void BlockState::processWrite(RLEContext &Ctx, SILInstruction *I, SILValue Mem,
SILValue Val, RLEKind Kind) {
// Initialize the LSLocation.
LSLocation L(Mem);
// If we cant figure out the Base or Projection Path for the write,
// process it as an unknown memory instruction.
if (!L.isValid()) {
// we can ignore unknown store instructions if we are computing the
// AvailSetMax.
if (!isComputeAvailSetMax(Kind)) {
processUnknownWriteInst(Ctx, I, Kind);
}
return;
}
// Expand the given location and val into individual fields and process
// them as separate writes.
LSLocationList Locs;
LSLocation::expand(L, &I->getModule(), Locs, Ctx.getTE());
if (isComputeAvailSetMax(Kind)) {
for (unsigned i = 0; i < Locs.size(); ++i) {
updateMaxAvailForwardSetForWrite(Ctx, Ctx.getLocationBit(Locs[i]));
}
return;
}
// Are we computing the genset and killset ?
if (isComputeAvailGenKillSet(Kind)) {
for (unsigned i = 0; i < Locs.size(); ++i) {
updateGenKillSetForWrite(Ctx, Ctx.getLocationBit(Locs[i]));
}
return;
}
// Are we computing available set ?
if (isComputeAvailSet(Kind)) {
for (unsigned i = 0; i < Locs.size(); ++i) {
updateForwardSetForWrite(Ctx, Ctx.getLocationBit(Locs[i]));
}
return;
}
// Are we computing available value or performing RLE?
if (isComputeAvailValue(Kind) || isPerformingRLE(Kind)) {
LSValueList Vals;
LSValue::expand(Val, &I->getModule(), Vals, Ctx.getTE());
for (unsigned i = 0; i < Locs.size(); ++i) {
updateForwardSetAndValForWrite(Ctx, Ctx.getLocationBit(Locs[i]),
Ctx.getValueBit(Vals[i]));
}
return;
}
llvm_unreachable("Unknown RLE compute kind");
}
void BlockState::processRead(RLEContext &Ctx, SILInstruction *I, SILValue Mem,
SILValue Val, RLEKind Kind) {
// Initialize the LSLocation.
LSLocation L(Mem);
// If we cant figure out the Base or Projection Path for the read, simply
// ignore it for now.
if (!L.isValid())
return;
// Expand the given LSLocation and Val into individual fields and process
// them as separate reads.
LSLocationList Locs;
LSLocation::expand(L, &I->getModule(), Locs, Ctx.getTE());
// Are we computing available set ?.
if (isComputeAvailSet(Kind)) {
for (auto &X : Locs) {
if (isTrackingLSLocation(Ctx.getLSLocationBit(X)))
continue;
updateForwardSetForRead(Ctx, Ctx.getLSLocationBit(X));
}
return;
}
// Are we computing available values ?.
bool CanForward = true;
if (isComputeAvailValue(Kind) || isPerformRLE(Kind)) {
LSValueList Vals;
LSValue::expand(Val, &I->getModule(), Vals, Ctx.getTE());
for (unsigned i = 0; i < Locs.size(); ++i) {
if (isTrackingLSLocation(Ctx.getLSLocationBit(Locs[i])))
continue;
updateForwardValForRead(Ctx, Ctx.getLSLocationBit(Locs[i]),
Ctx.getLSValueBit(Vals[i]));
CanForward = false;
}
}
// Simply return if we are not performing RLE or we do not have all the
// values available to perform RLE.
if (!isPerformRLE(Kind) || !CanForward)
return;
// Lastly, forward value to the load.
setupRLE(Ctx, I, Mem);
}
SILValue BlockState::reduceValuesAtEndOfBlock(RLEContext &Ctx, LSLocation &L) {
// First, collect current available locations and their corresponding values
// into a map.
LSLocationValueMap Values;
LSLocationList Locs;
LSLocation::expand(L, &BB->getModule(), Locs, Ctx.getTE());
// Find the values that this basic block defines and the locations which
// we do not have a concrete value in the current basic block.
ValueTableMap &OTM = getForwardValOut();
for (unsigned i = 0; i < Locs.size(); ++i) {
Values[Locs[i]] = Ctx.getLSValue(OTM[Ctx.getLSLocationBit(Locs[i])]);
}
// Second, reduce the available values into a single SILValue we can use to
// forward.
SILValue TheForwardingValue;
TheForwardingValue = LSValue::reduce(L, &BB->getModule(), Values,
BB->getTerminator(), Ctx.getTE());
/// Return the forwarding value.
return TheForwardingValue;
}
bool BlockState::setupRLE(RLEContext &Ctx, SILInstruction *I, SILValue Mem) {
// Try to construct a SILValue for the current LSLocation.
//
// Collect the locations and their corresponding values into a map.
LSLocation L(Mem);
LSLocationValueMap Values;
// Use the ForwardValIn as we are currently processing the basic block.
if (!Ctx.gatherLocationValues(I->getParent(), L, Values, getForwardValIn()))
return false;
// Reduce the available values into a single SILValue we can use to forward.
SILModule *Mod = &I->getModule();
SILValue TheForwardingValue;
TheForwardingValue = LSValue::reduce(L, Mod, Values, I, Ctx.getTE());
if (!TheForwardingValue)
return false;
// Now we have the forwarding value, record it for forwarding!.
//
// NOTE: we do not perform the RLE right here because doing so could introduce
// new LSLocations.
//
// e.g.
// %0 = load %x
// %1 = load %x
// %2 = extract_struct %1, #a
// %3 = load %2
//
// If we perform the RLE and replace %1 with %0, we end up having a memory
// location we do not have before, i.e. Base == %0, and Path == #a.
//
// We may be able to add the LSLocation to the vault, but it gets
// complicated very quickly, e.g. we need to resize the bit vectors size,
// etc.
//
// However, since we already know the instruction to replace and the value to
// replace it with, we can record it for now and forwarded it after all the
// forwardable values are recorded in the function.
//
RedundantLoads[I] = TheForwardingValue;
return true;
}
BlockState::ValueState BlockState::getValueStateAtEndOfBlock(RLEContext &Ctx,
LSLocation &L) {
LSLocationList Locs;
LSLocation::expand(L, &BB->getModule(), Locs, Ctx.getTE());
// Find number of covering value and concrete values for the locations
// expanded from the given location.
unsigned CSCount = 0, CTCount = 0;
ValueTableMap &OTM = getForwardValOut();
for (auto &X : Locs) {
LSValue &V = Ctx.getLSValue(OTM[Ctx.getLSLocationBit(X)]);
if (V.isCoveringValue()) {
++CSCount;
continue;
}
++CTCount;
}
if (CSCount == Locs.size())
return ValueState::CoverValues;
if (CTCount == Locs.size())
return ValueState::ConcreteValues;
return ValueState::CoverAndConcreteValues;
}