On Tue, Oct 15, 2019 at 11:05:56AM -0700, Nick Desaulniers wrote: > Hmmm...I would have liked to remove it outright, as it is an ABI > mismatch that is likely to result in instability and non-fun-to-debug > runtime issues in the future. I suspect my patch does work for GCC > 7.1+. The question is: Do we want to either: > 1. mark AMDGPU broken for GCC < 7.1, or > 2. continue supporting it via stack alignment mismatch? > > 2 is brittle, and may break at any point in the future, but if it's > working for someone it does make me feel bad to outright disable it. > What I'd image 2 looks like is (psuedo code in a Makefile): > > if CC_IS_GCC && GCC_VERSION < 7.1: > set stack alignment to 16B and hope for the best > > So my diff would be amended to keep the stack alignment flags, but > only to support GCC < 7.1. And that assumes my change compiles with > GCC 7.1+. (Looks like it does for me locally with GCC 8.3, but I would > feel even more confident if someone with hardware to test on and GCC > 7.1+ could boot test). > -- > Thanks, > ~Nick Desaulniers If we do keep it, would adding -mstackrealign make it more robust? That's simple and will only add the alignment to functions that require 16-byte alignment (at least on gcc). Alternative is to use __attribute__((force_align_arg_pointer)) on functions that might be called from 8-byte-aligned code. It looks like -mstackrealign should work from gcc 5.3 onwards. _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
