[PATCH] Enable ExitValue rewrite only when expansion cost is low.

[hfinkel at anl.gov]

Thanks for continuing to work on this. A few comments below, and I'd like Andy to look at this.


REPOSITORY
  rL LLVM

================
Comment at: lib/Transforms/Scalar/IndVarSimplify.cpp:718
@@ +717,3 @@
+                                    SmallVector<RewritePhi, 8> &RewritePhiSet) {
+  bool LoopCanBeDel = true;
+
----------------
Once LoopCanBeDel is false, it will never become true again. Please remove this variable and just 'return false' in all places where you set LoopCanBeDel to false.


================
Comment at: lib/Transforms/Scalar/IndVarSimplify.cpp:740
@@ +739,3 @@
+  while (LoopCanBeDel && (P = dyn_cast<PHINode>(BI))) {
+    Value *incoming = P->getIncomingValueForBlock(ExitingBlocks[0]);
+
----------------
incoming -> Incoming

http://reviews.llvm.org/D9800

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