[PATCH] D95286: [LSR] Drop potentially invalid nowrap flags when switching to post-inc IV (PR46943)

[Florian Hahn via Phabricator via llvm-commits]

fhahn added inline comments.


================
Comment at: lib/Transforms/Utils/ScalarEvolutionExpander.cpp:1446
+    // those flags for which SCEV has proven that they always hold.
+    if (auto *BO = dyn_cast<BinaryOperator>(Result)) {
+      if (!S->hasNoUnsignedWrap())
----------------
`OverflowingBinaryOperator`?


================
Comment at: test/Transforms/LoopStrengthReduce/X86/pr46943.ll:48
 ; CHECK-NEXT:    call void @use(i8 [[IV]])
-; CHECK-NEXT:    [[IV_NEXT]] = add nsw i8 [[IV]], -1
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], -1
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i8 [[IV_NEXT]], 127
----------------
Is this transform actually still helpful, if we have to drop flags to do it?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D95286/new/

https://reviews.llvm.org/D95286