[PATCH] D92367: [SCEV] Fix incorrect exit count calculated in error scope

[Mindong Chen via Phabricator via llvm-commits]

mdchen created this revision.
mdchen added reviewers: nikic, lebedev.ri, fhahn.
Herald added subscribers: llvm-commits, hiraditya.
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mdchen requested review of this revision.

In computeLoadConstantCompareExitLimit, the specified loop of the
addrec, which is used to compute the exit count, should contain the
loop which the exiting block belongs to.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92367

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp


Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -7822,9 +7822,10 @@
   Idx = getSCEVAtScope(Idx, L);
 
   // We can only recognize very limited forms of loop index expressions, in
-  // particular, only affine AddRec's like {C1,+,C2}.
+  // particular, only affine AddRec's like {C1,+,C2}<L2> where L is inside L2.
   const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
-  if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
+  if (!IdxExpr || !IdxExpr->getLoop()->contains(L) || !IdxExpr->isAffine() ||
+      isLoopInvariant(IdxExpr, L) ||
       !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
       !isa<SCEVConstant>(IdxExpr->getOperand(1)))
     return getCouldNotCompute();


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