recommit 96626, evidence that it broke things appears
to be spurious
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96662 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index e699261..60492b0 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -246,6 +246,13 @@
if (!PN->getType()->isIntegerTy() && !PN->getType()->isPointerTy())
continue;
+ // It's necessary to tell ScalarEvolution about this explicitly so that
+ // it can walk the def-use list and forget all SCEVs, as it may not be
+ // watching the PHI itself. Once the new exit value is in place, there
+ // may not be a def-use connection between the loop and every instruction
+ // which got a SCEVAddRecExpr for that loop.
+ SE->forgetValue(PN);
+
// Iterate over all of the values in all the PHI nodes.
for (unsigned i = 0; i != NumPreds; ++i) {
// If the value being merged in is not integer or is not defined