From: Davide Italiano <davide@freebsd.org>
Date: Mon, 11 May 2015 21:02:34 +0000 (+0000)
Subject: [LoopIdiomRecognize] Transform backedge-taken count check into an assertion.
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=383c55870eda2ce1664d8e9d199b1ba7bacd32ba

[LoopIdiomRecognize] Transform backedge-taken count check into an assertion.

runOnCountable() allowed the caller to call on a loop without a
predictable backedge-taken count. Change the code so that only loops
with computable backdge-count can call this function, in order to catch
abuses.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237044 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index 7bc291784ab..b57b7c276d7 100644
--- a/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -611,7 +611,9 @@ bool NclPopcountRecognize::recognize() {
 
 bool LoopIdiomRecognize::runOnCountableLoop() {
   const SCEV *BECount = SE->getBackedgeTakenCount(CurLoop);
-  if (isa<SCEVCouldNotCompute>(BECount)) return false;
+  assert(!isa<SCEVCouldNotCompute>(BECount) &&
+    "runOnCountableLoop() called on a loop without a predictable"
+    "backedge-taken count");
 
   // If this loop executes exactly one time, then it should be peeled, not
   // optimized by this pass.