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[ValueTracking] Refactor isKnownNonEqualFromContext #127388

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merged 2 commits into from
Apr 18, 2025
Merged

[ValueTracking] Refactor isKnownNonEqualFromContext #127388

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88464ba
[ValueTracking] Refactor `isKnownNonEqualFromContext`
dtcxzyw Feb 16, 2025
62ac8d6
[InstCombine] Add more tests. NFC.
dtcxzyw Feb 17, 2025
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105 changes: 61 additions & 44 deletions llvm/lib/Analysis/ValueTracking.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3786,6 +3786,63 @@ static bool isNonEqualPointersWithRecursiveGEP(const Value *A, const Value *B,
(StartOffset.sle(OffsetB) && StepOffset.isNegative()));
}

static bool isKnownNonEqualFromContext(const Value *V1, const Value *V2,
unsigned Depth, const SimplifyQuery &Q) {
if (!Q.CxtI)
return false;

// Try to infer NonEqual based on information from dominating conditions.
if (Q.DC && Q.DT) {
auto IsKnownNonEqualFromDominatingCondition = [&](const Value *V) {
for (BranchInst *BI : Q.DC->conditionsFor(V)) {
Value *Cond = BI->getCondition();
BasicBlockEdge Edge0(BI->getParent(), BI->getSuccessor(0));
if (Q.DT->dominates(Edge0, Q.CxtI->getParent()) &&
isImpliedCondition(Cond, ICmpInst::ICMP_NE, V1, V2, Q.DL,
/*LHSIsTrue=*/true, Depth)
.value_or(false))
return true;

BasicBlockEdge Edge1(BI->getParent(), BI->getSuccessor(1));
if (Q.DT->dominates(Edge1, Q.CxtI->getParent()) &&
isImpliedCondition(Cond, ICmpInst::ICMP_NE, V1, V2, Q.DL,
/*LHSIsTrue=*/false, Depth)
.value_or(false))
return true;
}

return false;
};

if (IsKnownNonEqualFromDominatingCondition(V1) ||
IsKnownNonEqualFromDominatingCondition(V2))
return true;
}

if (!Q.AC)
return false;

// Try to infer NonEqual based on information from assumptions.
for (auto &AssumeVH : Q.AC->assumptionsFor(V1)) {
if (!AssumeVH)
continue;
CallInst *I = cast<CallInst>(AssumeVH);

assert(I->getFunction() == Q.CxtI->getFunction() &&
"Got assumption for the wrong function!");
assert(I->getIntrinsicID() == Intrinsic::assume &&
"must be an assume intrinsic");

if (isImpliedCondition(I->getArgOperand(0), ICmpInst::ICMP_NE, V1, V2, Q.DL,
/*LHSIsTrue=*/true, Depth)
.value_or(false) &&
isValidAssumeForContext(I, Q.CxtI, Q.DT))
return true;
}

return false;
}

/// Return true if it is known that V1 != V2.
static bool isKnownNonEqual(const Value *V1, const Value *V2,
const APInt &DemandedElts, unsigned Depth,
Expand Down Expand Up @@ -3857,49 +3914,8 @@ static bool isKnownNonEqual(const Value *V1, const Value *V2,
match(V2, m_PtrToIntSameSize(Q.DL, m_Value(B))))
return isKnownNonEqual(A, B, DemandedElts, Depth + 1, Q);

if (!Q.CxtI)
return false;

// Try to infer NonEqual based on information from dominating conditions.
if (Q.DC && Q.DT) {
for (BranchInst *BI : Q.DC->conditionsFor(V1)) {
Value *Cond = BI->getCondition();
BasicBlockEdge Edge0(BI->getParent(), BI->getSuccessor(0));
if (Q.DT->dominates(Edge0, Q.CxtI->getParent()) &&
isImpliedCondition(Cond, ICmpInst::ICMP_NE, V1, V2, Q.DL,
/*LHSIsTrue=*/true, Depth)
.value_or(false))
return true;

BasicBlockEdge Edge1(BI->getParent(), BI->getSuccessor(1));
if (Q.DT->dominates(Edge1, Q.CxtI->getParent()) &&
isImpliedCondition(Cond, ICmpInst::ICMP_NE, V1, V2, Q.DL,
/*LHSIsTrue=*/false, Depth)
.value_or(false))
return true;
}
}

if (!Q.AC)
return false;

// Try to infer NonEqual based on information from assumptions.
for (auto &AssumeVH : Q.AC->assumptionsFor(V1)) {
if (!AssumeVH)
continue;
CallInst *I = cast<CallInst>(AssumeVH);

assert(I->getFunction() == Q.CxtI->getFunction() &&
"Got assumption for the wrong function!");
assert(I->getIntrinsicID() == Intrinsic::assume &&
"must be an assume intrinsic");

if (isImpliedCondition(I->getArgOperand(0), ICmpInst::ICMP_NE, V1, V2, Q.DL,
/*LHSIsTrue=*/true, Depth)
.value_or(false) &&
isValidAssumeForContext(I, Q.CxtI, Q.DT))
return true;
}
if (isKnownNonEqualFromContext(V1, V2, Depth, Q))
return true;

return false;
}
Expand Down Expand Up @@ -10278,7 +10294,8 @@ void llvm::findValuesAffectedByCondition(
bool HasRHSC = match(B, m_ConstantInt());
if (ICmpInst::isEquality(Pred)) {
AddAffected(A);
AddAffected(B);
if (IsAssume)
AddAffected(B);
if (HasRHSC) {
Value *Y;
// (X & C) or (X | C).
Expand Down
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