[PATCH] D116952: [ConstantFolding] Respect denormal handling mode attributes when folding instructions

Wed Jun 29 05:55:21 PDT 2022

spatel added a comment.

In D116952#3600716 <https://reviews.llvm.org/D116952#3600716>, @shchenz wrote:

> Hi, this patch causes mis-compile for above case, now `%_res` is true while before this patch it is false. We can not handle the denormal constantFP in fcmp? Will the denormal constantFP be in other opcodes as well?

Catching up after being out for a few days...
Yes, we'll need to make more of FP constant-folding aware of these function attributes to get consistent results. 
D128647 <https://reviews.llvm.org/D128647> looks like it will fix fcmp. We'll need something similar for constant-folded FP intrinsics and libcalls too. And there was a comment about updating LangRef to document the behavior (the flushing mode does not affect signbit ops like fneg/fabs/copysign).

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https://reviews.llvm.org/D116952