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[SCEV] Clean up isKnownPredicateViaConstantRanges; NFCI

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- ScalarEvolution::isKnownPredicateViaConstantRanges duplicates some
   logic already present in ConstantRange, use ConstantRange for those
   bits.

 - In some cases ScalarEvolution::isKnownPredicateViaConstantRanges
   returns `false` to mean "definitely false" (e.g. see the
   `LHSRange.getSignedMin().sge(RHSRange.getSignedMax())` case for
   `ICmpInst::ICMP_SLT`), but for `isKnownPredicateViaConstantRanges`,
   `false` actually means "don't know".  Get rid of this extra bit of
   code to avoid confusion.

llvm-svn: 259401
This commit is contained in:
Sanjoy Das 2016-02-01 20:48:14 +00:00
parent b45b869e7d
commit 49cbccc04a
1 changed files with 20 additions and 63 deletions
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83
lib/Analysis/ScalarEvolution.cpp
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@ -7268,70 +7268,27 @@ bool ScalarEvolution::isKnownPredicateViaConstantRanges(
// This code is split out from isKnownPredicate because it is called from
// within isLoopEntryGuardedByCond.
switch (Pred) {
default:
llvm_unreachable("Unexpected ICmpInst::Predicate value!");
case ICmpInst::ICMP_SGT:
std::swap(LHS, RHS);
case ICmpInst::ICMP_SLT: {
ConstantRange LHSRange = getSignedRange(LHS);
ConstantRange RHSRange = getSignedRange(RHS);
if (LHSRange.getSignedMax().slt(RHSRange.getSignedMin()))
return true;
if (LHSRange.getSignedMin().sge(RHSRange.getSignedMax()))
return false;
break;
}
case ICmpInst::ICMP_SGE:
std::swap(LHS, RHS);
case ICmpInst::ICMP_SLE: {
ConstantRange LHSRange = getSignedRange(LHS);
ConstantRange RHSRange = getSignedRange(RHS);
if (LHSRange.getSignedMax().sle(RHSRange.getSignedMin()))
return true;
if (LHSRange.getSignedMin().sgt(RHSRange.getSignedMax()))
return false;
break;
}
case ICmpInst::ICMP_UGT:
std::swap(LHS, RHS);
case ICmpInst::ICMP_ULT: {
ConstantRange LHSRange = getUnsignedRange(LHS);
ConstantRange RHSRange = getUnsignedRange(RHS);
if (LHSRange.getUnsignedMax().ult(RHSRange.getUnsignedMin()))
return true;
if (LHSRange.getUnsignedMin().uge(RHSRange.getUnsignedMax()))
return false;
break;
}
case ICmpInst::ICMP_UGE:
std::swap(LHS, RHS);
case ICmpInst::ICMP_ULE: {
ConstantRange LHSRange = getUnsignedRange(LHS);
ConstantRange RHSRange = getUnsignedRange(RHS);
if (LHSRange.getUnsignedMax().ule(RHSRange.getUnsignedMin()))
return true;
if (LHSRange.getUnsignedMin().ugt(RHSRange.getUnsignedMax()))
return false;
break;
}
case ICmpInst::ICMP_NE: {
if (getUnsignedRange(LHS).intersectWith(getUnsignedRange(RHS)).isEmptySet())
return true;
if (getSignedRange(LHS).intersectWith(getSignedRange(RHS)).isEmptySet())
return true;
const SCEV *Diff = getMinusSCEV(LHS, RHS);
if (isKnownNonZero(Diff))
return true;
break;
}
case ICmpInst::ICMP_EQ:
// The check at the top of the function catches the case where
// the values are known to be equal.
break;
}
return false;
auto CheckRanges =
[&](const ConstantRange &RangeLHS, const ConstantRange &RangeRHS) {
return ConstantRange::makeSatisfyingICmpRegion(Pred, RangeRHS)
.contains(RangeLHS);
};
// The check at the top of the function catches the case where the values are
// known to be equal.
if (Pred == CmpInst::ICMP_EQ)
return false;
if (Pred == CmpInst::ICMP_NE)
return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)) ||
CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)) ||
isKnownNonZero(getMinusSCEV(LHS, RHS));
if (CmpInst::isSigned(Pred))
return CheckRanges(getSignedRange(LHS), getSignedRange(RHS));
return CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS));
}
bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,