forked from OSchip/llvm-project
Do not create new pre-header. Reuse original pre-header.
llvm-svn: 35825
This commit is contained in:
Devang Patel
parent
ce38beb6a4
commit
b9af5747a5
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@ -33,11 +33,11 @@ namespace {
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class VISIBILITY_HIDDEN RenameData {
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public:
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RenameData(Instruction *O, Instruction *P, Instruction *H)
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RenameData(Instruction *O, Value *P, Instruction *H)
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: Original(O), PreHeader(P), Header(H) { }
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public:
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Instruction *Original; // Original instruction
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Instruction *PreHeader; // New pre-header replacement
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Value *PreHeader; // Original pre-header replacement
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Instruction *Header; // New header replacement
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};
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@ -65,7 +65,7 @@ namespace {
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/// Make sure all Exit block PHINodes have required incoming values.
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/// If incoming value is constant or defined outside the loop then
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/// PHINode may not have an entry for new pre-header.
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/// PHINode may not have an entry for original pre-header.
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void updateExitBlock();
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/// Return true if this instruction is used outside original header.
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@ -82,7 +82,6 @@ namespace {
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BasicBlock *OrigPreHeader;
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BasicBlock *OrigLatch;
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BasicBlock *NewHeader;
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BasicBlock *NewPreHeader;
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BasicBlock *Exit;
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SmallVector<RenameData, MAX_HEADER_SIZE> LoopHeaderInfo;
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@ -125,6 +124,9 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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if (!OrigHeader || !OrigLatch || !OrigPreHeader)
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return false;
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if (!OrigHeader || !OrigLatch || !OrigPreHeader)
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return false;
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// If loop header is not one of the loop exit block then
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// either this loop is already rotated or it is not
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// suitable for loop rotation transformations.
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@ -164,42 +166,40 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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// Now, this loop is suitable for rotation.
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// Copy PHI nodes and other instructions from original header
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// into new pre-header. Unlike original header, new pre-header is
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// not a member of loop. New pre-header has only one predecessor,
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// that is original loop pre-header.
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// into original pre-header. Unlike original header, original pre-header is
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// not a member of loop.
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//
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// New loop header is one and only successor of original header that
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// is inside the loop. All other original header successors are outside
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// the loop. Copy PHI Nodes from original header into new loop header.
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// Add second incoming value, from new loop pre-header into these phi
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// Add second incoming value, from original loop pre-header into these phi
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// nodes. If a value defined in original header is used outside original
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// header then new loop header will need new phi nodes with two incoming
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// values, one definition from original header and second definition is
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// from new loop pre-header (which is a clone of original header definition).
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// from original loop pre-header.
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NewPreHeader = new BasicBlock("bb.nph", OrigHeader->getParent(), OrigHeader);
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// Remove terminator from Original pre-header. Original pre-header will
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// receive a clone of original header terminator as a new terminator.
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OrigPreHeader->getInstList().pop_back();
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BasicBlock::iterator I = OrigHeader->begin(), E = OrigHeader->end();
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PHINode *PN = NULL;
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for (; (PN = dyn_cast<PHINode>(I)); ++I) {
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Instruction *In = I;
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// Create new PHI node with one value incoming from OrigPreHeader.
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// NewPreHeader has only one predecessor, OrigPreHeader.
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PHINode *NPH = new PHINode(In->getType(), In->getName());
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NPH->addIncoming(PN->getIncomingValueForBlock(OrigPreHeader),
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OrigPreHeader);
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NewPreHeader->getInstList().push_back(NPH);
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// PHI nodes are not copied into original pre-header. Instead their values
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// are directly propagated.
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Value * NPV = PN->getIncomingValueForBlock(OrigPreHeader);
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// Create new PHI node with two incoming values for NewHeader.
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// One incoming value is from OrigLatch (through OrigHeader) and
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// second incoming value is from NewPreHeader.
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// second incoming value is from original pre-header.
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PHINode *NH = new PHINode(In->getType(), In->getName());
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NH->addIncoming(PN->getIncomingValueForBlock(OrigLatch), OrigHeader);
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NH->addIncoming(NPH, NewPreHeader);
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NH->addIncoming(NPV, OrigPreHeader);
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NewHeader->getInstList().push_front(NH);
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// "In" can be replaced by NPH or NH at various places.
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LoopHeaderInfo.push_back(RenameData(In, NPH, NH));
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// "In" can be replaced by NH at various places.
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LoopHeaderInfo.push_back(RenameData(In, NPV, NH));
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}
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// Now, handle non-phi instructions.
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@ -207,20 +207,36 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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Instruction *In = I;
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assert (!isa<PHINode>(In) && "PHINode is not expected here");
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// This is not a PHI instruction. Insert its clone into NewPreHeader.
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// This is not a PHI instruction. Insert its clone into original pre-header.
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// If this instruction is using a value from same basic block then
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// update it to use value from cloned instruction.
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Instruction *C = In->clone();
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C->setName(In->getName());
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NewPreHeader->getInstList().push_back(C);
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OrigPreHeader->getInstList().push_back(C);
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for (unsigned opi = 0, e = In->getNumOperands(); opi != e; ++opi) {
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if (Instruction *OpPhi = dyn_cast<PHINode>(In->getOperand(opi))) {
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if (const RenameData *D = findReplacementData(OpPhi)) {
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// This is using values from original header PHI node.
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// Here, directly used incoming value from original pre-header.
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C->setOperand(opi, D->PreHeader);
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}
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}
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else if (Instruction *OpInsn =
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dyn_cast<Instruction>(In->getOperand(opi))) {
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if (const RenameData *D = findReplacementData(OpInsn))
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C->setOperand(opi, D->PreHeader);
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}
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}
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// If this instruction is used outside this basic block then
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// create new PHINode for this instruction.
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Instruction *NewHeaderReplacement = NULL;
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if (usedOutsideOriginalHeader(In)) {
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PHINode *PN = new PHINode(In->getType(), In->getName());
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PN->addIncoming(In, OrigHeader);
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PN->addIncoming(C, NewPreHeader);
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PN->addIncoming(C, OrigPreHeader);
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NewHeader->getInstList().push_front(PN);
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NewHeaderReplacement = PN;
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}
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@ -229,38 +245,8 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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LoopHeaderInfo.push_back(RenameData(In, C, NewHeaderReplacement));
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}
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// Update new pre-header.
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// Rename values that are defined in original header to reflects values
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// defined in new pre-header.
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for(unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
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const RenameData &ILoopHeaderInfo = LoopHeaderInfo[LHI];
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Instruction *In = ILoopHeaderInfo.Original;
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Instruction *C = ILoopHeaderInfo.PreHeader;
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// If this instruction is not from new pre-header then is not new
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// pre-header then this instruction is not handled here.
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if (C->getParent() != NewPreHeader)
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continue;
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// PHINodes uses value from pre-header predecessors.
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if (isa<PHINode>(In))
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continue;
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for (unsigned opi = 0, e = In->getNumOperands(); opi != e; ++opi) {
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if (Instruction *OpPhi = dyn_cast<PHINode>(In->getOperand(opi))) {
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if (const RenameData *D = findReplacementData(OpPhi))
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C->setOperand(opi, D->PreHeader);
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}
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else if (Instruction *OpInsn =
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dyn_cast<Instruction>(In->getOperand(opi))) {
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if (const RenameData *D = findReplacementData(OpInsn))
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C->setOperand(opi, D->PreHeader);
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}
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}
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}
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// Rename uses of original header instructions to reflect their new
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// definitions (either from new pre-header node or from newly created
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// definitions (either from original pre-header node or from newly created
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// new header PHINodes.
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//
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// Original header instructions are used in
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@ -268,7 +254,7 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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//
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// If instruction is used in non-phi instructions then it is using
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// defintion from original heder iteself. Do not replace this use
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// with definition from new header or new pre-header.
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// with definition from new header or original pre-header.
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//
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// If instruction is used in phi node then it is an incoming
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// value. Rename its use to reflect new definition from new-preheader
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@ -334,7 +320,7 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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// UPhi already has one incoming argument from original header.
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// Add second incoming argument from new Pre header.
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UPhi->addIncoming(ILoopHeaderInfo.PreHeader, NewPreHeader);
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UPhi->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
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}
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}
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@ -345,16 +331,15 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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// Removing incoming branch from loop preheader to original header.
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// Now original header is inside the loop.
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OrigHeader->removePredecessor(OrigPreHeader);
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for (BasicBlock::iterator I = OrigHeader->begin(), E = OrigHeader->end();
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I != E; ++I) {
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Instruction *In = I;
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PHINode *PN = dyn_cast<PHINode>(In);
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if (!PN)
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break;
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// Establish NewPreHeader as loop preheader. Add unconditional branch
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// from original loop pre-header to new loop pre-header. Add NewPreHEader
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// in loop nest.
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BranchInst *PH_BI = cast<BranchInst>(OrigPreHeader->getTerminator());
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PH_BI->setSuccessor(0, NewPreHeader);
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LoopInfo &LI = LPM.getAnalysis<LoopInfo>();
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if (Loop *PL = LI.getLoopFor(OrigPreHeader))
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PL->addBasicBlockToLoop(NewPreHeader, LI);
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PN->removeIncomingValue(OrigPreHeader);
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}
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// Make NewHeader as the new header for the loop.
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L->moveToHeader(NewHeader);
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@ -365,7 +350,7 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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/// Make sure all Exit block PHINodes have required incoming values.
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/// If incoming value is constant or defined outside the loop then
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/// PHINode may not have an entry for new pre-header.
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/// PHINode may not have an entry for original pre-header.
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void LoopRotate::updateExitBlock() {
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for (BasicBlock::iterator I = Exit->begin(), E = Exit->end();
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@ -375,8 +360,8 @@ void LoopRotate::updateExitBlock() {
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if (!PN)
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break;
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// There is already one incoming value from new pre-header block.
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if (PN->getBasicBlockIndex(NewPreHeader) != -1)
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// There is already one incoming value from original pre-header block.
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if (PN->getBasicBlockIndex(OrigPreHeader) != -1)
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return;
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const RenameData *ILoopHeaderInfo;
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@ -384,9 +369,9 @@ void LoopRotate::updateExitBlock() {
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if (isa<Instruction>(V) &&
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(ILoopHeaderInfo = findReplacementData(cast<Instruction>(V)))) {
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assert (ILoopHeaderInfo->PreHeader && "Missing New Preheader Instruction");
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PN->addIncoming(ILoopHeaderInfo->PreHeader, NewPreHeader);
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PN->addIncoming(ILoopHeaderInfo->PreHeader, OrigPreHeader);
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} else {
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PN->addIncoming(V, NewPreHeader);
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PN->addIncoming(V, OrigPreHeader);
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}
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}
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}
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@ -397,7 +382,6 @@ void LoopRotate::initialize() {
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OrigHeader = NULL;
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OrigPreHeader = NULL;
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NewHeader = NULL;
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NewPreHeader = NULL;
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Exit = NULL;
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LoopHeaderInfo.clear();
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