[PATCH] D38415: [SimplifyIndVar] Replace IVUsers with loop invariant if possible

[Hongbin Zheng via Phabricator via llvm-commits]

etherzhhb added inline comments.


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Comment at: lib/Transforms/Utils/SimplifyIndVar.cpp:555
 
-  Constant *V = C->getValue();
-  // The SCEV will have a different type than the instruction if the instruction
-  // has a pointer type. Skip the replacement
-  // TODO: Replace ConstantInt Zero by ConstantPointerNull
-  if (V->getType() != I->getType())
-    return false;
+  auto *Invariant = Rewriter.expandCodeFor(S, I->getType(), I);
 
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efriedma wrote:
> "I" is probably not the right place the put any expansion code, given it's inside the loop.
SCEVExpander figure out the correct place by itself (at least in test4 of test/Transforms/IndVarSimplify/replace-iv-with-loop-invariant.ll), otherwise we need to find the preheader (and fallback to I if there is no preheader)


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Comment at: test/Transforms/IndVarSimplify/replace-iv-with-loop-invariant.ll:84
+; CHECK-LABEL: void @test4
+; CHECK:         [[P:%[a-zA-Z$._0-9]+]] = getelementptr i32, i32* %loop.invariant
+; CHECK:         phi
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Here the SCEVExpander expand the expression before the loop (before the phi)


https://reviews.llvm.org/D38415