jfb added inline comments.
================ Comment at: compiler-rt/test/ubsan/TestCases/Integer/unsigned-shift.cpp:6 + volatile unsigned _v = (val); \ + volatile unsigned _a = (amount); \ + unsigned res = _v << _a; \ ---------------- vsk wrote: > jfb wrote: > > vsk wrote: > > > Does the test not work without the volatiles? > > It seems that LLVM sees too much without volatile, yes. > The optimizer isn't running. Perhaps this is necessary because clang's > constant folder kicks in? Probably, I haven't investigate. It's brittle is the main thing, and this forces it to not be. ================ Comment at: llvm/docs/ReleaseNotes.rst:151 + +One can silence the check with masking, for example: + ---------------- vsk wrote: > This could use some more explanation, maybe s/with masking/by clearing bits > that would be shifted out/? I just dropped it, I don't think release notes are the right place for this anyways. ================ Comment at: llvm/docs/ReleaseNotes.rst:153 + + `(lhs & ~(~1U << ((sizeof(lhs)*CHAR_BIT) - rhs))) << rhs` + ---------------- lebedev.ri wrote: > vsk wrote: > > jfb wrote: > > > lebedev.ri wrote: > > > > Surely not `~1U`. > > > Indeed, fixed. > > I don't think this pattern works when rhs = 0 > > (https://godbolt.org/z/rvEGqh). > Surely not `1U` either :) Right, I don't think it's something we want to explain here. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D86000/new/ https://reviews.llvm.org/D86000 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
