Am Di., 9. Juni 2026 um 09:49 Uhr schrieb Richard Biener <[email protected]>: > > On Sat, Jun 6, 2026 at 2:34 PM Oleg Tolmatcev <[email protected]> > wrote: > > > > From: oltolm <[email protected]> > > > > Fix PR54412 by preserving over-alignment for stack slots used for > > indirect argument passing and returns on Win64 targets that require it. > > > > On x86_64-w64-mingw32, TARGET_SEH limits > > MAX_SUPPORTED_STACK_ALIGNMENT to 128 bits, but fixed-size AVX and > > AVX512 values can still require greater alignment when passed or > > returned indirectly. Generic stack-slot allocation can therefore > > produce under-aligned slots, leading to misaligned aligned-move > > accesses and runtime failures. > > I think this is a x86 specific bug in how it optimizes things, the target uses > carefully orchestrated code to "optimize" "unnecessary" alignment, so I > suspect the proper fix would be to x86 target code, not to complicate the > middle-end side. But see below for comments on the patch.
Thanks for the review. I agree and I will try to fix it properly in i386.cc. I won't submit this patch anymore.
