| author |  Matthew Lugg <mlugg@mlugg.co.uk> 2025-03-16 03:26:29+00:00 |
| committer | Matthew Lugg <mlugg@mlugg.co.uk> 2025-04-28 01:14:24+01:00 |
| log | 95932e98e50f3762c3faf5ac3ee7c8f11f09096e |
| tree | 3496052f75c6aad4aada9aab8caec4ba5196646e |
| parent | d4c539664661a93fe193a9559688e7c6c3955e0d |
| signature |  Commit is signed but in an unrecognized format. |
Sema: fix alignment of runtime field pointer of underaligned tuple
2 files changed, 30 insertions(+), 4 deletions(-)
src/Sema.zig+12-4
| ... | ... | @@ -28617,7 +28617,8 @@ fn tupleFieldPtr( |
| 28617 | 28617 | const pt = sema.pt; |
| 28618 | 28618 | const zcu = pt.zcu; |
| 28619 | 28619 | const tuple_ptr_ty = sema.typeOf(tuple_ptr); |
| 28620 | const tuple_ty = tuple_ptr_ty.childType(zcu); | |
| 28620 | const tuple_ptr_info = tuple_ptr_ty.ptrInfo(zcu); | |
| 28621 | const tuple_ty: Type = .fromInterned(tuple_ptr_info.child); | |
| 28621 | 28622 | try tuple_ty.resolveFields(pt); |
| 28622 | 28623 | const field_count = tuple_ty.structFieldCount(zcu); |
| 28623 | 28624 | |
| ... | ... | @@ -28635,9 +28636,16 @@ fn tupleFieldPtr( |
| 28635 | 28636 | const ptr_field_ty = try pt.ptrTypeSema(.{ |
| 28636 | 28637 | .child = field_ty.toIntern(), |
| 28637 | 28638 | .flags = .{ |
| 28638 | .is_const = !tuple_ptr_ty.ptrIsMutable(zcu), | |
| 28639 | .is_volatile = tuple_ptr_ty.isVolatilePtr(zcu), | |
| 28640 | .address_space = tuple_ptr_ty.ptrAddressSpace(zcu), | |
| 28639 | .is_const = tuple_ptr_info.flags.is_const, | |
| 28640 | .is_volatile = tuple_ptr_info.flags.is_volatile, | |
| 28641 | .address_space = tuple_ptr_info.flags.address_space, | |
| 28642 | .alignment = a: { | |
| 28643 | if (tuple_ptr_info.flags.alignment == .none) break :a .none; | |
| 28644 | // The tuple pointer isn't naturally aligned, so the field pointer might be underaligned. | |
| 28645 | const tuple_align = tuple_ptr_info.flags.alignment; | |
| 28646 | const field_align = try field_ty.abiAlignmentSema(pt); | |
| 28647 | break :a tuple_align.min(field_align); | |
| 28648 | }, | |
| 28641 | 28649 | }, |
| 28642 | 28650 | }); |
| 28643 | 28651 |
test/behavior/tuple.zig+18
| ... | ... | @@ -602,3 +602,21 @@ test "empty union in tuple" { |
| 602 | 602 | try std.testing.expectEqualStrings("0", info.@"struct".fields[0].name); |
| 603 | 603 | try std.testing.expect(@typeInfo(info.@"struct".fields[0].type) == .@"union"); |
| 604 | 604 | } |
| 605 | ||
| 606 | test "field pointer of underaligned tuple" { | |
| 607 | if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest; | |
| 608 | const S = struct { | |
| 609 | fn doTheTest() !void { | |
| 610 | const T = struct { u8, u32 }; | |
| 611 | var val: T align(2) = .{ 1, 2 }; | |
| 612 | ||
| 613 | comptime assert(@TypeOf(&val[0]) == *u8); // `u8` field pointer isn't overaligned | |
| 614 | comptime assert(@TypeOf(&val[1]) == *align(2) u32); // `u32` field pointer is correctly underaligned | |
| 615 | ||
| 616 | try expect(val[0] == 1); | |
| 617 | try expect(val[1] == 2); | |
| 618 | } | |
| 619 | }; | |
| 620 | try S.doTheTest(); | |
| 621 | try comptime S.doTheTest(); | |
| 622 | } |