| //===- Scope.cpp - Lexical scope information --------------------*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the Scope class, which is used for recording |
| // information about a lexical scope. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/Sema/Scope.h" |
| #include "clang/AST/Decl.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace clang; |
| |
| void Scope::setFlags(Scope *parent, unsigned flags) { |
| AnyParent = parent; |
| Flags = flags; |
| |
| if (parent && !(flags & FnScope)) { |
| BreakParent = parent->BreakParent; |
| ContinueParent = parent->ContinueParent; |
| } else { |
| // Control scopes do not contain the contents of nested function scopes for |
| // control flow purposes. |
| BreakParent = ContinueParent = nullptr; |
| } |
| |
| if (parent) { |
| Depth = parent->Depth + 1; |
| PrototypeDepth = parent->PrototypeDepth; |
| PrototypeIndex = 0; |
| FnParent = parent->FnParent; |
| BlockParent = parent->BlockParent; |
| TemplateParamParent = parent->TemplateParamParent; |
| DeclParent = parent->DeclParent; |
| MSLastManglingParent = parent->MSLastManglingParent; |
| MSCurManglingNumber = getMSLastManglingNumber(); |
| if ((Flags & (FnScope | ClassScope | BlockScope | TemplateParamScope | |
| FunctionPrototypeScope | AtCatchScope | ObjCMethodScope)) == |
| 0) |
| Flags |= parent->getFlags() & OpenMPSimdDirectiveScope; |
| // transmit the parent's 'order' flag, if exists |
| if (parent->getFlags() & OpenMPOrderClauseScope) |
| Flags |= OpenMPOrderClauseScope; |
| } else { |
| Depth = 0; |
| PrototypeDepth = 0; |
| PrototypeIndex = 0; |
| MSLastManglingParent = FnParent = BlockParent = nullptr; |
| TemplateParamParent = nullptr; |
| DeclParent = nullptr; |
| MSLastManglingNumber = 1; |
| MSCurManglingNumber = 1; |
| } |
| |
| // If this scope is a function or contains breaks/continues, remember it. |
| if (flags & FnScope) FnParent = this; |
| // The MS mangler uses the number of scopes that can hold declarations as |
| // part of an external name. |
| if (Flags & (ClassScope | FnScope)) { |
| MSLastManglingNumber = getMSLastManglingNumber(); |
| MSLastManglingParent = this; |
| MSCurManglingNumber = 1; |
| } |
| if (flags & BreakScope) BreakParent = this; |
| if (flags & ContinueScope) ContinueParent = this; |
| if (flags & BlockScope) BlockParent = this; |
| if (flags & TemplateParamScope) TemplateParamParent = this; |
| |
| // If this is a prototype scope, record that. Lambdas have an extra prototype |
| // scope that doesn't add any depth. |
| if (flags & FunctionPrototypeScope && !(flags & LambdaScope)) |
| PrototypeDepth++; |
| |
| if (flags & DeclScope) { |
| DeclParent = this; |
| if (flags & FunctionPrototypeScope) |
| ; // Prototype scopes are uninteresting. |
| else if ((flags & ClassScope) && getParent()->isClassScope()) |
| ; // Nested class scopes aren't ambiguous. |
| else if ((flags & ClassScope) && getParent()->getFlags() == DeclScope) |
| ; // Classes inside of namespaces aren't ambiguous. |
| else if ((flags & EnumScope)) |
| ; // Don't increment for enum scopes. |
| else |
| incrementMSManglingNumber(); |
| } |
| } |
| |
| void Scope::Init(Scope *parent, unsigned flags) { |
| setFlags(parent, flags); |
| |
| DeclsInScope.clear(); |
| UsingDirectives.clear(); |
| Entity = nullptr; |
| ErrorTrap.reset(); |
| NRVO = std::nullopt; |
| } |
| |
| bool Scope::containedInPrototypeScope() const { |
| const Scope *S = this; |
| while (S) { |
| if (S->isFunctionPrototypeScope()) |
| return true; |
| S = S->getParent(); |
| } |
| return false; |
| } |
| |
| void Scope::AddFlags(unsigned FlagsToSet) { |
| assert((FlagsToSet & ~(BreakScope | ContinueScope)) == 0 && |
| "Unsupported scope flags"); |
| if (FlagsToSet & BreakScope) { |
| assert((Flags & BreakScope) == 0 && "Already set"); |
| BreakParent = this; |
| } |
| if (FlagsToSet & ContinueScope) { |
| assert((Flags & ContinueScope) == 0 && "Already set"); |
| ContinueParent = this; |
| } |
| Flags |= FlagsToSet; |
| } |
| |
| // The algorithm for updating NRVO candidate is as follows: |
| // 1. All previous candidates become invalid because a new NRVO candidate is |
| // obtained. Therefore, we need to clear return slots for other |
| // variables defined before the current return statement in the current |
| // scope and in outer scopes. |
| // 2. Store the new candidate if its return slot is available. Otherwise, |
| // there is no NRVO candidate so far. |
| void Scope::updateNRVOCandidate(VarDecl *VD) { |
| auto UpdateReturnSlotsInScopeForVD = [VD](Scope *S) -> bool { |
| bool IsReturnSlotFound = S->ReturnSlots.contains(VD); |
| |
| // We found a candidate variable that can be put into a return slot. |
| // Clear the set, because other variables cannot occupy a return |
| // slot in the same scope. |
| S->ReturnSlots.clear(); |
| |
| if (IsReturnSlotFound) |
| S->ReturnSlots.insert(VD); |
| |
| return IsReturnSlotFound; |
| }; |
| |
| bool CanBePutInReturnSlot = false; |
| |
| for (auto *S = this; S; S = S->getParent()) { |
| CanBePutInReturnSlot |= UpdateReturnSlotsInScopeForVD(S); |
| |
| if (S->getEntity()) |
| break; |
| } |
| |
| // Consider the variable as NRVO candidate if the return slot is available |
| // for it in the current scope, or if it can be available in outer scopes. |
| NRVO = CanBePutInReturnSlot ? VD : nullptr; |
| } |
| |
| void Scope::applyNRVO() { |
| // There is no NRVO candidate in the current scope. |
| if (!NRVO.has_value()) |
| return; |
| |
| if (*NRVO && isDeclScope(*NRVO)) |
| (*NRVO)->setNRVOVariable(true); |
| |
| // It's necessary to propagate NRVO candidate to the parent scope for cases |
| // when the parent scope doesn't contain a return statement. |
| // For example: |
| // X foo(bool b) { |
| // X x; |
| // if (b) |
| // return x; |
| // exit(0); |
| // } |
| // Also, we need to propagate nullptr value that means NRVO is not |
| // allowed in this scope. |
| // For example: |
| // X foo(bool b) { |
| // X x; |
| // if (b) |
| // return x; |
| // else |
| // return X(); // NRVO is not allowed |
| // } |
| if (!getEntity()) |
| getParent()->NRVO = *NRVO; |
| } |
| |
| LLVM_DUMP_METHOD void Scope::dump() const { dumpImpl(llvm::errs()); } |
| |
| void Scope::dumpImpl(raw_ostream &OS) const { |
| unsigned Flags = getFlags(); |
| bool HasFlags = Flags != 0; |
| |
| if (HasFlags) |
| OS << "Flags: "; |
| |
| std::pair<unsigned, const char *> FlagInfo[] = { |
| {FnScope, "FnScope"}, |
| {BreakScope, "BreakScope"}, |
| {ContinueScope, "ContinueScope"}, |
| {DeclScope, "DeclScope"}, |
| {ControlScope, "ControlScope"}, |
| {ClassScope, "ClassScope"}, |
| {BlockScope, "BlockScope"}, |
| {TemplateParamScope, "TemplateParamScope"}, |
| {FunctionPrototypeScope, "FunctionPrototypeScope"}, |
| {FunctionDeclarationScope, "FunctionDeclarationScope"}, |
| {AtCatchScope, "AtCatchScope"}, |
| {ObjCMethodScope, "ObjCMethodScope"}, |
| {SwitchScope, "SwitchScope"}, |
| {TryScope, "TryScope"}, |
| {FnTryCatchScope, "FnTryCatchScope"}, |
| {OpenMPDirectiveScope, "OpenMPDirectiveScope"}, |
| {OpenMPLoopDirectiveScope, "OpenMPLoopDirectiveScope"}, |
| {OpenMPSimdDirectiveScope, "OpenMPSimdDirectiveScope"}, |
| {EnumScope, "EnumScope"}, |
| {SEHTryScope, "SEHTryScope"}, |
| {SEHExceptScope, "SEHExceptScope"}, |
| {SEHFilterScope, "SEHFilterScope"}, |
| {CompoundStmtScope, "CompoundStmtScope"}, |
| {ClassInheritanceScope, "ClassInheritanceScope"}, |
| {CatchScope, "CatchScope"}, |
| {OpenACCComputeConstructScope, "OpenACCComputeConstructScope"}, |
| }; |
| |
| for (auto Info : FlagInfo) { |
| if (Flags & Info.first) { |
| OS << Info.second; |
| Flags &= ~Info.first; |
| if (Flags) |
| OS << " | "; |
| } |
| } |
| |
| assert(Flags == 0 && "Unknown scope flags"); |
| |
| if (HasFlags) |
| OS << '\n'; |
| |
| if (const Scope *Parent = getParent()) |
| OS << "Parent: (clang::Scope*)" << Parent << '\n'; |
| |
| OS << "Depth: " << Depth << '\n'; |
| OS << "MSLastManglingNumber: " << getMSLastManglingNumber() << '\n'; |
| OS << "MSCurManglingNumber: " << getMSCurManglingNumber() << '\n'; |
| if (const DeclContext *DC = getEntity()) |
| OS << "Entity : (clang::DeclContext*)" << DC << '\n'; |
| |
| if (!NRVO) |
| OS << "there is no NRVO candidate\n"; |
| else if (*NRVO) |
| OS << "NRVO candidate : (clang::VarDecl*)" << *NRVO << '\n'; |
| else |
| OS << "NRVO is not allowed\n"; |
| } |