class VISIBILITY_HIDDEN RenameData {
public:
- RenameData(Instruction *O, Instruction *P, Instruction *H)
+ RenameData(Instruction *O, Value *P, Instruction *H)
: Original(O), PreHeader(P), Header(H) { }
public:
Instruction *Original; // Original instruction
- Instruction *PreHeader; // New pre-header replacement
+ Value *PreHeader; // Original pre-header replacement
Instruction *Header; // New header replacement
};
/// Make sure all Exit block PHINodes have required incoming values.
/// If incoming value is constant or defined outside the loop then
- /// PHINode may not have an entry for new pre-header.
+ /// PHINode may not have an entry for original pre-header.
void updateExitBlock();
/// Return true if this instruction is used outside original header.
BasicBlock *OrigPreHeader;
BasicBlock *OrigLatch;
BasicBlock *NewHeader;
- BasicBlock *NewPreHeader;
BasicBlock *Exit;
SmallVector<RenameData, MAX_HEADER_SIZE> LoopHeaderInfo;
if (!OrigHeader || !OrigLatch || !OrigPreHeader)
return false;
+ if (!OrigHeader || !OrigLatch || !OrigPreHeader)
+ return false;
+
// If loop header is not one of the loop exit block then
// either this loop is already rotated or it is not
// suitable for loop rotation transformations.
// Now, this loop is suitable for rotation.
// Copy PHI nodes and other instructions from original header
- // into new pre-header. Unlike original header, new pre-header is
- // not a member of loop. New pre-header has only one predecessor,
- // that is original loop pre-header.
+ // into original pre-header. Unlike original header, original pre-header is
+ // not a member of loop.
//
// New loop header is one and only successor of original header that
// is inside the loop. All other original header successors are outside
// the loop. Copy PHI Nodes from original header into new loop header.
- // Add second incoming value, from new 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
// header then new loop header will need new phi nodes with two incoming
// values, one definition from original header and second definition is
- // from new loop pre-header (which is a clone of original header definition).
+ // from original loop pre-header.
- NewPreHeader = new BasicBlock("bb.nph", OrigHeader->getParent(), OrigHeader);
+ // Remove terminator from Original pre-header. Original pre-header will
+ // receive a clone of original header terminator as a new terminator.
+ OrigPreHeader->getInstList().pop_back();
BasicBlock::iterator I = OrigHeader->begin(), E = OrigHeader->end();
PHINode *PN = NULL;
for (; (PN = dyn_cast<PHINode>(I)); ++I) {
Instruction *In = I;
- // Create new PHI node with one value incoming from OrigPreHeader.
- // NewPreHeader has only one predecessor, OrigPreHeader.
- PHINode *NPH = new PHINode(In->getType(), In->getName());
- NPH->addIncoming(PN->getIncomingValueForBlock(OrigPreHeader),
- OrigPreHeader);
- NewPreHeader->getInstList().push_back(NPH);
-
+ // PHI nodes are not copied into original pre-header. Instead their values
+ // are directly propagated.
+ Value * NPV = PN->getIncomingValueForBlock(OrigPreHeader);
+
// Create new PHI node with two incoming values for NewHeader.
// One incoming value is from OrigLatch (through OrigHeader) and
- // second incoming value is from NewPreHeader.
+ // second incoming value is from original pre-header.
PHINode *NH = new PHINode(In->getType(), In->getName());
NH->addIncoming(PN->getIncomingValueForBlock(OrigLatch), OrigHeader);
- NH->addIncoming(NPH, NewPreHeader);
+ NH->addIncoming(NPV, OrigPreHeader);
NewHeader->getInstList().push_front(NH);
- // "In" can be replaced by NPH or NH at various places.
- LoopHeaderInfo.push_back(RenameData(In, NPH, NH));
+ // "In" can be replaced by NH at various places.
+ LoopHeaderInfo.push_back(RenameData(In, NPV, NH));
}
// Now, handle non-phi instructions.
Instruction *In = I;
assert (!isa<PHINode>(In) && "PHINode is not expected here");
- // This is not a PHI instruction. Insert its clone into NewPreHeader.
+ // This is not a PHI instruction. Insert its clone into original pre-header.
// If this instruction is using a value from same basic block then
// update it to use value from cloned instruction.
Instruction *C = In->clone();
C->setName(In->getName());
- NewPreHeader->getInstList().push_back(C);
-
+ OrigPreHeader->getInstList().push_back(C);
+
+ for (unsigned opi = 0, e = In->getNumOperands(); opi != e; ++opi) {
+ if (Instruction *OpPhi = dyn_cast<PHINode>(In->getOperand(opi))) {
+ if (const RenameData *D = findReplacementData(OpPhi)) {
+ // This is using values from original header PHI node.
+ // Here, directly used incoming value from original pre-header.
+ C->setOperand(opi, D->PreHeader);
+ }
+ }
+ else if (Instruction *OpInsn =
+ dyn_cast<Instruction>(In->getOperand(opi))) {
+ if (const RenameData *D = findReplacementData(OpInsn))
+ C->setOperand(opi, D->PreHeader);
+ }
+ }
+
+
// If this instruction is used outside this basic block then
// create new PHINode for this instruction.
Instruction *NewHeaderReplacement = NULL;
if (usedOutsideOriginalHeader(In)) {
PHINode *PN = new PHINode(In->getType(), In->getName());
PN->addIncoming(In, OrigHeader);
- PN->addIncoming(C, NewPreHeader);
+ PN->addIncoming(C, OrigPreHeader);
NewHeader->getInstList().push_front(PN);
NewHeaderReplacement = PN;
}
LoopHeaderInfo.push_back(RenameData(In, C, NewHeaderReplacement));
}
- // Update new pre-header.
- // Rename values that are defined in original header to reflects values
- // defined in new pre-header.
- for(unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
- const RenameData &ILoopHeaderInfo = LoopHeaderInfo[LHI];
- Instruction *In = ILoopHeaderInfo.Original;
- Instruction *C = ILoopHeaderInfo.PreHeader;
-
- // If this instruction is not from new pre-header then is not new
- // pre-header then this instruction is not handled here.
- if (C->getParent() != NewPreHeader)
- continue;
-
- // PHINodes uses value from pre-header predecessors.
- if (isa<PHINode>(In))
- continue;
-
- for (unsigned opi = 0, e = In->getNumOperands(); opi != e; ++opi) {
- if (Instruction *OpPhi = dyn_cast<PHINode>(In->getOperand(opi))) {
- if (const RenameData *D = findReplacementData(OpPhi))
- C->setOperand(opi, D->PreHeader);
- }
- else if (Instruction *OpInsn =
- dyn_cast<Instruction>(In->getOperand(opi))) {
- if (const RenameData *D = findReplacementData(OpInsn))
- C->setOperand(opi, D->PreHeader);
- }
- }
- }
-
// Rename uses of original header instructions to reflect their new
- // definitions (either from new pre-header node or from newly created
+ // definitions (either from original pre-header node or from newly created
// new header PHINodes.
//
// Original header instructions are used in
//
// If instruction is used in non-phi instructions then it is using
// defintion from original heder iteself. Do not replace this use
- // with definition from new header or new pre-header.
+ // with definition from new header or original pre-header.
//
// If instruction is used in phi node then it is an incoming
// value. Rename its use to reflect new definition from new-preheader
// UPhi already has one incoming argument from original header.
// Add second incoming argument from new Pre header.
- UPhi->addIncoming(ILoopHeaderInfo.PreHeader, NewPreHeader);
+ UPhi->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
}
}
// Removing incoming branch from loop preheader to original header.
// Now original header is inside the loop.
- OrigHeader->removePredecessor(OrigPreHeader);
+ for (BasicBlock::iterator I = OrigHeader->begin(), E = OrigHeader->end();
+ I != E; ++I) {
+ Instruction *In = I;
+ PHINode *PN = dyn_cast<PHINode>(In);
+ if (!PN)
+ break;
- // Establish NewPreHeader as loop preheader. Add unconditional branch
- // from original loop pre-header to new loop pre-header. Add NewPreHEader
- // in loop nest.
- BranchInst *PH_BI = cast<BranchInst>(OrigPreHeader->getTerminator());
- PH_BI->setSuccessor(0, NewPreHeader);
- LoopInfo &LI = LPM.getAnalysis<LoopInfo>();
- if (Loop *PL = LI.getLoopFor(OrigPreHeader))
- PL->addBasicBlockToLoop(NewPreHeader, LI);
+ PN->removeIncomingValue(OrigPreHeader);
+ }
// Make NewHeader as the new header for the loop.
L->moveToHeader(NewHeader);
/// Make sure all Exit block PHINodes have required incoming values.
/// If incoming value is constant or defined outside the loop then
-/// PHINode may not have an entry for new pre-header.
+/// PHINode may not have an entry for original pre-header.
void LoopRotate::updateExitBlock() {
for (BasicBlock::iterator I = Exit->begin(), E = Exit->end();
if (!PN)
break;
- // There is already one incoming value from new pre-header block.
- if (PN->getBasicBlockIndex(NewPreHeader) != -1)
+ // There is already one incoming value from original pre-header block.
+ if (PN->getBasicBlockIndex(OrigPreHeader) != -1)
return;
const RenameData *ILoopHeaderInfo;
if (isa<Instruction>(V) &&
(ILoopHeaderInfo = findReplacementData(cast<Instruction>(V)))) {
assert (ILoopHeaderInfo->PreHeader && "Missing New Preheader Instruction");
- PN->addIncoming(ILoopHeaderInfo->PreHeader, NewPreHeader);
+ PN->addIncoming(ILoopHeaderInfo->PreHeader, OrigPreHeader);
} else {
- PN->addIncoming(V, NewPreHeader);
+ PN->addIncoming(V, OrigPreHeader);
}
}
}
OrigHeader = NULL;
OrigPreHeader = NULL;
NewHeader = NULL;
- NewPreHeader = NULL;
Exit = NULL;
LoopHeaderInfo.clear();
projects / oota-llvm.git / commitdiff