ahatanak added a comment. In https://reviews.llvm.org/D30810#701141, @jaykang10 wrote:
> In https://reviews.llvm.org/D30810#701132, @ahatanak wrote: > > > Actually, it's not a mis-compile. The record layout shows that there is a > > padding before field f2 and f2 starts at byte 16. So using "store <4 x > > float>" doesn't overwrite the field. > > > It depends on float3's alignment. I guess the float3's alignment is 16 on > your target so there is a padding bytes before f2 to be aligned by 16. If you > add __attribute__((packed)) on struct type, you could see overwrite. I looked at ItaniumRecordLayoutBuilder to understand how __attribute__((packed)) affects the struct's layout. If the number of elements of a vector is not a power of 2, ASTContext::getTypeInfoImpl rounds up the width and alignment to the next power of 2. So the size of float3 is 16 bytes. __attribute__((packed)) can change the alignment of float3, but it doesn't change its size, so there is a 4-byte padding between field f1 and f2. https://reviews.llvm.org/D30810 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
