void MemLocation::reduce(MemLocation &Base, SILModule *Mod,
MemLocationSet &Locs) {
// First, construct the MemLocation by appending the projection path from the
// accessed node to the leaf nodes.
MemLocationList ALocs;
ProjectionPathList Paths;
ProjectionPath::expandTypeIntoLeafProjectionPaths(Base.getType(), Mod, Paths,
false);
for (auto &X : Paths) {
ALocs.push_back(MemLocation::createMemLocation(Base.getBase(), X.getValue(),
Base.getPath().getValue()));
}
// Second, go from leaf nodes to their parents. This guarantees that at the
// point the parent is processed, its children have been processed already.
for (auto I = ALocs.rbegin(), E = ALocs.rend(); I != E; ++I) {
MemLocationList FirstLevel;
I->getFirstLevelMemLocations(FirstLevel, Mod);
// Reached the end of the projection tree, this is a leaf node.
if (FirstLevel.empty())
continue;
// If this is a class reference type, we have reached end of the type tree.
if (I->getType().getClassOrBoundGenericClass())
continue;
// This is NOT a leaf node, check whether all its first level children are
// alive.
bool Alive = true;
for (auto &X : FirstLevel) {
if (Locs.find(X) != Locs.end())
continue;
Alive = false;
}
// All first level locations are alive, create the new aggregated location.
if (Alive) {
for (auto &X : FirstLevel)
Locs.erase(X);
Locs.insert(*I);
}
}
}
SILValue MemLocation::reduceWithValues(MemLocation &Base, SILModule *Mod,
MemLocationValueMap &Values,
SILInstruction *InsertPt) {
// Walk bottom up the projection tree, try to reason about how to construct
// a single SILValue out of all the available values for all the memory
// locations.
//
// First, get a list of all the leaf nodes and intermediate nodes for the
// Base memory location.
MemLocationList ALocs;
ProjectionPathList Paths;
ProjectionPath::expandTypeIntoLeafProjectionPaths(Base.getType(), Mod, Paths,
false);
for (auto &X : Paths) {
ALocs.push_back(MemLocation::createMemLocation(Base.getBase(), X.getValue(),
Base.getPath().getValue()));
}
// Second, go from leaf nodes to their parents. This guarantees that at the
// point the parent is processed, its children have been processed already.
for (auto I = ALocs.rbegin(), E = ALocs.rend(); I != E; ++I) {
// This is a leaf node, we have a value for it.
//
// Reached the end of the projection tree, this is a leaf node.
MemLocationList FirstLevel;
I->getFirstLevelMemLocations(FirstLevel, Mod);
if (FirstLevel.empty())
continue;
// If this is a class reference type, we have reached end of the type tree.
if (I->getType().getClassOrBoundGenericClass())
continue;
// This is NOT a leaf node, we need to construct a value for it.
//
// If there are more than 1 children and all the children nodes have
// LoadStoreValues with the same base. we can get away by not extracting
// value
// for every single field.
//
// Simply create a new node with all the aggregated base value, i.e.
// stripping off the last level projection.
//
bool HasIdenticalValueBase = true;
auto Iter = FirstLevel.begin();
LoadStoreValue &FirstVal = Values[*Iter];
SILValue FirstBase = FirstVal.getBase();
Iter = std::next(Iter);
for (auto EndIter = FirstLevel.end(); Iter != EndIter; ++Iter) {
LoadStoreValue &V = Values[*Iter];
HasIdenticalValueBase &= (FirstBase == V.getBase());
}
if (HasIdenticalValueBase &&
(FirstLevel.size() > 1 || !FirstVal.hasEmptyProjectionPath())) {
Values[*I] = FirstVal.stripLastLevelProjection();
// We have a value for the parent, remove all the values for children.
removeMemLocations(Values, FirstLevel);
continue;
}
// In 2 cases do we need aggregation.
//
// 1. If there is only 1 child and we can not strip off any projections,
// that means we need to create an aggregation.
//
// 2. Children have values from different bases, We need to create
// extractions and aggregation in this case.
//
llvm::SmallVector<SILValue, 8> Vals;
for (auto &X : FirstLevel) {
Vals.push_back(Values[X].materialize(InsertPt));
}
SILBuilder Builder(InsertPt);
NullablePtr<swift::SILInstruction> AI =
Projection::createAggFromFirstLevelProjections(
Builder, InsertPt->getLoc(), I->getType(), Vals);
// This is the Value for the current node.
ProjectionPath P;
Values[*I] = LoadStoreValue(SILValue(AI.get()), P);
removeMemLocations(Values, FirstLevel);
// Keep iterating until we have reach the top-most level of the projection
// tree.
// i.e. the memory location represented by the Base.
}
assert(Values.size() == 1 && "Should have a single location this point");
// Finally materialize and return the forwarding SILValue.
return Values.begin()->second.materialize(InsertPt);
}
