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Back out Devang's fix for PR1320 because it causes PR1542.

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llvm-svn: 37966
This commit is contained in:
Nick Lewycky 2007-07-07 16:23:34 +00:00
parent d9d3be078c
commit dc39ec317a
1 changed files with 19 additions and 93 deletions
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108
lib/Transforms/Scalar/LoopRotation.cpp
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@ -18,10 +18,7 @@
#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"
@ -58,17 +55,6 @@ namespace {
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>();
// Request DominanceFrontier now, even though Loop Rotate does
// not use it. This allows Pass Manager to schedule Dominance
// Frontier early enough such that one LPPassManager can handle
// loop rotate as well as licm pass.
AU.addRequired<DominanceFrontier>();
AU.addPreserved<DominanceFrontier>();
}
// Helper functions
@ -104,7 +90,7 @@ namespace {
BasicBlock *OrigLatch;
BasicBlock *NewHeader;
BasicBlock *Exit;
LPPassManager *LPM_Ptr;
SmallVector<RenameData, MAX_HEADER_SIZE> LoopHeaderInfo;
};
@ -120,7 +106,6 @@ 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)) {
@ -167,13 +152,6 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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.
@ -185,6 +163,13 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
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 original pre-header. Unlike original header, original pre-header is
// not a member of loop.
@ -331,22 +316,16 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
}
// 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 (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, 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);
}
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);
}
}
@ -482,63 +461,10 @@ void LoopRotate::preserveCanonicalLoopForm(LPPassManager &LPM) {
"Expected only one incoming value from Original PreHeader");
}
SplitEdge(L->getLoopLatch(), Exit, this);
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 same as original preheader.
DominanceFrontier::iterator DFI = DF->find(OrigPreHeader);
if (DFI != DF->end()) {
DominanceFrontier::DomSetType NPHSet(DFI->second), NHSet(DFI->second);
// NPHSet.insert(DFI->second.begin(), DFI->second.end(), NPHSet.begin());
DF->addBasicBlock(NewPreHeader, NPHSet);
DominanceFrontier::iterator DHI = DF->find(L->getHeader());
if (DHI != DF->end()) {
DominanceFrontier::DomSetType DHSet = DHI->second;
DHSet.clear();
DHSet.insert(DFI->second.begin(), DFI->second.end());
} else {
DominanceFrontier::DomSetType NHSet(DFI->second);
// NHSet.insert(DFI->second.begin(), DFI->second.end(), NHSet.begin());
DF->addBasicBlock(L->getHeader(), NHSet);
}
}
// Original header no longer dominates Exit
DFI = DF->find(OrigHeader);
if (DFI != DF->end()) {
for (succ_iterator SI = succ_begin(Exit), SE = succ_end(Exit);
SI != SE; ++SI) {
BasicBlock *Succ = *SI;
DominanceFrontier::DomSetType::iterator DSI = DFI->second.find(Succ);
if (DSI != DFI->second.end())
DFI->second.erase(DSI);
}
}
}
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");
}