[llvm-commits] [llvm] r40941 - /llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp
Devang Patel
dpatel at apple.com
Wed Aug 8 14:02:17 PDT 2007
Author: dpatel
Date: Wed Aug 8 16:02:17 2007
New Revision: 40941
URL: http://llvm.org/viewvc/llvm-project?rev=40941&view=rev
Log:
Handle multiple split conditions.
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp?rev=40941&r1=40940&r2=40941&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp Wed Aug 8 16:02:17 2007
@@ -46,6 +46,28 @@
}
private:
+
+ class SplitInfo {
+ public:
+ SplitInfo() : IndVar(NULL), SplitValue(NULL), ExitValue(NULL),
+ SplitCondition(NULL), ExitCondition(NULL) {}
+ // Induction variable whose range is being split by this transformation.
+ PHINode *IndVar;
+
+ // Induction variable's range is split at this value.
+ Value *SplitValue;
+
+ // Induction variable's final loop exit value.
+ Value *ExitValue;
+
+ // This compare instruction compares IndVar against SplitValue.
+ ICmpInst *SplitCondition;
+
+ // Loop exit condition.
+ ICmpInst *ExitCondition;
+ };
+
+ private:
/// Find condition inside a loop that is suitable candidate for index split.
void findSplitCondition();
@@ -54,17 +76,17 @@
/// 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(LPPassManager &LPM);
+ bool processOneIterationLoop(SplitInfo &SD, LPPassManager &LPM);
// If loop header includes loop variant instruction operands then
// this loop may not be eliminated.
- bool safeHeader(BasicBlock *BB);
+ bool safeHeader(SplitInfo &SD, BasicBlock *BB);
// If Exit block includes loop variant instructions then this
// loop may not be eliminated.
- bool safeExitBlock(BasicBlock *BB);
+ bool safeExitBlock(SplitInfo &SD, BasicBlock *BB);
- bool splitLoop();
+ bool splitLoop(SplitInfo &SD);
private:
@@ -72,20 +94,7 @@
Loop *L;
ScalarEvolution *SE;
- // Induction variable whose range is being split by this transformation.
- PHINode *IndVar;
-
- // Induction variable's range is split at this value.
- Value *SplitValue;
-
- // Induction variable's final loop exit value.
- Value *ExitValue;
-
- // This compare instruction compares IndVar against SplitValue.
- ICmpInst *SplitCondition;
-
- // Loop exit condition.
- ICmpInst *ExitCondition;
+ SmallVector<SplitInfo, 4> SplitData;
};
char LoopIndexSplit::ID = 0;
@@ -100,30 +109,51 @@
bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM) {
bool Changed = false;
L = IncomingLoop;
- SplitCondition = NULL;
+
SE = &getAnalysis<ScalarEvolution>();
findSplitCondition();
- if (!SplitCondition)
+ if (SplitData.empty())
return false;
- if (SplitCondition->getPredicate() == ICmpInst::ICMP_EQ)
- // If it is possible to eliminate loop then do so.
- Changed = processOneIterationLoop(LPM);
- else
- Changed = splitLoop();
+ // First see if it is possible to eliminate loop itself or not.
+ for (SmallVector<SplitInfo, 4>::iterator SI = SplitData.begin(),
+ E = SplitData.end(); SI != E; ++SI) {
+ SplitInfo &SD = *SI;
+ if (SD.SplitCondition->getPredicate() == ICmpInst::ICMP_EQ) {
+ Changed = processOneIterationLoop(SD,LPM);
+ if (Changed) {
+ ++NumIndexSplit;
+ // If is loop is eliminated then nothing else to do here.
+ return Changed;
+ }
+ }
+ }
+
+ for (SmallVector<SplitInfo, 4>::iterator SI = SplitData.begin(),
+ E = SplitData.end(); SI != E; ++SI) {
+ SplitInfo &SD = *SI;
+
+ // ICM_EQs are already handled above.
+ if (SD.SplitCondition->getPredicate() == ICmpInst::ICMP_EQ)
+ continue;
+
+ // FIXME : Collect Spliting cost for all SD. Only operate on profitable SDs.
+ Changed = splitLoop(SD);
+ }
if (Changed)
++NumIndexSplit;
-
+
return Changed;
}
/// Find condition inside a loop that is suitable candidate for index split.
void LoopIndexSplit::findSplitCondition() {
- BasicBlock *Header = L->getHeader();
+ SplitInfo SD;
+ BasicBlock *Header = L->getHeader();
for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
PHINode *PN = cast<PHINode>(I);
@@ -140,29 +170,29 @@
for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
UI != E; ++UI) {
if (ICmpInst *CI = dyn_cast<ICmpInst>(*UI)) {
- SplitCondition = CI;
+ SD.SplitCondition = CI;
break;
}
}
// Valid SplitCondition's one operand is phi node and the other operand
// is loop invariant.
- if (SplitCondition) {
- if (SplitCondition->getOperand(0) != PN)
- SplitValue = SplitCondition->getOperand(0);
+ if (SD.SplitCondition) {
+ if (SD.SplitCondition->getOperand(0) != PN)
+ SD.SplitValue = SD.SplitCondition->getOperand(0);
else
- SplitValue = SplitCondition->getOperand(1);
- SCEVHandle ValueSCEV = SE->getSCEV(SplitValue);
+ SD.SplitValue = SD.SplitCondition->getOperand(1);
+ SCEVHandle ValueSCEV = SE->getSCEV(SD.SplitValue);
// If SplitValue is not invariant then SplitCondition is not appropriate.
if (!ValueSCEV->isLoopInvariant(L))
- SplitCondition = NULL;
+ SD.SplitCondition = NULL;
}
// We are looking for only one split condition.
- if (SplitCondition) {
- IndVar = PN;
- break;
+ if (SD.SplitCondition) {
+ SD.IndVar = PN;
+ SplitData.push_back(SD);
}
}
}
@@ -182,7 +212,7 @@
/// i = somevalue;
/// loop_body
/// }
-bool LoopIndexSplit::processOneIterationLoop(LPPassManager &LPM) {
+bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD, LPPassManager &LPM) {
BasicBlock *Header = L->getHeader();
@@ -191,7 +221,7 @@
// If SplitCondition is not in loop header then this loop is not suitable
// for this transformation.
- if (SplitCondition->getParent() != Header)
+ if (SD.SplitCondition->getParent() != Header)
return false;
// If one of the Header block's successor is not an exit block then this
@@ -209,12 +239,12 @@
// If loop header includes loop variant instruction operands then
// this loop may not be eliminated.
- if (!safeHeader(Header))
+ if (!safeHeader(SD, Header))
return false;
// If Exit block includes loop variant instructions then this
// loop may not be eliminated.
- if (!safeExitBlock(ExitBlock))
+ if (!safeExitBlock(SD, ExitBlock))
return false;
// Update CFG.
@@ -235,7 +265,7 @@
BasicBlock *Preheader = L->getLoopPreheader();
Instruction *Terminator = Header->getTerminator();
- Value *StartValue = IndVar->getIncomingValueForBlock(Preheader);
+ Value *StartValue = SD.IndVar->getIncomingValueForBlock(Preheader);
// Replace split condition in header.
// Transform
@@ -244,16 +274,19 @@
// c1 = icmp uge i32 SplitValue, StartValue
// c2 = icmp ult i32 vSplitValue, ExitValue
// and i32 c1, c2
- bool SignedPredicate = ExitCondition->isSignedPredicate();
+ bool SignedPredicate = SD.ExitCondition->isSignedPredicate();
Instruction *C1 = new ICmpInst(SignedPredicate ?
ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE,
- SplitValue, StartValue, "lisplit", Terminator);
+ SD.SplitValue, StartValue, "lisplit",
+ Terminator);
Instruction *C2 = new ICmpInst(SignedPredicate ?
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
- SplitValue, ExitValue, "lisplit", Terminator);
- Instruction *NSplitCond = BinaryOperator::createAnd(C1, C2, "lisplit", Terminator);
- SplitCondition->replaceAllUsesWith(NSplitCond);
- SplitCondition->eraseFromParent();
+ SD.SplitValue, SD.ExitValue, "lisplit",
+ Terminator);
+ Instruction *NSplitCond = BinaryOperator::createAnd(C1, C2, "lisplit",
+ Terminator);
+ SD.SplitCondition->replaceAllUsesWith(NSplitCond);
+ SD.SplitCondition->eraseFromParent();
// Now, clear latch block. Remove instructions that are responsible
// to increment induction variable.
@@ -275,7 +308,7 @@
// If loop header includes loop variant instruction operands then
// this loop can not be eliminated. This is used by processOneIterationLoop().
-bool LoopIndexSplit::safeHeader(BasicBlock *Header) {
+bool LoopIndexSplit::safeHeader(SplitInfo &SD, BasicBlock *Header) {
Instruction *Terminator = Header->getTerminator();
for(BasicBlock::iterator BI = Header->begin(), BE = Header->end();
@@ -287,7 +320,7 @@
continue;
// SplitCondition itself is OK.
- if (I == SplitCondition)
+ if (I == SD.SplitCondition)
continue;
// Terminator is also harmless.
@@ -303,7 +336,7 @@
// If Exit block includes loop variant instructions then this
// loop may not be eliminated. This is used by processOneIterationLoop().
-bool LoopIndexSplit::safeExitBlock(BasicBlock *ExitBlock) {
+bool LoopIndexSplit::safeExitBlock(SplitInfo &SD, BasicBlock *ExitBlock) {
Instruction *IndVarIncrement = NULL;
@@ -334,7 +367,7 @@
IndVarIncrement = I;
}
- if (IndVarIncrement && PN == IndVar && CI->isOne())
+ if (IndVarIncrement && PN == SD.IndVar && CI->isOne())
continue;
}
@@ -345,7 +378,7 @@
++BI;
Instruction *N = BI;
if (N == ExitBlock->getTerminator()) {
- ExitCondition = EC;
+ SD.ExitCondition = EC;
continue;
}
}
@@ -357,19 +390,19 @@
// Check if Exit condition is comparing induction variable against
// loop invariant value. If one operand is induction variable and
// the other operand is loop invaraint then Exit condition is safe.
- if (ExitCondition) {
- Value *Op0 = ExitCondition->getOperand(0);
- Value *Op1 = ExitCondition->getOperand(1);
+ if (SD.ExitCondition) {
+ Value *Op0 = SD.ExitCondition->getOperand(0);
+ Value *Op1 = SD.ExitCondition->getOperand(1);
Instruction *Insn0 = dyn_cast<Instruction>(Op0);
Instruction *Insn1 = dyn_cast<Instruction>(Op1);
if (Insn0 && Insn0 == IndVarIncrement)
- ExitValue = Op1;
+ SD.ExitValue = Op1;
else if (Insn1 && Insn1 == IndVarIncrement)
- ExitValue = Op0;
+ SD.ExitValue = Op0;
- SCEVHandle ValueSCEV = SE->getSCEV(ExitValue);
+ SCEVHandle ValueSCEV = SE->getSCEV(SD.ExitValue);
if (!ValueSCEV->isLoopInvariant(L))
return false;
}
@@ -378,7 +411,7 @@
return true;
}
-bool LoopIndexSplit::splitLoop() {
+bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
// FIXME :)
return false;
}
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