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Expose isNonConstantNegative to users of ScalarEvolution.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147700 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick
2012-01-07 00:27:31 +00:00
parent 4bf76e0e28
commit f8fd841a4b
3 changed files with 24 additions and 20 deletions
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14
lib/Analysis/ScalarEvolution.cpp
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@@ -284,6 +284,20 @@ bool SCEV::isAllOnesValue() const {
return false;
}
/// isNonConstantNegative - Return true if the specified scev is negated, but
/// not a constant.
bool SCEV::isNonConstantNegative() const {
const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
if (!Mul) return false;
// If there is a constant factor, it will be first.
const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
if (!SC) return false;
// Return true if the value is negative, this matches things like (-42 * V).
return SC->getValue()->getValue().isNegative();
}
SCEVCouldNotCompute::SCEVCouldNotCompute() :
SCEV(FoldingSetNodeIDRef(), scCouldNotCompute) {}