[PATCH] D138180: InstCombine: Fold negations of is_fpclass intrinsics

[Serge Pavlov via Phabricator via llvm-commits]

sepavloff added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:3715-3717
+      II->setArgOperand(
+          1, ConstantInt::get(ClassMask->getType(),
+                              ~ClassMask->getZExtValue() & fcAllFlags));
----------------
It must work for IEEE numbers. But for non-IEEE it is possible that a value does not belong to any of the classes known to `is_fpclass`. For example, type `x86_fp80` has so-called unsupported values. Do you think this transformation can be safely applied to such numbers also or it is better to limit it to IEEE numbers only?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D138180/new/

https://reviews.llvm.org/D138180