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Merge pull request #23256 from xtexx/fix-gh-20113

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x86_64: fix packedStore miscomp by spilling EFLAGS
This commit is contained in:
Jacob Young 2025-03-23 21:46:46 -04:00
commit f7e045c806
2 changed files with 34 additions and 3 deletions
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9
src/arch/x86_64/CodeGen.zig
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@ -88178,12 +88178,15 @@ fn airStore(self: *CodeGen, inst: Air.Inst.Index, safety: bool) !void {
const reg_locks = self.register_manager.lockRegsAssumeUnused(3, .{ .rdi, .rsi, .rcx });
defer for (reg_locks) |lock| self.register_manager.unlockReg(lock);
const ptr_ty = self.typeOf(bin_op.lhs);
const ptr_info = ptr_ty.ptrInfo(zcu);
const is_packed = ptr_info.flags.vector_index != .none or ptr_info.packed_offset.host_size > 0;
if (is_packed) try self.spillEflagsIfOccupied();
const src_mcv = try self.resolveInst(bin_op.rhs);
const ptr_mcv = try self.resolveInst(bin_op.lhs);
const ptr_ty = self.typeOf(bin_op.lhs);
const ptr_info = ptr_ty.ptrInfo(zcu);
if (ptr_info.flags.vector_index != .none or ptr_info.packed_offset.host_size > 0) {
if (is_packed) {
try self.packedStore(ptr_ty, ptr_mcv, src_mcv);
} else {
try self.store(ptr_ty, ptr_mcv, src_mcv, .{ .safety = safety });

28
test/behavior/packed-struct.zig
View File

@ -1349,3 +1349,31 @@ test "byte-aligned packed relocation" {
try expect(S.packed_value.x == 111);
try expect(S.packed_value.y == &S.global);
}
test "packed struct store of comparison result" {
if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
const S1 = packed struct {
val1: u3,
val2: u3,
};
const S2 = packed struct {
a: bool,
b: bool,
};
var A: S1 = .{ .val1 = 1, .val2 = 1 };
A.val2 += 1;
try expectEqual(1, A.val1);
try expectEqual(2, A.val2);
try expect((A.val2 & 1) != 1);
const result1: S2 = .{ .a = (A.val2 & 1) != 1, .b = (A.val1 & 1) != 1 };
try expect(result1.a);
try expect(!result1.b);
try expect((A.val2 == 3) == false);
try expect((A.val2 == 2) == true);
const result2: S2 = .{ .a = !(A.val2 == 3), .b = (A.val1 == 2) };
try expect(result2.a);
try expect(!result2.b);
}