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ValueTracking: Make isSafeToSpeculativelyExecute a little cleaner 

No functional change intended.

llvm-svn: 227760
This commit is contained in:
David Majnemer 2015-02-01 19:10:19 +00:00
parent e3d2b20c2b
commit 8a6578a0e7
1 changed files with 14 additions and 14 deletions
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28
llvm/lib/Analysis/ValueTracking.cpp
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@ -2620,20 +2620,20 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V,
case Instruction::SDiv:
case Instruction::SRem: {
// x / y is undefined if y == 0 or x == INT_MIN and y == -1
const APInt *X, *Y;
if (match(Inst->getOperand(1), m_APInt(Y))) {
if (*Y != 0) {
if (*Y == -1) {
// The numerator can't be MinSignedValue if the denominator is -1.
if (match(Inst->getOperand(0), m_APInt(X)))
return !Y->isMinSignedValue();
// The numerator *might* be MinSignedValue.
return false;
}
// The denominator is not 0 or -1, it's safe to proceed.
return true;
}
}
const APInt *Numerator, *Denominator;
if (!match(Inst->getOperand(1), m_APInt(Denominator)))
return false;
// We cannot hoist this division if the denominator is 0.
if (*Denominator == 0)
return false;
// It's safe to hoist if the denominator is not 0 or -1.
if (*Denominator != -1)
return true;
// At this point we know that the denominator is -1. It is safe to hoist as
// long we know that the numerator is not INT_MIN.
if (match(Inst->getOperand(0), m_APInt(Numerator)))
return !Numerator->isMinSignedValue();
// The numerator *might* be MinSignedValue.
return false;
}
case Instruction::Load: {