Author: dpatel
Date: Tue Aug 14 13:35:57 2007
New Revision: 41082
URL: http://llvm.org/viewvc/llvm-project?rev=41082&view=rev
Log:
Fix dominance frontier update while removing blocks.
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp?rev=41082&r1=41081&r2=41082&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp Tue Aug 14 13:35:57 2007
@@ -97,8 +97,10 @@
/// loop may not be eliminated.
bool safeExitBlock(SplitInfo &SD, BasicBlock *BB);
- /// removeBlocks - Remove basic block BB and all blocks dominated by BB.
- void removeBlocks(BasicBlock *InBB, Loop *LP);
+ /// removeBlocks - Remove basic block DeadBB and all blocks dominated by
DeadBB.
+ /// This routine is used to remove split condition's dead branch,
dominated by
+ /// DeadBB. LiveBB dominates split conidition's other branch.
+ void removeBlocks(BasicBlock *DeadBB, Loop *LP, BasicBlock *LiveBB);
/// Find cost of spliting loop L.
unsigned findSplitCost(Loop *L, SplitInfo &SD);
@@ -589,11 +591,14 @@
return Cost;
}
-/// removeBlocks - Remove basic block BB and all blocks dominated by BB.
-void LoopIndexSplit::removeBlocks(BasicBlock *InBB, Loop *LP) {
+/// removeBlocks - Remove basic block DeadBB and all blocks dominated by
DeadBB.
+/// This routine is used to remove split condition's dead branch, dominated by
+/// DeadBB. LiveBB dominates split conidition's other branch.
+void LoopIndexSplit::removeBlocks(BasicBlock *DeadBB, Loop *LP,
+ BasicBlock *LiveBB) {
SmallVector<std::pair<BasicBlock *, succ_iterator>, 8> WorkList;
- WorkList.push_back(std::make_pair(InBB, succ_begin(InBB)));
+ WorkList.push_back(std::make_pair(DeadBB, succ_begin(DeadBB)));
while (!WorkList.empty()) {
BasicBlock *BB = WorkList.back(). first;
succ_iterator SIter =WorkList.back().second;
@@ -630,10 +635,28 @@
break;
}
+ DT->changeImmediateDominator(SuccBB, LiveBB);
+
// If BB is not dominating SuccBB then SuccBB is in BB's dominance
// frontiner.
DominanceFrontier::iterator BBDF = DF->find(BB);
DF->removeFromFrontier(BBDF, SuccBB);
+
+ // LiveBB is now dominating SuccBB. Which means SuccBB's dominance
+ // frontier is member of LiveBB's dominance frontier. However, SuccBB
+ // itself is not member of LiveBB's dominance frontier.
+ DominanceFrontier::iterator LiveDF = DF->find(LiveBB);
+ DominanceFrontier::iterator SuccDF = DF->find(SuccBB);
+ DominanceFrontier::DomSetType SuccBBSet = SuccDF->second;
+ for (DominanceFrontier::DomSetType::iterator SuccBBSetI =
SuccBBSet.begin(),
+ SuccBBSetE = SuccBBSet.end(); SuccBBSetI != SuccBBSetE;
++SuccBBSetI) {
+ BasicBlock *DFMember = *SuccBBSetI;
+ // Insert only if LiveBB dominates DFMember.
+ if (!DT->dominates(LiveBB, DFMember))
+ LiveDF->second.insert(DFMember);
+ }
+ DF->removeFromFrontier(LiveDF, SuccBB);
+
}
}
}
@@ -747,7 +770,7 @@
BranchInst *BR = cast<BranchInst>(SplitBlock->getTerminator());
BasicBlock *FBB = BR->getSuccessor(1);
BR->setUnconditionalDest(BR->getSuccessor(0));
- removeBlocks(FBB, L);
+ removeBlocks(FBB, L, BR->getSuccessor(0));
//[*] Update True loop's exit value using new exit value.
ExitCondition->setOperand(ExitValueNum, TLExitValue);
@@ -757,7 +780,7 @@
BranchInst *FBR = cast<BranchInst>(FSplitBlock->getTerminator());
BasicBlock *TBB = FBR->getSuccessor(0);
FBR->setUnconditionalDest(FBR->getSuccessor(1));
- removeBlocks(TBB, FalseLoop);
+ removeBlocks(TBB, FalseLoop, cast<BasicBlock>(FBR->getSuccessor(0)));
return true;
}
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