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Merged
merged 3 commits into from
Oct 18, 2025
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[LVI][SCCP] Avoid copying ValueLatticeElement #163901

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6a67889
[LVI][SCCP] Avoid copying ValueLatticeElement
dtcxzyw Oct 17, 2025
6b08eeb
[SCCP] Avoid implicit reallocation
dtcxzyw Oct 17, 2025
4ea449b
[SCCP] Address review comments
dtcxzyw Oct 18, 2025
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10 changes: 4 additions & 6 deletions llvm/lib/Analysis/LazyValueInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -947,9 +947,8 @@ LazyValueInfoImpl::solveBlockValueSelect(SelectInst *SI, BasicBlock *BB) {
/*UseBlockValue*/ false));
}

ValueLatticeElement Result = TrueVal;
Result.mergeIn(FalseVal);
return Result;
TrueVal.mergeIn(FalseVal);
return TrueVal;
}

std::optional<ConstantRange>
Expand Down Expand Up @@ -1778,9 +1777,8 @@ ValueLatticeElement LazyValueInfoImpl::getValueInBlock(Value *V, BasicBlock *BB,
assert(OptResult && "Value not available after solving");
}

ValueLatticeElement Result = *OptResult;
LLVM_DEBUG(dbgs() << " Result = " << Result << "\n");
return Result;
LLVM_DEBUG(dbgs() << " Result = " << *OptResult << "\n");
return *OptResult;
}

ValueLatticeElement LazyValueInfoImpl::getValueAt(Value *V, Instruction *CxtI) {
Expand Down
96 changes: 49 additions & 47 deletions llvm/lib/Transforms/Utils/SCCPSolver.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -634,18 +634,10 @@ class SCCPInstVisitor : public InstVisitor<SCCPInstVisitor> {
/// Merge \p MergeWithV into \p IV and push \p V to the worklist, if \p IV
/// changes.
bool mergeInValue(ValueLatticeElement &IV, Value *V,
ValueLatticeElement MergeWithV,
const ValueLatticeElement &MergeWithV,
ValueLatticeElement::MergeOptions Opts = {
/*MayIncludeUndef=*/false, /*CheckWiden=*/false});

bool mergeInValue(Value *V, ValueLatticeElement MergeWithV,
ValueLatticeElement::MergeOptions Opts = {
/*MayIncludeUndef=*/false, /*CheckWiden=*/false}) {
assert(!V->getType()->isStructTy() &&
"non-structs should use markConstant");
return mergeInValue(ValueState[V], V, MergeWithV, Opts);
}

/// getValueState - Return the ValueLatticeElement object that corresponds to
/// the value. This function handles the case when the value hasn't been seen
/// yet by properly seeding constants etc.
Expand Down Expand Up @@ -987,7 +979,7 @@ class SCCPInstVisitor : public InstVisitor<SCCPInstVisitor> {
void trackValueOfArgument(Argument *A) {
if (A->getType()->isStructTy())
return (void)markOverdefined(A);
mergeInValue(A, getArgAttributeVL(A));
mergeInValue(ValueState[A], A, getArgAttributeVL(A));
}

bool isStructLatticeConstant(Function *F, StructType *STy);
Expand Down Expand Up @@ -1128,8 +1120,7 @@ bool SCCPInstVisitor::isStructLatticeConstant(Function *F, StructType *STy) {
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
const auto &It = TrackedMultipleRetVals.find(std::make_pair(F, i));
assert(It != TrackedMultipleRetVals.end());
ValueLatticeElement LV = It->second;
if (!SCCPSolver::isConstant(LV))
if (!SCCPSolver::isConstant(It->second))
return false;
}
return true;
Expand Down Expand Up @@ -1160,7 +1151,7 @@ Constant *SCCPInstVisitor::getConstantOrNull(Value *V) const {
std::vector<Constant *> ConstVals;
auto *ST = cast<StructType>(V->getType());
for (unsigned I = 0, E = ST->getNumElements(); I != E; ++I) {
ValueLatticeElement LV = LVs[I];
const ValueLatticeElement &LV = LVs[I];
ConstVals.push_back(SCCPSolver::isConstant(LV)
? getConstant(LV, ST->getElementType(I))
: UndefValue::get(ST->getElementType(I)));
Expand Down Expand Up @@ -1225,7 +1216,7 @@ void SCCPInstVisitor::visitInstruction(Instruction &I) {
}

bool SCCPInstVisitor::mergeInValue(ValueLatticeElement &IV, Value *V,
ValueLatticeElement MergeWithV,
const ValueLatticeElement &MergeWithV,
ValueLatticeElement::MergeOptions Opts) {
if (IV.mergeIn(MergeWithV, Opts)) {
pushUsersToWorkList(V);
Expand Down Expand Up @@ -1264,7 +1255,7 @@ void SCCPInstVisitor::getFeasibleSuccessors(Instruction &TI,
return;
}

ValueLatticeElement BCValue = getValueState(BI->getCondition());
const ValueLatticeElement &BCValue = getValueState(BI->getCondition());
ConstantInt *CI = getConstantInt(BCValue, BI->getCondition()->getType());
if (!CI) {
// Overdefined condition variables, and branches on unfoldable constant
Expand Down Expand Up @@ -1326,7 +1317,7 @@ void SCCPInstVisitor::getFeasibleSuccessors(Instruction &TI,
// the target as executable.
if (auto *IBR = dyn_cast<IndirectBrInst>(&TI)) {
// Casts are folded by visitCastInst.
ValueLatticeElement IBRValue = getValueState(IBR->getAddress());
const ValueLatticeElement &IBRValue = getValueState(IBR->getAddress());
BlockAddress *Addr = dyn_cast_or_null<BlockAddress>(
getConstant(IBRValue, IBR->getAddress()->getType()));
if (!Addr) { // Overdefined or unknown condition?
Expand Down Expand Up @@ -1408,7 +1399,7 @@ void SCCPInstVisitor::visitPHINode(PHINode &PN) {
if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent()))
continue;

ValueLatticeElement IV = getValueState(PN.getIncomingValue(i));
const ValueLatticeElement &IV = getValueState(PN.getIncomingValue(i));
PhiState.mergeIn(IV);
NumActiveIncoming++;
if (PhiState.isOverdefined())
Expand All @@ -1420,10 +1411,10 @@ void SCCPInstVisitor::visitPHINode(PHINode &PN) {
// extensions to match the number of active incoming values. This helps to
// limit multiple extensions caused by the same incoming value, if other
// incoming values are equal.
mergeInValue(&PN, PhiState,
ValueLatticeElement &PhiStateRef = ValueState[&PN];
mergeInValue(PhiStateRef, &PN, PhiState,
ValueLatticeElement::MergeOptions().setMaxWidenSteps(
NumActiveIncoming + 1));
ValueLatticeElement &PhiStateRef = getValueState(&PN);
PhiStateRef.setNumRangeExtensions(
std::max(NumActiveIncoming, PhiStateRef.getNumRangeExtensions()));
}
Expand Down Expand Up @@ -1481,7 +1472,7 @@ void SCCPInstVisitor::visitCastInst(CastInst &I) {
}
}

ValueLatticeElement OpSt = getValueState(I.getOperand(0));
const ValueLatticeElement &OpSt = getValueState(I.getOperand(0));
if (OpSt.isUnknownOrUndef())
return;

Expand All @@ -1496,9 +1487,9 @@ void SCCPInstVisitor::visitCastInst(CastInst &I) {
if (I.getDestTy()->isIntOrIntVectorTy() &&
I.getSrcTy()->isIntOrIntVectorTy() &&
I.getOpcode() != Instruction::BitCast) {
auto &LV = getValueState(&I);
ConstantRange OpRange =
OpSt.asConstantRange(I.getSrcTy(), /*UndefAllowed=*/false);
auto &LV = getValueState(&I);

Type *DestTy = I.getDestTy();
ConstantRange Res = ConstantRange::getEmpty(DestTy->getScalarSizeInBits());
Expand All @@ -1516,19 +1507,24 @@ void SCCPInstVisitor::handleExtractOfWithOverflow(ExtractValueInst &EVI,
const WithOverflowInst *WO,
unsigned Idx) {
Value *LHS = WO->getLHS(), *RHS = WO->getRHS();
ValueLatticeElement L = getValueState(LHS);
ValueLatticeElement R = getValueState(RHS);
Type *Ty = LHS->getType();

addAdditionalUser(LHS, &EVI);
addAdditionalUser(RHS, &EVI);
if (L.isUnknownOrUndef() || R.isUnknownOrUndef())
return; // Wait to resolve.

Type *Ty = LHS->getType();
const ValueLatticeElement &L = getValueState(LHS);
if (L.isUnknownOrUndef())
return; // Wait to resolve.
ConstantRange LR = L.asConstantRange(Ty, /*UndefAllowed=*/false);

const ValueLatticeElement &R = getValueState(RHS);
if (R.isUnknownOrUndef())
return; // Wait to resolve.

ConstantRange RR = R.asConstantRange(Ty, /*UndefAllowed=*/false);
if (Idx == 0) {
ConstantRange Res = LR.binaryOp(WO->getBinaryOp(), RR);
mergeInValue(&EVI, ValueLatticeElement::getRange(Res));
mergeInValue(ValueState[&EVI], &EVI, ValueLatticeElement::getRange(Res));
} else {
assert(Idx == 1 && "Index can only be 0 or 1");
ConstantRange NWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
Expand Down Expand Up @@ -1560,7 +1556,7 @@ void SCCPInstVisitor::visitExtractValueInst(ExtractValueInst &EVI) {
if (auto *WO = dyn_cast<WithOverflowInst>(AggVal))
return handleExtractOfWithOverflow(EVI, WO, i);
ValueLatticeElement EltVal = getStructValueState(AggVal, i);
mergeInValue(getValueState(&EVI), &EVI, EltVal);
mergeInValue(ValueState[&EVI], &EVI, EltVal);
} else {
// Otherwise, must be extracting from an array.
return (void)markOverdefined(&EVI);
Expand Down Expand Up @@ -1616,14 +1612,18 @@ void SCCPInstVisitor::visitSelectInst(SelectInst &I) {
if (ValueState[&I].isOverdefined())
return (void)markOverdefined(&I);

ValueLatticeElement CondValue = getValueState(I.getCondition());
const ValueLatticeElement &CondValue = getValueState(I.getCondition());
if (CondValue.isUnknownOrUndef())
return;

if (ConstantInt *CondCB =
getConstantInt(CondValue, I.getCondition()->getType())) {
Value *OpVal = CondCB->isZero() ? I.getFalseValue() : I.getTrueValue();
mergeInValue(&I, getValueState(OpVal));
const ValueLatticeElement &OpValState = getValueState(OpVal);
// Safety: ValueState[&I] doesn't invalidate OpValState since it is already
// in the map.
assert(ValueState.contains(&I) && "&I is not in ValueState map.");
mergeInValue(ValueState[&I], &I, OpValState);
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@nikic nikic Oct 17, 2025

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It's unfortunate that ValueState.at(&I) returns a const reference, otherwise we could use that to assert existence.

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@dtcxzyw dtcxzyw Oct 18, 2025

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I added an assertion here.

return;
}

Expand Down Expand Up @@ -1721,7 +1721,7 @@ void SCCPInstVisitor::visitBinaryOperator(Instruction &I) {
// being a special floating value.
ValueLatticeElement NewV;
NewV.markConstant(C, /*MayIncludeUndef=*/true);
return (void)mergeInValue(&I, NewV);
return (void)mergeInValue(ValueState[&I], &I, NewV);
}
}

Expand All @@ -1741,7 +1741,7 @@ void SCCPInstVisitor::visitBinaryOperator(Instruction &I) {
R = A.overflowingBinaryOp(BO->getOpcode(), B, OBO->getNoWrapKind());
else
R = A.binaryOp(BO->getOpcode(), B);
mergeInValue(&I, ValueLatticeElement::getRange(R));
mergeInValue(ValueState[&I], &I, ValueLatticeElement::getRange(R));

// TODO: Currently we do not exploit special values that produce something
// better than overdefined with an overdefined operand for vector or floating
Expand All @@ -1767,7 +1767,7 @@ void SCCPInstVisitor::visitCmpInst(CmpInst &I) {
if (C) {
ValueLatticeElement CV;
CV.markConstant(C);
mergeInValue(&I, CV);
mergeInValue(ValueState[&I], &I, CV);
return;
}

Expand Down Expand Up @@ -1802,7 +1802,7 @@ void SCCPInstVisitor::visitGetElementPtrInst(GetElementPtrInst &I) {
Operands.reserve(I.getNumOperands());

for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
ValueLatticeElement State = getValueState(I.getOperand(i));
const ValueLatticeElement &State = getValueState(I.getOperand(i));
if (State.isUnknownOrUndef())
return; // Operands are not resolved yet.

Expand Down Expand Up @@ -1881,14 +1881,13 @@ void SCCPInstVisitor::visitLoadInst(LoadInst &I) {
if (ValueState[&I].isOverdefined())
return (void)markOverdefined(&I);

ValueLatticeElement PtrVal = getValueState(I.getOperand(0));
const ValueLatticeElement &PtrVal = getValueState(I.getOperand(0));
if (PtrVal.isUnknownOrUndef())
return; // The pointer is not resolved yet!

ValueLatticeElement &IV = ValueState[&I];

if (SCCPSolver::isConstant(PtrVal)) {
Constant *Ptr = getConstant(PtrVal, I.getOperand(0)->getType());
ValueLatticeElement &IV = ValueState[&I];

// load null is undefined.
if (isa<ConstantPointerNull>(Ptr)) {
Expand Down Expand Up @@ -1916,7 +1915,7 @@ void SCCPInstVisitor::visitLoadInst(LoadInst &I) {
}

// Fall back to metadata.
mergeInValue(&I, getValueFromMetadata(&I));
mergeInValue(ValueState[&I], &I, getValueFromMetadata(&I));
}

void SCCPInstVisitor::visitCallBase(CallBase &CB) {
Expand Down Expand Up @@ -1944,7 +1943,7 @@ void SCCPInstVisitor::handleCallOverdefined(CallBase &CB) {
return markOverdefined(&CB); // Can't handle struct args.
if (A.get()->getType()->isMetadataTy())
continue; // Carried in CB, not allowed in Operands.
ValueLatticeElement State = getValueState(A);
const ValueLatticeElement &State = getValueState(A);

if (State.isUnknownOrUndef())
return; // Operands are not resolved yet.
Expand All @@ -1964,7 +1963,7 @@ void SCCPInstVisitor::handleCallOverdefined(CallBase &CB) {
}

// Fall back to metadata.
mergeInValue(&CB, getValueFromMetadata(&CB));
mergeInValue(ValueState[&CB], &CB, getValueFromMetadata(&CB));
}

void SCCPInstVisitor::handleCallArguments(CallBase &CB) {
Expand Down Expand Up @@ -1992,10 +1991,11 @@ void SCCPInstVisitor::handleCallArguments(CallBase &CB) {
mergeInValue(getStructValueState(&*AI, i), &*AI, CallArg,
getMaxWidenStepsOpts());
}
} else
mergeInValue(&*AI,
getValueState(*CAI).intersect(getArgAttributeVL(&*AI)),
getMaxWidenStepsOpts());
} else {
ValueLatticeElement CallArg =
getValueState(*CAI).intersect(getArgAttributeVL(&*AI));
mergeInValue(ValueState[&*AI], &*AI, CallArg, getMaxWidenStepsOpts());
}
}
}
}
Expand Down Expand Up @@ -2076,7 +2076,8 @@ void SCCPInstVisitor::handleCallResult(CallBase &CB) {
if (II->getIntrinsicID() == Intrinsic::vscale) {
unsigned BitWidth = CB.getType()->getScalarSizeInBits();
const ConstantRange Result = getVScaleRange(II->getFunction(), BitWidth);
return (void)mergeInValue(II, ValueLatticeElement::getRange(Result));
return (void)mergeInValue(ValueState[II], II,
ValueLatticeElement::getRange(Result));
}

if (ConstantRange::isIntrinsicSupported(II->getIntrinsicID())) {
Expand All @@ -2094,7 +2095,8 @@ void SCCPInstVisitor::handleCallResult(CallBase &CB) {

ConstantRange Result =
ConstantRange::intrinsic(II->getIntrinsicID(), OpRanges);
return (void)mergeInValue(II, ValueLatticeElement::getRange(Result));
return (void)mergeInValue(ValueState[II], II,
ValueLatticeElement::getRange(Result));
}
}

Expand All @@ -2121,7 +2123,7 @@ void SCCPInstVisitor::handleCallResult(CallBase &CB) {
return handleCallOverdefined(CB); // Not tracking this callee.

// If so, propagate the return value of the callee into this call result.
mergeInValue(&CB, TFRVI->second, getMaxWidenStepsOpts());
mergeInValue(ValueState[&CB], &CB, TFRVI->second, getMaxWidenStepsOpts());
}
}

Expand Down