#include "llvm/Instructions.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/Statistic.h"
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
};
class VISIBILITY_HIDDEN LoopRotate : public LoopPass {
public:
-
+ static char ID; // Pass ID, replacement for typeid
+ LoopRotate() : LoopPass((intptr_t)&ID) {}
+
// Rotate Loop L as many times as possible. Return true if
// loop is rotated at least once.
bool runOnLoop(Loop *L, LPPassManager &LPM);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(LCSSAID);
AU.addPreservedID(LCSSAID);
+ AU.addPreserved<ScalarEvolution>();
+ AU.addPreserved<LoopInfo>();
+ AU.addRequiredID(LoopSimplifyID);
+ AU.addPreservedID(LoopSimplifyID);
+ AU.addPreserved<DominatorTree>();
+ AU.addPreserved<DominanceFrontier>();
}
// Helper functions
/// 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.
/// Find Replacement information for instruction. Return NULL if it is
/// not available.
- RenameData *findReplacementData(Instruction *I);
+ const RenameData *findReplacementData(Instruction *I);
+
+ /// After loop rotation, loop pre-header has multiple sucessors.
+ /// Insert one forwarding basic block to ensure that loop pre-header
+ /// has only one successor.
+ void preserveCanonicalLoopForm(LPPassManager &LPM);
private:
BasicBlock *OrigPreHeader;
BasicBlock *OrigLatch;
BasicBlock *NewHeader;
- BasicBlock *NewPreHeader;
BasicBlock *Exit;
-
+ LPPassManager *LPM_Ptr;
SmallVector<RenameData, MAX_HEADER_SIZE> LoopHeaderInfo;
};
+ char LoopRotate::ID = 0;
RegisterPass<LoopRotate> X ("loop-rotate", "Rotate Loops");
}
/// Rotate Loop L as many times as possible. Return true if
/// loop is rotated at least once.
bool LoopRotate::runOnLoop(Loop *Lp, LPPassManager &LPM) {
-
+
bool RotatedOneLoop = false;
initialize();
+ LPM_Ptr = &LPM;
// One loop can be rotated multiple times.
while (rotateLoop(Lp,LPM)) {
return RotatedOneLoop;
}
-/// Rotate loop LP. Return true if it loop is rotated.
+/// Rotate loop LP. Return true if the loop is rotated.
bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
L = Lp;
if (L->getBlocks().size() == 1)
return false;
- if (!OrigHeader || !OrigLatch || !OrigPreHeader)
- return false;
+ assert (OrigHeader && OrigLatch && OrigPreHeader &&
+ "Loop is not in canonical form");
// If loop header is not one of the loop exit block then
// either this loop is already rotated or it is not
if (ExitBlocks.size() > 1)
return false;
+ // Check size of original header and reject
+ // loop if it is very big.
+ if (OrigHeader->getInstList().size() > MAX_HEADER_SIZE)
+ return false;
+
+ // Now, this loop is suitable for rotation.
+
// Find new Loop header. NewHeader is a Header's one and only successor
// that is inside loop. Header's other successor is out side the
// loop. Otherwise loop is not suitable for rotation.
assert(L->contains(NewHeader) && !L->contains(Exit) &&
"Unable to determine loop header and exit blocks");
- // Check size of original header and reject
- // loop if it is very big.
- if (OrigHeader->getInstList().size() > MAX_HEADER_SIZE)
- return false;
-
- // 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();
- for (; I != E; ++I) {
+ PHINode *PN = NULL;
+ for (; (PN = dyn_cast<PHINode>(I)); ++I) {
Instruction *In = I;
- PHINode *PN = dyn_cast<PHINode>(I);
- if (!PN)
- break;
+ // 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 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);
-
// 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 (SmallVector<RenameData, MAX_HEADER_SIZE>::iterator
- I = LoopHeaderInfo.begin(), E = LoopHeaderInfo.end(); I != E; ++I) {
-
- const RenameData &ILoopHeaderInfo = *I;
- 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 (RenameData *D = findReplacementData(OpPhi))
- C->setOperand(opi, D->PreHeader);
- }
- else if (Instruction *OpInsn =
- dyn_cast<Instruction>(In->getOperand(opi))) {
- if (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
// 2) Inside loop but not in original header
//
// Replace this use to reflect definition from new header.
- for (SmallVector<RenameData, MAX_HEADER_SIZE>::iterator
- I = LoopHeaderInfo.begin(), E = LoopHeaderInfo.end(); I != E; ++I) {
+ for(unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
+ const RenameData &ILoopHeaderInfo = LoopHeaderInfo[LHI];
- const RenameData &ILoopHeaderInfo = *I;
if (!ILoopHeaderInfo.Header)
continue;
if (PU->getBasicBlockIndex(NewHeader) != -1
&& PU->getIncomingValueForBlock(NewHeader) == U)
continue;
-
+
U->replaceUsesOfWith(OldPhi, NewPhi);
continue;
}
U->replaceUsesOfWith(OldPhi, NewPhi);
continue;
}
-
- // Used inside Exit Block. Since we are in LCSSA form, U must be PHINode.
- assert (U->getParent() == Exit
- && "Need to propagate new PHI into Exit blocks");
- assert (isa<PHINode>(U) && "Use in Exit Block that is not PHINode");
-
- PHINode *UPhi = cast<PHINode>(U);
-
- // UPhi already has one incoming argument from original header.
- // Add second incoming argument from new Pre header.
- UPhi->addIncoming(ILoopHeaderInfo.PreHeader, NewPreHeader);
+ // Used inside Exit Block. Since we are in LCSSA form, U must be PHINode.
+ if (U->getParent() == Exit) {
+ assert (isa<PHINode>(U) && "Use in Exit Block that is not PHINode");
+
+ PHINode *UPhi = cast<PHINode>(U);
+ // UPhi already has one incoming argument from original header.
+ // Add second incoming argument from new Pre header.
+ UPhi->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
+ } else {
+ // Used outside Exit block. Create a new PHI node from exit block
+ // to receive value from ne new header ane pre header.
+ PHINode *PN = new PHINode(U->getType(), U->getName());
+ PN->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
+ PN->addIncoming(OldPhi, OrigHeader);
+ Exit->getInstList().push_front(PN);
+ U->replaceUsesOfWith(OldPhi, PN);
+ }
}
}
// 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);
+ preserveCanonicalLoopForm(LPM);
+
NumRotated++;
return true;
}
-
/// 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;
- if (PN->getBasicBlockIndex(NewPreHeader) == -1) {
- Value *V = PN->getIncomingValueForBlock(OrigHeader);
- if (isa<Constant>(V))
- PN->addIncoming(V, NewPreHeader);
- else {
- RenameData *ILoopHeaderInfo = findReplacementData(cast<Instruction>(V));
- assert (ILoopHeaderInfo && ILoopHeaderInfo->PreHeader && "Missing New Preheader Instruction");
- PN->addIncoming(ILoopHeaderInfo->PreHeader, NewPreHeader);
- }
+ // There is already one incoming value from original pre-header block.
+ if (PN->getBasicBlockIndex(OrigPreHeader) != -1)
+ continue;
+
+ const RenameData *ILoopHeaderInfo;
+ Value *V = PN->getIncomingValueForBlock(OrigHeader);
+ if (isa<Instruction>(V) &&
+ (ILoopHeaderInfo = findReplacementData(cast<Instruction>(V)))) {
+ assert(ILoopHeaderInfo->PreHeader && "Missing New Preheader Instruction");
+ PN->addIncoming(ILoopHeaderInfo->PreHeader, OrigPreHeader);
+ } else {
+ PN->addIncoming(V, OrigPreHeader);
}
}
}
-
/// Initialize local data
void LoopRotate::initialize() {
L = NULL;
OrigHeader = NULL;
OrigPreHeader = NULL;
NewHeader = NULL;
- NewPreHeader = NULL;
Exit = NULL;
LoopHeaderInfo.clear();
/// Find Replacement information for instruction. Return NULL if it is
/// not available.
-RenameData *LoopRotate::findReplacementData(Instruction *In) {
+const RenameData *LoopRotate::findReplacementData(Instruction *In) {
// Since LoopHeaderInfo is small, linear walk is OK.
- for (SmallVector<RenameData, MAX_HEADER_SIZE>::iterator
- I = LoopHeaderInfo.begin(), E = LoopHeaderInfo.end(); I != E; ++I)
- if (I->Original == In)
- return &(*I);
-
+ for(unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
+ const RenameData &ILoopHeaderInfo = LoopHeaderInfo[LHI];
+ if (ILoopHeaderInfo.Original == In)
+ return &ILoopHeaderInfo;
+ }
return NULL;
}
+
+/// After loop rotation, loop pre-header has multiple sucessors.
+/// Insert one forwarding basic block to ensure that loop pre-header
+/// has only one successor.
+void LoopRotate::preserveCanonicalLoopForm(LPPassManager &LPM) {
+
+ // Right now original pre-header has two successors, new header and
+ // exit block. Insert new block between original pre-header and
+ // new header such that loop's new pre-header has only one successor.
+ BasicBlock *NewPreHeader = new BasicBlock("bb.nph", OrigHeader->getParent(),
+ NewHeader);
+ LoopInfo &LI = LPM.getAnalysis<LoopInfo>();
+ if (Loop *PL = LI.getLoopFor(OrigPreHeader))
+ PL->addBasicBlockToLoop(NewPreHeader, LI);
+ new BranchInst(NewHeader, NewPreHeader);
+
+ BranchInst *OrigPH_BI = cast<BranchInst>(OrigPreHeader->getTerminator());
+ if (OrigPH_BI->getSuccessor(0) == NewHeader)
+ OrigPH_BI->setSuccessor(0, NewPreHeader);
+ else {
+ assert (OrigPH_BI->getSuccessor(1) == NewHeader &&
+ "Unexpected original pre-header terminator");
+ OrigPH_BI->setSuccessor(1, NewPreHeader);
+ }
+
+ for (BasicBlock::iterator I = NewHeader->begin(), E = NewHeader->end();
+ I != E; ++I) {
+ Instruction *In = I;
+ PHINode *PN = dyn_cast<PHINode>(In);
+ if (!PN)
+ break;
+
+ int index = PN->getBasicBlockIndex(OrigPreHeader);
+ assert (index != -1 && "Expected incoming value from Original PreHeader");
+ PN->setIncomingBlock(index, NewPreHeader);
+ assert (PN->getBasicBlockIndex(OrigPreHeader) == -1 &&
+ "Expected only one incoming value from Original PreHeader");
+ }
+
+ if (DominatorTree *DT = getAnalysisToUpdate<DominatorTree>()) {
+ DT->addNewBlock(NewPreHeader, OrigPreHeader);
+ DT->changeImmediateDominator(L->getHeader(), NewPreHeader);
+ DT->changeImmediateDominator(Exit, OrigPreHeader);
+ for (Loop::block_iterator BI = L->block_begin(), BE = L->block_end();
+ BI != BE; ++BI) {
+ BasicBlock *B = *BI;
+ if (L->getHeader() != B) {
+ DomTreeNode *Node = DT->getNode(B);
+ if (Node && Node->getBlock() == OrigHeader)
+ DT->changeImmediateDominator(*BI, L->getHeader());
+ }
+ }
+ DT->changeImmediateDominator(OrigHeader, OrigLatch);
+ }
+
+ if(DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>()) {
+
+ // New Preheader's dominance frontier is Exit block.
+ DominanceFrontier::DomSetType NewPHSet;
+ NewPHSet.insert(Exit);
+ DF->addBasicBlock(NewPreHeader, NewPHSet);
+
+ // New Header's dominance frontier now includes itself and Exit block
+ DominanceFrontier::iterator HeadI = DF->find(L->getHeader());
+ if (HeadI != DF->end()) {
+ DominanceFrontier::DomSetType & HeaderSet = HeadI->second;
+ HeaderSet.clear();
+ HeaderSet.insert(L->getHeader());
+ HeaderSet.insert(Exit);
+ } else {
+ DominanceFrontier::DomSetType HeaderSet;
+ HeaderSet.insert(L->getHeader());
+ HeaderSet.insert(Exit);
+ DF->addBasicBlock(L->getHeader(), HeaderSet);
+ }
+
+ // Original header (new Loop Latch)'s dominance frontier is Exit.
+ DominanceFrontier::iterator LatchI = DF->find(L->getLoopLatch());
+ if (LatchI != DF->end()) {
+ DominanceFrontier::DomSetType &LatchSet = LatchI->second;
+ LatchSet = LatchI->second;
+ LatchSet.clear();
+ LatchSet.insert(Exit);
+ } else {
+ DominanceFrontier::DomSetType LatchSet;
+ LatchSet.insert(Exit);
+ DF->addBasicBlock(L->getHeader(), LatchSet);
+ }
+
+ // If a loop block dominates new loop latch then its frontier is
+ // new header and Exit.
+ BasicBlock *NewLatch = L->getLoopLatch();
+ DominatorTree *DT = getAnalysisToUpdate<DominatorTree>();
+ for (Loop::block_iterator BI = L->block_begin(), BE = L->block_end();
+ BI != BE; ++BI) {
+ BasicBlock *B = *BI;
+ if (DT->dominates(B, NewLatch)) {
+ DominanceFrontier::iterator BDFI = DF->find(B);
+ if (BDFI != DF->end()) {
+ DominanceFrontier::DomSetType &BSet = BDFI->second;
+ BSet = BDFI->second;
+ BSet.clear();
+ BSet.insert(L->getHeader());
+ BSet.insert(Exit);
+ } else {
+ DominanceFrontier::DomSetType BSet;
+ BSet.insert(L->getHeader());
+ BSet.insert(Exit);
+ DF->addBasicBlock(B, BSet);
+ }
+ }
+ }
+ }
+
+ // Preserve canonical loop form, which means Exit block should
+ // have only one predecessor.
+ BasicBlock *NExit = SplitEdge(L->getLoopLatch(), Exit, this);
+
+ // Preserve LCSSA.
+ BasicBlock::iterator I = Exit->begin(), E = Exit->end();
+ PHINode *PN = NULL;
+ for (; (PN = dyn_cast<PHINode>(I)); ++I) {
+ PHINode *NewPN = new PHINode(PN->getType(), PN->getName());
+ unsigned N = PN->getNumIncomingValues();
+ for (unsigned index = 0; index < N; ++index)
+ if (PN->getIncomingBlock(index) == NExit) {
+ NewPN->addIncoming(PN->getIncomingValue(index), L->getLoopLatch());
+ PN->setIncomingValue(index, NewPN);
+ PN->setIncomingBlock(index, NExit);
+ NExit->getInstList().push_front(NewPN);
+ }
+ }
+
+ assert (NewHeader && L->getHeader() == NewHeader
+ && "Invalid loop header after loop rotation");
+ assert (NewPreHeader && L->getLoopPreheader() == NewPreHeader
+ && "Invalid loop preheader after loop rotation");
+ assert (L->getLoopLatch()
+ && "Invalid loop latch after loop rotation");
+
+}
projects / oota-llvm.git / blobdiff