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Sema: fix alignment of runtime field pointer of underaligned tuple

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mlugg 2025-03-16 03:26:29 +00:00
parent d4c5396646
commit 95932e98e5
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GPG key ID: 3F5B7DCCBF4AF02E
2 changed files with 30 additions and 4 deletions
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16
src/Sema.zig
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@ -28617,7 +28617,8 @@ fn tupleFieldPtr(
const pt = sema.pt;
const zcu = pt.zcu;
const tuple_ptr_ty = sema.typeOf(tuple_ptr);
const tuple_ty = tuple_ptr_ty.childType(zcu);
const tuple_ptr_info = tuple_ptr_ty.ptrInfo(zcu);
const tuple_ty: Type = .fromInterned(tuple_ptr_info.child);
try tuple_ty.resolveFields(pt);
const field_count = tuple_ty.structFieldCount(zcu);
@ -28635,9 +28636,16 @@ fn tupleFieldPtr(
const ptr_field_ty = try pt.ptrTypeSema(.{
.child = field_ty.toIntern(),
.flags = .{
.is_const = !tuple_ptr_ty.ptrIsMutable(zcu),
.is_volatile = tuple_ptr_ty.isVolatilePtr(zcu),
.address_space = tuple_ptr_ty.ptrAddressSpace(zcu),
.is_const = tuple_ptr_info.flags.is_const,
.is_volatile = tuple_ptr_info.flags.is_volatile,
.address_space = tuple_ptr_info.flags.address_space,
.alignment = a: {
if (tuple_ptr_info.flags.alignment == .none) break :a .none;
// The tuple pointer isn't naturally aligned, so the field pointer might be underaligned.
const tuple_align = tuple_ptr_info.flags.alignment;
const field_align = try field_ty.abiAlignmentSema(pt);
break :a tuple_align.min(field_align);
},
},
});

18
test/behavior/tuple.zig
View file

@ -602,3 +602,21 @@ test "empty union in tuple" {
try std.testing.expectEqualStrings("0", info.@"struct".fields[0].name);
try std.testing.expect(@typeInfo(info.@"struct".fields[0].type) == .@"union");
}
test "field pointer of underaligned tuple" {
if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
const S = struct {
fn doTheTest() !void {
const T = struct { u8, u32 };
var val: T align(2) = .{ 1, 2 };
comptime assert(@TypeOf(&val[0]) == *u8); // `u8` field pointer isn't overaligned
comptime assert(@TypeOf(&val[1]) == *align(2) u32); // `u32` field pointer is correctly underaligned
try expect(val[0] == 1);
try expect(val[1] == 2);
}
};
try S.doTheTest();
try comptime S.doTheTest();
}