llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Sjoerd Meijer (sjoerdmeijer) <details> <summary>Changes</summary> We had an internal discussion about -ffp-contract, how it compared to GCC which defaults to fast, and standard compliance. Looking at our docs, I think most information is there, but also thought it could be a little bit more explicit about when it is and isn't standard compliant. Let me know if you think this is an improvement or not; happy to abandon this if you think it is not helping much. --- Full diff: https://github.com/llvm/llvm-project/pull/127621.diff 1 Files Affected: - (modified) clang/docs/UsersManual.rst (+14-8) ``````````diff diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst index d977868b8a2c6..8809632479a00 100644 --- a/clang/docs/UsersManual.rst +++ b/clang/docs/UsersManual.rst @@ -1681,19 +1681,25 @@ for more details. permitted to produce more precise results than performing the same operations separately. - The C standard permits intermediate floating-point results within an + The C/C++ standard permits intermediate floating-point results within an expression to be computed with more precision than their type would normally allow. This permits operation fusing, and Clang takes advantage - of this by default. This behavior can be controlled with the ``FP_CONTRACT`` - and ``clang fp contract`` pragmas. Please refer to the pragma documentation - for a description of how the pragmas interact with this option. + of this by default (``on``). Fusion across statements is non-C/C++ standard + compliant behavior and can be enabled (``fast``). + + Fusion can be controlled with the ``FP_CONTRACT`` and ``clang fp contract`` + pragmas. Please refer to the pragma documentation for a description of how + the pragmas interact with this option. Valid values are: - * ``fast`` (fuse across statements disregarding pragmas, default for CUDA) - * ``on`` (fuse in the same statement unless dictated by pragmas, default for languages other than CUDA/HIP) - * ``off`` (never fuse) - * ``fast-honor-pragmas`` (fuse across statements unless dictated by pragmas, default for HIP) + * ``fast``: enable non-C/C++ standard compliant behavior and fusion across + statements disregarding pragmas (default for CUDA) + * ``on``: enable C/C++ standard complaint fusion in the same statement unless + dictated by pragmas (default for languages other than CUDA/HIP) + * ``off``: disable fusion + * ``fast-honor-pragmas``: fuse across statements unless dictated by pragmas + (default for HIP) .. option:: -f[no-]honor-infinities `````````` </details> https://github.com/llvm/llvm-project/pull/127621 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
