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[LoopPredication] NFC. Extract LoopICmp struct and parseLoopICmp helper 

llvm-svn: 303427
This commit is contained in:
Artur Pilipenko 2017-05-19 14:02:46 +00:00
parent 6780ba65b9
commit a6c278049a
1 changed files with 44 additions and 18 deletions
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62
llvm/lib/Transforms/Scalar/LoopPredication.cpp
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@ -64,6 +64,18 @@ class LoopPredication {
const DataLayout *DL;
BasicBlock *Preheader;
/// Represents an induction variable check:
/// icmp Pred, <induction variable>, <loop invariant limit>
struct LoopICmp {
ICmpInst::Predicate Pred;
const SCEVAddRecExpr *IV;
const SCEV *Limit;
LoopICmp(ICmpInst::Predicate Pred, const SCEVAddRecExpr *IV, const SCEV *Limit)
: Pred(Pred), IV(IV), Limit(Limit) {}
LoopICmp() {}
};
Optional<LoopICmp> parseLoopICmp(ICmpInst *ICI);
Value *expandCheck(SCEVExpander &Expander, IRBuilder<> &Builder,
ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS,
Instruction *InsertAt);
@ -120,6 +132,33 @@ PreservedAnalyses LoopPredicationPass::run(Loop &L, LoopAnalysisManager &AM,
return getLoopPassPreservedAnalyses();
}
Optional<LoopPredication::LoopICmp>
LoopPredication::parseLoopICmp(ICmpInst *ICI) {
ICmpInst::Predicate Pred = ICI->getPredicate();
Value *LHS = ICI->getOperand(0);
Value *RHS = ICI->getOperand(1);
const SCEV *LHSS = SE->getSCEV(LHS);
if (isa<SCEVCouldNotCompute>(LHSS))
return None;
const SCEV *RHSS = SE->getSCEV(RHS);
if (isa<SCEVCouldNotCompute>(RHSS))
return None;
// Canonicalize RHS to be loop invariant bound, LHS - a loop computable IV
if (SE->isLoopInvariant(LHSS, L)) {
std::swap(LHS, RHS);
std::swap(LHSS, RHSS);
Pred = ICmpInst::getSwappedPredicate(Pred);
}
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHSS);
if (!AR || AR->getLoop() != L)
return None;
return LoopICmp(Pred, AR, RHSS);
}
Value *LoopPredication::expandCheck(SCEVExpander &Expander,
IRBuilder<> &Builder,
ICmpInst::Predicate Pred, const SCEV *LHS,
@ -140,22 +179,13 @@ Optional<Value *> LoopPredication::widenICmpRangeCheck(ICmpInst *ICI,
DEBUG(dbgs() << "Analyzing ICmpInst condition:\n");
DEBUG(ICI->dump());
ICmpInst::Predicate Pred = ICI->getPredicate();
Value *LHS = ICI->getOperand(0);
Value *RHS = ICI->getOperand(1);
const SCEV *LHSS = SE->getSCEV(LHS);
if (isa<SCEVCouldNotCompute>(LHSS))
return None;
const SCEV *RHSS = SE->getSCEV(RHS);
if (isa<SCEVCouldNotCompute>(RHSS))
auto RangeCheck = parseLoopICmp(ICI);
if (!RangeCheck)
return None;
// Canonicalize RHS to be loop invariant bound, LHS - a loop computable index
if (SE->isLoopInvariant(LHSS, L)) {
std::swap(LHS, RHS);
std::swap(LHSS, RHSS);
Pred = ICmpInst::getSwappedPredicate(Pred);
}
ICmpInst::Predicate Pred = RangeCheck->Pred;
const SCEVAddRecExpr *IndexAR = RangeCheck->IV;
const SCEV *RHSS = RangeCheck->Limit;
auto CanExpand = [this](const SCEV *S) {
return SE->isLoopInvariant(S, L) && isSafeToExpand(S, *SE);
@ -163,10 +193,6 @@ Optional<Value *> LoopPredication::widenICmpRangeCheck(ICmpInst *ICI,
if (!CanExpand(RHSS))
return None;
const SCEVAddRecExpr *IndexAR = dyn_cast<SCEVAddRecExpr>(LHSS);
if (!IndexAR || IndexAR->getLoop() != L)
return None;
DEBUG(dbgs() << "IndexAR: ");
DEBUG(IndexAR->dump());