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chromium / v8 / v8 / 04d81120368173ee91fab193f8cd0837d9628dd4 / . / src / ast / scopes.cc
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// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/ast/scopes.h"
#include <set>
#include "src/accessors.h"
#include "src/bootstrapper.h"
#include "src/messages.h"
#include "src/parsing/parse-info.h"
namespace v8 {
namespace internal {
// ----------------------------------------------------------------------------
// Implementation of LocalsMap
//
// Note: We are storing the handle locations as key values in the hash map.
// When inserting a new variable via Declare(), we rely on the fact that
// the handle location remains alive for the duration of that variable
// use. Because a Variable holding a handle with the same location exists
// this is ensured.
VariableMap::VariableMap(Zone* zone)
: ZoneHashMap(ZoneHashMap::PointersMatch, 8, ZoneAllocationPolicy(zone)) {}
Variable* VariableMap::Declare(Zone* zone, Scope* scope,
const AstRawString* name, VariableMode mode,
Variable::Kind kind,
InitializationFlag initialization_flag,
MaybeAssignedFlag maybe_assigned_flag,
bool* added) {
// AstRawStrings are unambiguous, i.e., the same string is always represented
// by the same AstRawString*.
// FIXME(marja): fix the type of Lookup.
Entry* p =
ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->hash(),
ZoneAllocationPolicy(zone));
if (added) *added = p->value == nullptr;
if (p->value == nullptr) {
// The variable has not been declared yet -> insert it.
DCHECK_EQ(name, p->key);
p->value = new (zone) Variable(scope, name, mode, kind, initialization_flag,
maybe_assigned_flag);
}
return reinterpret_cast<Variable*>(p->value);
}
void VariableMap::Remove(Variable* var) {
const AstRawString* name = var->raw_name();
ZoneHashMap::Remove(const_cast<AstRawString*>(name), name->hash());
}
void VariableMap::Add(Zone* zone, Variable* var) {
const AstRawString* name = var->raw_name();
Entry* p =
ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->hash(),
ZoneAllocationPolicy(zone));
DCHECK_NULL(p->value);
DCHECK_EQ(name, p->key);
p->value = var;
}
Variable* VariableMap::Lookup(const AstRawString* name) {
Entry* p = ZoneHashMap::Lookup(const_cast<AstRawString*>(name), name->hash());
if (p != NULL) {
DCHECK(reinterpret_cast<const AstRawString*>(p->key) == name);
DCHECK(p->value != NULL);
return reinterpret_cast<Variable*>(p->value);
}
return NULL;
}
SloppyBlockFunctionMap::SloppyBlockFunctionMap(Zone* zone)
: ZoneHashMap(ZoneHashMap::PointersMatch, 8, ZoneAllocationPolicy(zone)) {}
void SloppyBlockFunctionMap::Declare(Zone* zone, const AstRawString* name,
SloppyBlockFunctionStatement* stmt) {
// AstRawStrings are unambiguous, i.e., the same string is always represented
// by the same AstRawString*.
Entry* p =
ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->hash(),
ZoneAllocationPolicy(zone));
stmt->set_next(static_cast<SloppyBlockFunctionStatement*>(p->value));
p->value = stmt;
}
// ----------------------------------------------------------------------------
// Implementation of Scope
Scope::Scope(Zone* zone, ScopeType scope_type)
: zone_(zone),
outer_scope_(nullptr),
variables_(zone),
locals_(4, zone),
decls_(4, zone),
scope_type_(scope_type) {
DCHECK(scope_type == SCRIPT_SCOPE || scope_type == WITH_SCOPE);
SetDefaults();
#ifdef DEBUG
if (scope_type == WITH_SCOPE) {
already_resolved_ = true;
}
#endif
}
Scope::Scope(Zone* zone, Scope* outer_scope, ScopeType scope_type)
: zone_(zone),
outer_scope_(outer_scope),
variables_(zone),
locals_(4, zone),
decls_(4, zone),
scope_type_(scope_type) {
DCHECK_NE(SCRIPT_SCOPE, scope_type);
SetDefaults();
set_language_mode(outer_scope->language_mode());
force_context_allocation_ =
!is_function_scope() && outer_scope->has_forced_context_allocation();
outer_scope_->AddInnerScope(this);
}
Scope::Snapshot::Snapshot(Scope* scope)
: outer_scope_(scope),
top_inner_scope_(scope->inner_scope_),
top_unresolved_(scope->unresolved_),
top_local_(scope->GetClosureScope()->locals_.length()),
top_decl_(scope->GetClosureScope()->decls_.length()) {}
DeclarationScope::DeclarationScope(Zone* zone)
: Scope(zone),
function_kind_(kNormalFunction),
params_(4, zone),
sloppy_block_function_map_(zone) {
SetDefaults();
}
DeclarationScope::DeclarationScope(Zone* zone, Scope* outer_scope,
ScopeType scope_type,
FunctionKind function_kind)
: Scope(zone, outer_scope, scope_type),
function_kind_(function_kind),
params_(4, zone),
sloppy_block_function_map_(zone) {
SetDefaults();
asm_function_ = outer_scope_->IsAsmModule();
}
ModuleScope::ModuleScope(DeclarationScope* script_scope,
AstValueFactory* ast_value_factory)
: DeclarationScope(ast_value_factory->zone(), script_scope, MODULE_SCOPE) {
Zone* zone = ast_value_factory->zone();
module_descriptor_ = new (zone) ModuleDescriptor(zone);
set_language_mode(STRICT);
DeclareThis(ast_value_factory);
}
Scope::Scope(Zone* zone, ScopeType scope_type, Handle<ScopeInfo> scope_info)
: zone_(zone),
outer_scope_(nullptr),
variables_(zone),
locals_(0, zone),
decls_(0, zone),
scope_info_(scope_info),
scope_type_(scope_type) {
DCHECK(!scope_info.is_null());
SetDefaults();
#ifdef DEBUG
already_resolved_ = true;
#endif
if (scope_info->CallsEval()) RecordEvalCall();
set_language_mode(scope_info->language_mode());
num_heap_slots_ = scope_info->ContextLength();
DCHECK_LE(Context::MIN_CONTEXT_SLOTS, num_heap_slots_);
}
DeclarationScope::DeclarationScope(Zone* zone, ScopeType scope_type,
Handle<ScopeInfo> scope_info)
: Scope(zone, scope_type, scope_info),
function_kind_(scope_info->function_kind()),
params_(0, zone),
sloppy_block_function_map_(zone) {
SetDefaults();
}
Scope::Scope(Zone* zone, const AstRawString* catch_variable_name)
: zone_(zone),
outer_scope_(nullptr),
variables_(zone),
locals_(0, zone),
decls_(0, zone),
scope_type_(CATCH_SCOPE) {
SetDefaults();
#ifdef DEBUG
already_resolved_ = true;
#endif
Variable* variable = Declare(zone, this, catch_variable_name, VAR,
Variable::NORMAL, kCreatedInitialized);
AllocateHeapSlot(variable);
}
void DeclarationScope::SetDefaults() {
is_declaration_scope_ = true;
has_simple_parameters_ = true;
asm_module_ = false;
asm_function_ = false;
force_eager_compilation_ = false;
has_arguments_parameter_ = false;
scope_uses_super_property_ = false;
has_rest_ = false;
receiver_ = nullptr;
new_target_ = nullptr;
function_ = nullptr;
arguments_ = nullptr;
this_function_ = nullptr;
arity_ = 0;
}
void Scope::SetDefaults() {
#ifdef DEBUG
scope_name_ = nullptr;
already_resolved_ = false;
#endif
inner_scope_ = nullptr;
sibling_ = nullptr;
unresolved_ = nullptr;
start_position_ = kNoSourcePosition;
end_position_ = kNoSourcePosition;
num_stack_slots_ = 0;
num_heap_slots_ = Context::MIN_CONTEXT_SLOTS;
num_global_slots_ = 0;
set_language_mode(SLOPPY);
scope_calls_eval_ = false;
scope_nonlinear_ = false;
is_hidden_ = false;
is_debug_evaluate_scope_ = false;
inner_scope_calls_eval_ = false;
force_context_allocation_ = false;
is_declaration_scope_ = false;
}
bool Scope::HasSimpleParameters() {
DeclarationScope* scope = GetClosureScope();
return !scope->is_function_scope() || scope->has_simple_parameters();
}
bool Scope::IsAsmModule() const {
return is_function_scope() && AsDeclarationScope()->asm_module();
}
bool Scope::IsAsmFunction() const {
return is_function_scope() && AsDeclarationScope()->asm_function();
}
Scope* Scope::DeserializeScopeChain(Isolate* isolate, Zone* zone,
Context* context,
DeclarationScope* script_scope,
AstValueFactory* ast_value_factory,
DeserializationMode deserialization_mode) {
// Reconstruct the outer scope chain from a closure's context chain.
Scope* current_scope = nullptr;
Scope* innermost_scope = nullptr;
Scope* outer_scope = nullptr;
while (!context->IsNativeContext()) {
if (context->IsWithContext() || context->IsDebugEvaluateContext()) {
// For scope analysis, debug-evaluate is equivalent to a with scope.
outer_scope = new (zone) Scope(zone, WITH_SCOPE);
// TODO(yangguo): Remove once debug-evaluate properly keeps track of the
// function scope in which we are evaluating.
if (context->IsDebugEvaluateContext()) {
outer_scope->set_is_debug_evaluate_scope();
}
} else if (context->IsScriptContext()) {
// If we reach a script context, it's the outermost context with scope
// info. The next context will be the native context. Install the scope
// info of this script context onto the existing script scope to avoid
// nesting script scopes.
Handle<ScopeInfo> scope_info(context->scope_info(), isolate);
script_scope->SetScriptScopeInfo(scope_info);
DCHECK(context->previous()->IsNativeContext());
break;
} else if (context->IsFunctionContext()) {
Handle<ScopeInfo> scope_info(context->closure()->shared()->scope_info(),
isolate);
// TODO(neis): For an eval scope, we currently create an ordinary function
// context. This is wrong and needs to be fixed.
// https://bugs.chromium.org/p/v8/issues/detail?id=5295
DCHECK(scope_info->scope_type() == FUNCTION_SCOPE ||
scope_info->scope_type() == EVAL_SCOPE);
outer_scope =
new (zone) DeclarationScope(zone, FUNCTION_SCOPE, scope_info);
if (scope_info->IsAsmFunction())
outer_scope->AsDeclarationScope()->set_asm_function();
if (scope_info->IsAsmModule())
outer_scope->AsDeclarationScope()->set_asm_module();
} else if (context->IsBlockContext()) {
Handle<ScopeInfo> scope_info(context->scope_info(), isolate);
DCHECK_EQ(scope_info->scope_type(), BLOCK_SCOPE);
if (scope_info->is_declaration_scope()) {
outer_scope =
new (zone) DeclarationScope(zone, BLOCK_SCOPE, scope_info);
} else {
outer_scope = new (zone) Scope(zone, BLOCK_SCOPE, scope_info);
}
} else {
DCHECK(context->IsCatchContext());
String* name = context->catch_name();
outer_scope = new (zone)
Scope(zone, ast_value_factory->GetString(handle(name, isolate)));
}
if (current_scope != nullptr) {
outer_scope->AddInnerScope(current_scope);
}
current_scope = outer_scope;
if (deserialization_mode == DeserializationMode::kDeserializeOffHeap) {
current_scope->DeserializeScopeInfo(isolate, ast_value_factory);
}
if (innermost_scope == nullptr) innermost_scope = current_scope;
context = context->previous();
}
if (innermost_scope == nullptr) return script_scope;
script_scope->AddInnerScope(current_scope);
script_scope->PropagateScopeInfo();
return innermost_scope;
}
void Scope::DeserializeScopeInfo(Isolate* isolate,
AstValueFactory* ast_value_factory) {
if (scope_info_.is_null()) return;
DCHECK(ThreadId::Current().Equals(isolate->thread_id()));
std::set<const AstRawString*> names_seen;
// Internalize context local & globals variables.
for (int var = 0; var < scope_info_->ContextLocalCount() +
scope_info_->ContextGlobalCount();
++var) {
Handle<String> name_handle(scope_info_->ContextLocalName(var), isolate);
const AstRawString* name = ast_value_factory->GetString(name_handle);
if (!names_seen.insert(name).second) continue;
int index = Context::MIN_CONTEXT_SLOTS + var;
VariableMode mode = scope_info_->ContextLocalMode(var);
InitializationFlag init_flag = scope_info_->ContextLocalInitFlag(var);
MaybeAssignedFlag maybe_assigned_flag =
scope_info_->ContextLocalMaybeAssignedFlag(var);
VariableLocation location = var < scope_info_->ContextLocalCount()
? VariableLocation::CONTEXT
: VariableLocation::GLOBAL;
Variable::Kind kind = Variable::NORMAL;
if (index == scope_info_->ReceiverContextSlotIndex()) {
kind = Variable::THIS;
}
Variable* result = variables_.Declare(zone(), this, name, mode, kind,
init_flag, maybe_assigned_flag);
result->AllocateTo(location, index);
}
// We must read parameters from the end since for multiply declared
// parameters the value of the last declaration of that parameter is used
// inside a function (and thus we need to look at the last index). Was bug#
// 1110337.
for (int index = scope_info_->ParameterCount() - 1; index >= 0; --index) {
Handle<String> name_handle(scope_info_->ParameterName(index), isolate);
const AstRawString* name = ast_value_factory->GetString(name_handle);
if (!names_seen.insert(name).second) continue;
VariableMode mode = DYNAMIC;
InitializationFlag init_flag = kCreatedInitialized;
MaybeAssignedFlag maybe_assigned_flag = kMaybeAssigned;
VariableLocation location = VariableLocation::LOOKUP;
Variable::Kind kind = Variable::NORMAL;
Variable* result = variables_.Declare(zone(), this, name, mode, kind,
init_flag, maybe_assigned_flag);
result->AllocateTo(location, index);
}
// Internalize function proxy for this scope.
if (scope_info_->HasFunctionName()) {
Handle<String> name_handle(scope_info_->FunctionName(), isolate);
const AstRawString* name = ast_value_factory->GetString(name_handle);
VariableMode mode;
int index = scope_info_->FunctionContextSlotIndex(*name_handle, &mode);
if (index >= 0) {
Variable* result = AsDeclarationScope()->DeclareFunctionVar(name);
DCHECK_EQ(mode, result->mode());
result->AllocateTo(VariableLocation::CONTEXT, index);
}
}
scope_info_ = Handle<ScopeInfo>::null();
}
DeclarationScope* Scope::AsDeclarationScope() {
DCHECK(is_declaration_scope());
return static_cast<DeclarationScope*>(this);
}
const DeclarationScope* Scope::AsDeclarationScope() const {
DCHECK(is_declaration_scope());
return static_cast<const DeclarationScope*>(this);
}
ModuleScope* Scope::AsModuleScope() {
DCHECK(is_module_scope());
return static_cast<ModuleScope*>(this);
}
const ModuleScope* Scope::AsModuleScope() const {
DCHECK(is_module_scope());
return static_cast<const ModuleScope*>(this);
}
int Scope::num_parameters() const {
return is_declaration_scope() ? AsDeclarationScope()->num_parameters() : 0;
}
void Scope::Analyze(ParseInfo* info) {
DCHECK(info->literal() != NULL);
DeclarationScope* scope = info->literal()->scope();
// We are compiling one of three cases:
// 1) top-level code,
// 2) a function/eval/module on the top-level
// 3) a function/eval in a scope that was already resolved.
DCHECK(scope->scope_type() == SCRIPT_SCOPE ||
scope->outer_scope()->scope_type() == SCRIPT_SCOPE ||
scope->outer_scope()->already_resolved_);
scope->AllocateVariables(info);
#ifdef DEBUG
if (info->script_is_native() ? FLAG_print_builtin_scopes
: FLAG_print_scopes) {
scope->Print();
}
scope->CheckScopePositions();
scope->CheckZones();
#endif
}
void DeclarationScope::DeclareThis(AstValueFactory* ast_value_factory) {
DCHECK(!already_resolved_);
DCHECK(is_declaration_scope());
DCHECK(has_this_declaration());
bool subclass_constructor = IsSubclassConstructor(function_kind_);
Variable* var = Declare(
zone(), this, ast_value_factory->this_string(),
subclass_constructor ? CONST : VAR, Variable::THIS,
subclass_constructor ? kNeedsInitialization : kCreatedInitialized);
receiver_ = var;
}
void DeclarationScope::DeclareDefaultFunctionVariables(
AstValueFactory* ast_value_factory) {
DCHECK(is_function_scope());
DCHECK(!is_arrow_scope());
// Declare 'arguments' variable which exists in all non arrow functions.
// Note that it might never be accessed, in which case it won't be
// allocated during variable allocation.
arguments_ = Declare(zone(), this, ast_value_factory->arguments_string(), VAR,
Variable::ARGUMENTS, kCreatedInitialized);
new_target_ = Declare(zone(), this, ast_value_factory->new_target_string(),
CONST, Variable::NORMAL, kCreatedInitialized);
if (IsConciseMethod(function_kind_) || IsClassConstructor(function_kind_) ||
IsAccessorFunction(function_kind_)) {
this_function_ =
Declare(zone(), this, ast_value_factory->this_function_string(), CONST,
Variable::NORMAL, kCreatedInitialized);
}
}
Variable* DeclarationScope::DeclareFunctionVar(const AstRawString* name) {
DCHECK(is_function_scope());
DCHECK_NULL(function_);
VariableMode mode = is_strict(language_mode()) ? CONST : CONST_LEGACY;
function_ = new (zone())
Variable(this, name, mode, Variable::NORMAL, kCreatedInitialized);
return function_;
}
Scope* Scope::FinalizeBlockScope() {
DCHECK(is_block_scope());
if (variables_.occupancy() > 0 ||
(is_declaration_scope() && calls_sloppy_eval())) {
return this;
}
// Remove this scope from outer scope.
outer_scope()->RemoveInnerScope(this);
// Reparent inner scopes.
if (inner_scope_ != nullptr) {
Scope* scope = inner_scope_;
scope->outer_scope_ = outer_scope();
while (scope->sibling_ != nullptr) {
scope = scope->sibling_;
scope->outer_scope_ = outer_scope();
}
scope->sibling_ = outer_scope()->inner_scope_;
outer_scope()->inner_scope_ = inner_scope_;
inner_scope_ = nullptr;
}
// Move unresolved variables
if (unresolved_ != nullptr) {
if (outer_scope()->unresolved_ != nullptr) {
VariableProxy* unresolved = unresolved_;
while (unresolved->next_unresolved() != nullptr) {
unresolved = unresolved->next_unresolved();
}
unresolved->set_next_unresolved(outer_scope()->unresolved_);
}
outer_scope()->unresolved_ = unresolved_;
unresolved_ = nullptr;
}
PropagateUsageFlagsToScope(outer_scope_);
// This block does not need a context.
num_heap_slots_ = 0;
return NULL;
}
void Scope::Snapshot::Reparent(DeclarationScope* new_parent) const {
DCHECK_EQ(new_parent, outer_scope_->inner_scope_);
DCHECK_EQ(new_parent->outer_scope_, outer_scope_);
DCHECK_EQ(new_parent, new_parent->GetClosureScope());
DCHECK_NULL(new_parent->inner_scope_);
DCHECK_NULL(new_parent->unresolved_);
DCHECK_EQ(0, new_parent->locals_.length());
Scope* inner_scope = new_parent->sibling_;
if (inner_scope != top_inner_scope_) {
for (; inner_scope->sibling() != top_inner_scope_;
inner_scope = inner_scope->sibling()) {
inner_scope->outer_scope_ = new_parent;
DCHECK_NE(inner_scope, new_parent);
}
inner_scope->outer_scope_ = new_parent;
new_parent->inner_scope_ = new_parent->sibling_;
inner_scope->sibling_ = nullptr;
// Reset the sibling rather than the inner_scope_ since we
// want to keep new_parent there.
new_parent->sibling_ = top_inner_scope_;
}
if (outer_scope_->unresolved_ != top_unresolved_) {
VariableProxy* last = outer_scope_->unresolved_;
while (last->next_unresolved() != top_unresolved_) {
last = last->next_unresolved();
}
last->set_next_unresolved(nullptr);
new_parent->unresolved_ = outer_scope_->unresolved_;
outer_scope_->unresolved_ = top_unresolved_;
}
// TODO(verwaest): This currently only moves do-expression declared variables
// in default arguments that weren't already previously declared with the same
// name in the closure-scope. See
// test/mjsunit/harmony/default-parameter-do-expression.js.
DeclarationScope* outer_closure = outer_scope_->GetClosureScope();
for (int i = top_local_; i < outer_closure->locals_.length(); i++) {
Variable* local = outer_closure->locals_.at(i);
DCHECK(local->mode() == TEMPORARY || local->mode() == VAR);
DCHECK_EQ(local->scope(), local->scope()->GetClosureScope());
DCHECK_NE(local->scope(), new_parent);
local->set_scope(new_parent);
new_parent->AddLocal(local);
if (local->mode() == VAR) {
outer_closure->variables_.Remove(local);
new_parent->variables_.Add(new_parent->zone(), local);
}
}
outer_closure->locals_.Rewind(top_local_);
outer_closure->decls_.Rewind(top_decl_);
}
void Scope::ReplaceOuterScope(Scope* outer) {
DCHECK_NOT_NULL(outer);
DCHECK_NOT_NULL(outer_scope_);
DCHECK(!already_resolved_);
DCHECK(!outer->already_resolved_);
DCHECK(!outer_scope_->already_resolved_);
outer_scope_->RemoveInnerScope(this);
outer->AddInnerScope(this);
outer_scope_ = outer;
}
void Scope::PropagateUsageFlagsToScope(Scope* other) {
DCHECK_NOT_NULL(other);
DCHECK(!already_resolved_);
DCHECK(!other->already_resolved_);
if (calls_eval()) other->RecordEvalCall();
}
Variable* Scope::LookupInScopeInfo(const AstRawString* name) {
Handle<String> name_handle = name->string();
// The Scope is backed up by ScopeInfo. This means it cannot operate in a
// heap-independent mode, and all strings must be internalized immediately. So
// it's ok to get the Handle<String> here.
// If we have a serialized scope info, we might find the variable there.
// There should be no local slot with the given name.
DCHECK(scope_info_->StackSlotIndex(*name_handle) < 0);
VariableMode mode;
InitializationFlag init_flag;
MaybeAssignedFlag maybe_assigned_flag;
VariableLocation location = VariableLocation::CONTEXT;
int index = ScopeInfo::ContextSlotIndex(scope_info_, name_handle, &mode,
&init_flag, &maybe_assigned_flag);
if (index < 0) {
location = VariableLocation::GLOBAL;
index = ScopeInfo::ContextGlobalSlotIndex(scope_info_, name_handle, &mode,
&init_flag, &maybe_assigned_flag);
DCHECK(index < 0 || (is_script_scope() && mode == VAR));
}
if (index < 0) {
location = VariableLocation::LOOKUP;
index = scope_info_->ParameterIndex(*name_handle);
if (index >= 0) {
mode = DYNAMIC;
init_flag = kCreatedInitialized;
// Be conservative and flag parameters as maybe assigned. Better
// information would require ScopeInfo to serialize the maybe_assigned bit
// also for parameters.
maybe_assigned_flag = kMaybeAssigned;
}
}
if (index < 0 && scope_type() == MODULE_SCOPE) {
location = VariableLocation::MODULE;
index = -1; // TODO(neis): Find module variables in scope info.
}
if (index < 0) return nullptr; // Nowhere found.
Variable::Kind kind = Variable::NORMAL;
if (location == VariableLocation::CONTEXT &&
index == scope_info_->ReceiverContextSlotIndex()) {
kind = Variable::THIS;
}
// TODO(marja, rossberg): Correctly declare FUNCTION, CLASS, NEW_TARGET, and
// ARGUMENTS bindings as their corresponding Variable::Kind.
Variable* var = variables_.Declare(zone(), this, name, mode, kind, init_flag,
maybe_assigned_flag);
var->AllocateTo(location, index);
return var;
}
Variable* DeclarationScope::LookupFunctionVar(const AstRawString* name) {
if (function_ != nullptr && function_->raw_name() == name) {
return function_;
} else if (!scope_info_.is_null()) {
// If we are backed by a scope info, try to lookup the variable there.
VariableMode mode;
int index = scope_info_->FunctionContextSlotIndex(*(name->string()), &mode);
if (index < 0) return nullptr;
Variable* var = DeclareFunctionVar(name);
DCHECK_EQ(mode, var->mode());
var->AllocateTo(VariableLocation::CONTEXT, index);
return var;
} else {
return nullptr;
}
}
Variable* Scope::Lookup(const AstRawString* name) {
for (Scope* scope = this;
scope != NULL;
scope = scope->outer_scope()) {
Variable* var = scope->LookupLocal(name);
if (var != NULL) return var;
}
return NULL;
}
Variable* DeclarationScope::DeclareParameter(
const AstRawString* name, VariableMode mode, bool is_optional, bool is_rest,
bool* is_duplicate, AstValueFactory* ast_value_factory) {
DCHECK(!already_resolved_);
DCHECK(is_function_scope());
DCHECK(!has_rest_);
DCHECK(!is_optional || !is_rest);
Variable* var;
if (mode == TEMPORARY) {
var = NewTemporary(name);
} else {
var = Declare(zone(), this, name, mode, Variable::NORMAL,
kCreatedInitialized);
// TODO(wingo): Avoid O(n^2) check.
*is_duplicate = IsDeclaredParameter(name);
}
if (!is_optional && !is_rest && arity_ == params_.length()) {
++arity_;
}
has_rest_ = is_rest;
params_.Add(var, zone());
if (name == ast_value_factory->arguments_string()) {
has_arguments_parameter_ = true;
}
return var;
}
Variable* Scope::DeclareLocal(const AstRawString* name, VariableMode mode,
InitializationFlag init_flag, Variable::Kind kind,
MaybeAssignedFlag maybe_assigned_flag) {
DCHECK(!already_resolved_);
// This function handles VAR, LET, and CONST modes. DYNAMIC variables are
// introduced during variable allocation, and TEMPORARY variables are
// allocated via NewTemporary().
DCHECK(IsDeclaredVariableMode(mode));
return Declare(zone(), this, name, mode, kind, init_flag,
maybe_assigned_flag);
}
Variable* DeclarationScope::DeclareDynamicGlobal(const AstRawString* name,
Variable::Kind kind) {
DCHECK(is_script_scope());
return variables_.Declare(zone(), this, name, DYNAMIC_GLOBAL, kind,
kCreatedInitialized);
}
bool Scope::RemoveUnresolved(VariableProxy* var) {
if (unresolved_ == var) {
unresolved_ = var->next_unresolved();
var->set_next_unresolved(nullptr);
return true;
}
VariableProxy* current = unresolved_;
while (current != nullptr) {
VariableProxy* next = current->next_unresolved();
if (var == next) {
current->set_next_unresolved(next->next_unresolved());
var->set_next_unresolved(nullptr);
return true;
}
current = next;
}
return false;
}
Variable* Scope::NewTemporary(const AstRawString* name) {
DeclarationScope* scope = GetClosureScope();
Variable* var = new(zone()) Variable(scope,
name,
TEMPORARY,
Variable::NORMAL,
kCreatedInitialized);
scope->AddLocal(var);
return var;
}
void Scope::AddDeclaration(Declaration* declaration) {
DCHECK(!already_resolved_);
decls_.Add(declaration, zone());
}
Declaration* Scope::CheckConflictingVarDeclarations() {
int length = decls_.length();
for (int i = 0; i < length; i++) {
Declaration* decl = decls_[i];
VariableMode mode = decl->proxy()->var()->mode();
if (IsLexicalVariableMode(mode) && !is_block_scope()) continue;
// Iterate through all scopes until and including the declaration scope.
Scope* previous = NULL;
Scope* current = decl->scope();
// Lexical vs lexical conflicts within the same scope have already been
// captured in Parser::Declare. The only conflicts we still need to check
// are lexical vs VAR, or any declarations within a declaration block scope
// vs lexical declarations in its surrounding (function) scope.
if (IsLexicalVariableMode(mode)) current = current->outer_scope_;
do {
// There is a conflict if there exists a non-VAR binding.
Variable* other_var =
current->variables_.Lookup(decl->proxy()->raw_name());
if (other_var != NULL && IsLexicalVariableMode(other_var->mode())) {
return decl;
}
previous = current;
current = current->outer_scope_;
} while (!previous->is_declaration_scope());
}
return NULL;
}
Declaration* Scope::CheckLexDeclarationsConflictingWith(
const ZoneList<const AstRawString*>& names) {
DCHECK(is_block_scope());
for (int i = 0; i < names.length(); ++i) {
Variable* var = LookupLocal(names.at(i));
if (var != nullptr) {
// Conflict; find and return its declaration.
DCHECK(IsLexicalVariableMode(var->mode()));
const AstRawString* name = names.at(i);
for (int j = 0; j < decls_.length(); ++j) {
if (decls_[j]->proxy()->raw_name() == name) {
return decls_[j];
}
}
DCHECK(false);
}
}
return nullptr;
}
void Scope::CollectVariables(ZoneList<Variable*>* stack_locals,
ZoneList<Variable*>* context_locals,
ZoneList<Variable*>* context_globals) {
// TODO(verwaest): Just pass out locals_ directly and walk it?
DCHECK_NOT_NULL(stack_locals);
DCHECK_NOT_NULL(context_locals);
DCHECK_NOT_NULL(context_globals);
for (int i = 0; i < locals_.length(); i++) {
Variable* var = locals_[i];
if (var->IsStackLocal()) {
stack_locals->Add(var, zone());
} else if (var->IsContextSlot()) {
context_locals->Add(var, zone());
} else if (var->IsGlobalSlot()) {
context_globals->Add(var, zone());
}
}
}
void DeclarationScope::AllocateVariables(ParseInfo* info) {
// 1) Propagate scope information.
PropagateScopeInfo();
// 2) Resolve variables.
ResolveVariablesRecursively(info);
// 3) Allocate variables.
AllocateVariablesRecursively();
}
bool Scope::AllowsLazyParsing() const {
// If we are inside a block scope, we must parse eagerly to find out how
// to allocate variables on the block scope. At this point, declarations may
// not have yet been parsed.
for (const Scope* s = this; s != nullptr; s = s->outer_scope_) {
if (s->is_block_scope()) return false;
}
return true;
}
bool DeclarationScope::AllowsLazyCompilation() const {
return !force_eager_compilation_;
}
bool DeclarationScope::AllowsLazyCompilationWithoutContext() const {
if (force_eager_compilation_) return false;
// Disallow lazy compilation without context if any outer scope needs a
// context.
for (const Scope* scope = outer_scope_; scope != nullptr;
scope = scope->outer_scope_) {
if (scope->NeedsContext()) return false;
}
return true;
}
int Scope::ContextChainLength(Scope* scope) const {
int n = 0;
for (const Scope* s = this; s != scope; s = s->outer_scope_) {
DCHECK(s != NULL); // scope must be in the scope chain
if (s->NeedsContext()) n++;
}
return n;
}
int Scope::ContextChainLengthUntilOutermostSloppyEval() const {
int result = 0;
int length = 0;
for (const Scope* s = this; s != nullptr; s = s->outer_scope()) {
if (!s->NeedsContext()) continue;
length++;
if (s->calls_sloppy_eval()) result = length;
}
return result;
}
int Scope::MaxNestedContextChainLength() {
int max_context_chain_length = 0;
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
max_context_chain_length = std::max(scope->MaxNestedContextChainLength(),
max_context_chain_length);
}
if (NeedsContext()) {
max_context_chain_length += 1;
}
return max_context_chain_length;
}
DeclarationScope* Scope::GetDeclarationScope() {
Scope* scope = this;
while (!scope->is_declaration_scope()) {
scope = scope->outer_scope();
}
return scope->AsDeclarationScope();
}
DeclarationScope* Scope::GetClosureScope() {
Scope* scope = this;
while (!scope->is_declaration_scope() || scope->is_block_scope()) {
scope = scope->outer_scope();
}
return scope->AsDeclarationScope();
}
DeclarationScope* Scope::GetReceiverScope() {
Scope* scope = this;
while (!scope->is_script_scope() &&
(!scope->is_function_scope() ||
scope->AsDeclarationScope()->is_arrow_scope())) {
scope = scope->outer_scope();
}
return scope->AsDeclarationScope();
}
Handle<ScopeInfo> Scope::GetScopeInfo(Isolate* isolate) {
if (scope_info_.is_null()) {
scope_info_ = ScopeInfo::Create(isolate, zone(), this);
}
return scope_info_;
}
Handle<StringSet> DeclarationScope::CollectNonLocals(
ParseInfo* info, Handle<StringSet> non_locals) {
VariableProxy* free_variables = FetchFreeVariables(this, info);
for (VariableProxy* proxy = free_variables; proxy != nullptr;
proxy = proxy->next_unresolved()) {
non_locals = StringSet::Add(non_locals, proxy->name());
}
return non_locals;
}
void DeclarationScope::AnalyzePartially(DeclarationScope* migrate_to,
AstNodeFactory* ast_node_factory) {
// Gather info from inner scopes.
PropagateScopeInfo();
// Try to resolve unresolved variables for this Scope and migrate those which
// cannot be resolved inside. It doesn't make sense to try to resolve them in
// the outer Scopes here, because they are incomplete.
for (VariableProxy* proxy = FetchFreeVariables(this); proxy != nullptr;
proxy = proxy->next_unresolved()) {
DCHECK(!proxy->is_resolved());
VariableProxy* copy = ast_node_factory->CopyVariableProxy(proxy);
migrate_to->AddUnresolved(copy);
}
// Push scope data up to migrate_to. Note that migrate_to and this Scope
// describe the same Scope, just in different Zones.
PropagateUsageFlagsToScope(migrate_to);
if (scope_uses_super_property_) migrate_to->scope_uses_super_property_ = true;
if (inner_scope_calls_eval_) migrate_to->inner_scope_calls_eval_ = true;
DCHECK(!force_eager_compilation_);
migrate_to->set_start_position(start_position_);
migrate_to->set_end_position(end_position_);
migrate_to->set_language_mode(language_mode());
migrate_to->arity_ = arity_;
migrate_to->force_context_allocation_ = force_context_allocation_;
outer_scope_->RemoveInnerScope(this);
DCHECK_EQ(outer_scope_, migrate_to->outer_scope_);
DCHECK_EQ(outer_scope_->zone(), migrate_to->zone());
DCHECK_EQ(NeedsHomeObject(), migrate_to->NeedsHomeObject());
DCHECK_EQ(asm_function_, migrate_to->asm_function_);
DCHECK_EQ(arguments() != nullptr, migrate_to->arguments() != nullptr);
}
#ifdef DEBUG
static const char* Header(ScopeType scope_type, FunctionKind function_kind,
bool is_declaration_scope) {
switch (scope_type) {
case EVAL_SCOPE: return "eval";
// TODO(adamk): Should we print concise method scopes specially?
case FUNCTION_SCOPE:
if (IsGeneratorFunction(function_kind)) return "function*";
if (IsAsyncFunction(function_kind)) return "async function";
if (IsArrowFunction(function_kind)) return "arrow";
return "function";
case MODULE_SCOPE: return "module";
case SCRIPT_SCOPE: return "global";
case CATCH_SCOPE: return "catch";
case BLOCK_SCOPE: return is_declaration_scope ? "varblock" : "block";
case WITH_SCOPE: return "with";
}
UNREACHABLE();
return NULL;
}
static void Indent(int n, const char* str) {
PrintF("%*s%s", n, "", str);
}
static void PrintName(const AstRawString* name) {
PrintF("%.*s", name->length(), name->raw_data());
}
static void PrintLocation(Variable* var) {
switch (var->location()) {
case VariableLocation::UNALLOCATED:
break;
case VariableLocation::PARAMETER:
PrintF("parameter[%d]", var->index());
break;
case VariableLocation::LOCAL:
PrintF("local[%d]", var->index());
break;
case VariableLocation::CONTEXT:
PrintF("context[%d]", var->index());
break;
case VariableLocation::GLOBAL:
PrintF("global[%d]", var->index());
break;
case VariableLocation::LOOKUP:
PrintF("lookup");
break;
case VariableLocation::MODULE:
PrintF("module");
break;
}
}
static void PrintVar(int indent, Variable* var) {
if (var->is_used() || !var->IsUnallocated()) {
Indent(indent, Variable::Mode2String(var->mode()));
PrintF(" ");
if (var->raw_name()->IsEmpty())
PrintF(".%p", reinterpret_cast<void*>(var));
else
PrintName(var->raw_name());
PrintF("; // ");
PrintLocation(var);
bool comma = !var->IsUnallocated();
if (var->has_forced_context_allocation()) {
if (comma) PrintF(", ");
PrintF("forced context allocation");
comma = true;
}
if (var->maybe_assigned() == kMaybeAssigned) {
if (comma) PrintF(", ");
PrintF("maybe assigned");
}
PrintF("\n");
}
}
static void PrintMap(int indent, VariableMap* map, bool locals) {
for (VariableMap::Entry* p = map->Start(); p != nullptr; p = map->Next(p)) {
Variable* var = reinterpret_cast<Variable*>(p->value);
bool local = !IsDynamicVariableMode(var->mode());
if (locals ? local : !local) {
if (var == nullptr) {
Indent(indent, "<?>\n");
} else {
PrintVar(indent, var);
}
}
}
}
void DeclarationScope::PrintParameters() {
PrintF(" (");
for (int i = 0; i < params_.length(); i++) {
if (i > 0) PrintF(", ");
const AstRawString* name = params_[i]->raw_name();
if (name->IsEmpty())
PrintF(".%p", reinterpret_cast<void*>(params_[i]));
else
PrintName(name);
}
PrintF(")");
}
void Scope::Print(int n) {
int n0 = (n > 0 ? n : 0);
int n1 = n0 + 2; // indentation
// Print header.
FunctionKind function_kind = is_function_scope()
? AsDeclarationScope()->function_kind()
: kNormalFunction;
Indent(n0, Header(scope_type_, function_kind, is_declaration_scope()));
if (scope_name_ != nullptr && !scope_name_->IsEmpty()) {
PrintF(" ");
PrintName(scope_name_);
}
// Print parameters, if any.
Variable* function = nullptr;
if (is_function_scope()) {
AsDeclarationScope()->PrintParameters();
function = AsDeclarationScope()->function_var();
}
PrintF(" { // (%d, %d)\n", start_position(), end_position());
// Function name, if any (named function literals, only).
if (function != nullptr) {
Indent(n1, "// (local) function name: ");
PrintName(function->raw_name());
PrintF("\n");
}
// Scope info.
if (is_strict(language_mode())) {
Indent(n1, "// strict mode scope\n");
}
if (IsAsmModule()) Indent(n1, "// scope is an asm module\n");
if (IsAsmFunction()) Indent(n1, "// scope is an asm function\n");
if (scope_calls_eval_) Indent(n1, "// scope calls 'eval'\n");
if (is_declaration_scope() && AsDeclarationScope()->uses_super_property()) {
Indent(n1, "// scope uses 'super' property\n");
}
if (inner_scope_calls_eval_) Indent(n1, "// inner scope calls 'eval'\n");
if (num_stack_slots_ > 0) {
Indent(n1, "// ");
PrintF("%d stack slots\n", num_stack_slots_);
}
if (num_heap_slots_ > 0) {
Indent(n1, "// ");
PrintF("%d heap slots (including %d global slots)\n", num_heap_slots_,
num_global_slots_);
}
// Print locals.
if (function != nullptr) {
Indent(n1, "// function var:\n");
PrintVar(n1, function);
}
if (variables_.Start() != NULL) {
Indent(n1, "// local vars:\n");
PrintMap(n1, &variables_, true);
Indent(n1, "// dynamic vars:\n");
PrintMap(n1, &variables_, false);
}
// Print inner scopes (disable by providing negative n).
if (n >= 0) {
for (Scope* scope = inner_scope_; scope != nullptr;
scope = scope->sibling_) {
PrintF("\n");
scope->Print(n1);
}
}
Indent(n0, "}\n");
}
void Scope::CheckScopePositions() {
// A scope is allowed to have invalid positions if it is hidden and has no
// inner scopes
if (!is_hidden() && inner_scope_ == nullptr) {
CHECK_NE(kNoSourcePosition, start_position());
CHECK_NE(kNoSourcePosition, end_position());
}
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
scope->CheckScopePositions();
}
}
void Scope::CheckZones() {
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
CHECK_EQ(scope->zone(), zone());
}
}
#endif // DEBUG
Variable* Scope::NonLocal(const AstRawString* name, VariableMode mode) {
// Declare a new non-local.
DCHECK(IsDynamicVariableMode(mode));
Variable* var = variables_.Declare(zone(), NULL, name, mode, Variable::NORMAL,
kCreatedInitialized);
// Allocate it by giving it a dynamic lookup.
var->AllocateTo(VariableLocation::LOOKUP, -1);
return var;
}
Variable* Scope::LookupRecursive(VariableProxy* proxy, bool declare_free,
Scope* outer_scope_end) {
DCHECK_NE(outer_scope_end, this);
// Short-cut: whenever we find a debug-evaluate scope, just look everything up
// dynamically. Debug-evaluate doesn't properly create scope info for the
// lookups it does. It may not have a valid 'this' declaration, and anything
// accessed through debug-evaluate might invalidly resolve to stack-allocated
// variables.
// TODO(yangguo): Remove once debug-evaluate creates proper ScopeInfo for the
// scopes in which it's evaluating.
if (is_debug_evaluate_scope_) {
if (!declare_free) return nullptr;
return NonLocal(proxy->raw_name(), DYNAMIC);
}
// Try to find the variable in this scope.
Variable* var = LookupLocal(proxy->raw_name());
// We found a variable and we are done. (Even if there is an 'eval' in this
// scope which introduces the same variable again, the resulting variable
// remains the same.)
if (var != nullptr) return var;
// We did not find a variable locally. Check against the function variable, if
// any.
if (is_function_scope()) {
var = AsDeclarationScope()->LookupFunctionVar(proxy->raw_name());
if (var != nullptr) {
if (calls_sloppy_eval()) return NonLocal(proxy->raw_name(), DYNAMIC);
return var;
}
}
if (outer_scope_ == outer_scope_end) {
if (!declare_free) return nullptr;
DCHECK(is_script_scope());
// No binding has been found. Declare a variable on the global object.
return AsDeclarationScope()->DeclareDynamicGlobal(proxy->raw_name(),
Variable::NORMAL);
}
DCHECK(!is_script_scope());
var = outer_scope_->LookupRecursive(proxy, declare_free, outer_scope_end);
// The variable could not be resolved statically.
if (var == nullptr) return var;
if (is_function_scope() && !var->is_dynamic()) {
var->ForceContextAllocation();
}
// "this" can't be shadowed by "eval"-introduced bindings or by "with"
// scopes.
// TODO(wingo): There are other variables in this category; add them.
if (var->is_this()) return var;
if (is_with_scope()) {
// The current scope is a with scope, so the variable binding can not be
// statically resolved. However, note that it was necessary to do a lookup
// in the outer scope anyway, because if a binding exists in an outer
// scope, the associated variable has to be marked as potentially being
// accessed from inside of an inner with scope (the property may not be in
// the 'with' object).
if (!var->is_dynamic() && var->IsUnallocated()) {
DCHECK(!already_resolved_);
var->set_is_used();
var->ForceContextAllocation();
if (proxy->is_assigned()) var->set_maybe_assigned();
}
return NonLocal(proxy->raw_name(), DYNAMIC);
}
if (calls_sloppy_eval() && is_declaration_scope()) {
// A variable binding may have been found in an outer scope, but the current
// scope makes a sloppy 'eval' call, so the found variable may not be the
// correct one (the 'eval' may introduce a binding with the same name). In
// that case, change the lookup result to reflect this situation. Only
// scopes that can host var bindings (declaration scopes) need be considered
// here (this excludes block and catch scopes), and variable lookups at
// script scope are always dynamic.
if (var->IsGlobalObjectProperty()) {
return NonLocal(proxy->raw_name(), DYNAMIC_GLOBAL);
}
if (var->is_dynamic()) return var;
Variable* invalidated = var;
var = NonLocal(proxy->raw_name(), DYNAMIC_LOCAL);
var->set_local_if_not_shadowed(invalidated);
}
return var;
}
void Scope::ResolveVariable(ParseInfo* info, VariableProxy* proxy) {
DCHECK(info->script_scope()->is_script_scope());
// If the proxy is already resolved there's nothing to do
// (functions and consts may be resolved by the parser).
if (proxy->is_resolved()) return;
// Otherwise, try to resolve the variable.
Variable* var = LookupRecursive(proxy, true, nullptr);
ResolveTo(info, proxy, var);
}
void Scope::ResolveTo(ParseInfo* info, VariableProxy* proxy, Variable* var) {
#ifdef DEBUG
if (info->script_is_native()) {
// To avoid polluting the global object in native scripts
// - Variables must not be allocated to the global scope.
CHECK_NOT_NULL(outer_scope());
// - Variables must be bound locally or unallocated.
if (var->IsGlobalObjectProperty()) {
// The following variable name may be minified. If so, disable
// minification in js2c.py for better output.
Handle<String> name = proxy->raw_name()->string();
V8_Fatal(__FILE__, __LINE__, "Unbound variable: '%s' in native script.",
name->ToCString().get());
}
VariableLocation location = var->location();
CHECK(location == VariableLocation::LOCAL ||
location == VariableLocation::CONTEXT ||
location == VariableLocation::PARAMETER ||
location == VariableLocation::UNALLOCATED);
}
#endif
DCHECK_NOT_NULL(var);
if (proxy->is_assigned()) var->set_maybe_assigned();
proxy->BindTo(var);
}
void Scope::ResolveVariablesRecursively(ParseInfo* info) {
DCHECK(info->script_scope()->is_script_scope());
// Resolve unresolved variables for this scope.
for (VariableProxy* proxy = unresolved_; proxy != nullptr;
proxy = proxy->next_unresolved()) {
ResolveVariable(info, proxy);
}
// Resolve unresolved variables for inner scopes.
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
scope->ResolveVariablesRecursively(info);
}
}
VariableProxy* Scope::FetchFreeVariables(DeclarationScope* max_outer_scope,
ParseInfo* info,
VariableProxy* stack) {
for (VariableProxy *proxy = unresolved_, *next = nullptr; proxy != nullptr;
proxy = next) {
next = proxy->next_unresolved();
if (proxy->is_resolved()) continue;
Variable* var =
LookupRecursive(proxy, false, max_outer_scope->outer_scope());
if (var == nullptr) {
proxy->set_next_unresolved(stack);
stack = proxy;
} else if (info != nullptr) {
ResolveTo(info, proxy, var);
}
}
// Clear unresolved_ as it's in an inconsistent state.
unresolved_ = nullptr;
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
stack = scope->FetchFreeVariables(max_outer_scope, info, stack);
}
return stack;
}
void Scope::PropagateScopeInfo() {
for (Scope* inner = inner_scope_; inner != nullptr; inner = inner->sibling_) {
inner->PropagateScopeInfo();
if (IsAsmModule() && inner->is_function_scope()) {
inner->AsDeclarationScope()->set_asm_function();
}
}
}
bool Scope::MustAllocate(Variable* var) {
DCHECK(var->location() != VariableLocation::MODULE);
// Give var a read/write use if there is a chance it might be accessed
// via an eval() call. This is only possible if the variable has a
// visible name.
if ((var->is_this() || !var->raw_name()->IsEmpty()) &&
(inner_scope_calls_eval_ || is_catch_scope() || is_script_scope())) {
var->set_is_used();
if (inner_scope_calls_eval_) var->set_maybe_assigned();
}
DCHECK(!var->has_forced_context_allocation() || var->is_used());
// Global variables do not need to be allocated.
return !var->IsGlobalObjectProperty() && var->is_used();
}
bool Scope::MustAllocateInContext(Variable* var) {
// If var is accessed from an inner scope, or if there is a possibility
// that it might be accessed from the current or an inner scope (through
// an eval() call or a runtime with lookup), it must be allocated in the
// context.
//
// Exceptions: If the scope as a whole has forced context allocation, all
// variables will have context allocation, even temporaries. Otherwise
// temporary variables are always stack-allocated. Catch-bound variables are
// always context-allocated.
if (has_forced_context_allocation()) return true;
if (var->mode() == TEMPORARY) return false;
if (is_catch_scope()) return true;
if (is_script_scope() && IsLexicalVariableMode(var->mode())) return true;
return var->has_forced_context_allocation() || inner_scope_calls_eval_;
}
void Scope::AllocateStackSlot(Variable* var) {
if (is_block_scope()) {
outer_scope()->GetDeclarationScope()->AllocateStackSlot(var);
} else {
var->AllocateTo(VariableLocation::LOCAL, num_stack_slots_++);
}
}
void Scope::AllocateHeapSlot(Variable* var) {
var->AllocateTo(VariableLocation::CONTEXT, num_heap_slots_++);
}
void DeclarationScope::AllocateParameterLocals() {
DCHECK(is_function_scope());
bool uses_sloppy_arguments = false;
// Functions have 'arguments' declared implicitly in all non arrow functions.
if (arguments_ != nullptr) {
// 'arguments' is used. Unless there is also a parameter called
// 'arguments', we must be conservative and allocate all parameters to
// the context assuming they will be captured by the arguments object.
// If we have a parameter named 'arguments', a (new) value is always
// assigned to it via the function invocation. Then 'arguments' denotes
// that specific parameter value and cannot be used to access the
// parameters, which is why we don't need to allocate an arguments
// object in that case.
if (MustAllocate(arguments_) && !has_arguments_parameter_) {
// In strict mode 'arguments' does not alias formal parameters.
// Therefore in strict mode we allocate parameters as if 'arguments'
// were not used.
// If the parameter list is not simple, arguments isn't sloppy either.
uses_sloppy_arguments =
is_sloppy(language_mode()) && has_simple_parameters();
} else {
// 'arguments' is unused. Tell the code generator that it does not need to
// allocate the arguments object by nulling out arguments_.
arguments_ = nullptr;
}
} else {
DCHECK(is_arrow_scope());
}
// The same parameter may occur multiple times in the parameters_ list.
// If it does, and if it is not copied into the context object, it must
// receive the highest parameter index for that parameter; thus iteration
// order is relevant!
for (int i = num_parameters() - 1; i >= 0; --i) {
Variable* var = params_[i];
DCHECK(!has_rest_ || var != rest_parameter());
DCHECK_EQ(this, var->scope());
if (uses_sloppy_arguments) {
var->ForceContextAllocation();
}
AllocateParameter(var, i);
}
}
void DeclarationScope::AllocateParameter(Variable* var, int index) {
if (MustAllocate(var)) {
if (MustAllocateInContext(var)) {
DCHECK(var->IsUnallocated() || var->IsContextSlot());
if (var->IsUnallocated()) {
AllocateHeapSlot(var);
}
} else {
DCHECK(var->IsUnallocated() || var->IsParameter());
if (var->IsUnallocated()) {
var->AllocateTo(VariableLocation::PARAMETER, index);
}
}
} else {
DCHECK(!var->IsGlobalSlot());
}
}
void DeclarationScope::AllocateReceiver() {
if (!has_this_declaration()) return;
DCHECK_NOT_NULL(receiver());
DCHECK_EQ(receiver()->scope(), this);
AllocateParameter(receiver(), -1);
}
void Scope::AllocateNonParameterLocal(Variable* var) {
DCHECK(var->scope() == this);
if (var->IsUnallocated() && MustAllocate(var)) {
if (MustAllocateInContext(var)) {
AllocateHeapSlot(var);
} else {
AllocateStackSlot(var);
}
}
}
void Scope::AllocateDeclaredGlobal(Variable* var) {
DCHECK(var->scope() == this);
if (var->IsUnallocated()) {
if (var->IsStaticGlobalObjectProperty()) {
DCHECK_EQ(-1, var->index());
DCHECK(var->name()->IsString());
var->AllocateTo(VariableLocation::GLOBAL, num_heap_slots_++);
num_global_slots_++;
} else {
// There must be only DYNAMIC_GLOBAL in the script scope.
DCHECK(!is_script_scope() || DYNAMIC_GLOBAL == var->mode());
}
}
}
void Scope::AllocateNonParameterLocalsAndDeclaredGlobals() {
for (int i = 0; i < locals_.length(); i++) {
AllocateNonParameterLocal(locals_[i]);
}
if (FLAG_global_var_shortcuts) {
for (int i = 0; i < locals_.length(); i++) {
AllocateDeclaredGlobal(locals_[i]);
}
}
if (is_declaration_scope()) {
AsDeclarationScope()->AllocateLocals();
}
}
void DeclarationScope::AllocateLocals() {
// For now, function_ must be allocated at the very end. If it gets
// allocated in the context, it must be the last slot in the context,
// because of the current ScopeInfo implementation (see
// ScopeInfo::ScopeInfo(FunctionScope* scope) constructor).
if (function_ != nullptr) {
AllocateNonParameterLocal(function_);
}
DCHECK(!has_rest_ || !MustAllocate(rest_parameter()) ||
!rest_parameter()->IsUnallocated());
if (new_target_ != nullptr && !MustAllocate(new_target_)) {
new_target_ = nullptr;
}
if (this_function_ != nullptr && !MustAllocate(this_function_)) {
this_function_ = nullptr;
}
}
void ModuleScope::AllocateModuleVariables() {
for (const auto& it : module()->regular_imports()) {
Variable* var = LookupLocal(it.first);
// TODO(neis): Use a meaningful index.
var->AllocateTo(VariableLocation::MODULE, 42);
}
for (const auto& it : module()->regular_exports()) {
Variable* var = LookupLocal(it.first);
var->AllocateTo(VariableLocation::MODULE, 0);
}
}
void Scope::AllocateVariablesRecursively() {
DCHECK(!already_resolved_);
DCHECK_EQ(0, num_stack_slots_);
// Allocate variables for inner scopes.
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
scope->AllocateVariablesRecursively();
}
DCHECK(!already_resolved_);
DCHECK_EQ(Context::MIN_CONTEXT_SLOTS, num_heap_slots_);
// Allocate variables for this scope.
// Parameters must be allocated first, if any.
if (is_declaration_scope()) {
if (is_module_scope()) {
AsModuleScope()->AllocateModuleVariables();
} else if (is_function_scope()) {
AsDeclarationScope()->AllocateParameterLocals();
}
AsDeclarationScope()->AllocateReceiver();
}
AllocateNonParameterLocalsAndDeclaredGlobals();
// Force allocation of a context for this scope if necessary. For a 'with'
// scope and for a function scope that makes an 'eval' call we need a context,
// even if no local variables were statically allocated in the scope.
// Likewise for modules.
bool must_have_context =
is_with_scope() || is_module_scope() ||
(is_function_scope() && calls_sloppy_eval()) ||
(is_block_scope() && is_declaration_scope() && calls_sloppy_eval());
// If we didn't allocate any locals in the local context, then we only
// need the minimal number of slots if we must have a context.
if (num_heap_slots_ == Context::MIN_CONTEXT_SLOTS && !must_have_context) {
num_heap_slots_ = 0;
}
// Allocation done.
DCHECK(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS);
}
int Scope::StackLocalCount() const {
Variable* function =
is_function_scope() ? AsDeclarationScope()->function_var() : nullptr;
return num_stack_slots() -
(function != nullptr && function->IsStackLocal() ? 1 : 0);
}
int Scope::ContextLocalCount() const {
if (num_heap_slots() == 0) return 0;
Variable* function =
is_function_scope() ? AsDeclarationScope()->function_var() : nullptr;
bool is_function_var_in_context =
function != nullptr && function->IsContextSlot();
return num_heap_slots() - Context::MIN_CONTEXT_SLOTS - num_global_slots() -
(is_function_var_in_context ? 1 : 0);
}
int Scope::ContextGlobalCount() const { return num_global_slots(); }
} // namespace internal
} // namespace v8