout.payload_size) { |
| 2978 | 2986 | break :ty aligned_field_llvm_ty; |
| ... | ... | @@ -2993,7 +3001,7 @@ pub const Object = struct { |
| 2993 | 3001 | |
| 2994 | 3002 | o.builder.namedTypeSetBody( |
| 2995 | 3003 | ty, |
| 2996 | try o.builder.structType(.normal, &.{payload_ty}), | |
| 3004 | try o.builder.structType(struct_kind, &.{payload_ty}), | |
| 2997 | 3005 | ); |
| 2998 | 3006 | return ty; |
| 2999 | 3007 | } |
| ... | ... | @@ -3021,7 +3029,7 @@ pub const Object = struct { |
| 3021 | 3029 | |
| 3022 | 3030 | o.builder.namedTypeSetBody( |
| 3023 | 3031 | ty, |
| 3024 | try o.builder.structType(.normal, llvm_fields[0..llvm_fields_len]), | |
| 3032 | try o.builder.structType(struct_kind, llvm_fields[0..llvm_fields_len]), | |
| 3025 | 3033 | ); |
| 3026 | 3034 | return ty; |
| 3027 | 3035 | }, |
test/behavior/align.zig+36
| ... | ... | @@ -495,6 +495,42 @@ test "struct field explicit alignment" { |
| 495 | 495 | try expect(@intFromPtr(&node.massive_byte) % 64 == 0); |
| 496 | 496 | } |
| 497 | 497 | |
| 498 | test "nested struct field alignment" { | |
| 499 | const S = struct { | |
| 500 | fn doTheTest() !void { | |
| 501 | const T = struct { | |
| 502 | a: u8, | |
| 503 | b: struct { c: u16 align(1) }, | |
| 504 | }; | |
| 505 | const init: T = .{ .a = 0, .b = .{ .c = ~@as(u16, 0) } }; | |
| 506 | var t: T = init; // copy constant aggregate | |
| 507 | _ = &t; | |
| 508 | try expect(t.b.c == ~@as(u16, 0)); | |
| 509 | } | |
| 510 | }; | |
| 511 | ||
| 512 | try S.doTheTest(); | |
| 513 | try comptime S.doTheTest(); | |
| 514 | } | |
| 515 | ||
| 516 | test "nested union field alignment" { | |
| 517 | const S = struct { | |
| 518 | fn doTheTest() !void { | |
| 519 | const T = struct { | |
| 520 | a: u8, | |
| 521 | b: union { c: u16 align(1) }, | |
| 522 | }; | |
| 523 | const init: T = .{ .a = 0, .b = .{ .c = ~@as(u16, 0) } }; | |
| 524 | var t: T = init; // copy constant aggregate | |
| 525 | _ = &t; | |
| 526 | try expect(t.b.c == ~@as(u16, 0)); | |
| 527 | } | |
| 528 | }; | |
| 529 | ||
| 530 | try S.doTheTest(); | |
| 531 | try comptime S.doTheTest(); | |
| 532 | } | |
| 533 | ||
| 498 | 534 | test "align(N) on functions" { |
| 499 | 535 | if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO |
| 500 | 536 | if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO |