================
@@ -2539,9 +2548,22 @@ TypeInfo ASTContext::getTypeInfoImpl(const Type *T)
const {
const ASTRecordLayout &Layout = getASTRecordLayout(RD);
Width = toBits(Layout.getSize());
Align = toBits(Layout.getAlignment());
- AlignRequirement = RD->hasAttr<AlignedAttr>()
- ? AlignRequirementKind::RequiredByRecord
- : AlignRequirementKind::None;
+ // Check if the record has an aligned attribute, or if it contains
+ // fields with ABI-required alignment (e.g., x86_fp80).
+ if (RD->hasAttr<AlignedAttr>()) {
+ AlignRequirement = AlignRequirementKind::RequiredByRecord;
+ } else {
+ // Check if any field has RequiredByABI alignment requirement.
+ // If so, propagate it to the record.
----------------
ojhunt wrote:
The different behavior here is not relevant. The packing behavior is defined by
the target platform, not the compiler.
I cannot emphasize this enough: comparing object layout across different
operating systems is not relevant to correctness. Correctness is defined as
matching what the target platform specifies as the ABI.
As a few examples to make this clear
```cpp
struct MatchingUnderlyingStorage {
int first: 7;
int second: 25;
};
struct MismatchingUnderlyingStorage {
char first: 7;
int second: 25;
};
```
`sizeof(MatchingUnderlyingStorage)` is 4 bytes on windows and linux, but
`sizeof(MismatchingUnderlyingStorage)` is 8 bytes on windows, and 4 bytes on
linux. This is correct behavior.
or as another case
```cpp
enum Foo {
Foo1 = 0,
Foo2 = 1
};
struct EnumHolder {
Foo f: 1;
};
result = EnumHolder{Foo2}.f;
```
On linux `result` is `Foo2`, on windows it is -1. This is again *correct*.
Different results on different operating systems is not a sign of incorrect
behavior.
https://github.com/llvm/llvm-project/pull/208256
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