//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "loop-rotate"
-
#include "llvm/Transforms/Scalar.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SmallVector.h"
-
using namespace llvm;
#define MAX_HEADER_SIZE 16
char LoopRotate::ID = 0;
static RegisterPass<LoopRotate> X("loop-rotate", "Rotate Loops");
-LoopPass *llvm::createLoopRotatePass() { return new LoopRotate(); }
+Pass *llvm::createLoopRotatePass() { return new LoopRotate(); }
/// Rotate Loop L as many times as possible. Return true if
/// loop is rotated at least once.
/// Rotate loop LP. Return true if the loop is rotated.
bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
-
L = Lp;
OrigHeader = L->getHeader();
if (L->getBlocks().size() == 1)
return false;
- assert (OrigHeader && OrigLatch && OrigPreHeader &&
- "Loop is not in canonical form");
+ 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
BranchInst *BI = dyn_cast<BranchInst>(OrigHeader->getTerminator());
if (!BI)
return false;
- assert (BI->isConditional() && "Branch Instruction is not conditional");
+ assert(BI->isConditional() && "Branch Instruction is not conditional");
// Updating PHInodes in loops with multiple exits adds complexity.
// Keep it simple, and restrict loop rotation to loops with one exit only.
// 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.
+ // that is inside loop. Header's other successor is outside the
+ // loop. Otherwise loop is not suitable for rotation.
Exit = BI->getSuccessor(0);
NewHeader = BI->getSuccessor(1);
if (L->contains(Exit))
std::swap(Exit, NewHeader);
- assert (NewHeader && "Unable to determine new loop header");
+ assert(NewHeader && "Unable to determine new loop header");
assert(L->contains(NewHeader) && !L->contains(Exit) &&
"Unable to determine loop header and exit blocks");
+
+ // This code assumes that new header has exactly one predecessor. Remove any
+ // single entry PHI nodes in it.
+ assert(NewHeader->getSinglePredecessor() &&
+ "New header doesn't have one pred!");
+ FoldSingleEntryPHINodes(NewHeader);
// Copy PHI nodes and other instructions from original header
// into original pre-header. Unlike original header, original pre-header is
// 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;
+ PHINode *PN = 0;
for (; (PN = dyn_cast<PHINode>(I)); ++I) {
- Instruction *In = I;
-
// PHI nodes are not copied into original pre-header. Instead their values
// are directly propagated.
- Value * NPV = PN->getIncomingValueForBlock(OrigPreHeader);
+ 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 original pre-header.
- PHINode *NH = PHINode::Create(In->getType(), In->getName(),
+ PHINode *NH = PHINode::Create(PN->getType(), PN->getName(),
NewHeader->begin());
NH->addIncoming(PN->getIncomingValueForBlock(OrigLatch), OrigHeader);
NH->addIncoming(NPV, OrigPreHeader);
// "In" can be replaced by NH at various places.
- LoopHeaderInfo.push_back(RenameData(In, NPV, NH));
+ LoopHeaderInfo.push_back(RenameData(PN, NPV, NH));
}
// Now, handle non-phi instructions.
for (; I != E; ++I) {
Instruction *In = I;
-
- assert (!isa<PHINode>(In) && "PHINode is not expected here");
+ assert(!isa<PHINode>(In) && "PHINode is not expected here");
+
// 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.
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);
- }
+ Instruction *OpInsn = dyn_cast<Instruction>(In->getOperand(opi));
+ if (!OpInsn) continue; // Ignore non-instruction values.
+ 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;
// 2) Inside loop but not in original header
//
// Replace this use to reflect definition from new header.
- for(unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
+ for (unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
const RenameData &ILoopHeaderInfo = LoopHeaderInfo[LHI];
if (!ILoopHeaderInfo.Header)
// not invalidated.
SmallVector<Instruction *, 16> AllUses;
for (Value::use_iterator UI = OldPhi->use_begin(), UE = OldPhi->use_end();
- UI != UE; ++UI) {
- Instruction *U = cast<Instruction>(UI);
- AllUses.push_back(U);
- }
+ UI != UE; ++UI)
+ AllUses.push_back(cast<Instruction>(UI));
for (SmallVector<Instruction *, 16>::iterator UI = AllUses.begin(),
UE = AllUses.end(); UI != UE; ++UI) {
// 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");
+ 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.
// Removing incoming branch from loop preheader to original header.
// Now original header is inside the loop.
for (BasicBlock::iterator I = OrigHeader->begin(), E = OrigHeader->end();
- I != E; ++I) {
- Instruction *In = I;
- PHINode *PN = dyn_cast<PHINode>(In);
- if (!PN)
- break;
-
- PN->removeIncomingValue(OrigPreHeader);
- }
+ I != E; ++I)
+ if (PHINode *PN = dyn_cast<PHINode>(I))
+ PN->removeIncomingValue(OrigPreHeader);
// Make NewHeader as the new header for the loop.
L->moveToHeader(NewHeader);
/// Return true if this instruction is used by any instructions in the loop that
/// aren't in original header.
bool LoopRotate::usedOutsideOriginalHeader(Instruction *In) {
-
for (Value::use_iterator UI = In->use_begin(), UE = In->use_end();
UI != UE; ++UI) {
- Instruction *U = cast<Instruction>(UI);
- if (U->getParent() != OrigHeader) {
- if (L->contains(U->getParent()))
- return true;
- }
+ BasicBlock *UserBB = cast<Instruction>(UI)->getParent();
+ if (UserBB != OrigHeader && L->contains(UserBB))
+ return true;
}
return false;
const RenameData *LoopRotate::findReplacementData(Instruction *In) {
// Since LoopHeaderInfo is small, linear walk is OK.
- for(unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
+ for (unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
const RenameData &ILoopHeaderInfo = LoopHeaderInfo[LHI];
if (ILoopHeaderInfo.Original == In)
return &ILoopHeaderInfo;
if (OrigPH_BI->getSuccessor(0) == NewHeader)
OrigPH_BI->setSuccessor(0, NewPreHeader);
else {
- assert (OrigPH_BI->getSuccessor(1) == NewHeader &&
- "Unexpected original pre-header terminator");
+ 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);
+ PHINode *PN = dyn_cast<PHINode>(I);
if (!PN)
break;
int index = PN->getBasicBlockIndex(OrigPreHeader);
- assert (index != -1 && "Expected incoming value from Original PreHeader");
+ 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");
+ assert(PN->getBasicBlockIndex(OrigPreHeader) == -1 &&
+ "Expected only one incoming value from Original PreHeader");
}
- if (DominatorTree *DT = getAnalysisToUpdate<DominatorTree>()) {
+ if (DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>()) {
DT->addNewBlock(NewPreHeader, OrigPreHeader);
DT->changeImmediateDominator(L->getHeader(), NewPreHeader);
DT->changeImmediateDominator(Exit, OrigPreHeader);
DT->changeImmediateDominator(OrigHeader, OrigLatch);
}
- if(DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>()) {
-
+ if (DominanceFrontier *DF = getAnalysisIfAvailable<DominanceFrontier>()) {
// New Preheader's dominance frontier is Exit block.
DominanceFrontier::DomSetType NewPHSet;
NewPHSet.insert(Exit);
// If a loop block dominates new loop latch then its frontier is
// new header and Exit.
BasicBlock *NewLatch = L->getLoopLatch();
- DominatorTree *DT = getAnalysisToUpdate<DominatorTree>();
+ DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>();
for (Loop::block_iterator BI = L->block_begin(), BE = L->block_end();
BI != BE; ++BI) {
BasicBlock *B = *BI;
}
}
- 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");
-
+ 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");
}
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