unsigned ArgumentDescriptor::updateOptimizedBBArgs(SILBuilder &Builder,
SILBasicBlock *BB,
unsigned ArgOffset) {
// If this argument is completely dead, delete this argument and return
// ArgOffset.
if (IsDead) {
// If we have a callee release and we are dead, set the callee release's
// operand to undef. We do not need it to have the argument anymore, but we
// do need the instruction to be non-null.
//
// TODO: This should not be necessary.
if (CalleeRelease) {
SILType CalleeReleaseTy = CalleeRelease->getOperand(0).getType();
CalleeRelease->setOperand(
0, SILUndef::get(CalleeReleaseTy, Builder.getModule()));
// TODO: Currently we cannot mark arguments as dead if they are released
// in a throw block. But as soon as we can do this, we have to handle
// CalleeReleaseInThrowBlock as well.
assert(!CalleeReleaseInThrowBlock &&
"released arg in throw block cannot be dead");
}
// We should be able to recursively delete all of the remaining
// instructions.
SILArgument *Arg = BB->getBBArg(ArgOffset);
eraseUsesOfValue(Arg);
BB->eraseBBArg(ArgOffset);
return ArgOffset;
}
// If this argument is not dead and we did not perform SROA, increment the
// offset and return.
if (!shouldExplode()) {
return ArgOffset + 1;
}
// Create values for the leaf types.
llvm::SmallVector<SILValue, 8> LeafValues;
// Create a reference to the old arg offset and increment arg offset so we can
// create the new arguments.
unsigned OldArgOffset = ArgOffset++;
// We do this in the same order as leaf types since ProjTree expects that the
// order of leaf values matches the order of leaf types.
{
llvm::SmallVector<SILType, 8> LeafTypes;
ProjTree.getLeafTypes(LeafTypes);
for (auto Ty : LeafTypes) {
LeafValues.push_back(BB->insertBBArg(
ArgOffset++, Ty, BB->getBBArg(OldArgOffset)->getDecl()));
}
}
// Then go through the projection tree constructing aggregates and replacing
// uses.
//
// TODO: What is the right location to use here?
ProjTree.replaceValueUsesWithLeafUses(Builder, BB->getParent()->getLocation(),
LeafValues);
// Replace all uses of the original arg with undef so it does not have any
// uses.
SILValue OrigArg = SILValue(BB->getBBArg(OldArgOffset));
OrigArg.replaceAllUsesWith(SILUndef::get(OrigArg.getType(), BB->getModule()));
// Now erase the old argument since it does not have any uses. We also
// decrement ArgOffset since we have one less argument now.
BB->eraseBBArg(OldArgOffset);
--ArgOffset;
return ArgOffset;
}
