[PATCH] D40035: [LoopRotate] processLoop should return true even if it just simplified the loop latch without making any other changes

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.

Simplifying a loop latch changes the IR and we need to make sure the pass manager knows to invalidate analysis passes if that happened.

PR35210 discovered a case where we failed to invalidate the post dominator tree after this simplification because we no changes other than simplifying the loop latch.

I'm still trying to put together a reduced test that triggers only the latch simplification, but I don't know anything about this pass so if anyone wants to help that would be great.

Fixes PR35210.


https://reviews.llvm.org/D40035

Files:
  lib/Transforms/Scalar/LoopRotation.cpp


Index: lib/Transforms/Scalar/LoopRotation.cpp
===================================================================
--- lib/Transforms/Scalar/LoopRotation.cpp
+++ lib/Transforms/Scalar/LoopRotation.cpp
@@ -634,7 +634,7 @@
   if ((MadeChange || SimplifiedLatch) && LoopMD)
     L->setLoopID(LoopMD);
 
-  return MadeChange;
+  return MadeChange || SimplifiedLatch;
 }
 
 LoopRotatePass::LoopRotatePass(bool EnableHeaderDuplication)


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