nikic added a comment. In D150670#4368241 <https://reviews.llvm.org/D150670#4368241>, @pmatos wrote:
> In D150670#4368238 <https://reviews.llvm.org/D150670#4368238>, @pmatos wrote: > >> In D150670#4352163 <https://reviews.llvm.org/D150670#4352163>, @nikic wrote: >> >>> 1. Say that we prefer preserving rotates over "simplifying" funnel shifts >>> (ending up with the rot2 pattern). Basically by skipping the optimization >>> at >>> https://github.com/llvm/llvm-project/blob/7f54b38e28b3b66195de672848f2b5366d0d51e3/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp#L927-L931 >>> if both fsh operands are the same. Assuming this doesn't cause test >>> regressions, I think this would be acceptable to do. From a backend >>> perspective, even for targets that have a native funnel shift (aarch64, >>> x86), the difference between the rot1/rot2 patterns looks pretty neutral. > > OK, I just re-read your comment above and I am starting to assume that what > you mean is skipping the optimization for all targets if the funnel shift is > a rotate (i.e. same first two operands). Is this correct? That's right. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D150670/new/ https://reviews.llvm.org/D150670 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
