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Avoid triangle loops.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41093 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel
2007-08-15 02:14:55 +00:00
parent 4f5d78e9c1
commit 3fe4f2135a
1 changed files with 16 additions and 4 deletions
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18
lib/Transforms/Scalar/LoopIndexSplit.cpp
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@@ -154,7 +154,7 @@ bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
L = IncomingLoop;
LPM = &LPM_Ref;
// FIXME - Nested loops makes dominator info updates tricky.
// FIXME - Nested loops make dominator info updates tricky.
if (!L->getSubLoops().empty())
return false;
@@ -659,8 +659,8 @@ void LoopIndexSplit::removeBlocks(BasicBlock *DeadBB, Loop *LP,
if (!DT->dominates(LiveBB, DFMember))
LiveDF->second.insert(DFMember);
}
DF->removeFromFrontier(LiveDF, SuccBB);
DF->removeFromFrontier(LiveDF, SuccBB);
}
}
}
@@ -669,6 +669,19 @@ void LoopIndexSplit::removeBlocks(BasicBlock *DeadBB, Loop *LP,
bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
BasicBlock *Preheader = L->getLoopPreheader();
BasicBlock *SplitBlock = SD.SplitCondition->getParent();
BasicBlock *Latch = L->getLoopLatch();
BasicBlock *Header = L->getHeader();
BranchInst *SplitTerminator = cast<BranchInst>(SplitBlock->getTerminator());
// FIXME - Unable to handle triange loops at the moment.
// In triangle loop, split condition is in header and one of the
// the split destination is loop latch. If split condition is EQ
// then such loops are already handle in processOneIterationLoop().
if (Header == SplitBlock
&& (Latch == SplitTerminator->getSuccessor(0)
|| Latch == SplitTerminator->getSuccessor(1)))
return false;
// True loop is original loop. False loop is cloned loop.
@@ -770,7 +783,6 @@ bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
SplitEdge(ExitBlock, FalseHeader, this);
//[*] Eliminate split condition's false branch from True loop.
BasicBlock *SplitBlock = SD.SplitCondition->getParent();
BranchInst *BR = cast<BranchInst>(SplitBlock->getTerminator());
BasicBlock *FBB = BR->getSuccessor(1);
BR->setUnconditionalDest(BR->getSuccessor(0));