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-rw-r--r--lib/Transforms/Scalar/LoopUnswitch.cpp300
1 files changed, 19 insertions, 281 deletions
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index 28051fa210..5473bac555 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -77,21 +77,13 @@ namespace {
BasicBlock *loopHeader;
BasicBlock *loopPreheader;
- /// LoopDF - Loop's dominance frontier. This set is a collection of
- /// loop exiting blocks' DF member blocks. However this does set does not
- /// includes basic blocks that are inside loop.
- SmallPtrSet<BasicBlock *, 8> LoopDF;
-
- /// OrigLoopExitMap - This is used to map loop exiting block with
- /// corresponding loop exit block, before updating CFG.
- DenseMap<BasicBlock *, BasicBlock *> OrigLoopExitMap;
-
// LoopBlocks contains all of the basic blocks of the loop, including the
// preheader of the loop, the body of the loop, and the exit blocks of the
// loop, in that order.
std::vector<BasicBlock*> LoopBlocks;
// NewBlocks contained cloned copy of basic blocks from LoopBlocks.
std::vector<BasicBlock*> NewBlocks;
+
public:
static char ID; // Pass ID, replacement for typeid
explicit LoopUnswitch(bool Os = false) :
@@ -134,14 +126,8 @@ namespace {
/// Split all of the edges from inside the loop to their exit blocks.
/// Update the appropriate Phi nodes as we do so.
- void SplitExitEdges(Loop *L, const SmallVector<BasicBlock *, 8> &ExitBlocks,
- SmallVector<BasicBlock *, 8> &MiddleBlocks);
+ void SplitExitEdges(Loop *L, const SmallVector<BasicBlock *, 8> &ExitBlocks);
- /// If BB's dominance frontier has a member that is not part of loop L then
- /// remove it. Add NewDFMember in BB's dominance frontier.
- void ReplaceLoopExternalDFMember(Loop *L, BasicBlock *BB,
- BasicBlock *NewDFMember);
-
bool UnswitchIfProfitable(Value *LoopCond, Constant *Val);
unsigned getLoopUnswitchCost(Value *LIC);
void UnswitchTrivialCondition(Loop *L, Value *Cond, Constant *Val,
@@ -480,87 +466,6 @@ static inline void RemapInstruction(Instruction *I,
}
}
-// CloneDomInfo - NewBB is cloned from Orig basic block. Now clone Dominator
-// Info.
-//
-// If Orig block's immediate dominator is mapped in VM then use corresponding
-// immediate dominator from the map. Otherwise Orig block's dominator is also
-// NewBB's dominator.
-//
-// OrigPreheader is loop pre-header before this pass started
-// updating CFG. NewPrehader is loops new pre-header. However, after CFG
-// manipulation, loop L may not exist. So rely on input parameter NewPreheader.
-static void CloneDomInfo(BasicBlock *NewBB, BasicBlock *Orig,
- BasicBlock *NewPreheader, BasicBlock *OrigPreheader,
- BasicBlock *OrigHeader,
- DominatorTree *DT, DominanceFrontier *DF,
- DenseMap<const Value*, Value*> &VM) {
-
- // If NewBB alreay has found its place in domiantor tree then no need to do
- // anything.
- if (DT->getNode(NewBB))
- return;
-
- // If Orig does not have any immediate domiantor then its clone, NewBB, does
- // not need any immediate dominator.
- DomTreeNode *OrigNode = DT->getNode(Orig);
- if (!OrigNode)
- return;
- DomTreeNode *OrigIDomNode = OrigNode->getIDom();
- if (!OrigIDomNode)
- return;
-
- BasicBlock *OrigIDom = NULL;
-
- // If Orig is original loop header then its immediate dominator is
- // NewPreheader.
- if (Orig == OrigHeader)
- OrigIDom = NewPreheader;
-
- // If Orig is new pre-header then its immediate dominator is
- // original pre-header.
- else if (Orig == NewPreheader)
- OrigIDom = OrigPreheader;
-
- // Otherwise ask DT to find Orig's immediate dominator.
- else
- OrigIDom = OrigIDomNode->getBlock();
-
- // Initially use Orig's immediate dominator as NewBB's immediate dominator.
- BasicBlock *NewIDom = OrigIDom;
- DenseMap<const Value*, Value*>::iterator I = VM.find(OrigIDom);
- if (I != VM.end()) {
- NewIDom = cast<BasicBlock>(I->second);
-
- // If NewIDom does not have corresponding dominatore tree node then
- // get one.
- if (!DT->getNode(NewIDom))
- CloneDomInfo(NewIDom, OrigIDom, NewPreheader, OrigPreheader,
- OrigHeader, DT, DF, VM);
- }
-
- DT->addNewBlock(NewBB, NewIDom);
-
- // Copy cloned dominance frontiner set
- DominanceFrontier::DomSetType NewDFSet;
- if (DF) {
- DominanceFrontier::iterator DFI = DF->find(Orig);
- if ( DFI != DF->end()) {
- DominanceFrontier::DomSetType S = DFI->second;
- for (DominanceFrontier::DomSetType::iterator I = S.begin(), E = S.end();
- I != E; ++I) {
- BasicBlock *BB = *I;
- DenseMap<const Value*, Value*>::iterator IDM = VM.find(BB);
- if (IDM != VM.end())
- NewDFSet.insert(cast<BasicBlock>(IDM->second));
- else
- NewDFSet.insert(BB);
- }
- }
- DF->addBasicBlock(NewBB, NewDFSet);
- }
-}
-
/// CloneLoop - Recursively clone the specified loop and all of its children,
/// mapping the blocks with the specified map.
static Loop *CloneLoop(Loop *L, Loop *PL, DenseMap<const Value*, Value*> &VM,
@@ -602,7 +507,6 @@ void LoopUnswitch::EmitPreheaderBranchOnCondition(Value *LIC, Constant *Val,
BranchInst::Create(TrueDest, FalseDest, BranchVal, InsertPt);
}
-
/// UnswitchTrivialCondition - Given a loop that has a trivial unswitchable
/// condition in it (a cond branch from its header block to its latch block,
/// where the path through the loop that doesn't execute its body has no
@@ -636,27 +540,6 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
// insert the new conditional branch.
EmitPreheaderBranchOnCondition(Cond, Val, NewExit, NewPH,
loopPreheader->getTerminator());
- if (DT) {
- DT->changeImmediateDominator(NewExit, loopPreheader);
- DT->changeImmediateDominator(NewPH, loopPreheader);
- }
-
- if (DF) {
- // NewExit is now part of NewPH and Loop Header's dominance
- // frontier.
- DominanceFrontier::iterator DFI = DF->find(NewPH);
- if (DFI != DF->end())
- DF->addToFrontier(DFI, NewExit);
- DFI = DF->find(loopHeader);
- DF->addToFrontier(DFI, NewExit);
-
- // ExitBlock does not have successors then NewExit is part of
- // its dominance frontier.
- if (succ_begin(ExitBlock) == succ_end(ExitBlock)) {
- DFI = DF->find(ExitBlock);
- DF->addToFrontier(DFI, NewExit);
- }
- }
LPM->deleteSimpleAnalysisValue(loopPreheader->getTerminator(), L);
loopPreheader->getTerminator()->eraseFromParent();
@@ -670,93 +553,52 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
++NumTrivial;
}
-/// ReplaceLoopExternalDFMember -
-/// If BB's dominance frontier has a member that is not part of loop L then
-/// remove it. Add NewDFMember in BB's dominance frontier.
-void LoopUnswitch::ReplaceLoopExternalDFMember(Loop *L, BasicBlock *BB,
- BasicBlock *NewDFMember) {
-
- DominanceFrontier::iterator DFI = DF->find(BB);
- if (DFI == DF->end())
- return;
-
- DominanceFrontier::DomSetType &DFSet = DFI->second;
- for (DominanceFrontier::DomSetType::iterator DI = DFSet.begin(),
- DE = DFSet.end(); DI != DE;) {
- BasicBlock *B = *DI++;
- if (L->contains(B))
- continue;
-
- DF->removeFromFrontier(DFI, B);
- LoopDF.insert(B);
- }
-
- DF->addToFrontier(DFI, NewDFMember);
-}
-
/// SplitExitEdges - Split all of the edges from inside the loop to their exit
/// blocks. Update the appropriate Phi nodes as we do so.
void LoopUnswitch::SplitExitEdges(Loop *L,
- const SmallVector<BasicBlock *, 8> &ExitBlocks,
- SmallVector<BasicBlock *, 8> &MiddleBlocks) {
+ const SmallVector<BasicBlock *, 8> &ExitBlocks)
+{
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
BasicBlock *ExitBlock = ExitBlocks[i];
std::vector<BasicBlock*> Preds(pred_begin(ExitBlock), pred_end(ExitBlock));
for (unsigned j = 0, e = Preds.size(); j != e; ++j) {
- BasicBlock* MiddleBlock = SplitEdge(Preds[j], ExitBlock, this);
- MiddleBlocks.push_back(MiddleBlock);
+ BasicBlock* NewExitBlock = SplitEdge(Preds[j], ExitBlock, this);
BasicBlock* StartBlock = Preds[j];
BasicBlock* EndBlock;
- if (MiddleBlock->getSinglePredecessor() == ExitBlock) {
- EndBlock = MiddleBlock;
- MiddleBlock = EndBlock->getSinglePredecessor();;
+ if (NewExitBlock->getSinglePredecessor() == ExitBlock) {
+ EndBlock = NewExitBlock;
+ NewExitBlock = EndBlock->getSinglePredecessor();;
} else {
EndBlock = ExitBlock;
}
- OrigLoopExitMap[StartBlock] = EndBlock;
-
std::set<PHINode*> InsertedPHIs;
PHINode* OldLCSSA = 0;
for (BasicBlock::iterator I = EndBlock->begin();
(OldLCSSA = dyn_cast<PHINode>(I)); ++I) {
- Value* OldValue = OldLCSSA->getIncomingValueForBlock(MiddleBlock);
+ Value* OldValue = OldLCSSA->getIncomingValueForBlock(NewExitBlock);
PHINode* NewLCSSA = PHINode::Create(OldLCSSA->getType(),
OldLCSSA->getName() + ".us-lcssa",
- MiddleBlock->getTerminator());
+ NewExitBlock->getTerminator());
NewLCSSA->addIncoming(OldValue, StartBlock);
- OldLCSSA->setIncomingValue(OldLCSSA->getBasicBlockIndex(MiddleBlock),
+ OldLCSSA->setIncomingValue(OldLCSSA->getBasicBlockIndex(NewExitBlock),
NewLCSSA);
InsertedPHIs.insert(NewLCSSA);
}
BasicBlock::iterator InsertPt = EndBlock->getFirstNonPHI();
- for (BasicBlock::iterator I = MiddleBlock->begin();
+ for (BasicBlock::iterator I = NewExitBlock->begin();
(OldLCSSA = dyn_cast<PHINode>(I)) && InsertedPHIs.count(OldLCSSA) == 0;
++I) {
PHINode *NewLCSSA = PHINode::Create(OldLCSSA->getType(),
OldLCSSA->getName() + ".us-lcssa",
InsertPt);
OldLCSSA->replaceAllUsesWith(NewLCSSA);
- NewLCSSA->addIncoming(OldLCSSA, MiddleBlock);
+ NewLCSSA->addIncoming(OldLCSSA, NewExitBlock);
}
- if (DF && DT) {
- // StartBlock -- > MiddleBlock -- > EndBlock
- // StartBlock is loop exiting block. EndBlock will become merge point
- // of two loop exits after loop unswitch.
-
- // If StartBlock's DF member includes a block that is not loop member
- // then replace that DF member with EndBlock.
-
- // If MiddleBlock's DF member includes a block that is not loop member
- // tnen replace that DF member with EndBlock.
-
- ReplaceLoopExternalDFMember(L, StartBlock, EndBlock);
- ReplaceLoopExternalDFMember(L, MiddleBlock, EndBlock);
- }
}
}
@@ -789,8 +631,7 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
// Split all of the edges from inside the loop to their exit blocks. Update
// the appropriate Phi nodes as we do so.
- SmallVector<BasicBlock *,8> MiddleBlocks;
- SplitExitEdges(L, ExitBlocks, MiddleBlocks);
+ SplitExitEdges(L, ExitBlocks);
// The exit blocks may have been changed due to edge splitting, recompute.
ExitBlocks.clear();
@@ -811,21 +652,6 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
LPM->cloneBasicBlockSimpleAnalysis(LoopBlocks[i], New, L);
}
- // OutSiders are basic block that are dominated by original header and
- // at the same time they are not part of loop.
- SmallPtrSet<BasicBlock *, 8> OutSiders;
- if (DT) {
- DomTreeNode *OrigHeaderNode = DT->getNode(loopHeader);
- for(std::vector<DomTreeNode*>::iterator DI = OrigHeaderNode->begin(),
- DE = OrigHeaderNode->end(); DI != DE; ++DI) {
- BasicBlock *B = (*DI)->getBlock();
-
- DenseMap<const Value*, Value*>::iterator VI = ValueMap.find(B);
- if (VI == ValueMap.end())
- OutSiders.insert(B);
- }
- }
-
// Splice the newly inserted blocks into the function right before the
// original preheader.
F->getBasicBlockList().splice(LoopBlocks[0], F->getBasicBlockList(),
@@ -849,7 +675,7 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
assert(NewExit->getTerminator()->getNumSuccessors() == 1 &&
"Exit block should have been split to have one successor!");
BasicBlock *ExitSucc = NewExit->getTerminator()->getSuccessor(0);
-
+
// If the successor of the exit block had PHI nodes, add an entry for
// NewExit.
PHINode *PN;
@@ -878,94 +704,6 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
LPM->deleteSimpleAnalysisValue(OldBR, L);
OldBR->eraseFromParent();
- // Update dominator info
- if (DF && DT) {
-
- SmallVector<BasicBlock *,4> ExitingBlocks;
- L->getExitingBlocks(ExitingBlocks);
-
- // Clone dominator info for all cloned basic block.
- for (unsigned i = 0, e = LoopBlocks.size(); i != e; ++i) {
- BasicBlock *LBB = LoopBlocks[i];
- BasicBlock *NBB = NewBlocks[i];
- CloneDomInfo(NBB, LBB, NewPreheader, loopPreheader,
- loopHeader, DT, DF, ValueMap);
-
- // If LBB's dominance frontier includes DFMember
- // such that DFMember is also a member of LoopDF then
- // - Remove DFMember from LBB's dominance frontier
- // - Copy loop exiting blocks', that are dominated by BB,
- // dominance frontier member in BB's dominance frontier
-
- DominanceFrontier::iterator LBBI = DF->find(LBB);
- DominanceFrontier::iterator NBBI = DF->find(NBB);
- if (LBBI == DF->end())
- continue;
-
- DominanceFrontier::DomSetType &LBSet = LBBI->second;
- for (DominanceFrontier::DomSetType::iterator LI = LBSet.begin(),
- LE = LBSet.end(); LI != LE; /* NULL */) {
- BasicBlock *B = *LI++;
- if (B == LBB && B == loopHeader)
- continue;
- bool removeB = false;
- if (!LoopDF.count(B))
- continue;
-
- // If LBB dominates loop exits then insert loop exit block's DF
- // into B's DF.
- for(SmallVector<BasicBlock *, 4>::iterator
- LExitI = ExitingBlocks.begin(),
- LExitE = ExitingBlocks.end(); LExitI != LExitE; ++LExitI) {
- BasicBlock *E = *LExitI;
-
- if (!DT->dominates(LBB,E))
- continue;
-
- DenseMap<BasicBlock *, BasicBlock *>::iterator DFBI =
- OrigLoopExitMap.find(E);
- if (DFBI == OrigLoopExitMap.end())
- continue;
-
- BasicBlock *DFB = DFBI->second;
- DF->addToFrontier(LBBI, DFB);
- DF->addToFrontier(NBBI, DFB);
- removeB = true;
- }
-
- // If B's replacement is inserted in DF then now is the time to remove
- // B.
- if (removeB) {
- DF->removeFromFrontier(LBBI, B);
- if (L->contains(B))
- DF->removeFromFrontier(NBBI, cast<BasicBlock>(ValueMap[B]));
- else
- DF->removeFromFrontier(NBBI, B);
- }
- }
-
- }
-
- // MiddleBlocks are dominated by original pre header. SplitEdge updated
- // MiddleBlocks' dominance frontier appropriately.
- for (unsigned i = 0, e = MiddleBlocks.size(); i != e; ++i) {
- BasicBlock *MBB = MiddleBlocks[i];
- if (!MBB->getSinglePredecessor())
- DT->changeImmediateDominator(MBB, loopPreheader);
- }
-
- // All Outsiders are now dominated by original pre header.
- for (SmallPtrSet<BasicBlock *, 8>::iterator OI = OutSiders.begin(),
- OE = OutSiders.end(); OI != OE; ++OI) {
- BasicBlock *OB = *OI;
- DT->changeImmediateDominator(OB, loopPreheader);
- }
-
- // New loop headers are dominated by original preheader
- DT->changeImmediateDominator(NewBlocks[0], loopPreheader);
- DT->changeImmediateDominator(LoopBlocks[0], loopPreheader);
- }
-
LoopProcessWorklist.push_back(NewLoop);
redoLoop = true;
@@ -977,6 +715,7 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
// deleted. If so, don't simplify it.
if (!LoopProcessWorklist.empty() && LoopProcessWorklist.back() == NewLoop)
RewriteLoopBodyWithConditionConstant(NewLoop, LIC, Val, true);
+
}
/// RemoveFromWorklist - Remove all instances of I from the worklist vector
@@ -1130,8 +869,6 @@ void LoopUnswitch::RemoveLoopFromHierarchy(Loop *L) {
RemoveLoopFromWorklist(L);
}
-
-
// RewriteLoopBodyWithConditionConstant - We know either that the value LIC has
// the value specified by Val in the specified loop, or we know it does NOT have
// that value. Rewrite any uses of LIC or of properties correlated to it.
@@ -1193,18 +930,19 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
// trying to update it is complicated. So instead we preserve the
// loop structure and put the block on an dead code path.
+ BasicBlock *SISucc = SI->getSuccessor(i);
BasicBlock* Old = SI->getParent();
BasicBlock* Split = SplitBlock(Old, SI, this);
Instruction* OldTerm = Old->getTerminator();
- BranchInst::Create(Split, SI->getSuccessor(i),
+ BranchInst::Create(Split, SISucc,
ConstantInt::getTrue(), OldTerm);
LPM->deleteSimpleAnalysisValue(Old->getTerminator(), L);
Old->getTerminator()->eraseFromParent();
PHINode *PN;
- for (BasicBlock::iterator II = SI->getSuccessor(i)->begin();
+ for (BasicBlock::iterator II = SISucc->begin();
(PN = dyn_cast<PHINode>(II)); ++II) {
Value *InVal = PN->removeIncomingValue(Split, false);
PN->addIncoming(InVal, Old);
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-05-03 17:33:40 +0000