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Update LoopSimplify to require and preserve DominatorTree only. 

Now LoopSimplify does not require nor preserve ETForest.

llvm-svn: 37512
This commit is contained in:
Devang Patel 2007-06-08 01:50:32 +00:00
parent 86798e5e11
commit becc466451
3 changed files with 42 additions and 35 deletions
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4
llvm/include/llvm/Analysis/Dominators.h
View File

@ -195,6 +195,10 @@ protected:
return NULL;
return Common->getData<BasicBlock>();
}
/// isReachableFromEntry - Return true if A is dominated by the entry
/// block of the function containing it.
const bool isReachableFromEntry(BasicBlock* A);
/// dominates - Returns true iff this dominates N. Note that this is not a
/// constant time operation!

58
llvm/lib/Transforms/Utils/LoopSimplify.cpp
View File

@ -68,10 +68,8 @@ namespace {
// We need loop information to identify the loops...
AU.addRequired<LoopInfo>();
AU.addRequired<DominatorTree>();
AU.addRequired<ETForest>();
AU.addPreserved<LoopInfo>();
AU.addPreserved<ETForest>();
AU.addPreserved<DominatorTree>();
AU.addPreserved<DominanceFrontier>();
AU.addPreservedID(BreakCriticalEdgesID); // No critical edges added.
@ -315,10 +313,10 @@ BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
// Can we eliminate this phi node now?
if (Value *V = PN->hasConstantValue(true)) {
Instruction *I = dyn_cast<Instruction>(V);
// If I is in NewBB, the ETForest call will fail, because NewBB isn't
// registered in ETForest yet. Handle this case explicitly.
// If I is in NewBB, the Dominator call will fail, because NewBB isn't
// registered in DominatorTree yet. Handle this case explicitly.
if (!I || (I->getParent() != NewBB &&
getAnalysis<ETForest>().dominates(I, PN))) {
getAnalysis<DominatorTree>().dominates(I, PN))) {
PN->replaceAllUsesWith(V);
if (AA) AA->deleteValue(PN);
BB->getInstList().erase(PN);
@ -429,13 +427,13 @@ static void AddBlockAndPredsToSet(BasicBlock *InputBB, BasicBlock *StopBlock,
/// FindPHIToPartitionLoops - The first part of loop-nestification is to find a
/// PHI node that tells us how to partition the loops.
static PHINode *FindPHIToPartitionLoops(Loop *L, ETForest *EF,
static PHINode *FindPHIToPartitionLoops(Loop *L, DominatorTree *DT,
AliasAnalysis *AA) {
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I);
++I;
if (Value *V = PN->hasConstantValue())
if (!isa<Instruction>(V) || EF->dominates(cast<Instruction>(V), PN)) {
if (!isa<Instruction>(V) || DT->dominates(cast<Instruction>(V), PN)) {
// This is a degenerate PHI already, don't modify it!
PN->replaceAllUsesWith(V);
if (AA) AA->deleteValue(PN);
@ -509,8 +507,8 @@ void LoopSimplify::PlaceSplitBlockCarefully(BasicBlock *NewBB,
/// created.
///
Loop *LoopSimplify::SeparateNestedLoop(Loop *L) {
ETForest *EF = getAnalysisToUpdate<ETForest>();
PHINode *PN = FindPHIToPartitionLoops(L, EF, AA);
DominatorTree *DT = getAnalysisToUpdate<DominatorTree>();
PHINode *PN = FindPHIToPartitionLoops(L, DT, AA);
if (PN == 0) return 0; // No known way to partition.
// Pull out all predecessors that have varying values in the loop. This
@ -555,7 +553,7 @@ Loop *LoopSimplify::SeparateNestedLoop(Loop *L) {
// the Outer loop now.
std::set<BasicBlock*> BlocksInL;
for (pred_iterator PI = pred_begin(Header), E = pred_end(Header); PI!=E; ++PI)
if (EF->dominates(Header, *PI))
if (DT->dominates(Header, *PI))
AddBlockAndPredsToSet(*PI, Header, BlocksInL);
@ -686,10 +684,10 @@ void LoopSimplify::InsertUniqueBackedgeBlock(Loop *L) {
// Returns true if BasicBlock A dominates at least one block in vector B
// Helper function for UpdateDomInfoForRevectoredPreds
static bool BlockDominatesAny(BasicBlock* A, const std::vector<BasicBlock*>& B,
ETForest& ETF) {
DominatorTree &DT) {
for (std::vector<BasicBlock*>::const_iterator BI = B.begin(), BE = B.end();
BI != BE; ++BI) {
if (ETF.dominates(A, *BI))
if (DT.dominates(A, *BI))
return true;
}
return false;
@ -715,8 +713,8 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
++succ_begin(NewBB) == succ_end(NewBB) &&
"NewBB should have a single successor!");
BasicBlock *NewBBSucc = *succ_begin(NewBB);
ETForest& ETF = getAnalysis<ETForest>();
DominatorTree &DT = getAnalysis<DominatorTree>();
// The newly inserted basic block will dominate existing basic blocks iff the
// PredBlocks dominate all of the non-pred blocks. If all predblocks dominate
// the non-pred blocks, then they all must be the same block!
@ -725,13 +723,13 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
{
BasicBlock *OnePred = PredBlocks[0];
unsigned i = 1, e = PredBlocks.size();
for (i = 1; !ETF.isReachableFromEntry(OnePred); ++i) {
for (i = 1; !DT.isReachableFromEntry(OnePred); ++i) {
assert(i != e && "Didn't find reachable pred?");
OnePred = PredBlocks[i];
}
for (; i != e; ++i)
if (PredBlocks[i] != OnePred && ETF.isReachableFromEntry(OnePred)){
if (PredBlocks[i] != OnePred && DT.isReachableFromEntry(OnePred)){
NewBBDominatesNewBBSucc = false;
break;
}
@ -739,7 +737,7 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
if (NewBBDominatesNewBBSucc)
for (pred_iterator PI = pred_begin(NewBBSucc), E = pred_end(NewBBSucc);
PI != E; ++PI)
if (*PI != NewBB && !ETF.dominates(NewBBSucc, *PI)) {
if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) {
NewBBDominatesNewBBSucc = false;
break;
}
@ -752,7 +750,7 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
NewBBDominatesNewBBSucc = true;
for (pred_iterator PI = pred_begin(NewBBSucc), E = pred_end(NewBBSucc);
PI != E; ++PI)
if (*PI != NewBB && !ETF.dominates(NewBBSucc, *PI)) {
if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI)) {
NewBBDominatesNewBBSucc = false;
break;
}
@ -767,14 +765,16 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
if (!NewBBIDom) {
unsigned i = 0;
for (i = 0; i < PredBlocks.size(); ++i)
if (ETF.dominates(&PredBlocks[i]->getParent()->getEntryBlock(), PredBlocks[i])) {
if (DT->dominates(&PredBlocks[i]->getParent()->getEntryBlock(),
PredBlocks[i])) {
NewBBIDom = PredBlocks[i];
break;
}
assert(i != PredBlocks.size() && "No reachable preds?");
for (i = i + 1; i < PredBlocks.size(); ++i) {
if (ETF.dominates(&PredBlocks[i]->getParent()->getEntryBlock(), PredBlocks[i]))
NewBBIDom = ETF.nearestCommonDominator(NewBBIDom, PredBlocks[i]);
if (DT->dominates(&PredBlocks[i]->getParent()->getEntryBlock(),
PredBlocks[i]))
NewBBIDom = DT->nearestCommonDominator(NewBBIDom, PredBlocks[i]);
}
assert(NewBBIDom && "No immediate dominator found??");
}
@ -790,13 +790,6 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
}
}
// Update ET-Forest information if it is active.
if (ETForest *EF = getAnalysisToUpdate<ETForest>()) {
EF->addNewBlock(NewBB, NewBBIDom);
if (NewBBDominatesNewBBSucc)
EF->setImmediateDominator(NewBBSucc, NewBB);
}
// Update dominance frontier information...
if (DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>()) {
// If NewBB dominates NewBBSucc, then DF(NewBB) is now going to be the
@ -812,7 +805,7 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
bool DominatesPred = false;
for (pred_iterator PI = pred_begin(*SetI), E = pred_end(*SetI);
PI != E; ++PI)
if (ETF.dominates(NewBB, *PI))
if (DT.dominates(NewBB, *PI))
DominatesPred = true;
if (!DominatesPred)
Set.erase(SetI++);
@ -845,17 +838,18 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
// Only consider dominators of NewBBSucc
if (!DFI->second.count(NewBBSucc)) continue;
if (BlockDominatesAny(FI, PredBlocks, ETF)) {
if (BlockDominatesAny(FI, PredBlocks, DT)) {
// If NewBBSucc should not stay in our dominator frontier, remove it.
// We remove it unless there is a predecessor of NewBBSucc that we
// dominate, but we don't strictly dominate NewBBSucc.
bool ShouldRemove = true;
if ((BasicBlock*)FI == NewBBSucc || !ETF.dominates(FI, NewBBSucc)) {
if ((BasicBlock*)FI == NewBBSucc
|| !DT.dominates(FI, NewBBSucc)) {
// Okay, we know that PredDom does not strictly dominate NewBBSucc.
// Check to see if it dominates any predecessors of NewBBSucc.
for (pred_iterator PI = pred_begin(NewBBSucc),
E = pred_end(NewBBSucc); PI != E; ++PI)
if (ETF.dominates(FI, *PI)) {
if (DT.dominates(FI, *PI)) {
ShouldRemove = false;
break;
}

15
llvm/lib/VMCore/Dominators.cpp
View File

@ -316,14 +316,23 @@ void DominatorTreeBase::updateDFSNumbers()
for (df_iterator<BasicBlock*> I = df_begin(Roots[i]),
E = df_end(Roots[i]); I != E; ++I) {
BasicBlock *BB = *I;
ETNode *ETN = getNode(BB)->getETNode();
if (ETN && !ETN->hasFather())
ETN->assignDFSNumber(dfsnum);
DomTreeNode *BBNode = getNode(BB);
if (BBNode) {
ETNode *ETN = BBNode->getETNode();
if (ETN && !ETN->hasFather())
ETN->assignDFSNumber(dfsnum);
}
}
SlowQueries = 0;
DFSInfoValid = true;
}
/// isReachableFromEntry - Return true if A is dominated by the entry
/// block of the function containing it.
const bool DominatorTreeBase::isReachableFromEntry(BasicBlock* A) {
return dominates(&A->getParent()->getEntryBlock(), A);
}
// dominates - Return true if A dominates B. THis performs the
// special checks necessary if A and B are in the same basic block.
bool DominatorTreeBase::dominates(Instruction *A, Instruction *B) {