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Add a utility function to LoopInfo to return the exit block 

when the loop has exactly one exit, and make use of it in
LoopIndexSplit.

llvm-svn: 64388
This commit is contained in:
Dan Gohman 2009-02-12 18:08:24 +00:00
parent 6a60fa2428
commit 656b097b8a
2 changed files with 14 additions and 5 deletions
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10
llvm/include/llvm/Analysis/LoopInfo.h
View File

@ -184,6 +184,16 @@ public:
} }
} }
/// getExitingBlock - If getExitingBlocks would return exactly one block,
/// return that block. Otherwise return null.
BlockT *getExitingBlock() const {
SmallVector<BlockT*, 8> ExitingBlocks;
getExitingBlocks(ExitingBlocks);
if (ExitingBlocks.size() == 1)
return ExitingBlocks[0];
return 0;
}
/// getExitBlocks - Return all of the successor blocks of this loop. These /// getExitBlocks - Return all of the successor blocks of this loop. These
/// are the blocks _outside of the current loop_ which are branched to. /// are the blocks _outside of the current loop_ which are branched to.
/// ///

9
llvm/lib/Transforms/Scalar/LoopIndexSplit.cpp
View File

@ -236,15 +236,14 @@ bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
} }
// Reject loop if loop exit condition is not suitable. // Reject loop if loop exit condition is not suitable.
SmallVector<BasicBlock *, 2> EBs; BasicBlock *ExitingBlock = L->getExitingBlock();
L->getExitingBlocks(EBs); if (!ExitingBlock)
if (EBs.size() != 1)
return false; return false;
BranchInst *EBR = dyn_cast<BranchInst>(EBs[0]->getTerminator()); BranchInst *EBR = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
if (!EBR) return false; if (!EBR) return false;
ExitCondition = dyn_cast<ICmpInst>(EBR->getCondition()); ExitCondition = dyn_cast<ICmpInst>(EBR->getCondition());
if (!ExitCondition) return false; if (!ExitCondition) return false;
if (EBs[0] != L->getLoopLatch()) return false; if (ExitingBlock != L->getLoopLatch()) return false;
IVExitValue = ExitCondition->getOperand(1); IVExitValue = ExitCondition->getOperand(1);
if (!L->isLoopInvariant(IVExitValue)) if (!L->isLoopInvariant(IVExitValue))
IVExitValue = ExitCondition->getOperand(0); IVExitValue = ExitCondition->getOperand(0);