namespace {
class CorrelatedValuePropagation : public FunctionPass {
LazyValueInfo *LVI;
-
+
bool processSelect(SelectInst *SI);
bool processPHI(PHINode *P);
bool processMemAccess(Instruction *I);
bool processCmp(CmpInst *C);
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+
public:
static char ID;
CorrelatedValuePropagation(): FunctionPass(ID) {
initializeCorrelatedValuePropagationPass(*PassRegistry::getPassRegistry());
}
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+
bool runOnFunction(Function &F);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<LazyValueInfo>();
}
bool CorrelatedValuePropagation::processSelect(SelectInst *S) {
if (S->getType()->isVectorTy()) return false;
if (isa<Constant>(S->getOperand(0))) return false;
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+
Constant *C = LVI->getConstant(S->getOperand(0), S->getParent());
if (!C) return false;
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+
ConstantInt *CI = dyn_cast<ConstantInt>(C);
if (!CI) return false;
-
- S->replaceAllUsesWith(S->getOperand(CI->isOne() ? 1 : 2));
+
+ Value *ReplaceWith = S->getOperand(1);
+ Value *Other = S->getOperand(2);
+ if (!CI->isOne()) std::swap(ReplaceWith, Other);
+ if (ReplaceWith == S) ReplaceWith = UndefValue::get(S->getType());
+
+ S->replaceAllUsesWith(ReplaceWith);
S->eraseFromParent();
++NumSelects;
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+
return true;
}
bool CorrelatedValuePropagation::processPHI(PHINode *P) {
bool Changed = false;
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+
BasicBlock *BB = P->getParent();
for (unsigned i = 0, e = P->getNumIncomingValues(); i < e; ++i) {
Value *Incoming = P->getIncomingValue(i);
if (isa<Constant>(Incoming)) continue;
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+
Constant *C = LVI->getConstantOnEdge(P->getIncomingValue(i),
P->getIncomingBlock(i),
BB);
if (!C) continue;
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+
P->setIncomingValue(i, C);
Changed = true;
}
}
++NumPhis;
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+
return Changed;
}
Pointer = L->getPointerOperand();
else
Pointer = cast<StoreInst>(I)->getPointerOperand();
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+
if (isa<Constant>(Pointer)) return false;
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+
Constant *C = LVI->getConstant(Pointer, I->getParent());
if (!C) return false;
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++NumMemAccess;
I->replaceUsesOfWith(Pointer, C);
return true;
if (isa<Instruction>(Op0) &&
cast<Instruction>(Op0)->getParent() == C->getParent())
return false;
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+
Constant *Op1 = dyn_cast<Constant>(C->getOperand(1));
if (!Op1) return false;
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+
pred_iterator PI = pred_begin(C->getParent()), PE = pred_end(C->getParent());
if (PI == PE) return false;
-
- LazyValueInfo::Tristate Result = LVI->getPredicateOnEdge(C->getPredicate(),
+
+ LazyValueInfo::Tristate Result = LVI->getPredicateOnEdge(C->getPredicate(),
C->getOperand(0), Op1, *PI, C->getParent());
if (Result == LazyValueInfo::Unknown) return false;
++PI;
while (PI != PE) {
- LazyValueInfo::Tristate Res = LVI->getPredicateOnEdge(C->getPredicate(),
+ LazyValueInfo::Tristate Res = LVI->getPredicateOnEdge(C->getPredicate(),
C->getOperand(0), Op1, *PI, C->getParent());
if (Res != Result) return false;
++PI;
}
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+
++NumCmps;
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+
if (Result == LazyValueInfo::True)
C->replaceAllUsesWith(ConstantInt::getTrue(C->getContext()));
else
C->replaceAllUsesWith(ConstantInt::getFalse(C->getContext()));
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+
C->eraseFromParent();
return true;
bool CorrelatedValuePropagation::runOnFunction(Function &F) {
LVI = &getAnalysis<LazyValueInfo>();
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+
bool FnChanged = false;
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+
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) {
bool BBChanged = false;
for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE; ) {
break;
}
}
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+
FnChanged |= BBChanged;
}
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+
return FnChanged;
}