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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40915 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2007-08-08 01:51:27 +00:00
parent 51cbf3c980
commit 6a2bfdaab6
1 changed files with 23 additions and 23 deletions
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46
lib/Transforms/Scalar/LoopIndexSplit.cpp
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@ -217,13 +217,26 @@ bool LoopIndexSplit::processOneIterationLoop(LPPassManager &LPM) {
if (!safeExitBlock(ExitBlock))
return false;
// Update CFG.
// As a first step to break this loop, remove Latch to Header edge.
BasicBlock *Latch = L->getLoopLatch();
BasicBlock *LatchSucc = NULL;
BranchInst *BR = dyn_cast<BranchInst>(Latch->getTerminator());
if (!BR)
return false;
Header->removePredecessor(Latch);
for (succ_iterator SI = succ_begin(Latch), E = succ_end(Latch);
SI != E; ++SI) {
if (Header != *SI)
LatchSucc = *SI;
}
BR->setUnconditionalDest(LatchSucc);
BasicBlock *Preheader = L->getLoopPreheader();
Instruction *Terminator = Header->getTerminator();
Value *StartValue = IndVar->getIncomingValueForBlock(Preheader);
// Update CFG.
// Replace split condition in header.
// Transform
// SplitCondition : icmp eq i32 IndVar, SplitValue
@ -238,22 +251,10 @@ bool LoopIndexSplit::processOneIterationLoop(LPPassManager &LPM) {
Instruction *C2 = new ICmpInst(SignedPredicate ?
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
SplitValue, ExitValue, "lisplit", Terminator);
Instruction *NSplitCond = BinaryOperator::create(Instruction::And,
C1, C2, "lisplit", Terminator);
Instruction *NSplitCond = BinaryOperator::createAnd(C1, C2, "lisplit", Terminator);
SplitCondition->replaceAllUsesWith(NSplitCond);
SplitCondition->eraseFromParent();
// As a first step to break this loop, remove Latch to Header edge.
BasicBlock *LatchSucc = NULL;
Header->removePredecessor(Latch);
for (succ_iterator SI = succ_begin(Latch), E = succ_end(Latch);
SI != E; ++SI) {
if (Header != *SI)
LatchSucc = *SI;
}
BranchInst *BR = dyn_cast<BranchInst>(Latch->getTerminator());
BR->setUnconditionalDest(LatchSucc);
// Now, clear latch block. Remove instructions that are responsible
// to increment induction variable.
Instruction *LTerminator = Latch->getTerminator();
@ -281,15 +282,13 @@ bool LoopIndexSplit::safeHeader(BasicBlock *Header) {
BI != BE; ++BI) {
Instruction *I = BI;
// PHI Nodes are OK.
// PHI Nodes are OK. FIXME : Handle last value assignments.
if (isa<PHINode>(I))
continue;
// SplitCondition itself is OK.
if (ICmpInst *CI = dyn_cast<ICmpInst>(I)) {
if (CI == SplitCondition)
continue;
}
if (I == SplitCondition)
continue;
// Terminator is also harmless.
if (I == Terminator)
@ -307,12 +306,12 @@ bool LoopIndexSplit::safeHeader(BasicBlock *Header) {
bool LoopIndexSplit::safeExitBlock(BasicBlock *ExitBlock) {
Instruction *IndVarIncrement = NULL;
for (BasicBlock::iterator BI = ExitBlock->begin(), BE = ExitBlock->end();
BI != BE; ++BI) {
Instruction *I = BI;
// PHI Nodes are OK.
// PHI Nodes are OK. FIXME : Handle last value assignments.
if (isa<PHINode>(I))
continue;
@ -338,6 +337,7 @@ bool LoopIndexSplit::safeExitBlock(BasicBlock *ExitBlock) {
if (IndVarIncrement && PN == IndVar && CI->isOne())
continue;
}
// I is an Exit condition if next instruction is block terminator.
// Exit condition is OK if it compares loop invariant exit value,
// which is checked below.
@ -346,7 +346,7 @@ bool LoopIndexSplit::safeExitBlock(BasicBlock *ExitBlock) {
Instruction *N = BI;
if (N == ExitBlock->getTerminator()) {
ExitCondition = EC;
break;
continue;
}
}