uweigand wrote: @MaskRay I've done a bit more analysis now, and what seems to be going on is that with stack safety analysis off, this check: ``` char array[len]; assert(!(reinterpret_cast<uintptr_t>(array) & 31L)); ``` succeeds because the VLA allocation gets instrumented, and therefore the VLA address is guaranteed to be 32-byte aligned.
However, with stack safety analysis *on*, that analysis (correctly) detects that the VLA is actually never accessed, and therefore the allocation does not need be instrumented. Because it is isn't instrumented, it remains a regular alloca without special alignment requirements. Therefore, there is no guarantee that the assert will succeed. If the incoming stack pointer happened to already be 32-byte aligned, it will succeed - otherwise (and that's the cases where we're seeing failures on s390x), it will not. This seems to be a platform-independent bug that just happens to be visible only on some platforms sometimes. https://github.com/llvm/llvm-project/pull/77210 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
