static void getWitnessMethodSubstitutions(ApplySite AI, SILFunction *F,
ArrayRef<Substitution> Subs,
SmallVectorImpl<Substitution> &NewSubs) {
auto &Module = AI.getModule();
auto CalleeCanType = F->getLoweredFunctionType();
ProtocolDecl *proto = nullptr;
if (CalleeCanType->getRepresentation() ==
SILFunctionTypeRepresentation::WitnessMethod) {
proto = CalleeCanType->getDefaultWitnessMethodProtocol(
*Module.getSwiftModule());
}
ArrayRef<Substitution> origSubs = AI.getSubstitutions();
if (proto != nullptr) {
// If the callee is a default witness method thunk, preserve substitutions
// from the call site.
NewSubs.append(origSubs.begin(), origSubs.end());
return;
}
// If the callee is a concrete witness method thunk, apply substitutions
// from the conformance, and drop any substitutions derived from the Self
// type.
NewSubs.append(Subs.begin(), Subs.end());
if (auto generics = AI.getOrigCalleeType()->getGenericSignature()) {
for (auto genericParam : generics->getAllDependentTypes()) {
auto origSub = origSubs.front();
origSubs = origSubs.slice(1);
// If the callee is a concrete witness method thunk, we ignore
// generic parameters derived from 'self', the generic parameter at
// depth 0, index 0.
auto type = genericParam->getCanonicalType();
while (auto memberType = dyn_cast<DependentMemberType>(type)) {
type = memberType.getBase();
}
auto paramType = cast<GenericTypeParamType>(type);
if (paramType->getDepth() == 0) {
// There shouldn't be any other parameters at this depth.
assert(paramType->getIndex() == 0);
continue;
}
// Okay, remember this substitution.
NewSubs.push_back(origSub);
}
}
assert(origSubs.empty() && "subs not parallel to dependent types");
}
static void getWitnessMethodSubstitutions(ApplySite AI, SILFunction *F,
ProtocolConformanceRef CRef,
SmallVectorImpl<Substitution> &NewSubs) {
auto &Module = AI.getModule();
auto requirementSig = AI.getOrigCalleeType()->getGenericSignature();
auto witnessThunkSig = F->getLoweredFunctionType()->getGenericSignature();
SubstitutionList origSubs = AI.getSubstitutions();
bool isDefaultWitness =
F->getLoweredFunctionType()->getRepresentation()
== SILFunctionTypeRepresentation::WitnessMethod &&
F->getLoweredFunctionType()->getDefaultWitnessMethodProtocol(
*Module.getSwiftModule())
== CRef.getRequirement();
getWitnessMethodSubstitutions(Module, CRef, requirementSig, witnessThunkSig,
origSubs, isDefaultWitness, NewSubs);
}
/// Generate a new apply of a function_ref to replace an apply of a
/// witness_method when we've determined the actual function we'll end
/// up calling.
static ApplySite devirtualizeWitnessMethod(ApplySite AI, SILFunction *F,
ArrayRef<Substitution> Subs) {
// We know the witness thunk and the corresponding set of substitutions
// required to invoke the protocol method at this point.
auto &Module = AI.getModule();
// Collect all the required substitutions.
//
// The complete set of substitutions may be different, e.g. because the found
// witness thunk F may have been created by a specialization pass and have
// additional generic parameters.
SmallVector<Substitution, 16> NewSubstList(Subs.begin(), Subs.end());
if (auto generics = AI.getOrigCalleeType()->getGenericSignature()) {
ArrayRef<Substitution> origSubs = AI.getSubstitutions();
for (auto genericParam : generics->getAllDependentTypes()) {
auto origSub = origSubs.front();
origSubs = origSubs.slice(1);
// Ignore generic parameters derived from 'self', the generic
// parameter at depth 0, index 0.
auto type = genericParam->getCanonicalType();
while (auto memberType = dyn_cast<DependentMemberType>(type)) {
type = memberType.getBase();
}
auto paramType = cast<GenericTypeParamType>(type);
if (paramType->getDepth() == 0) {
// There shouldn't be any other parameters at this depth.
assert(paramType->getIndex() == 0);
continue;
}
// Okay, remember this substitution.
NewSubstList.push_back(origSub);
}
assert(origSubs.empty() && "subs not parallel to dependent types");
}
// Figure out the exact bound type of the function to be called by
// applying all substitutions.
auto CalleeCanType = F->getLoweredFunctionType();
auto SubstCalleeCanType = CalleeCanType->substGenericArgs(
Module, Module.getSwiftModule(), NewSubstList);
// Collect arguments from the apply instruction.
auto Arguments = SmallVector<SILValue, 4>();
// Iterate over the non self arguments and add them to the
// new argument list, upcasting when required.
SILBuilderWithScope B(AI.getInstruction());
for (unsigned ArgN = 0, ArgE = AI.getNumArguments(); ArgN != ArgE; ++ArgN) {
SILValue A = AI.getArgument(ArgN);
auto ParamType = SubstCalleeCanType->getSILArgumentType(
SubstCalleeCanType->getNumSILArguments() - AI.getNumArguments() + ArgN);
if (A->getType() != ParamType)
A = B.createUpcast(AI.getLoc(), A, ParamType);
Arguments.push_back(A);
}
// Replace old apply instruction by a new apply instruction that invokes
// the witness thunk.
SILBuilderWithScope Builder(AI.getInstruction());
SILLocation Loc = AI.getLoc();
FunctionRefInst *FRI = Builder.createFunctionRef(Loc, F);
auto SubstCalleeSILType = SILType::getPrimitiveObjectType(SubstCalleeCanType);
auto ResultSILType = SubstCalleeCanType->getSILResult();
ApplySite SAI;
if (auto *A = dyn_cast<ApplyInst>(AI))
SAI = Builder.createApply(Loc, FRI, SubstCalleeSILType,
ResultSILType, NewSubstList, Arguments,
A->isNonThrowing());
if (auto *TAI = dyn_cast<TryApplyInst>(AI))
SAI = Builder.createTryApply(Loc, FRI, SubstCalleeSILType,
NewSubstList, Arguments,
TAI->getNormalBB(), TAI->getErrorBB());
if (auto *PAI = dyn_cast<PartialApplyInst>(AI))
SAI = Builder.createPartialApply(Loc, FRI, SubstCalleeSILType,
NewSubstList, Arguments, PAI->getType());
NumWitnessDevirt++;
return SAI;
}
