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//===- 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;
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;
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.
if (flags & FunctionPrototypeScope) PrototypeDepth++;
if (flags & DeclScope) {
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"},
};
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";
}
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