nikic added a comment. In D87188#2281093 <https://reviews.llvm.org/D87188#2281093>, @mstorsjo wrote:
> This broke a few tests for me (generating code that now gives the fail result > at runtime). > > I'm not entirely sure which bit is the culprit, but the difference in output > (that breaks tests) for one object file is available at > https://martin.st/temp/vc1_block-diff-aarch64.txt, and > https://martin.st/temp/vc1_block-diff-armv7.txt. For the aarch64 version, it > looks like some conditionals are inverted, like these changes: > > - b.ge .LBB1_124 > + b.hs .LBB1_124 > > and > > - csel w14, w15, w14, gt > + csel w14, w15, w14, hi > > (with no seemingly related changes that would change the roles of the > registers). > > The input files for reproducing the issues are available at > https://martin.st/temp/vc1_block-aarch64.c and > https://martin.st/temp/vc1_block-armv7.c, which can be compiled with `clang > -target {aarch64,armv7}-w64-mingw32 -c -O2 vc1_block-{aarch64,armv7}.c`. Based on an initial look, the changes in comparison predicates here are probably a red herring. If I understand right, those predicates are switching from signed to unsigned comparison (e.g. gt to hi). I also see similar changes in IR. However, all the cases I looked at are actually correct (e.g. abs(x) > abs(y) can be compared signed or unsigned for poisoning abs). Assuming that this code is clean under ubsan, the problem is likely something else. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D87188/new/ https://reviews.llvm.org/D87188 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
