CanSILFunctionType
FunctionSignatureTransformDescriptor::createOptimizedSILFunctionType() {
SILFunction *F = OriginalFunction;
CanSILFunctionType FTy = F->getLoweredFunctionType();
auto ExpectedFTy = F->getLoweredType().castTo<SILFunctionType>();
auto HasGenericSignature = FTy->getGenericSignature() != nullptr;
// The only way that we modify the arity of function parameters is here for
// dead arguments. Doing anything else is unsafe since by definition non-dead
// arguments will have SSA uses in the function. We would need to be smarter
// in our moving to handle such cases.
llvm::SmallVector<SILParameterInfo, 8> InterfaceParams;
for (auto &ArgDesc : ArgumentDescList) {
computeOptimizedArgInterface(ArgDesc, InterfaceParams);
}
// ResultDescs only covers the direct results; we currently can't ever
// change an indirect result. Piece the modified direct result information
// back into the all-results list.
llvm::SmallVector<SILResultInfo, 8> InterfaceResults;
for (SILResultInfo InterfaceResult : FTy->getResults()) {
if (InterfaceResult.isFormalDirect()) {
auto &RV = ResultDescList[0];
if (!RV.CalleeRetain.empty()) {
++NumOwnedConvertedToNotOwnedResult;
InterfaceResults.push_back(SILResultInfo(InterfaceResult.getType(),
ResultConvention::Unowned));
continue;
}
}
InterfaceResults.push_back(InterfaceResult);
}
llvm::SmallVector<SILYieldInfo, 8> InterfaceYields;
for (SILYieldInfo InterfaceYield : FTy->getYields()) {
// For now, don't touch the yield types.
InterfaceYields.push_back(InterfaceYield);
}
bool UsesGenerics = false;
if (HasGenericSignature) {
// Not all of the generic type parameters are used by the function
// parameters.
// Check which of the generic type parameters are not used and check if they
// are used anywhere in the function body. If this is not the case, we can
// remove the unused generic type parameters from the generic signature.
// This makes the code both smaller and faster, because no implicit
// parameters for type metadata and conformances need to be passed to the
// callee at the LLVM IR level.
// TODO: Implement a more precise analysis, so that we can eliminate only
// those generic parameters which are not used.
UsesGenerics = usesGenerics(F, InterfaceParams, InterfaceResults);
// The set of used archetypes is complete now.
if (!UsesGenerics) {
// None of the generic type parameters are used.
LLVM_DEBUG(llvm::dbgs() << "None of generic parameters are used by "
<< F->getName() << "\n";
llvm::dbgs() << "Interface params:\n";
for (auto Param : InterfaceParams) {
Param.getType().dump();
}
llvm::dbgs() << "Interface results:\n";
for (auto Result : InterfaceResults) {
Result.getType().dump();
});
}
void FunctionSignatureTransform::createFunctionSignatureOptimizedFunction() {
// Create the optimized function !
SILModule &M = F->getModule();
std::string Name = createOptimizedSILFunctionName();
SILLinkage linkage = F->getLinkage();
if (isAvailableExternally(linkage))
linkage = SILLinkage::Shared;
DEBUG(llvm::dbgs() << " -> create specialized function " << Name << "\n");
NewF = M.createFunction(linkage, Name, createOptimizedSILFunctionType(),
F->getGenericEnvironment(), F->getLocation(),
F->isBare(), F->isTransparent(), F->isSerialized(),
F->isThunk(), F->getClassVisibility(),
F->getInlineStrategy(), F->getEffectsKind(), nullptr,
F->getDebugScope());
if (F->hasUnqualifiedOwnership()) {
NewF->setUnqualifiedOwnership();
}
// Then we transfer the body of F to NewF.
NewF->spliceBody(F);
// Array semantic clients rely on the signature being as in the original
// version.
for (auto &Attr : F->getSemanticsAttrs()) {
if (!StringRef(Attr).startswith("array."))
NewF->addSemanticsAttr(Attr);
}
// Do the last bit of work to the newly created optimized function.
ArgumentExplosionFinalizeOptimizedFunction();
DeadArgumentFinalizeOptimizedFunction();
// Create the thunk body !
F->setThunk(IsThunk);
// The thunk now carries the information on how the signature is
// optimized. If we inline the thunk, we will get the benefit of calling
// the signature optimized function without additional setup on the
// caller side.
F->setInlineStrategy(AlwaysInline);
SILBasicBlock *ThunkBody = F->createBasicBlock();
for (auto &ArgDesc : ArgumentDescList) {
ThunkBody->createFunctionArgument(ArgDesc.Arg->getType(), ArgDesc.Decl);
}
SILLocation Loc = ThunkBody->getParent()->getLocation();
SILBuilder Builder(ThunkBody);
Builder.setCurrentDebugScope(ThunkBody->getParent()->getDebugScope());
FunctionRefInst *FRI = Builder.createFunctionRef(Loc, NewF);
// Create the args for the thunk's apply, ignoring any dead arguments.
llvm::SmallVector<SILValue, 8> ThunkArgs;
for (auto &ArgDesc : ArgumentDescList) {
addThunkArgument(ArgDesc, Builder, ThunkBody, ThunkArgs);
}
// We are ignoring generic functions and functions with out parameters for
// now.
SILValue ReturnValue;
SILType LoweredType = NewF->getLoweredType();
SILType ResultType = NewF->getConventions().getSILResultType();
auto FunctionTy = LoweredType.castTo<SILFunctionType>();
if (FunctionTy->hasErrorResult()) {
// We need a try_apply to call a function with an error result.
SILFunction *Thunk = ThunkBody->getParent();
SILBasicBlock *NormalBlock = Thunk->createBasicBlock();
ReturnValue =
NormalBlock->createPHIArgument(ResultType, ValueOwnershipKind::Owned);
SILBasicBlock *ErrorBlock = Thunk->createBasicBlock();
SILType Error =
SILType::getPrimitiveObjectType(FunctionTy->getErrorResult().getType());
auto *ErrorArg =
ErrorBlock->createPHIArgument(Error, ValueOwnershipKind::Owned);
Builder.createTryApply(Loc, FRI, LoweredType, SubstitutionList(),
ThunkArgs, NormalBlock, ErrorBlock);
Builder.setInsertionPoint(ErrorBlock);
Builder.createThrow(Loc, ErrorArg);
Builder.setInsertionPoint(NormalBlock);
} else {
ReturnValue = Builder.createApply(Loc, FRI, LoweredType, ResultType,
SubstitutionList(), ThunkArgs,
false);
}
// Set up the return results.
if (NewF->isNoReturnFunction()) {
Builder.createUnreachable(Loc);
} else {
Builder.createReturn(Loc, ReturnValue);
}
// Do the last bit work to finalize the thunk.
OwnedToGuaranteedFinalizeThunkFunction(Builder, F);
assert(F->getDebugScope()->Parent != NewF->getDebugScope()->Parent);
}