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Cleanup removeBlocks.

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Use dominance frontier to fixup incoming edges of successor blocks not domianted by DeadBB.
Use df_iterator to walk and delete basic blocks dominated by DeadBB.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41095 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2007-08-15 03:31:47 +00:00
parent e9dd95ad9c
commit 5b8ec614f5
1 changed files with 73 additions and 59 deletions
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132
lib/Transforms/Scalar/LoopIndexSplit.cpp
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@ -20,6 +20,7 @@
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
@ -47,6 +48,7 @@ namespace {
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
AU.addRequired<DominatorTree>();
AU.addRequired<DominanceFrontier>();
AU.addPreserved<DominatorTree>();
AU.addPreserved<DominanceFrontier>();
}
@ -600,69 +602,81 @@ unsigned LoopIndexSplit::findSplitCost(Loop *L, SplitInfo &SD) {
void LoopIndexSplit::removeBlocks(BasicBlock *DeadBB, Loop *LP,
BasicBlock *LiveBB) {
SmallVector<std::pair<BasicBlock *, succ_iterator>, 8> WorkList;
WorkList.push_back(std::make_pair(DeadBB, succ_begin(DeadBB)));
while (!WorkList.empty()) {
BasicBlock *BB = WorkList.back(). first;
succ_iterator SIter = WorkList.back().second;
// If all successor's are processed then remove this block.
if (SIter == succ_end(BB)) {
WorkList.pop_back();
for(BasicBlock::iterator BBI = BB->begin(), BBE = BB->end();
BBI != BBE; ++BBI) {
Instruction *I = BBI;
I->replaceAllUsesWith(UndefValue::get(I->getType()));
I->eraseFromParent();
}
LPM->deleteSimpleAnalysisValue(BB, LP);
DT->eraseNode(BB);
DF->removeBlock(BB);
LI->removeBlock(BB);
BB->eraseFromParent();
} else {
BasicBlock *SuccBB = *SIter;
++WorkList.back().second;
// First update DeadBB's dominance frontier.
DominanceFrontier::iterator DeadBBDF = DF->find(DeadBB);
if (DeadBBDF != DF->end()) {
SmallVector<BasicBlock *, 8> PredBlocks;
DominanceFrontier::DomSetType DeadBBSet = DeadBBDF->second;
for (DominanceFrontier::DomSetType::iterator DeadBBSetI = DeadBBSet.begin(),
DeadBBSetE = DeadBBSet.end(); DeadBBSetI != DeadBBSetE; ++DeadBBSetI) {
BasicBlock *FrontierBB = *DeadBBSetI;
if (DT->dominates(BB, SuccBB)) {
WorkList.push_back(std::make_pair(SuccBB, succ_begin(SuccBB)));
continue;
} else {
// If SuccBB is not dominated by BB then it is not removed, however remove
// any PHI incoming edge from BB.
for(BasicBlock::iterator SBI = SuccBB->begin(), SBE = SuccBB->end();
SBI != SBE; ++SBI) {
if (PHINode *PN = dyn_cast<PHINode>(SBI))
PN->removeIncomingValue(BB);
else
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);
// Rremove any PHI incoming edge from blocks dominated by DeadBB.
PredBlocks.clear();
for(pred_iterator PI = pred_begin(FrontierBB), PE = pred_end(FrontierBB);
PI != PE; ++PI) {
BasicBlock *P = *PI;
if (P == DeadBB || DT->dominates(DeadBB, P))
PredBlocks.push_back(P);
}
for(BasicBlock::iterator FBI = FrontierBB->begin(), FBE = FrontierBB->end();
FBI != FBE; ++FBI) {
if (PHINode *PN = dyn_cast<PHINode>(FBI)) {
for(SmallVector<BasicBlock *, 8>::iterator PI = PredBlocks.begin(),
PE = PredBlocks.end(); PI != PE; ++PI) {
BasicBlock *P = *PI;
PN->removeIncomingValue(P);
}
}
else
break;
}
DT->changeImmediateDominator(FrontierBB, LiveBB);
// LiveBB is now dominating FrontierBB. Which means FrontierBB's dominance
// frontier is member of LiveBB's dominance frontier. However, FrontierBB
// itself is not member of LiveBB's dominance frontier.
DominanceFrontier::iterator LiveDF = DF->find(LiveBB);
DominanceFrontier::iterator FrontierDF = DF->find(FrontierBB);
DominanceFrontier::DomSetType FrontierBBSet = FrontierDF->second;
for (DominanceFrontier::DomSetType::iterator FrontierBBSetI = FrontierBBSet.begin(),
FrontierBBSetE = FrontierBBSet.end(); FrontierBBSetI != FrontierBBSetE; ++FrontierBBSetI) {
BasicBlock *DFMember = *FrontierBBSetI;
// Insert only if LiveBB dominates DFMember.
if (!DT->dominates(LiveBB, DFMember))
LiveDF->second.insert(DFMember);
}
LiveDF->second.erase(FrontierBB);
}
}
// Now remove DeadBB and all nodes dominated by DeadBB in df order.
SmallVector<BasicBlock *, 32> WorkList;
DomTreeNode *DN = DT->getNode(DeadBB);
for (df_iterator<DomTreeNode*> DI = df_begin(DN),
E = df_end(DN); DI != E; ++DI) {
BasicBlock *BB = DI->getBlock();
WorkList.push_back(BB);
BB->getTerminator()->eraseFromParent();
}
while (!WorkList.empty()) {
BasicBlock *BB = WorkList.back(); WorkList.pop_back();
for(BasicBlock::iterator BBI = BB->begin(), BBE = BB->end();
BBI != BBE; ++BBI) {
Instruction *I = BBI;
I->replaceAllUsesWith(UndefValue::get(I->getType()));
I->eraseFromParent();
}
LPM->deleteSimpleAnalysisValue(BB, LP);
DT->eraseNode(BB);
DF->removeBlock(BB);
LI->removeBlock(BB);
BB->eraseFromParent();
}
}
bool LoopIndexSplit::splitLoop(SplitInfo &SD) {