kpn added a comment. In D104854#2957490 <https://reviews.llvm.org/D104854#2957490>, @lebedev.ri wrote:
> In D104854#2957471 <https://reviews.llvm.org/D104854#2957471>, @sepavloff > wrote: > >> In D104854#2957423 <https://reviews.llvm.org/D104854#2957423>, @spatel wrote: >> >>> Is it intentional that we are not canonicalizing the intrinsic call back to >>> `fcmp uno` in the default FP environment? >> >> It is lowered to unordered comparison by default. Changing `llvm.isnan` to >> `fcmp uno` somewhere in IR would make it possible to optimize out the latter >> if fast-math mode is on. Preserving semantics of `isnan` when fast-math is >> in effect was one of the goals of this change. > > Eeek. Was there an RFC about this? > This does not sound good to me at all, > much like "let's not apply fast-math flags to x86 vector intrinsics". We can switch into and out of the default FP environment inside a single function. If we want different behavior based on the FP environment then this should be a constrained intrinsic. Then the intrinsic would know the FP environment, or at least enough about it to know if traps and FP status bits are relevant. I think the distinction is constrained vs non-constrained because FMF can optionally be used in both cases. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D104854/new/ https://reviews.llvm.org/D104854 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
