[llvm] r237044 - [LoopIdiomRecognize] Transform backedge-taken count check into an assertion.

[Davide Italiano]

Author: davide
Date: Mon May 11 16:02:34 2015
New Revision: 237044

URL: http://llvm.org/viewvc/llvm-project?rev=237044&view=rev
Log:
[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.

Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp?rev=237044&r1=237043&r2=237044&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp Mon May 11 16:02:34 2015
@@ -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.