arsenm wrote: > * Which value allows generating the "fastest" math code -- disregarding > correctness? I'd assume that "dynamic" is least optimizable, "ieee" in the > middle, and "preserve-sign" is likely to generate the "fastest" code?
This depends on the target and operations. For some functions, on modern hardware, the preserve-sign code will be worse for AMDGPU. In other cases it's better > What is the likely actual impact of choosing the wrong value? Ie, what does > "it is not always safe" mean? Is this wrong beyond what is usually expected > from -ffast-math optimizations? The main example is the conversions performed between fcmp with 0 and llvm.is.fpclass. You'll get different results depending on whether the input is implicitly flushed in fcmp vs. not in the is.fpclass https://github.com/llvm/llvm-project/pull/80475 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
