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Clone loop.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40998 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2007-08-10 18:07:13 +00:00
parent 4bc2a0b420
commit 423c8b29b8
1 changed files with 25 additions and 5 deletions
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30
lib/Transforms/Scalar/LoopIndexSplit.cpp
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@ -18,6 +18,8 @@
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/Statistic.h"
@ -41,6 +43,7 @@ namespace {
AU.addPreserved<ScalarEvolution>();
AU.addRequiredID(LCSSAID);
AU.addPreservedID(LCSSAID);
AU.addRequired<LoopInfo>();
AU.addPreserved<LoopInfo>();
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
@ -84,7 +87,7 @@ namespace {
/// entire (i.e. meaningful) loop body is dominated by this compare
/// instruction then loop body is executed only for one iteration. In
/// such case eliminate loop structure surrounding this loop body. For
bool processOneIterationLoop(SplitInfo &SD, LPPassManager &LPM);
bool processOneIterationLoop(SplitInfo &SD);
/// If loop header includes loop variant instruction operands then
/// this loop may not be eliminated.
@ -109,6 +112,8 @@ namespace {
// Current Loop.
Loop *L;
LPPassManager *LPM;
LoopInfo *LI;
ScalarEvolution *SE;
DominatorTree *DT;
SmallVector<SplitInfo, 4> SplitData;
@ -136,12 +141,14 @@ LoopPass *llvm::createLoopIndexSplitPass() {
}
// Index split Loop L. Return true if loop is split.
bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM) {
bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
bool Changed = false;
L = IncomingLoop;
LPM = &LPM_Ref;
SE = &getAnalysis<ScalarEvolution>();
DT = &getAnalysis<DominatorTree>();
LI = &getAnalysis<LoopInfo>();
initialize();
@ -160,7 +167,7 @@ bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM) {
E = SplitData.end(); SI != E; ++SI) {
SplitInfo &SD = *SI;
if (SD.SplitCondition->getPredicate() == ICmpInst::ICMP_EQ) {
Changed = processOneIterationLoop(SD,LPM);
Changed = processOneIterationLoop(SD);
if (Changed) {
++NumIndexSplit;
// If is loop is eliminated then nothing else to do here.
@ -367,7 +374,7 @@ void LoopIndexSplit::findSplitCondition() {
/// i = somevalue;
/// loop_body
/// }
bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD, LPPassManager &LPM) {
bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
BasicBlock *Header = L->getHeader();
@ -444,7 +451,7 @@ bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD, LPPassManager &LPM)
I->eraseFromParent();
}
LPM.deleteLoopFromQueue(L);
LPM->deleteLoopFromQueue(L);
// Update Dominator Info.
// Only CFG change done is to remove Latch to Header edge. This
@ -605,9 +612,22 @@ bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
FLStartValue = new SelectInst(C2, SD.SplitValue, StartValue,
"lsplit.sv", Preheader->getTerminator());
}
//[*] Split Exit Edge.
BasicBlock *ExitBlock = ExitCondition->getParent();
BranchInst *ExitInsn = dyn_cast<BranchInst>(ExitBlock->getTerminator());
assert (ExitInsn && "Unable to find suitable loop exit branch");
BasicBlock *ExitDest = ExitInsn->getSuccessor(1);
if (L->contains(ExitDest))
ExitDest = ExitInsn->getSuccessor(0);
assert (!L->contains(ExitDest) && " Unable to find exit edge destination");
BasicBlock *ExitSplitBlock = SplitEdge(ExitBlock, ExitDest, this);
//[*] Clone loop. Avoid true destination of split condition and
// the blocks dominated by true destination.
DenseMap<const Value *, Value *> ValueMap;
Loop *FalseLoop = CloneLoop(L, LPM, LI, ValueMap, this);
//[*] True loops exit edge enters False loop.
//[*] Eliminate split condition's false branch from True loop.
// Update true loop dom info.