#define DEBUG_TYPE "loop-rotate"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Function.h"
-#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/Dominators.h"
Pass *llvm::createLoopRotatePass() { return new LoopRotate(); }
/// 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 RotatedOneLoop = false;
OrigPreHeader = L->getLoopPreheader();
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)
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 the loop header is not one of the loop exiting blocks then
+ // either this loop is already rotated or it is not
// suitable for loop rotation transformations.
if (!L->isLoopExit(OrigHeader))
return false;
// Check size of original header and reject
// loop if it is very big.
- if (OrigHeader->size() > MAX_HEADER_SIZE)
+ unsigned Size = 0;
+
+ // FIXME: Use common api to estimate size.
+ for (BasicBlock::const_iterator OI = OrigHeader->begin(),
+ OE = OrigHeader->end(); OI != OE; ++OI) {
+ if (isa<PHINode>(OI))
+ continue; // PHI nodes don't count.
+ if (isa<DbgInfoIntrinsic>(OI))
+ continue; // Debug intrinsics don't count as size.
+ Size++;
+ }
+
+ if (Size > MAX_HEADER_SIZE)
return false;
// Now, this loop is suitable for rotation.
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.
+ // This code assumes that the 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
- // not a member of loop.
+ // Copy PHI nodes and other instructions from the original header
+ // into the original pre-header. Unlike the original header, the original
+ // 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
- // 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
// 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
// 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
+ // Create a new PHI node with two incoming values for NewHeader.
+ // One incoming value is from OrigLatch (through OrigHeader) and the
// second incoming value is from original pre-header.
PHINode *NH = PHINode::Create(PN->getType(), PN->getName(),
NewHeader->begin());
// 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.
+ // Used outside Exit block. Create a new PHI node in the exit block
+ // to receive the value from the new header and pre-header.
PHINode *PN = PHINode::Create(U->getType(), U->getName(),
Exit->begin());
PN->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
// 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)
- if (PHINode *PN = dyn_cast<PHINode>(I))
- PN->removeIncomingValue(OrigPreHeader);
+ for (BasicBlock::iterator I = OrigHeader->begin();
+ (PN = dyn_cast<PHINode>(I)); ++I)
+ 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 original pre-header.
+/// If an incoming value is constant or defined outside the loop then
+/// PHINode may not have an entry for the original pre-header.
void LoopRotate::updateExitBlock() {
- for (BasicBlock::iterator I = Exit->begin(), E = Exit->end();
- I != E; ++I) {
-
- PHINode *PN = dyn_cast<PHINode>(I);
- if (!PN)
- break;
+ PHINode *PN;
+ for (BasicBlock::iterator I = Exit->begin();
+ (PN = dyn_cast<PHINode>(I)); ++I) {
// There is already one incoming value from original pre-header block.
if (PN->getBasicBlockIndex(OrigPreHeader) != -1)
const RenameData *ILoopHeaderInfo;
Value *V = PN->getIncomingValueForBlock(OrigHeader);
- if (isa<Instruction>(V) &&
+ if (isa<Instruction>(V) &&
(ILoopHeaderInfo = findReplacementData(cast<Instruction>(V)))) {
assert(ILoopHeaderInfo->PreHeader && "Missing New Preheader Instruction");
PN->addIncoming(ILoopHeaderInfo->PreHeader, OrigPreHeader);
"Unexpected original pre-header terminator");
OrigPH_BI->setSuccessor(1, NewPreHeader);
}
-
- for (BasicBlock::iterator I = NewHeader->begin(), E = NewHeader->end();
- I != E; ++I) {
- PHINode *PN = dyn_cast<PHINode>(I);
- if (!PN)
- break;
+ PHINode *PN;
+ for (BasicBlock::iterator I = NewHeader->begin();
+ (PN = dyn_cast<PHINode>(I)); ++I) {
int index = PN->getBasicBlockIndex(OrigPreHeader);
assert(index != -1 && "Expected incoming value from Original PreHeader");
PN->setIncomingBlock(index, NewPreHeader);
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) {
+ for (BasicBlock::iterator I = Exit->begin();
+ (PN = dyn_cast<PHINode>(I)); ++I) {
unsigned N = PN->getNumIncomingValues();
- for (unsigned index = 0; index < N; ++index)
+ for (unsigned index = 0; index != N; ++index)
if (PN->getIncomingBlock(index) == NExit) {
PHINode *NewPN = PHINode::Create(PN->getType(), PN->getName(),
NExit->begin());
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