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[ConstraintElimination] Convert NewIndices to vector and rename (NFCI). 

The callers of getConstraint only require a list of new variables.
Update the naming and types to make this clearer.
This commit is contained in:
Florian Hahn 2022-10-05 16:25:00 +01:00
parent 203d0b0ee1
commit 9aa004a04c
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GPG Key ID: EEF712BB5E80EBBA
1 changed files with 45 additions and 44 deletions
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89
llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
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@ -137,17 +137,18 @@ public:
/// Turn a comparison of the form \p Op0 \p Pred \p Op1 into a vector of
/// constraints, using indices from the corresponding constraint system.
/// Additional indices for newly discovered values are added to \p NewIndices.
/// New variables that need to be added to the system are collected in
/// \p NewVariables.
ConstraintTy getConstraint(CmpInst::Predicate Pred, Value *Op0, Value *Op1,
DenseMap<Value *, unsigned> &NewIndices) const;
SmallVectorImpl<Value *> &NewVariables) const;
/// Turn a condition \p CmpI into a vector of constraints, using indices from
/// the corresponding constraint system. Additional indices for newly
/// discovered values are added to \p NewIndices.
/// the corresponding constraint system. New variables that need to be added
/// to the system are collected in \p NewVariables.
ConstraintTy getConstraint(CmpInst *Cmp,
DenseMap<Value *, unsigned> &NewIndices) const {
SmallVectorImpl<Value *> &NewVariables) {
return getConstraint(Cmp->getPredicate(), Cmp->getOperand(0),
Cmp->getOperand(1), NewIndices);
Cmp->getOperand(1), NewVariables);
}
/// Try to add information from \p A \p Pred \p B to the unsigned/signed
@ -289,7 +290,8 @@ decompose(Value *V, SmallVector<PreconditionTy, 4> &Preconditions,
ConstraintTy
ConstraintInfo::getConstraint(CmpInst::Predicate Pred, Value *Op0, Value *Op1,
DenseMap<Value *, unsigned> &NewIndices) const {
SmallVectorImpl<Value *> &NewVariables) const {
assert(NewVariables.empty() && "NewVariables must be empty when passed in");
bool IsEq = false;
// Try to convert Pred to one of ULE/SLT/SLE/SLT.
switch (Pred) {
@ -343,25 +345,29 @@ ConstraintInfo::getConstraint(CmpInst::Predicate Pred, Value *Op0, Value *Op1,
auto VariablesA = llvm::drop_begin(ADec);
auto VariablesB = llvm::drop_begin(BDec);
// First try to look up \p V in Value2Index and NewIndices. Otherwise add a
// new entry to NewIndices.
auto GetOrAddIndex = [&Value2Index, &NewIndices](Value *V) -> unsigned {
// First try to look up \p V in Value2Index and NewVariables. Otherwise add a
// new entry to NewVariables.
DenseMap<Value *, unsigned> NewIndexMap;
auto GetOrAddIndex = [&Value2Index, &NewVariables,
&NewIndexMap](Value *V) -> unsigned {
auto V2I = Value2Index.find(V);
if (V2I != Value2Index.end())
return V2I->second;
auto Insert =
NewIndices.insert({V, Value2Index.size() + NewIndices.size() + 1});
NewIndexMap.insert({V, Value2Index.size() + NewVariables.size() + 1});
if (Insert.second)
NewVariables.push_back(V);
return Insert.first->second;
};
// Make sure all variables have entries in Value2Index or NewIndices.
// Make sure all variables have entries in Value2Index or NewVariables.
for (const auto &KV : concat<DecompEntry>(VariablesA, VariablesB))
GetOrAddIndex(KV.Variable);
// Build result constraint, by first adding all coefficients from A and then
// subtracting all coefficients from B.
ConstraintTy Res(
SmallVector<int64_t, 8>(Value2Index.size() + NewIndices.size() + 1, 0),
SmallVector<int64_t, 8>(Value2Index.size() + NewVariables.size() + 1, 0),
IsSigned);
// Collect variables that are known to be positive in all uses in the
// constraint.
@ -389,28 +395,23 @@ ConstraintInfo::getConstraint(CmpInst::Predicate Pred, Value *Op0, Value *Op1,
R[0] = OffsetSum;
Res.Preconditions = std::move(Preconditions);
// Remove any (Coefficient, Variable) entry where the Coefficient is 0 for the
// new variables that need to be added to the system. Set NewIndexNeeded to
// true if any of the new variables has a non-zero coefficient.
bool NewIndexNeeded = false;
for (unsigned I = 0; I < NewIndices.size(); ++I) {
// Remove any (Coefficient, Variable) entry where the Coefficient is 0 for new
// variables.
while (!NewVariables.empty()) {
int64_t Last = R.back();
if (Last != 0) {
NewIndexNeeded = true;
if (Last != 0)
break;
}
R.pop_back();
Value *RemovedV = NewVariables.pop_back_val();
NewIndexMap.erase(RemovedV);
}
// All new variables had Coefficients of 0, so no new variables are needed.
if (!NewIndexNeeded)
NewIndices.clear();
// Add extra constraints for variables that are known positive.
for (auto &KV : KnownPositiveVariables) {
if (!KV.second || (Value2Index.find(KV.first) == Value2Index.end() &&
NewIndices.find(KV.first) == NewIndices.end()))
NewIndexMap.find(KV.first) == NewIndexMap.end()))
continue;
SmallVector<int64_t, 8> C(Value2Index.size() + NewIndices.size() + 1, 0);
SmallVector<int64_t, 8> C(Value2Index.size() + NewVariables.size() + 1, 0);
C[GetOrAddIndex(KV.first)] = -1;
Res.ExtraInfo.push_back(C);
}
@ -426,14 +427,13 @@ bool ConstraintTy::isValid(const ConstraintInfo &Info) const {
bool ConstraintInfo::doesHold(CmpInst::Predicate Pred, Value *A,
Value *B) const {
DenseMap<Value *, unsigned> NewIndices;
auto R = getConstraint(Pred, A, B, NewIndices);
SmallVector<Value *> NewVariables;
auto R = getConstraint(Pred, A, B, NewVariables);
if (!NewIndices.empty())
if (!NewVariables.empty())
return false;
// TODO: properly check NewIndices.
return NewIndices.empty() && R.Preconditions.empty() && !R.IsEq &&
return NewVariables.empty() && R.Preconditions.empty() && !R.IsEq &&
!R.empty() &&
getCS(CmpInst::isSigned(Pred)).isConditionImplied(R.Coefficients);
}
@ -624,8 +624,8 @@ void ConstraintInfo::addFact(CmpInst::Predicate Pred, Value *A, Value *B,
SmallVectorImpl<StackEntry> &DFSInStack) {
// If the constraint has a pre-condition, skip the constraint if it does not
// hold.
DenseMap<Value *, unsigned> NewIndices;
auto R = getConstraint(Pred, A, B, NewIndices);
SmallVector<Value *> NewVariables;
auto R = getConstraint(Pred, A, B, NewVariables);
if (!R.isValid(*this))
return;
@ -641,13 +641,14 @@ void ConstraintInfo::addFact(CmpInst::Predicate Pred, Value *A, Value *B,
Added |= CSToUse.addVariableRowFill(R.Coefficients);
// If R has been added to the system, queue it for removal once it goes
// out-of-scope.
// If R has been added to the system, add the new variables and queue it for
// removal once it goes out-of-scope.
if (Added) {
SmallVector<Value *, 2> ValuesToRelease;
for (auto &KV : NewIndices) {
getValue2Index(R.IsSigned).insert(KV);
ValuesToRelease.push_back(KV.first);
auto &Value2Index = getValue2Index(R.IsSigned);
for (Value *V : NewVariables) {
Value2Index.insert({V, Value2Index.size() + 1});
ValuesToRelease.push_back(V);
}
LLVM_DEBUG({
@ -675,9 +676,9 @@ tryToSimplifyOverflowMath(IntrinsicInst *II, ConstraintInfo &Info,
SmallVectorImpl<Instruction *> &ToRemove) {
auto DoesConditionHold = [](CmpInst::Predicate Pred, Value *A, Value *B,
ConstraintInfo &Info) {
DenseMap<Value *, unsigned> NewIndices;
auto R = Info.getConstraint(Pred, A, B, NewIndices);
if (R.size() < 2 || !NewIndices.empty() || !R.isValid(Info))
SmallVector<Value *> NewVariables;
auto R = Info.getConstraint(Pred, A, B, NewVariables);
if (R.size() < 2 || !NewVariables.empty() || !R.isValid(Info))
return false;
auto &CSToUse = Info.getCS(CmpInst::isSigned(Pred));
@ -801,9 +802,9 @@ static bool eliminateConstraints(Function &F, DominatorTree &DT) {
continue;
LLVM_DEBUG(dbgs() << "Checking " << *Cmp << "\n");
DenseMap<Value *, unsigned> NewIndices;
auto R = Info.getConstraint(Cmp, NewIndices);
if (R.IsEq || R.empty() || !NewIndices.empty() || !R.isValid(Info))
SmallVector<Value *> NewVariables;
auto R = Info.getConstraint(Cmp, NewVariables);
if (R.IsEq || R.empty() || !NewVariables.empty() || !R.isValid(Info))
continue;
auto &CSToUse = Info.getCS(R.IsSigned);