| //===--- Devirtualize.cpp - Helper for devirtualizing apply ---------------===// |
| // |
| // This source file is part of the Swift.org open source project |
| // |
| // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors |
| // Licensed under Apache License v2.0 with Runtime Library Exception |
| // |
| // See https://swift.org/LICENSE.txt for license information |
| // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "sil-devirtualize-utility" |
| #include "swift/SILOptimizer/Analysis/ClassHierarchyAnalysis.h" |
| #include "swift/SILOptimizer/Utils/Devirtualize.h" |
| #include "swift/AST/Decl.h" |
| #include "swift/AST/ProtocolConformance.h" |
| #include "swift/AST/SubstitutionMap.h" |
| #include "swift/AST/Types.h" |
| #include "swift/SIL/SILDeclRef.h" |
| #include "swift/SIL/SILFunction.h" |
| #include "swift/SIL/SILInstruction.h" |
| #include "swift/SIL/SILModule.h" |
| #include "swift/SIL/SILType.h" |
| #include "swift/SIL/SILValue.h" |
| #include "swift/SIL/InstructionUtils.h" |
| #include "swift/SILOptimizer/Utils/Local.h" |
| #include "llvm/ADT/ArrayRef.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/Support/Casting.h" |
| using namespace swift; |
| |
| STATISTIC(NumClassDevirt, "Number of class_method applies devirtualized"); |
| STATISTIC(NumWitnessDevirt, "Number of witness_method applies devirtualized"); |
| |
| //===----------------------------------------------------------------------===// |
| // Class Method Optimization |
| //===----------------------------------------------------------------------===// |
| |
| /// Compute all subclasses of a given class. |
| /// |
| /// \p CHA class hierarchy analysis |
| /// \p CD class declaration |
| /// \p ClassType type of the instance |
| /// \p M SILModule |
| /// \p Subs a container to be used for storing the set of subclasses |
| static void getAllSubclasses(ClassHierarchyAnalysis *CHA, |
| ClassDecl *CD, |
| SILType ClassType, |
| SILModule &M, |
| ClassHierarchyAnalysis::ClassList &Subs) { |
| // Collect the direct and indirect subclasses for the class. |
| // Sort these subclasses in the order they should be tested by the |
| // speculative devirtualization. Different strategies could be used, |
| // E.g. breadth-first, depth-first, etc. |
| // Currently, let's use the breadth-first strategy. |
| // The exact static type of the instance should be tested first. |
| auto &DirectSubs = CHA->getDirectSubClasses(CD); |
| auto &IndirectSubs = CHA->getIndirectSubClasses(CD); |
| |
| Subs.append(DirectSubs.begin(), DirectSubs.end()); |
| //SmallVector<ClassDecl *, 8> Subs(DirectSubs); |
| Subs.append(IndirectSubs.begin(), IndirectSubs.end()); |
| |
| if (isa<BoundGenericClassType>(ClassType.getSwiftRValueType())) { |
| // Filter out any subclasses that do not inherit from this |
| // specific bound class. |
| auto RemovedIt = std::remove_if(Subs.begin(), Subs.end(), |
| [&ClassType, &M](ClassDecl *Sub){ |
| auto SubCanTy = Sub->getDeclaredType()->getCanonicalType(); |
| // Unbound generic type can override a method from |
| // a bound generic class, but this unbound generic |
| // class is not considered to be a subclass of a |
| // bound generic class in a general case. |
| if (isa<UnboundGenericType>(SubCanTy)) |
| return false; |
| // Handle the usual case here: the class in question |
| // should be a real subclass of a bound generic class. |
| return !ClassType.isBindableToSuperclassOf( |
| SILType::getPrimitiveObjectType(SubCanTy)); |
| }); |
| Subs.erase(RemovedIt, Subs.end()); |
| } |
| } |
| |
| /// \brief Returns true, if a method implementation corresponding to |
| /// the class_method applied to an instance of the class CD is |
| /// effectively final, i.e. it is statically known to be not overridden |
| /// by any subclasses of the class CD. |
| /// |
| /// \p AI invocation instruction |
| /// \p ClassType type of the instance |
| /// \p CD static class of the instance whose method is being invoked |
| /// \p CHA class hierarchy analysis |
| bool isEffectivelyFinalMethod(FullApplySite AI, |
| SILType ClassType, |
| ClassDecl *CD, |
| ClassHierarchyAnalysis *CHA) { |
| if (CD && CD->isFinal()) |
| return true; |
| |
| const DeclContext *DC = AI.getModule().getAssociatedContext(); |
| |
| // Without an associated context we cannot perform any |
| // access-based optimizations. |
| if (!DC) |
| return false; |
| |
| auto *CMI = cast<MethodInst>(AI.getCallee()); |
| |
| if (!calleesAreStaticallyKnowable(AI.getModule(), CMI->getMember())) |
| return false; |
| |
| auto *Method = CMI->getMember().getAbstractFunctionDecl(); |
| assert(Method && "Expected abstract function decl!"); |
| assert(!Method->isFinal() && "Unexpected indirect call to final method!"); |
| |
| // If this method is not overridden in the module, |
| // there is no other implementation. |
| if (!Method->isOverridden()) |
| return true; |
| |
| // Class declaration may be nullptr, e.g. for cases like: |
| // func foo<C:Base>(c: C) {}, where C is a class, but |
| // it does not have a class decl. |
| if (!CD) |
| return false; |
| |
| if (!CHA) |
| return false; |
| |
| // This is a private or a module internal class. |
| // |
| // We can analyze the class hierarchy rooted at it and |
| // eventually devirtualize a method call more efficiently. |
| |
| ClassHierarchyAnalysis::ClassList Subs; |
| getAllSubclasses(CHA, CD, ClassType, AI.getModule(), Subs); |
| |
| // This is the implementation of the method to be used |
| // if the exact class of the instance would be CD. |
| auto *ImplMethod = CD->findImplementingMethod(Method); |
| |
| // First, analyze all direct subclasses. |
| for (auto S : Subs) { |
| // Check if the subclass overrides a method and provides |
| // a different implementation. |
| auto *ImplFD = S->findImplementingMethod(Method); |
| if (ImplFD != ImplMethod) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /// Check if a given class is final in terms of a current |
| /// compilation, i.e.: |
| /// - it is really final |
| /// - or it is private and has not sub-classes |
| /// - or it is an internal class without sub-classes and |
| /// it is a whole-module compilation. |
| static bool isKnownFinalClass(ClassDecl *CD, SILModule &M, |
| ClassHierarchyAnalysis *CHA) { |
| const DeclContext *DC = M.getAssociatedContext(); |
| |
| if (CD->isFinal()) |
| return true; |
| |
| // Without an associated context we cannot perform any |
| // access-based optimizations. |
| if (!DC) |
| return false; |
| |
| // Only handle classes defined within the SILModule's associated context. |
| if (!CD->isChildContextOf(DC)) |
| return false; |
| |
| if (!CD->hasAccessibility()) |
| return false; |
| |
| // Only consider 'private' members, unless we are in whole-module compilation. |
| switch (CD->getEffectiveAccess()) { |
| case Accessibility::Open: |
| return false; |
| case Accessibility::Public: |
| case Accessibility::Internal: |
| if (!M.isWholeModule()) |
| return false; |
| break; |
| case Accessibility::FilePrivate: |
| case Accessibility::Private: |
| break; |
| } |
| |
| // Take the ClassHierarchyAnalysis into account. |
| // If a given class has no subclasses and |
| // - private |
| // - or internal and it is a WMO compilation |
| // then this class can be considered final for the purpose |
| // of devirtualization. |
| if (CHA) { |
| if (!CHA->hasKnownDirectSubclasses(CD)) { |
| switch (CD->getEffectiveAccess()) { |
| case Accessibility::Open: |
| return false; |
| case Accessibility::Public: |
| case Accessibility::Internal: |
| if (!M.isWholeModule()) |
| return false; |
| break; |
| case Accessibility::FilePrivate: |
| case Accessibility::Private: |
| break; |
| } |
| |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| |
| // Attempt to get the instance for S, whose static type is the same as |
| // its exact dynamic type, returning a null SILValue() if we cannot find it. |
| // The information that a static type is the same as the exact dynamic, |
| // can be derived e.g.: |
| // - from a constructor or |
| // - from a successful outcome of a checked_cast_br [exact] instruction. |
| SILValue swift::getInstanceWithExactDynamicType(SILValue S, SILModule &M, |
| ClassHierarchyAnalysis *CHA) { |
| |
| while (S) { |
| S = stripCasts(S); |
| |
| if (isa<AllocRefInst>(S) || isa<MetatypeInst>(S)) { |
| if (S->getType().getSwiftRValueType()->hasDynamicSelfType()) |
| return SILValue(); |
| return S; |
| } |
| |
| auto *Arg = dyn_cast<SILArgument>(S); |
| if (!Arg) |
| break; |
| |
| auto *SinglePred = Arg->getParent()->getSinglePredecessorBlock(); |
| if (!SinglePred) { |
| if (!isa<SILFunctionArgument>(Arg)) |
| break; |
| auto *CD = Arg->getType().getClassOrBoundGenericClass(); |
| // Check if this class is effectively final. |
| if (!CD || !isKnownFinalClass(CD, M, CHA)) |
| break; |
| return Arg; |
| } |
| |
| // Traverse the chain of predecessors. |
| if (isa<BranchInst>(SinglePred->getTerminator()) || |
| isa<CondBranchInst>(SinglePred->getTerminator())) { |
| S = cast<SILPHIArgument>(Arg)->getIncomingValue(SinglePred); |
| continue; |
| } |
| |
| // If it is a BB argument received on a success branch |
| // of a checked_cast_br, then we know its exact type. |
| auto *CCBI = dyn_cast<CheckedCastBranchInst>(SinglePred->getTerminator()); |
| if (!CCBI) |
| break; |
| if (!CCBI->isExact() || CCBI->getSuccessBB() != Arg->getParent()) |
| break; |
| return S; |
| } |
| |
| return SILValue(); |
| } |
| |
| /// Try to determine the exact dynamic type of an object. |
| /// returns the exact dynamic type of the object, or an empty type if the exact |
| /// type could not be determined. |
| SILType swift::getExactDynamicType(SILValue S, SILModule &M, |
| ClassHierarchyAnalysis *CHA, |
| bool ForUnderlyingObject) { |
| // Set of values to be checked for their exact types. |
| SmallVector<SILValue, 8> WorkList; |
| // The detected type of the underlying object. |
| SILType ResultType; |
| // Set of processed values. |
| llvm::SmallSet<SILValue, 8> Processed; |
| WorkList.push_back(S); |
| |
| while (!WorkList.empty()) { |
| auto V = WorkList.pop_back_val(); |
| if (!V) |
| return SILType(); |
| if (Processed.count(V)) |
| continue; |
| Processed.insert(V); |
| // For underlying object strip casts and projections. |
| // For the object itself, simply strip casts. |
| V = ForUnderlyingObject ? getUnderlyingObject(V) : stripCasts(V); |
| |
| if (isa<AllocRefInst>(V) || isa<MetatypeInst>(V)) { |
| if (ResultType && ResultType != V->getType()) |
| return SILType(); |
| ResultType = V->getType(); |
| continue; |
| } |
| |
| if (isa<LiteralInst>(V)) { |
| if (ResultType && ResultType != V->getType()) |
| return SILType(); |
| ResultType = V->getType(); |
| continue; |
| } |
| |
| if (isa<StructInst>(V) || isa<TupleInst>(V) || isa<EnumInst>(V)) { |
| if (ResultType && ResultType != V->getType()) |
| return SILType(); |
| ResultType = V->getType(); |
| continue; |
| } |
| |
| if (ForUnderlyingObject) { |
| if (isa<AllocationInst>(V)) { |
| if (ResultType && ResultType != V->getType()) |
| return SILType(); |
| ResultType = V->getType(); |
| continue; |
| } |
| // Look through strong_pin instructions. |
| if (isa<StrongPinInst>(V)) { |
| WorkList.push_back(cast<SILInstruction>(V)->getOperand(0)); |
| continue; |
| } |
| } |
| |
| auto Arg = dyn_cast<SILArgument>(V); |
| if (!Arg) { |
| // We don't know what it is. |
| return SILType(); |
| } |
| |
| if (auto *FArg = dyn_cast<SILFunctionArgument>(Arg)) { |
| // Bail on metatypes for now. |
| if (FArg->getType().getSwiftRValueType()->is<AnyMetatypeType>()) { |
| return SILType(); |
| } |
| auto *CD = FArg->getType().getClassOrBoundGenericClass(); |
| // If it is not class and it is a trivial type, then it |
| // should be the exact type. |
| if (!CD && FArg->getType().isTrivial(M)) { |
| if (ResultType && ResultType != FArg->getType()) |
| return SILType(); |
| ResultType = FArg->getType(); |
| continue; |
| } |
| |
| if (!CD) { |
| // It is not a class or a trivial type, so we don't know what it is. |
| return SILType(); |
| } |
| |
| // Check if this class is effectively final. |
| if (!isKnownFinalClass(CD, M, CHA)) { |
| return SILType(); |
| } |
| |
| if (ResultType && ResultType != FArg->getType()) |
| return SILType(); |
| ResultType = FArg->getType(); |
| continue; |
| } |
| |
| auto *SinglePred = Arg->getParent()->getSinglePredecessorBlock(); |
| if (SinglePred) { |
| // If it is a BB argument received on a success branch |
| // of a checked_cast_br, then we know its exact type. |
| auto *CCBI = dyn_cast<CheckedCastBranchInst>(SinglePred->getTerminator()); |
| if (CCBI && CCBI->isExact() && CCBI->getSuccessBB() == Arg->getParent()) { |
| if (ResultType && ResultType != Arg->getType()) |
| return SILType(); |
| ResultType = Arg->getType(); |
| continue; |
| } |
| } |
| |
| // It is a BB argument, look through incoming values. If they all have the |
| // same exact type, then we consider it to be the type of the BB argument. |
| SmallVector<SILValue, 4> IncomingValues; |
| |
| if (Arg->getIncomingValues(IncomingValues)) { |
| for (auto InValue : IncomingValues) { |
| WorkList.push_back(InValue); |
| } |
| continue; |
| } |
| |
| // The exact type is unknown. |
| return SILType(); |
| } |
| |
| return ResultType; |
| } |
| |
| |
| /// Try to determine the exact dynamic type of the underlying object. |
| /// returns the exact dynamic type of a value, or an empty type if the exact |
| /// type could not be determined. |
| SILType |
| swift::getExactDynamicTypeOfUnderlyingObject(SILValue S, SILModule &M, |
| ClassHierarchyAnalysis *CHA) { |
| return getExactDynamicType(S, M, CHA, /* ForUnderlyingObject */ true); |
| } |
| |
| // Start with the substitutions from the apply. |
| // Try to propagate them to find out the real substitutions required |
| // to invoke the method. |
| static void |
| getSubstitutionsForCallee(SILModule &M, |
| CanSILFunctionType baseCalleeType, |
| CanType derivedSelfType, |
| FullApplySite AI, |
| SmallVectorImpl<Substitution> &newSubs) { |
| |
| // If the base method is not polymorphic, no substitutions are required, |
| // even if we originally had substitutions for calling the derived method. |
| if (!baseCalleeType->isPolymorphic()) |
| return; |
| |
| // Add any generic substitutions for the base class. |
| Type baseSelfType = baseCalleeType->getSelfParameter().getType(); |
| if (auto metatypeType = baseSelfType->getAs<MetatypeType>()) |
| baseSelfType = metatypeType->getInstanceType(); |
| |
| auto *baseClassDecl = baseSelfType->getClassOrBoundGenericClass(); |
| assert(baseClassDecl && "not a class method"); |
| |
| unsigned baseDepth = 0; |
| SubstitutionMap baseSubMap; |
| if (auto baseClassSig = baseClassDecl->getGenericSignatureOfContext()) { |
| baseDepth = baseClassSig->getGenericParams().back()->getDepth() + 1; |
| |
| // Compute the type of the base class, starting from the |
| // derived class type and the type of the method's self |
| // parameter. |
| Type derivedClass = derivedSelfType; |
| if (auto metatypeType = derivedClass->getAs<MetatypeType>()) |
| derivedClass = metatypeType->getInstanceType(); |
| baseSubMap = derivedClass->getContextSubstitutionMap( |
| M.getSwiftModule(), baseClassDecl); |
| } |
| |
| SubstitutionMap origSubMap; |
| if (auto origCalleeSig = AI.getOrigCalleeType()->getGenericSignature()) |
| origSubMap = origCalleeSig->getSubstitutionMap(AI.getSubstitutions()); |
| |
| Type calleeSelfType = AI.getOrigCalleeType()->getSelfParameter().getType(); |
| if (auto metatypeType = calleeSelfType->getAs<MetatypeType>()) |
| calleeSelfType = metatypeType->getInstanceType(); |
| auto *calleeClassDecl = calleeSelfType->getClassOrBoundGenericClass(); |
| assert(calleeClassDecl && "self is not a class type"); |
| |
| // Add generic parameters from the method itself, ignoring any generic |
| // parameters from the derived class. |
| unsigned origDepth = 0; |
| if (auto calleeClassSig = calleeClassDecl->getGenericSignatureOfContext()) |
| origDepth = calleeClassSig->getGenericParams().back()->getDepth() + 1; |
| |
| auto baseCalleeSig = baseCalleeType->getGenericSignature(); |
| |
| auto subMap = SubstitutionMap::combineSubstitutionMaps(baseSubMap, |
| origSubMap, |
| baseDepth, |
| origDepth, |
| baseCalleeSig); |
| |
| // Build the new substitutions using the base method signature. |
| baseCalleeSig->getSubstitutions(subMap, newSubs); |
| } |
| |
| SILFunction *swift::getTargetClassMethod(SILModule &M, |
| SILType ClassOrMetatypeType, |
| MethodInst *MI) { |
| assert((isa<ClassMethodInst>(MI) || isa<WitnessMethodInst>(MI) || |
| isa<SuperMethodInst>(MI)) && |
| "Only class_method and witness_method instructions are supported"); |
| |
| SILDeclRef Member = MI->getMember(); |
| if (ClassOrMetatypeType.is<MetatypeType>()) |
| ClassOrMetatypeType = ClassOrMetatypeType.getMetatypeInstanceType(M); |
| |
| auto *CD = ClassOrMetatypeType.getClassOrBoundGenericClass(); |
| return M.lookUpFunctionInVTable(CD, Member); |
| } |
| |
| /// \brief Check if it is possible to devirtualize an Apply instruction |
| /// and a class member obtained using the class_method instruction into |
| /// a direct call to a specific member of a specific class. |
| /// |
| /// \p AI is the apply to devirtualize. |
| /// \p ClassOrMetatypeType is the class type or metatype type we are |
| /// devirtualizing for. |
| /// return true if it is possible to devirtualize, false - otherwise. |
| bool swift::canDevirtualizeClassMethod(FullApplySite AI, |
| SILType ClassOrMetatypeType) { |
| |
| DEBUG(llvm::dbgs() << " Trying to devirtualize : " << *AI.getInstruction()); |
| |
| SILModule &Mod = AI.getModule(); |
| |
| // First attempt to lookup the origin for our class method. The origin should |
| // either be a metatype or an alloc_ref. |
| DEBUG(llvm::dbgs() << " Origin Type: " << ClassOrMetatypeType); |
| |
| auto *MI = cast<MethodInst>(AI.getCallee()); |
| |
| // Find the implementation of the member which should be invoked. |
| auto *F = getTargetClassMethod(Mod, ClassOrMetatypeType, MI); |
| |
| // If we do not find any such function, we have no function to devirtualize |
| // to... so bail. |
| if (!F) { |
| DEBUG(llvm::dbgs() << " FAIL: Could not find matching VTable or " |
| "vtable method for this class.\n"); |
| return false; |
| } |
| |
| if (!F->shouldOptimize()) { |
| // Do not consider functions that should not be optimized. |
| DEBUG(llvm::dbgs() << " FAIL: Could not optimize function " |
| << " because it is marked no-opt: " << F->getName() |
| << "\n"); |
| return false; |
| } |
| |
| if (AI.getFunction()->isFragile()) { |
| // function_ref inside fragile function cannot reference a private or |
| // hidden symbol. |
| if (!F->hasValidLinkageForFragileRef()) |
| return false; |
| } |
| |
| if (MI->isVolatile()) { |
| // dynamic dispatch is semantically required, can't devirtualize |
| return false; |
| } |
| |
| // Type of the actual function to be called. |
| CanSILFunctionType GenCalleeType = F->getLoweredFunctionType(); |
| |
| // Type of the actual function to be called with substitutions applied. |
| CanSILFunctionType SubstCalleeType = GenCalleeType; |
| |
| // For polymorphic functions, bail if the number of substitutions is |
| // not the same as the number of expected generic parameters. |
| if (GenCalleeType->isPolymorphic()) { |
| // First, find proper list of substitutions for the concrete |
| // method to be called. |
| SmallVector<Substitution, 4> Subs; |
| getSubstitutionsForCallee(Mod, GenCalleeType, |
| ClassOrMetatypeType.getSwiftRValueType(), |
| AI, Subs); |
| SubstCalleeType = GenCalleeType->substGenericArgs(Mod, Subs); |
| } |
| |
| // Check if the optimizer knows how to cast the return type. |
| SILType ReturnType = |
| SILFunctionConventions(SubstCalleeType, Mod).getSILResultType(); |
| |
| if (!canCastValueToABICompatibleType(Mod, ReturnType, AI.getType())) |
| return false; |
| |
| return true; |
| } |
| |
| /// \brief Devirtualize an apply of a class method. |
| /// |
| /// \p AI is the apply to devirtualize. |
| /// \p ClassOrMetatype is a class value or metatype value that is the |
| /// self argument of the apply we will devirtualize. |
| /// return the result value of the new ApplyInst if created one or null. |
| DevirtualizationResult swift::devirtualizeClassMethod(FullApplySite AI, |
| SILValue ClassOrMetatype) { |
| DEBUG(llvm::dbgs() << " Trying to devirtualize : " << *AI.getInstruction()); |
| |
| SILModule &Mod = AI.getModule(); |
| auto *MI = cast<MethodInst>(AI.getCallee()); |
| auto ClassOrMetatypeType = ClassOrMetatype->getType(); |
| auto *F = getTargetClassMethod(Mod, ClassOrMetatypeType, MI); |
| |
| CanSILFunctionType GenCalleeType = F->getLoweredFunctionType(); |
| |
| SmallVector<Substitution, 4> Subs; |
| getSubstitutionsForCallee(Mod, GenCalleeType, |
| ClassOrMetatypeType.getSwiftRValueType(), |
| AI, Subs); |
| CanSILFunctionType SubstCalleeType = GenCalleeType; |
| if (GenCalleeType->isPolymorphic()) |
| SubstCalleeType = GenCalleeType->substGenericArgs(Mod, Subs); |
| SILFunctionConventions substConv(SubstCalleeType, Mod); |
| |
| SILBuilderWithScope B(AI.getInstruction()); |
| FunctionRefInst *FRI = B.createFunctionRef(AI.getLoc(), F); |
| |
| // Create the argument list for the new apply, casting when needed |
| // in order to handle covariant indirect return types and |
| // contravariant argument types. |
| llvm::SmallVector<SILValue, 8> NewArgs; |
| |
| auto IndirectResultArgIter = AI.getIndirectSILResults().begin(); |
| for (auto ResultTy : substConv.getIndirectSILResultTypes()) { |
| NewArgs.push_back( |
| castValueToABICompatibleType(&B, AI.getLoc(), *IndirectResultArgIter, |
| IndirectResultArgIter->getType(), ResultTy) |
| .getValue()); |
| ++IndirectResultArgIter; |
| } |
| |
| auto ParamArgIter = AI.getArgumentsWithoutIndirectResults().begin(); |
| // Skip the last parameter, which is `self`. Add it below. |
| for (auto param : substConv.getParameters().drop_back()) { |
| auto paramType = substConv.getSILType(param); |
| NewArgs.push_back( |
| castValueToABICompatibleType(&B, AI.getLoc(), *ParamArgIter, |
| ParamArgIter->getType(), paramType) |
| .getValue()); |
| ++ParamArgIter; |
| } |
| |
| // Add the self argument, upcasting if required because we're |
| // calling a base class's method. |
| auto SelfParamTy = substConv.getSILType(SubstCalleeType->getSelfParameter()); |
| NewArgs.push_back(castValueToABICompatibleType(&B, AI.getLoc(), |
| ClassOrMetatype, |
| ClassOrMetatypeType, |
| SelfParamTy).getValue()); |
| |
| SILType ResultTy = substConv.getSILResultType(); |
| |
| SILType SubstCalleeSILType = |
| SILType::getPrimitiveObjectType(SubstCalleeType); |
| FullApplySite NewAI; |
| |
| SILBasicBlock *ResultBB = nullptr; |
| SILBasicBlock *NormalBB = nullptr; |
| SILValue ResultValue; |
| bool ResultCastRequired = false; |
| SmallVector<Operand *, 4> OriginalResultUses; |
| |
| if (!isa<TryApplyInst>(AI)) { |
| NewAI = B.createApply(AI.getLoc(), FRI, SubstCalleeSILType, ResultTy, |
| Subs, NewArgs, cast<ApplyInst>(AI)->isNonThrowing()); |
| ResultValue = NewAI.getInstruction(); |
| } else { |
| auto *TAI = cast<TryApplyInst>(AI); |
| // Create new normal and error BBs only if: |
| // - re-using a BB would create a critical edge |
| // - or, the result of the new apply would be of different |
| // type than the argument of the original normal BB. |
| if (TAI->getNormalBB()->getSinglePredecessorBlock()) |
| ResultBB = TAI->getNormalBB(); |
| else { |
| ResultBB = B.getFunction().createBasicBlock(); |
| ResultBB->createPHIArgument(ResultTy, ValueOwnershipKind::Owned); |
| } |
| |
| NormalBB = TAI->getNormalBB(); |
| |
| SILBasicBlock *ErrorBB = nullptr; |
| if (TAI->getErrorBB()->getSinglePredecessorBlock()) |
| ErrorBB = TAI->getErrorBB(); |
| else { |
| ErrorBB = B.getFunction().createBasicBlock(); |
| ErrorBB->createPHIArgument(TAI->getErrorBB()->getArgument(0)->getType(), |
| ValueOwnershipKind::Owned); |
| } |
| |
| NewAI = B.createTryApply(AI.getLoc(), FRI, SubstCalleeSILType, |
| Subs, NewArgs, |
| ResultBB, ErrorBB); |
| if (ErrorBB != TAI->getErrorBB()) { |
| B.setInsertionPoint(ErrorBB); |
| B.createBranch(TAI->getLoc(), TAI->getErrorBB(), |
| {ErrorBB->getArgument(0)}); |
| } |
| |
| // Does the result value need to be casted? |
| ResultCastRequired = ResultTy != NormalBB->getArgument(0)->getType(); |
| |
| if (ResultBB != NormalBB) |
| B.setInsertionPoint(ResultBB); |
| else if (ResultCastRequired) { |
| B.setInsertionPoint(NormalBB->begin()); |
| // Collect all uses, before casting. |
| for (auto *Use : NormalBB->getArgument(0)->getUses()) { |
| OriginalResultUses.push_back(Use); |
| } |
| NormalBB->getArgument(0)->replaceAllUsesWith( |
| SILUndef::get(AI.getType(), Mod)); |
| NormalBB->replacePHIArgument(0, ResultTy, ValueOwnershipKind::Owned); |
| } |
| |
| // The result value is passed as a parameter to the normal block. |
| ResultValue = ResultBB->getArgument(0); |
| } |
| |
| // Check if any casting is required for the return value. |
| ResultValue = castValueToABICompatibleType(&B, NewAI.getLoc(), ResultValue, |
| ResultTy, AI.getType()).getValue(); |
| |
| DEBUG(llvm::dbgs() << " SUCCESS: " << F->getName() << "\n"); |
| NumClassDevirt++; |
| |
| if (NormalBB) { |
| if (NormalBB != ResultBB) { |
| // If artificial normal BB was introduced, branch |
| // to the original normal BB. |
| B.createBranch(NewAI.getLoc(), NormalBB, { ResultValue }); |
| } else if (ResultCastRequired) { |
| // Update all original uses by the new value. |
| for (auto *Use: OriginalResultUses) { |
| Use->set(ResultValue); |
| } |
| } |
| return std::make_pair(NewAI.getInstruction(), NewAI); |
| } |
| |
| // We need to return a pair of values here: |
| // - the first one is the actual result of the devirtualized call, possibly |
| // casted into an appropriate type. This SILValue may be a BB arg, if it |
| // was a cast between optional types. |
| // - the second one is the new apply site. |
| return std::make_pair(ResultValue, NewAI); |
| } |
| |
| DevirtualizationResult swift::tryDevirtualizeClassMethod(FullApplySite AI, |
| SILValue ClassInstance) { |
| if (!canDevirtualizeClassMethod(AI, ClassInstance->getType())) |
| return std::make_pair(nullptr, FullApplySite()); |
| return devirtualizeClassMethod(AI, ClassInstance); |
| } |
| |
| |
| //===----------------------------------------------------------------------===// |
| // Witness Method Optimization |
| //===----------------------------------------------------------------------===// |
| |
| static SubstitutionList |
| getSubstitutionsForProtocolConformance(ProtocolConformanceRef CRef) { |
| auto C = CRef.getConcrete(); |
| |
| // Walk down to the base NormalProtocolConformance. |
| SubstitutionList Subs; |
| const ProtocolConformance *ParentC = C; |
| while (!isa<NormalProtocolConformance>(ParentC)) { |
| switch (ParentC->getKind()) { |
| case ProtocolConformanceKind::Normal: |
| llvm_unreachable("should have exited the loop?!"); |
| case ProtocolConformanceKind::Inherited: |
| ParentC = cast<InheritedProtocolConformance>(ParentC) |
| ->getInheritedConformance(); |
| break; |
| case ProtocolConformanceKind::Specialized: { |
| auto SC = cast<SpecializedProtocolConformance>(ParentC); |
| ParentC = SC->getGenericConformance(); |
| assert(Subs.empty() && "multiple conformance specializations?!"); |
| Subs = SC->getGenericSubstitutions(); |
| break; |
| } |
| } |
| } |
| const NormalProtocolConformance *NormalC |
| = cast<NormalProtocolConformance>(ParentC); |
| |
| // If the normal conformance is for a generic type, and we didn't hit a |
| // specialized conformance, collect the substitutions from the generic type. |
| // FIXME: The AST should do this for us. |
| if (NormalC->getType()->isSpecialized() && Subs.empty()) { |
| Subs = NormalC->getType() |
| ->gatherAllSubstitutions(NormalC->getDeclContext()->getParentModule(), |
| nullptr); |
| } |
| |
| return Subs; |
| } |
| |
| /// Compute substitutions for making a direct call to a SIL function with |
| /// @convention(witness_method) convention. |
| /// |
| /// Such functions have a substituted generic signature where the |
| /// abstract `Self` parameter from the original type of the protocol |
| /// requirement is replaced by a concrete type. |
| /// |
| /// Thus, the original substitutions of the apply instruction that |
| /// are written in terms of the requirement's generic signature need |
| /// to be remapped to substitutions suitable for the witness signature. |
| /// |
| /// \param conformanceRef The (possibly-specialized) conformance |
| /// \param requirementSig The generic signature of the requirement |
| /// \param witnessThunkSig The generic signature of the witness method |
| /// \param origSubs The substitutions from the call instruction |
| /// \param newSubs New substitutions are stored here |
| static void getWitnessMethodSubstitutions( |
| SILModule &M, |
| ProtocolConformanceRef conformanceRef, |
| GenericSignature *requirementSig, |
| GenericSignature *witnessThunkSig, |
| SubstitutionList origSubs, |
| bool isDefaultWitness, |
| SmallVectorImpl<Substitution> &newSubs) { |
| |
| if (witnessThunkSig == nullptr) |
| return; |
| |
| if (isDefaultWitness) { |
| newSubs.append(origSubs.begin(), origSubs.end()); |
| return; |
| } |
| |
| assert(!conformanceRef.isAbstract()); |
| auto conformance = conformanceRef.getConcrete(); |
| |
| // Take apart substitutions from the conforming type. |
| SubstitutionList witnessSubs; |
| auto *rootConformance = conformance->getRootNormalConformance(); |
| auto *witnessSig = rootConformance->getGenericSignature(); |
| |
| // If `Self` maps to a bound generic type, this gives us the |
| // substitutions for the concrete type's generic parameters. |
| witnessSubs = getSubstitutionsForProtocolConformance(conformanceRef); |
| |
| SubstitutionMap baseSubMap; |
| unsigned baseDepth = 0; |
| if (!witnessSubs.empty()) { |
| baseSubMap = witnessSig->getSubstitutionMap(witnessSubs); |
| baseDepth = witnessSig->getGenericParams().back()->getDepth() + 1; |
| } |
| |
| // Next, take apart caller-side substitutions. |
| auto origDepth = 1; |
| auto origSubMap = requirementSig->getSubstitutionMap(origSubs); |
| |
| auto subMap = SubstitutionMap::combineSubstitutionMaps(baseSubMap, |
| origSubMap, |
| baseDepth, |
| origDepth, |
| witnessThunkSig); |
| |
| witnessThunkSig->getSubstitutions(subMap, newSubs); |
| } |
| |
| 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); |
| } |
| |
| /// Check if an upcast is legal. |
| /// The logic in this function is heavily based on the checks in |
| /// the SILVerifier. |
| bool swift::isLegalUpcast(SILType FromTy, SILType ToTy) { |
| if (ToTy.is<MetatypeType>()) { |
| CanType InstTy(ToTy.castTo<MetatypeType>()->getInstanceType()); |
| if (!FromTy.is<MetatypeType>()) |
| return false; |
| CanType OpInstTy(FromTy.castTo<MetatypeType>()->getInstanceType()); |
| auto InstClass = InstTy->getClassOrBoundGenericClass(); |
| if (!InstClass) |
| return false; |
| |
| bool CanBeUpcasted = |
| InstClass->usesObjCGenericsModel() |
| ? InstClass->getDeclaredTypeInContext()->isBindableToSuperclassOf( |
| OpInstTy, nullptr) |
| : InstTy->isExactSuperclassOf(OpInstTy, nullptr); |
| |
| return CanBeUpcasted; |
| } |
| |
| // Upcast from Optional<B> to Optional<A> is legal as long as B is a |
| // subclass of A. |
| if (ToTy.getSwiftRValueType().getAnyOptionalObjectType() && |
| FromTy.getSwiftRValueType().getAnyOptionalObjectType()) { |
| ToTy = SILType::getPrimitiveObjectType( |
| ToTy.getSwiftRValueType().getAnyOptionalObjectType()); |
| FromTy = SILType::getPrimitiveObjectType( |
| FromTy.getSwiftRValueType().getAnyOptionalObjectType()); |
| } |
| |
| auto ToClass = ToTy.getClassOrBoundGenericClass(); |
| if (!ToClass) |
| return false; |
| bool CanBeUpcasted = |
| ToClass->usesObjCGenericsModel() |
| ? ToClass->getDeclaredTypeInContext()->isBindableToSuperclassOf( |
| FromTy.getSwiftRValueType(), nullptr) |
| : ToTy.isExactSuperclassOf(FromTy); |
| |
| return CanBeUpcasted; |
| } |
| |
| /// Check if we can pass/convert all arguments of the original apply |
| /// as required by the found devirtualized method. |
| /// FIXME: This method was introduced as a workaround. We need to |
| /// revisit it and check if it is still needed. |
| static bool |
| canPassOrConvertAllArguments(ApplySite AI, |
| CanSILFunctionType SubstCalleeCanType) { |
| SILFunctionConventions substConv(SubstCalleeCanType, AI.getModule()); |
| unsigned substArgIdx = AI.getCalleeArgIndexOfFirstAppliedArg(); |
| for (auto arg : AI.getArguments()) { |
| // Check if we can cast the provided argument into the required |
| // parameter type. |
| auto FromTy = arg->getType(); |
| auto ToTy = substConv.getSILArgumentType(substArgIdx++); |
| // If types are the same, no conversion will be required. |
| if (FromTy == ToTy) |
| continue; |
| // Otherwise, it should be possible to upcast the arguments. |
| if (!isLegalUpcast(FromTy, ToTy)) |
| return false; |
| } |
| assert(substArgIdx == substConv.getNumSILArguments()); |
| return true; |
| } |
| |
| /// 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, |
| ProtocolConformanceRef C) { |
| // 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, 4> NewSubs; |
| |
| getWitnessMethodSubstitutions(AI, F, C, NewSubs); |
| |
| // 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, NewSubs); |
| |
| // Bail if some of the arguments cannot be converted into |
| // types required by the found devirtualized method. |
| if (!canPassOrConvertAllArguments(AI, SubstCalleeCanType)) |
| return ApplySite(); |
| |
| // 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()); |
| SILFunctionConventions substConv(SubstCalleeCanType, Module); |
| unsigned substArgIdx = AI.getCalleeArgIndexOfFirstAppliedArg(); |
| for (auto arg : AI.getArguments()) { |
| auto paramType = substConv.getSILArgumentType(substArgIdx++); |
| if (arg->getType() != paramType) |
| arg = B.createUpcast(AI.getLoc(), arg, paramType); |
| Arguments.push_back(arg); |
| } |
| assert(substArgIdx == substConv.getNumSILArguments()); |
| |
| // 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 = substConv.getSILResultType(); |
| ApplySite SAI; |
| |
| if (auto *A = dyn_cast<ApplyInst>(AI)) |
| SAI = Builder.createApply(Loc, FRI, SubstCalleeSILType, |
| ResultSILType, NewSubs, Arguments, |
| A->isNonThrowing()); |
| if (auto *TAI = dyn_cast<TryApplyInst>(AI)) |
| SAI = Builder.createTryApply(Loc, FRI, SubstCalleeSILType, |
| NewSubs, Arguments, |
| TAI->getNormalBB(), TAI->getErrorBB()); |
| if (auto *PAI = dyn_cast<PartialApplyInst>(AI)) |
| SAI = Builder.createPartialApply(Loc, FRI, SubstCalleeSILType, |
| NewSubs, Arguments, PAI->getType()); |
| |
| NumWitnessDevirt++; |
| return SAI; |
| } |
| |
| static bool canDevirtualizeWitnessMethod(ApplySite AI) { |
| SILFunction *F; |
| SILWitnessTable *WT; |
| |
| auto *WMI = cast<WitnessMethodInst>(AI.getCallee()); |
| |
| std::tie(F, WT) = |
| AI.getModule().lookUpFunctionInWitnessTable(WMI->getConformance(), |
| WMI->getMember()); |
| |
| if (!F) |
| return false; |
| |
| if (AI.getFunction()->isFragile()) { |
| // function_ref inside fragile function cannot reference a private or |
| // hidden symbol. |
| if (!F->hasValidLinkageForFragileRef()) |
| return false; |
| } |
| |
| // 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, 4> NewSubs; |
| |
| getWitnessMethodSubstitutions(AI, F, WMI->getConformance(), NewSubs); |
| |
| // Figure out the exact bound type of the function to be called by |
| // applying all substitutions. |
| auto &Module = AI.getModule(); |
| auto CalleeCanType = F->getLoweredFunctionType(); |
| auto SubstCalleeCanType = CalleeCanType->substGenericArgs(Module, NewSubs); |
| |
| // Bail if some of the arguments cannot be converted into |
| // types required by the found devirtualized method. |
| if (!canPassOrConvertAllArguments(AI, SubstCalleeCanType)) |
| return false; |
| |
| return true; |
| } |
| |
| /// In the cases where we can statically determine the function that |
| /// we'll call to, replace an apply of a witness_method with an apply |
| /// of a function_ref, returning the new apply. |
| DevirtualizationResult swift::tryDevirtualizeWitnessMethod(ApplySite AI) { |
| if (!canDevirtualizeWitnessMethod(AI)) |
| return std::make_pair(nullptr, FullApplySite()); |
| |
| SILFunction *F; |
| SILWitnessTable *WT; |
| |
| auto *WMI = cast<WitnessMethodInst>(AI.getCallee()); |
| |
| std::tie(F, WT) = |
| AI.getModule().lookUpFunctionInWitnessTable(WMI->getConformance(), |
| WMI->getMember()); |
| |
| auto Result = devirtualizeWitnessMethod(AI, F, WMI->getConformance()); |
| return std::make_pair(Result.getInstruction(), Result); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Top Level Driver |
| //===----------------------------------------------------------------------===// |
| |
| /// Attempt to devirtualize the given apply if possible, and return a |
| /// new instruction in that case, or nullptr otherwise. |
| DevirtualizationResult |
| swift::tryDevirtualizeApply(ApplySite AI, ClassHierarchyAnalysis *CHA) { |
| DEBUG(llvm::dbgs() << " Trying to devirtualize: " << *AI.getInstruction()); |
| |
| // Devirtualize apply instructions that call witness_method instructions: |
| // |
| // %8 = witness_method $Optional<UInt16>, #LogicValue.boolValue!getter.1 |
| // %9 = apply %8<Self = CodeUnit?>(%6#1) : ... |
| // |
| if (isa<WitnessMethodInst>(AI.getCallee())) |
| return tryDevirtualizeWitnessMethod(AI); |
| |
| // TODO: check if we can also de-virtualize partial applies of class methods. |
| FullApplySite FAS = FullApplySite::isa(AI.getInstruction()); |
| if (!FAS) |
| return std::make_pair(nullptr, ApplySite()); |
| |
| /// Optimize a class_method and alloc_ref pair into a direct function |
| /// reference: |
| /// |
| /// \code |
| /// %XX = alloc_ref $Foo |
| /// %YY = class_method %XX : $Foo, #Foo.get!1 : $@convention(method)... |
| /// \endcode |
| /// |
| /// or |
| /// |
| /// %XX = metatype $... |
| /// %YY = class_method %XX : ... |
| /// |
| /// into |
| /// |
| /// %YY = function_ref @... |
| if (auto *CMI = dyn_cast<ClassMethodInst>(FAS.getCallee())) { |
| auto &M = FAS.getModule(); |
| auto Instance = stripUpCasts(CMI->getOperand()); |
| auto ClassType = Instance->getType(); |
| if (ClassType.is<MetatypeType>()) |
| ClassType = ClassType.getMetatypeInstanceType(M); |
| |
| auto *CD = ClassType.getClassOrBoundGenericClass(); |
| |
| if (isEffectivelyFinalMethod(FAS, ClassType, CD, CHA)) |
| return tryDevirtualizeClassMethod(FAS, Instance); |
| |
| // Try to check if the exact dynamic type of the instance is statically |
| // known. |
| if (auto Instance = getInstanceWithExactDynamicType(CMI->getOperand(), |
| CMI->getModule(), |
| CHA)) |
| return tryDevirtualizeClassMethod(FAS, Instance); |
| |
| if (auto ExactTy = getExactDynamicType(CMI->getOperand(), CMI->getModule(), |
| CHA)) { |
| if (ExactTy == CMI->getOperand()->getType()) |
| return tryDevirtualizeClassMethod(FAS, CMI->getOperand()); |
| } |
| } |
| |
| if (isa<SuperMethodInst>(FAS.getCallee())) { |
| if (FAS.hasSelfArgument()) { |
| return tryDevirtualizeClassMethod(FAS, FAS.getSelfArgument()); |
| } |
| |
| // It is an invocation of a class method. |
| // Last operand is the metatype that should be used for dispatching. |
| return tryDevirtualizeClassMethod(FAS, FAS.getArguments().back()); |
| } |
| |
| return std::make_pair(nullptr, ApplySite()); |
| } |
| |
| bool swift::canDevirtualizeApply(FullApplySite AI, ClassHierarchyAnalysis *CHA) { |
| DEBUG(llvm::dbgs() << " Trying to devirtualize: " << *AI.getInstruction()); |
| |
| // Devirtualize apply instructions that call witness_method instructions: |
| // |
| // %8 = witness_method $Optional<UInt16>, #LogicValue.boolValue!getter.1 |
| // %9 = apply %8<Self = CodeUnit?>(%6#1) : ... |
| // |
| if (isa<WitnessMethodInst>(AI.getCallee())) |
| return canDevirtualizeWitnessMethod(AI); |
| |
| /// Optimize a class_method and alloc_ref pair into a direct function |
| /// reference: |
| /// |
| /// \code |
| /// %XX = alloc_ref $Foo |
| /// %YY = class_method %XX : $Foo, #Foo.get!1 : $@convention(method)... |
| /// \endcode |
| /// |
| /// or |
| /// |
| /// %XX = metatype $... |
| /// %YY = class_method %XX : ... |
| /// |
| /// into |
| /// |
| /// %YY = function_ref @... |
| if (auto *CMI = dyn_cast<ClassMethodInst>(AI.getCallee())) { |
| auto &M = AI.getModule(); |
| auto Instance = stripUpCasts(CMI->getOperand()); |
| auto ClassType = Instance->getType(); |
| if (ClassType.is<MetatypeType>()) |
| ClassType = ClassType.getMetatypeInstanceType(M); |
| |
| auto *CD = ClassType.getClassOrBoundGenericClass(); |
| |
| if (isEffectivelyFinalMethod(AI, ClassType, CD, CHA)) |
| return canDevirtualizeClassMethod(AI, Instance->getType()); |
| |
| // Try to check if the exact dynamic type of the instance is statically |
| // known. |
| if (auto Instance = getInstanceWithExactDynamicType(CMI->getOperand(), |
| CMI->getModule(), |
| CHA)) |
| return canDevirtualizeClassMethod(AI, Instance->getType()); |
| |
| if (auto ExactTy = getExactDynamicType(CMI->getOperand(), CMI->getModule(), |
| CHA)) { |
| if (ExactTy == CMI->getOperand()->getType()) |
| return canDevirtualizeClassMethod(AI, CMI->getOperand()->getType()); |
| } |
| } |
| |
| if (isa<SuperMethodInst>(AI.getCallee())) { |
| if (AI.hasSelfArgument()) { |
| return canDevirtualizeClassMethod(AI, AI.getSelfArgument()->getType()); |
| } |
| |
| // It is an invocation of a class method. |
| // Last operand is the metatype that should be used for dispatching. |
| return canDevirtualizeClassMethod(AI, AI.getArguments().back()->getType()); |
| } |
| |
| return false; |
| } |
