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Reword a few comments.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74146 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-06-25 00:22:44 +00:00
parent a278f3f552
commit cc4e605721
1 changed files with 17 additions and 17 deletions
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34
lib/Transforms/Scalar/LoopRotation.cpp
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@ -108,7 +108,7 @@ static RegisterPass<LoopRotate> X("loop-rotate", "Rotate Loops");
Pass *llvm::createLoopRotatePass() { return new LoopRotate(); } Pass *llvm::createLoopRotatePass() { return new LoopRotate(); }
/// Rotate Loop L as many times as possible. Return true if /// Rotate Loop L as many times as possible. Return true if
/// loop is rotated at least once. /// the loop is rotated at least once.
bool LoopRotate::runOnLoop(Loop *Lp, LPPassManager &LPM) { bool LoopRotate::runOnLoop(Loop *Lp, LPPassManager &LPM) {
bool RotatedOneLoop = false; bool RotatedOneLoop = false;
@ -132,15 +132,15 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
OrigPreHeader = L->getLoopPreheader(); OrigPreHeader = L->getLoopPreheader();
OrigLatch = L->getLoopLatch(); OrigLatch = L->getLoopLatch();
// If loop has only one block then there is not much to rotate. // If the loop has only one block then there is not much to rotate.
if (L->getBlocks().size() == 1) if (L->getBlocks().size() == 1)
return false; return false;
assert(OrigHeader && OrigLatch && OrigPreHeader && assert(OrigHeader && OrigLatch && OrigPreHeader &&
"Loop is not in canonical form"); "Loop is not in canonical form");
// If loop header is not one of the loop exit block then // If the loop header is not one of the loop exiting blocks then
// either this loop is already rotated or it is not // either this loop is already rotated or it is not
// suitable for loop rotation transformations. // suitable for loop rotation transformations.
if (!L->isLoopExit(OrigHeader)) if (!L->isLoopExit(OrigHeader))
return false; return false;
@ -189,19 +189,19 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
assert(L->contains(NewHeader) && !L->contains(Exit) && assert(L->contains(NewHeader) && !L->contains(Exit) &&
"Unable to determine loop header and exit blocks"); "Unable to determine loop header and exit blocks");
// This code assumes that new header has exactly one predecessor. Remove any // This code assumes that the new header has exactly one predecessor.
// single entry PHI nodes in it. // Remove any single-entry PHI nodes in it.
assert(NewHeader->getSinglePredecessor() && assert(NewHeader->getSinglePredecessor() &&
"New header doesn't have one pred!"); "New header doesn't have one pred!");
FoldSingleEntryPHINodes(NewHeader); FoldSingleEntryPHINodes(NewHeader);
// Copy PHI nodes and other instructions from original header // Copy PHI nodes and other instructions from the original header
// into original pre-header. Unlike original header, original pre-header is // into the original pre-header. Unlike the original header, the original
// not a member of loop. // pre-header is not a member of the loop.
// //
// New loop header is one and only successor of original header that // The new loop header is the one and only successor of original header that
// is inside the loop. All other original header successors are outside // is inside the loop. All other original header successors are outside
// the loop. Copy PHI Nodes from original header into new loop header. // the loop. Copy PHI Nodes from the original header into the new loop header.
// Add second incoming value, from original loop pre-header into these phi // Add second incoming value, from original loop pre-header into these phi
// nodes. If a value defined in original header is used outside original // nodes. If a value defined in original header is used outside original
// header then new loop header will need new phi nodes with two incoming // header then new loop header will need new phi nodes with two incoming
@ -218,8 +218,8 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
// are directly propagated. // are directly propagated.
Value *NPV = PN->getIncomingValueForBlock(OrigPreHeader); Value *NPV = PN->getIncomingValueForBlock(OrigPreHeader);
// Create new PHI node with two incoming values for NewHeader. // Create a new PHI node with two incoming values for NewHeader.
// One incoming value is from OrigLatch (through OrigHeader) and // One incoming value is from OrigLatch (through OrigHeader) and the
// second incoming value is from original pre-header. // second incoming value is from original pre-header.
PHINode *NH = PHINode::Create(PN->getType(), PN->getName(), PHINode *NH = PHINode::Create(PN->getType(), PN->getName(),
NewHeader->begin()); NewHeader->begin());
@ -334,8 +334,8 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
// Add second incoming argument from new Pre header. // Add second incoming argument from new Pre header.
UPhi->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader); UPhi->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
} else { } else {
// Used outside Exit block. Create a new PHI node from exit block // Used outside Exit block. Create a new PHI node in the exit block
// to receive value from ne new header ane pre header. // to receive the value from the new header and pre-header.
PHINode *PN = PHINode::Create(U->getType(), U->getName(), PHINode *PN = PHINode::Create(U->getType(), U->getName(),
Exit->begin()); Exit->begin());
PN->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader); PN->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
@ -367,8 +367,8 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
} }
/// Make sure all Exit block PHINodes have required incoming values. /// Make sure all Exit block PHINodes have required incoming values.
/// If incoming value is constant or defined outside the loop then /// If an incoming value is constant or defined outside the loop then
/// PHINode may not have an entry for original pre-header. /// PHINode may not have an entry for the original pre-header.
void LoopRotate::updateExitBlock() { void LoopRotate::updateExitBlock() {
for (BasicBlock::iterator I = Exit->begin(), E = Exit->end(); for (BasicBlock::iterator I = Exit->begin(), E = Exit->end();