void IndVarSimplify::EliminateIVComparisons() {
// Look for ICmp users.
for (IVUsers::iterator I = IU->begin(), E = IU->end(); I != E; ++I) {
IVStrideUse &UI = *I;
ICmpInst *ICmp = dyn_cast<ICmpInst>(UI.getUser());
if (!ICmp) continue;
bool Swapped = UI.getOperandValToReplace() == ICmp->getOperand(1);
ICmpInst::Predicate Pred = ICmp->getPredicate();
if (Swapped) Pred = ICmpInst::getSwappedPredicate(Pred);
// Get the SCEVs for the ICmp operands.
const SCEV *S = IU->getReplacementExpr(UI);
const SCEV *X = SE->getSCEV(ICmp->getOperand(!Swapped));
// Simplify unnecessary loops away.
const Loop *ICmpLoop = LI->getLoopFor(ICmp->getParent());
S = SE->getSCEVAtScope(S, ICmpLoop);
X = SE->getSCEVAtScope(X, ICmpLoop);
// If the condition is always true or always false, replace it with
// a constant value.
if (SE->isKnownPredicate(Pred, S, X))
ICmp->replaceAllUsesWith(ConstantInt::getTrue(ICmp->getContext()));
else if (SE->isKnownPredicate(ICmpInst::getInversePredicate(Pred), S, X))
ICmp->replaceAllUsesWith(ConstantInt::getFalse(ICmp->getContext()));
else
continue;
DEBUG(dbgs() << "INDVARS: Eliminated comparison: " << *ICmp << '\n');
DeadInsts.push_back(ICmp);
}
}
void TempScopInfo::buildAffineCondition(Value &V, bool inverted,
Comparison **Comp) const {
if (ConstantInt *C = dyn_cast<ConstantInt>(&V)) {
// If this is always true condition, we will create 0 <= 1,
// otherwise we will create 0 >= 1.
const SCEV *LHS = SE->getConstant(C->getType(), 0);
const SCEV *RHS = SE->getConstant(C->getType(), 1);
if (C->isOne() == inverted)
*Comp = new Comparison(LHS, RHS, ICmpInst::ICMP_SLE);
else
*Comp = new Comparison(LHS, RHS, ICmpInst::ICMP_SGE);
return;
}
ICmpInst *ICmp = dyn_cast<ICmpInst>(&V);
assert(ICmp && "Only ICmpInst of constant as condition supported!");
Loop *L = LI->getLoopFor(ICmp->getParent());
const SCEV *LHS = SE->getSCEVAtScope(ICmp->getOperand(0), L);
const SCEV *RHS = SE->getSCEVAtScope(ICmp->getOperand(1), L);
ICmpInst::Predicate Pred = ICmp->getPredicate();
// Invert the predicate if needed.
if (inverted)
Pred = ICmpInst::getInversePredicate(Pred);
switch (Pred) {
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
// TODO: At the moment we need to see everything as signed. This is an
// correctness issue that needs to be solved.
// AffLHS->setUnsigned();
// AffRHS->setUnsigned();
break;
default:
break;
}
*Comp = new Comparison(LHS, RHS, Pred);
}
void IndVarSimplify::EliminateIVComparisons() {
SmallVector<WeakVH, 16> DeadInsts;
// Look for ICmp users.
for (IVUsers::iterator I = IU->begin(), E = IU->end(); I != E; ++I) {
IVStrideUse &UI = *I;
ICmpInst *ICmp = dyn_cast<ICmpInst>(UI.getUser());
if (!ICmp) continue;
bool Swapped = UI.getOperandValToReplace() == ICmp->getOperand(1);
ICmpInst::Predicate Pred = ICmp->getPredicate();
if (Swapped) Pred = ICmpInst::getSwappedPredicate(Pred);
// Get the SCEVs for the ICmp operands.
const SCEV *S = IU->getReplacementExpr(UI);
const SCEV *X = SE->getSCEV(ICmp->getOperand(!Swapped));
// Simplify unnecessary loops away.
const Loop *ICmpLoop = LI->getLoopFor(ICmp->getParent());
S = SE->getSCEVAtScope(S, ICmpLoop);
X = SE->getSCEVAtScope(X, ICmpLoop);
// If the condition is always true or always false, replace it with
// a constant value.
if (SE->isKnownPredicate(Pred, S, X))
ICmp->replaceAllUsesWith(ConstantInt::getTrue(ICmp->getContext()));
else if (SE->isKnownPredicate(ICmpInst::getInversePredicate(Pred), S, X))
ICmp->replaceAllUsesWith(ConstantInt::getFalse(ICmp->getContext()));
else
continue;
DEBUG(dbgs() << "INDVARS: Eliminated comparison: " << *ICmp << '\n');
DeadInsts.push_back(ICmp);
}
// Now that we're done iterating through lists, clean up any instructions
// which are now dead.
while (!DeadInsts.empty())
if (Instruction *Inst =
dyn_cast_or_null<Instruction>(&*DeadInsts.pop_back_val()))
RecursivelyDeleteTriviallyDeadInstructions(Inst);
}
