[PATCH] D152456: SeparateConstOffsetFromGEP: Don't use SCEV

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp:1240
+      if (auto *Dom =
+              findClosestMatchingDominator({LHS, RHS}, I, DominatingAdds)) {
         Instruction *NewSExt = new SExtInst(Dom, I->getType(), "", I);
----------------
I believe the previous code would also detect cases where the add operands are swapped as the same. Could add something like
```
static std::pair<Value *, Value *> createNormalizedPair(Value *A, Value *B) {
  if (A < B)
    return {A, B};
  return {B, A};
}
```
and use it for the add case to preserve that behavior. Though the fact that it's apparently untested is not reassuring...


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D152456/new/

https://reviews.llvm.org/D152456