thopre added a comment. In D104854#2957735 <https://reviews.llvm.org/D104854#2957735>, @kpn wrote:
> 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. Really? The constrained intrinsic documentation claims the reverse (https://llvm.org/docs/LangRef.html#constrainedfp): > If any FP operation in a function is constrained then they all must be > constrained. This is required for correct LLVM IR. Optimizations that move > code around can create miscompiles if mixing of constrained and normal > operations is done. The correct way to mix constrained and less constrained > operations is to use the rounding mode and exception handling metadata to > mark constrained intrinsics as having LLVM’s default behavior. 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
