[PATCH] D118928: [FPEnv][InstSimplify] Fold fsub X, +0 ==> X

[Serge Pavlov via Phabricator via llvm-commits]

sepavloff added inline comments.


================
Comment at: llvm/lib/Analysis/InstructionSimplify.cpp:5133
 
+  // fsub X, +0 ==> X
+  if (canIgnoreSNaN(ExBehavior, FMF))
----------------
What if `X==+0` and rounding is downward? In this case `fsub X, +0` should produce `-0.0` (https://en.wikipedia.org/wiki/Signed_zero#Arithmetic).


Repository:
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  https://reviews.llvm.org/D118928/new/

https://reviews.llvm.org/D118928