[SCEVExpander] Make findExistingExpansion smarter
Summary:
Extending findExistingExpansion can use existing value in ExprValueMap.
This patch gives 0.3~0.5% performance improvements on
benchmarks(test-suite, spec2000, spec2006, commercial benchmark)
Reviewers: mzolotukhin, sanjoy, zzheng
Differential Revision: http://reviews.llvm.org/D15559
llvm-svn: 260938
diff --git a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
index ec0e491..232707d 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -311,9 +311,12 @@
return false;
BasicBlock *Header = L->getHeader();
+ BasicBlock *PH = L->getLoopPreheader();
+ BranchInst *PreHeaderBR = cast<BranchInst>(PH->getTerminator());
const DataLayout &DL = Header->getModule()->getDataLayout();
SCEVExpander Expander(*SE, DL, "loop-unroll");
- if (!AllowExpensiveTripCount && Expander.isHighCostExpansion(TripCountSC, L))
+ if (!AllowExpensiveTripCount &&
+ Expander.isHighCostExpansion(TripCountSC, L, PreHeaderBR))
return false;
// We only handle cases when the unroll factor is a power of 2.
@@ -331,13 +334,12 @@
if (Loop *ParentLoop = L->getParentLoop())
SE->forgetLoop(ParentLoop);
- BasicBlock *PH = L->getLoopPreheader();
BasicBlock *Latch = L->getLoopLatch();
// It helps to split the original preheader twice, one for the end of the
// prolog code and one for a new loop preheader.
BasicBlock *PEnd = SplitEdge(PH, Header, DT, LI);
BasicBlock *NewPH = SplitBlock(PEnd, PEnd->getTerminator(), DT, LI);
- BranchInst *PreHeaderBR = cast<BranchInst>(PH->getTerminator());
+ PreHeaderBR = cast<BranchInst>(PH->getTerminator());
// Compute the number of extra iterations required, which is:
// extra iterations = run-time trip count % (loop unroll factor + 1)