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Differential D12800 Diff 35649 lib/Analysis/ValueTracking.cpp

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lib/Analysis/ValueTracking.cpp

Show First 20 Lines • Show All 1,897 Lines • ▼ Show 20 Lines if ((BO->hasNoSignedWrap() || BO->hasNoUnsignedWrap()) &&
return true; return true;
} }
// (C ? X : Y) != 0 if X != 0 and Y != 0. // (C ? X : Y) != 0 if X != 0 and Y != 0.
else if (SelectInst *SI = dyn_cast<SelectInst>(V)) { else if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
if (isKnownNonZero(SI->getTrueValue(), DL, Depth, Q) && if (isKnownNonZero(SI->getTrueValue(), DL, Depth, Q) &&
isKnownNonZero(SI->getFalseValue(), DL, Depth, Q)) isKnownNonZero(SI->getFalseValue(), DL, Depth, Q))
return true; return true;
} }
// PHI
else if (PHINode *PN = dyn_cast<PHINode>(V)) {
// Try and detect a recurrence that monotonically increases from a
// starting value, as these are common as induction variables.
if (PN->getNumIncomingValues() == 2) {
Value *Start = PN->getIncomingValue(0);
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I find the Op1 vs Op0 naming confusing. Given this is inherently zero based indexing, mind either using that in the Op names or picking non-index based ones?

reames: I find the Op1 vs Op0 naming confusing. Given this is inherently zero based indexing, mind…
Value *Induction = PN->getIncomingValue(1);
if (isa<ConstantInt>(Induction) && !isa<ConstantInt>(Start))
std::swap(Start, Induction);
if (ConstantInt *C = dyn_cast<ConstantInt>(Start)) {
if (!C->isZero() && !C->isNegative()) {
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Might be time to introduce a isNonNegative on ConstantInt? Could be another patch.

reames: Might be time to introduce a isNonNegative on ConstantInt? Could be another patch.
ConstantInt *X;
if ((match(Induction, m_NSWAdd(m_Specific(PN), m_ConstantInt(X))) ||
match(Induction, m_NUWAdd(m_Specific(PN), m_ConstantInt(X)))) &&
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Given you're starting from zero, I think you only need the NSW check. Given INT_MAX is always less than UINT_MAX, I believe the former implies the later in this case. (But we might not yet have proved it.)

reames: Given you're starting from zero, I think you only need the NSW check. Given INT_MAX is always…
!X->isNegative())
return true;
}
}
}
}
if (!BitWidth) return false; if (!BitWidth) return false;
APInt KnownZero(BitWidth, 0); APInt KnownZero(BitWidth, 0);
APInt KnownOne(BitWidth, 0); APInt KnownOne(BitWidth, 0);
computeKnownBits(V, KnownZero, KnownOne, DL, Depth, Q); computeKnownBits(V, KnownZero, KnownOne, DL, Depth, Q);
return KnownOne != 0; return KnownOne != 0;
} }
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