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[LoopPrediction] Introduce utility function getLatchPredicateForGuard. NFC. 

Factor out getting the predicate for latch condition in a guard to
utility function getLatchPredicateForGuard.

llvm-svn: 324450
This commit is contained in:
Serguei Katkov 2018-02-07 06:53:37 +00:00
parent 282ae1632a
commit ebc9031b88
1 changed files with 30 additions and 17 deletions
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47
llvm/lib/Transforms/Scalar/LoopPredication.cpp
View File

@ -266,6 +266,11 @@ class LoopPredication {
// Return the loopLatchCheck corresponding to the RangeCheckType if safe to do
// so.
Optional<LoopICmp> generateLoopLatchCheck(Type *RangeCheckType);
// Returns the latch predicate for guard. SGT -> SGE, UGT -> UGE, SGE -> SGT,
// UGE -> UGT, etc.
ICmpInst::Predicate getLatchPredicateForGuard(ICmpInst::Predicate Pred);
public:
LoopPredication(ScalarEvolution *SE) : SE(SE){};
bool runOnLoop(Loop *L);
@ -391,6 +396,30 @@ bool LoopPredication::CanExpand(const SCEV* S) {
return SE->isLoopInvariant(S, L) && isSafeToExpand(S, *SE);
}
ICmpInst::Predicate
LoopPredication::getLatchPredicateForGuard(ICmpInst::Predicate Pred) {
switch (LatchCheck.Pred) {
case ICmpInst::ICMP_ULT:
return ICmpInst::ICMP_ULE;
case ICmpInst::ICMP_ULE:
return ICmpInst::ICMP_ULT;
case ICmpInst::ICMP_SLT:
return ICmpInst::ICMP_SLE;
case ICmpInst::ICMP_SLE:
return ICmpInst::ICMP_SLT;
case ICmpInst::ICMP_UGT:
return ICmpInst::ICMP_UGE;
case ICmpInst::ICMP_UGE:
return ICmpInst::ICMP_UGT;
case ICmpInst::ICMP_SGT:
return ICmpInst::ICMP_SGE;
case ICmpInst::ICMP_SGE:
return ICmpInst::ICMP_SGT;
default:
llvm_unreachable("Unsupported loop latch!");
}
}
Optional<Value *> LoopPredication::widenICmpRangeCheckIncrementingLoop(
LoopPredication::LoopICmp LatchCheck, LoopPredication::LoopICmp RangeCheck,
SCEVExpander &Expander, IRBuilder<> &Builder) {
@ -415,23 +444,7 @@ Optional<Value *> LoopPredication::widenICmpRangeCheckIncrementingLoop(
DEBUG(dbgs() << "Can't expand limit check!\n");
return None;
}
ICmpInst::Predicate LimitCheckPred;
switch (LatchCheck.Pred) {
case ICmpInst::ICMP_ULT:
LimitCheckPred = ICmpInst::ICMP_ULE;
break;
case ICmpInst::ICMP_ULE:
LimitCheckPred = ICmpInst::ICMP_ULT;
break;
case ICmpInst::ICMP_SLT:
LimitCheckPred = ICmpInst::ICMP_SLE;
break;
case ICmpInst::ICMP_SLE:
LimitCheckPred = ICmpInst::ICMP_SLT;
break;
default:
llvm_unreachable("Unsupported loop latch!");
}
auto LimitCheckPred = getLatchPredicateForGuard(LatchCheck.Pred);
DEBUG(dbgs() << "LHS: " << *LatchLimit << "\n");
DEBUG(dbgs() << "RHS: " << *RHS << "\n");