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// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "v8.h"
#include "scopes.h"
#include "bootstrapper.h"
#include "compiler.h"
#include "messages.h"
#include "scopeinfo.h"
#include "allocation-inl.h"
namespace v8 {
namespace internal {
// ----------------------------------------------------------------------------
// A Zone allocator for use with LocalsMap.
// TODO(isolates): It is probably worth it to change the Allocator class to
// take a pointer to an isolate.
class ZoneAllocator: public Allocator {
public:
/* nothing to do */
virtual ~ZoneAllocator() {}
virtual void* New(size_t size) { return ZONE->New(static_cast<int>(size)); }
/* ignored - Zone is freed in one fell swoop */
virtual void Delete(void* p) {}
};
static ZoneAllocator* LocalsMapAllocator = ::new ZoneAllocator();
// ----------------------------------------------------------------------------
// 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.
static bool Match(void* key1, void* key2) {
String* name1 = *reinterpret_cast<String**>(key1);
String* name2 = *reinterpret_cast<String**>(key2);
ASSERT(name1->IsSymbol());
ASSERT(name2->IsSymbol());
return name1 == name2;
}
VariableMap::VariableMap() : HashMap(Match, LocalsMapAllocator, 8) {}
VariableMap::~VariableMap() {}
Variable* VariableMap::Declare(
Scope* scope,
Handle<String> name,
VariableMode mode,
bool is_valid_lhs,
Variable::Kind kind,
InitializationFlag initialization_flag) {
HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), true);
if (p->value == NULL) {
// The variable has not been declared yet -> insert it.
ASSERT(p->key == name.location());
p->value = new Variable(scope,
name,
mode,
is_valid_lhs,
kind,
initialization_flag);
}
return reinterpret_cast<Variable*>(p->value);
}
Variable* VariableMap::Lookup(Handle<String> name) {
HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), false);
if (p != NULL) {
ASSERT(*reinterpret_cast<String**>(p->key) == *name);
ASSERT(p->value != NULL);
return reinterpret_cast<Variable*>(p->value);
}
return NULL;
}
// ----------------------------------------------------------------------------
// Implementation of Scope
Scope::Scope(Scope* outer_scope, ScopeType type)
: isolate_(Isolate::Current()),
inner_scopes_(4),
variables_(),
temps_(4),
params_(4),
unresolved_(16),
decls_(4),
already_resolved_(false) {
SetDefaults(type, outer_scope, Handle<ScopeInfo>::null());
// At some point we might want to provide outer scopes to
// eval scopes (by walking the stack and reading the scope info).
// In that case, the ASSERT below needs to be adjusted.
ASSERT_EQ(type == GLOBAL_SCOPE, outer_scope == NULL);
ASSERT(!HasIllegalRedeclaration());
}
Scope::Scope(Scope* inner_scope,
ScopeType type,
Handle<ScopeInfo> scope_info)
: isolate_(Isolate::Current()),
inner_scopes_(4),
variables_(),
temps_(4),
params_(4),
unresolved_(16),
decls_(4),
already_resolved_(true) {
SetDefaults(type, NULL, scope_info);
if (!scope_info.is_null()) {
num_heap_slots_ = scope_info_->ContextLength();
}
// Ensure at least MIN_CONTEXT_SLOTS to indicate a materialized context.
num_heap_slots_ = Max(num_heap_slots_,
static_cast<int>(Context::MIN_CONTEXT_SLOTS));
AddInnerScope(inner_scope);
}
Scope::Scope(Scope* inner_scope, Handle<String> catch_variable_name)
: isolate_(Isolate::Current()),
inner_scopes_(1),
variables_(),
temps_(0),
params_(0),
unresolved_(0),
decls_(0),
already_resolved_(true) {
SetDefaults(CATCH_SCOPE, NULL, Handle<ScopeInfo>::null());
AddInnerScope(inner_scope);
++num_var_or_const_;
num_heap_slots_ = Context::MIN_CONTEXT_SLOTS;
Variable* variable = variables_.Declare(this,
catch_variable_name,
VAR,
true, // Valid left-hand side.
Variable::NORMAL,
kCreatedInitialized);
AllocateHeapSlot(variable);
}
void Scope::SetDefaults(ScopeType type,
Scope* outer_scope,
Handle<ScopeInfo> scope_info) {
outer_scope_ = outer_scope;
type_ = type;
scope_name_ = isolate_->factory()->empty_symbol();
dynamics_ = NULL;
receiver_ = NULL;
function_ = NULL;
arguments_ = NULL;
illegal_redecl_ = NULL;
scope_inside_with_ = false;
scope_contains_with_ = false;
scope_calls_eval_ = false;
// Inherit the strict mode from the parent scope.
language_mode_ = (outer_scope != NULL)
? outer_scope->language_mode_ : CLASSIC_MODE;
outer_scope_calls_non_strict_eval_ = false;
inner_scope_calls_eval_ = false;
force_eager_compilation_ = false;
num_var_or_const_ = 0;
num_stack_slots_ = 0;
num_heap_slots_ = 0;
scope_info_ = scope_info;
start_position_ = RelocInfo::kNoPosition;
end_position_ = RelocInfo::kNoPosition;
if (!scope_info.is_null()) {
scope_calls_eval_ = scope_info->CallsEval();
language_mode_ = scope_info->language_mode();
}
}
Scope* Scope::DeserializeScopeChain(Context* context, Scope* global_scope) {
// Reconstruct the outer scope chain from a closure's context chain.
Scope* current_scope = NULL;
Scope* innermost_scope = NULL;
bool contains_with = false;
while (!context->IsGlobalContext()) {
if (context->IsWithContext()) {
Scope* with_scope = new Scope(current_scope,
WITH_SCOPE,
Handle<ScopeInfo>::null());
current_scope = with_scope;
// All the inner scopes are inside a with.
contains_with = true;
for (Scope* s = innermost_scope; s != NULL; s = s->outer_scope()) {
s->scope_inside_with_ = true;
}
} else if (context->IsFunctionContext()) {
ScopeInfo* scope_info = context->closure()->shared()->scope_info();
current_scope = new Scope(current_scope,
FUNCTION_SCOPE,
Handle<ScopeInfo>(scope_info));
} else if (context->IsBlockContext()) {
ScopeInfo* scope_info = ScopeInfo::cast(context->extension());
current_scope = new Scope(current_scope,
BLOCK_SCOPE,
Handle<ScopeInfo>(scope_info));
} else {
ASSERT(context->IsCatchContext());
String* name = String::cast(context->extension());
current_scope = new Scope(current_scope, Handle<String>(name));
}
if (contains_with) current_scope->RecordWithStatement();
if (innermost_scope == NULL) innermost_scope = current_scope;
// Forget about a with when we move to a context for a different function.
if (context->previous()->closure() != context->closure()) {
contains_with = false;
}
context = context->previous();
}
global_scope->AddInnerScope(current_scope);
global_scope->PropagateScopeInfo(false);
return (innermost_scope == NULL) ? global_scope : innermost_scope;
}
bool Scope::Analyze(CompilationInfo* info) {
ASSERT(info->function() != NULL);
Scope* scope = info->function()->scope();
Scope* top = scope;
// Traverse the scope tree up to the first unresolved scope or the global
// scope and start scope resolution and variable allocation from that scope.
while (!top->is_global_scope() &&
!top->outer_scope()->already_resolved()) {
top = top->outer_scope();
}
// Allocate the variables.
{
AstNodeFactory<AstNullVisitor> ast_node_factory(info->isolate());
top->AllocateVariables(info->global_scope(), &ast_node_factory);
}
#ifdef DEBUG
if (info->isolate()->bootstrapper()->IsActive()
? FLAG_print_builtin_scopes
: FLAG_print_scopes) {
scope->Print();
}
#endif
if (FLAG_harmony_scoping) {
VariableProxy* proxy = scope->CheckAssignmentToConst();
if (proxy != NULL) {
// Found an assignment to const. Throw a syntax error.
MessageLocation location(info->script(),
proxy->position(),
proxy->position());
Isolate* isolate = info->isolate();
Factory* factory = isolate->factory();
Handle<JSArray> array = factory->NewJSArray(0);
Handle<Object> result =
factory->NewSyntaxError("harmony_const_assign", array);
isolate->Throw(*result, &location);
return false;
}
}
info->SetScope(scope);
return true;
}
void Scope::Initialize() {
ASSERT(!already_resolved());
// Add this scope as a new inner scope of the outer scope.
if (outer_scope_ != NULL) {
outer_scope_->inner_scopes_.Add(this);
scope_inside_with_ = outer_scope_->scope_inside_with_ || is_with_scope();
} else {
scope_inside_with_ = is_with_scope();
}
// Declare convenience variables.
// Declare and allocate receiver (even for the global scope, and even
// if naccesses_ == 0).
// NOTE: When loading parameters in the global scope, we must take
// care not to access them as properties of the global object, but
// instead load them directly from the stack. Currently, the only
// such parameter is 'this' which is passed on the stack when
// invoking scripts
if (is_declaration_scope()) {
Variable* var =
variables_.Declare(this,
isolate_->factory()->this_symbol(),
VAR,
false,
Variable::THIS,
kCreatedInitialized);
var->AllocateTo(Variable::PARAMETER, -1);
receiver_ = var;
} else {
ASSERT(outer_scope() != NULL);
receiver_ = outer_scope()->receiver();
}
if (is_function_scope()) {
// Declare 'arguments' variable which exists in all functions.
// Note that it might never be accessed, in which case it won't be
// allocated during variable allocation.
variables_.Declare(this,
isolate_->factory()->arguments_symbol(),
VAR,
true,
Variable::ARGUMENTS,
kCreatedInitialized);
}
}
Scope* Scope::FinalizeBlockScope() {
ASSERT(is_block_scope());
ASSERT(temps_.is_empty());
ASSERT(params_.is_empty());
if (num_var_or_const() > 0) return this;
// Remove this scope from outer scope.
for (int i = 0; i < outer_scope_->inner_scopes_.length(); i++) {
if (outer_scope_->inner_scopes_[i] == this) {
outer_scope_->inner_scopes_.Remove(i);
break;
}
}
// Reparent inner scopes.
for (int i = 0; i < inner_scopes_.length(); i++) {
outer_scope()->AddInnerScope(inner_scopes_[i]);
}
// Move unresolved variables
for (int i = 0; i < unresolved_.length(); i++) {
outer_scope()->unresolved_.Add(unresolved_[i]);
}
return NULL;
}
Variable* Scope::LocalLookup(Handle<String> name) {
Variable* result = variables_.Lookup(name);
if (result != NULL || scope_info_.is_null()) {
return result;
}
// If we have a serialized scope info, we might find the variable there.
// There should be no local slot with the given name.
ASSERT(scope_info_->StackSlotIndex(*name) < 0);
// Check context slot lookup.
VariableMode mode;
InitializationFlag init_flag;
int index = scope_info_->ContextSlotIndex(*name, &mode, &init_flag);
if (index < 0) {
// Check parameters.
mode = VAR;
init_flag = kCreatedInitialized;
index = scope_info_->ParameterIndex(*name);
if (index < 0) return NULL;
}
Variable* var =
variables_.Declare(this,
name,
mode,
true,
Variable::NORMAL,
init_flag);
var->AllocateTo(Variable::CONTEXT, index);
return var;
}
Variable* Scope::LookupFunctionVar(Handle<String> name,
AstNodeFactory<AstNullVisitor>* factory) {
if (function_ != NULL && function_->name().is_identical_to(name)) {
return function_->var();
} 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, &mode);
if (index < 0) return NULL;
Variable* var = DeclareFunctionVar(name, mode, factory);
var->AllocateTo(Variable::CONTEXT, index);
return var;
} else {
return NULL;
}
}
Variable* Scope::Lookup(Handle<String> name) {
for (Scope* scope = this;
scope != NULL;
scope = scope->outer_scope()) {
Variable* var = scope->LocalLookup(name);
if (var != NULL) return var;
}
return NULL;
}
void Scope::DeclareParameter(Handle<String> name, VariableMode mode) {
ASSERT(!already_resolved());
ASSERT(is_function_scope());
Variable* var = variables_.Declare(
this, name, mode, true, Variable::NORMAL, kCreatedInitialized);
params_.Add(var);
}
Variable* Scope::DeclareLocal(Handle<String> name,
VariableMode mode,
InitializationFlag init_flag) {
ASSERT(!already_resolved());
// This function handles VAR and CONST modes. DYNAMIC variables are
// introduces during variable allocation, INTERNAL variables are allocated
// explicitly, and TEMPORARY variables are allocated via NewTemporary().
ASSERT(mode == VAR ||
mode == CONST ||
mode == CONST_HARMONY ||
mode == LET);
++num_var_or_const_;
return
variables_.Declare(this, name, mode, true, Variable::NORMAL, init_flag);
}
Variable* Scope::DeclareGlobal(Handle<String> name) {
ASSERT(is_global_scope());
return variables_.Declare(this,
name,
DYNAMIC_GLOBAL,
true,
Variable::NORMAL,
kCreatedInitialized);
}
void Scope::RemoveUnresolved(VariableProxy* var) {
// Most likely (always?) any variable we want to remove
// was just added before, so we search backwards.
for (int i = unresolved_.length(); i-- > 0;) {
if (unresolved_[i] == var) {
unresolved_.Remove(i);
return;
}
}
}
Variable* Scope::NewTemporary(Handle<String> name) {
ASSERT(!already_resolved());
Variable* var = new Variable(this,
name,
TEMPORARY,
true,
Variable::NORMAL,
kCreatedInitialized);
temps_.Add(var);
return var;
}
void Scope::AddDeclaration(Declaration* declaration) {
decls_.Add(declaration);
}
void Scope::SetIllegalRedeclaration(Expression* expression) {
// Record only the first illegal redeclaration.
if (!HasIllegalRedeclaration()) {
illegal_redecl_ = expression;
}
ASSERT(HasIllegalRedeclaration());
}
void Scope::VisitIllegalRedeclaration(AstVisitor* visitor) {
ASSERT(HasIllegalRedeclaration());
illegal_redecl_->Accept(visitor);
}
Declaration* Scope::CheckConflictingVarDeclarations() {
int length = decls_.length();
for (int i = 0; i < length; i++) {
Declaration* decl = decls_[i];
if (decl->mode() != VAR) continue;
Handle<String> name = decl->proxy()->name();
// Iterate through all scopes until and including the declaration scope.
Scope* previous = NULL;
Scope* current = decl->scope();
do {
// There is a conflict if there exists a non-VAR binding.
Variable* other_var = current->variables_.Lookup(name);
if (other_var != NULL && other_var->mode() != VAR) {
return decl;
}
previous = current;
current = current->outer_scope_;
} while (!previous->is_declaration_scope());
}
return NULL;
}
VariableProxy* Scope::CheckAssignmentToConst() {
// Check this scope.
if (is_extended_mode()) {
for (int i = 0; i < unresolved_.length(); i++) {
ASSERT(unresolved_[i]->var() != NULL);
if (unresolved_[i]->var()->is_const_mode() &&
unresolved_[i]->IsLValue()) {
return unresolved_[i];
}
}
}
// Check inner scopes.
for (int i = 0; i < inner_scopes_.length(); i++) {
VariableProxy* proxy = inner_scopes_[i]->CheckAssignmentToConst();
if (proxy != NULL) return proxy;
}
// No assignments to const found.
return NULL;
}
void Scope::CollectStackAndContextLocals(ZoneList<Variable*>* stack_locals,
ZoneList<Variable*>* context_locals) {
ASSERT(stack_locals != NULL);
ASSERT(context_locals != NULL);
// Collect temporaries which are always allocated on the stack.
for (int i = 0; i < temps_.length(); i++) {
Variable* var = temps_[i];
if (var->is_used()) {
ASSERT(var->IsStackLocal());
stack_locals->Add(var);
}
}
// Collect declared local variables.
for (VariableMap::Entry* p = variables_.Start();
p != NULL;
p = variables_.Next(p)) {
Variable* var = reinterpret_cast<Variable*>(p->value);
if (var->is_used()) {
if (var->IsStackLocal()) {
stack_locals->Add(var);
} else if (var->IsContextSlot()) {
context_locals->Add(var);
}
}
}
}
void Scope::AllocateVariables(Scope* global_scope,
AstNodeFactory<AstNullVisitor>* factory) {
// 1) Propagate scope information.
bool outer_scope_calls_non_strict_eval = false;
if (outer_scope_ != NULL) {
outer_scope_calls_non_strict_eval =
outer_scope_->outer_scope_calls_non_strict_eval() |
outer_scope_->calls_non_strict_eval();
}
PropagateScopeInfo(outer_scope_calls_non_strict_eval);
// 2) Resolve variables.
ResolveVariablesRecursively(global_scope, factory);
// 3) Allocate variables.
AllocateVariablesRecursively();
}
bool Scope::AllowsLazyCompilation() const {
return !force_eager_compilation_ && HasTrivialOuterContext();
}
bool Scope::HasTrivialContext() const {
// A function scope has a trivial context if it always is the global
// context. We iteratively scan out the context chain to see if
// there is anything that makes this scope non-trivial; otherwise we
// return true.
for (const Scope* scope = this; scope != NULL; scope = scope->outer_scope_) {
if (scope->is_eval_scope()) return false;
if (scope->scope_inside_with_) return false;
if (scope->num_heap_slots_ > 0) return false;
}
return true;
}
bool Scope::HasTrivialOuterContext() const {
Scope* outer = outer_scope_;
if (outer == NULL) return true;
// Note that the outer context may be trivial in general, but the current
// scope may be inside a 'with' statement in which case the outer context
// for this scope is not trivial.
return !scope_inside_with_ && outer->HasTrivialContext();
}
int Scope::ContextChainLength(Scope* scope) {
int n = 0;
for (Scope* s = this; s != scope; s = s->outer_scope_) {
ASSERT(s != NULL); // scope must be in the scope chain
if (s->num_heap_slots() > 0) n++;
}
return n;
}
Scope* Scope::DeclarationScope() {
Scope* scope = this;
while (!scope->is_declaration_scope()) {
scope = scope->outer_scope();
}
return scope;
}
Handle<ScopeInfo> Scope::GetScopeInfo() {
if (scope_info_.is_null()) {
scope_info_ = ScopeInfo::Create(this);
}
return scope_info_;
}
void Scope::GetNestedScopeChain(
List<Handle<ScopeInfo> >* chain,
int position) {
if (!is_eval_scope()) chain->Add(Handle<ScopeInfo>(GetScopeInfo()));
for (int i = 0; i < inner_scopes_.length(); i++) {
Scope* scope = inner_scopes_[i];
int beg_pos = scope->start_position();
int end_pos = scope->end_position();
ASSERT(beg_pos >= 0 && end_pos >= 0);
if (beg_pos <= position && position < end_pos) {
scope->GetNestedScopeChain(chain, position);
return;
}
}
}
#ifdef DEBUG
static const char* Header(ScopeType type) {
switch (type) {
case EVAL_SCOPE: return "eval";
case FUNCTION_SCOPE: return "function";
case MODULE_SCOPE: return "module";
case GLOBAL_SCOPE: return "global";
case CATCH_SCOPE: return "catch";
case BLOCK_SCOPE: return "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(Handle<String> name) {
SmartArrayPointer<char> s = name->ToCString(DISALLOW_NULLS);
PrintF("%s", *s);
}
static void PrintLocation(Variable* var) {
switch (var->location()) {
case Variable::UNALLOCATED:
break;
case Variable::PARAMETER:
PrintF("parameter[%d]", var->index());
break;
case Variable::LOCAL:
PrintF("local[%d]", var->index());
break;
case Variable::CONTEXT:
PrintF("context[%d]", var->index());
break;
case Variable::LOOKUP:
PrintF("lookup");
break;
}
}
static void PrintVar(int indent, Variable* var) {
if (var->is_used() || !var->IsUnallocated()) {
Indent(indent, Variable::Mode2String(var->mode()));
PrintF(" ");
PrintName(var->name());
PrintF("; // ");
PrintLocation(var);
if (var->has_forced_context_allocation()) {
if (!var->IsUnallocated()) PrintF(", ");
PrintF("forced context allocation");
}
PrintF("\n");
}
}
static void PrintMap(int indent, VariableMap* map) {
for (VariableMap::Entry* p = map->Start(); p != NULL; p = map->Next(p)) {
Variable* var = reinterpret_cast<Variable*>(p->value);
PrintVar(indent, var);
}
}
void Scope::Print(int n) {
int n0 = (n > 0 ? n : 0);
int n1 = n0 + 2; // indentation
// Print header.
Indent(n0, Header(type_));
if (scope_name_->length() > 0) {
PrintF(" ");
PrintName(scope_name_);
}
// Print parameters, if any.
if (is_function_scope()) {
PrintF(" (");
for (int i = 0; i < params_.length(); i++) {
if (i > 0) PrintF(", ");
PrintName(params_[i]->name());
}
PrintF(")");
}
PrintF(" { // (%d, %d)\n", start_position(), end_position());
// Function name, if any (named function literals, only).
if (function_ != NULL) {
Indent(n1, "// (local) function name: ");
PrintName(function_->name());
PrintF("\n");
}
// Scope info.
if (HasTrivialOuterContext()) {
Indent(n1, "// scope has trivial outer context\n");
}
switch (language_mode()) {
case CLASSIC_MODE:
break;
case STRICT_MODE:
Indent(n1, "// strict mode scope\n");
break;
case EXTENDED_MODE:
Indent(n1, "// extended mode scope\n");
break;
}
if (scope_inside_with_) Indent(n1, "// scope inside 'with'\n");
if (scope_contains_with_) Indent(n1, "// scope contains 'with'\n");
if (scope_calls_eval_) Indent(n1, "// scope calls 'eval'\n");
if (outer_scope_calls_non_strict_eval_) {
Indent(n1, "// outer scope calls 'eval' in non-strict context\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\n", num_heap_slots_); }
// Print locals.
Indent(n1, "// function var\n");
if (function_ != NULL) {
PrintVar(n1, function_->var());
}
Indent(n1, "// temporary vars\n");
for (int i = 0; i < temps_.length(); i++) {
PrintVar(n1, temps_[i]);
}
Indent(n1, "// local vars\n");
PrintMap(n1, &variables_);
Indent(n1, "// dynamic vars\n");
if (dynamics_ != NULL) {
PrintMap(n1, dynamics_->GetMap(DYNAMIC));
PrintMap(n1, dynamics_->GetMap(DYNAMIC_LOCAL));
PrintMap(n1, dynamics_->GetMap(DYNAMIC_GLOBAL));
}
// Print inner scopes (disable by providing negative n).
if (n >= 0) {
for (int i = 0; i < inner_scopes_.length(); i++) {
PrintF("\n");
inner_scopes_[i]->Print(n1);
}
}
Indent(n0, "}\n");
}
#endif // DEBUG
Variable* Scope::NonLocal(Handle<String> name, VariableMode mode) {
if (dynamics_ == NULL) dynamics_ = new DynamicScopePart();
VariableMap* map = dynamics_->GetMap(mode);
Variable* var = map->Lookup(name);
if (var == NULL) {
// Declare a new non-local.
InitializationFlag init_flag = (mode == VAR)
? kCreatedInitialized : kNeedsInitialization;
var = map->Declare(NULL,
name,
mode,
true,
Variable::NORMAL,
init_flag);
// Allocate it by giving it a dynamic lookup.
var->AllocateTo(Variable::LOOKUP, -1);
}
return var;
}
Variable* Scope::LookupRecursive(Handle<String> name,
BindingKind* binding_kind,
AstNodeFactory<AstNullVisitor>* factory) {
ASSERT(binding_kind != NULL);
// Try to find the variable in this scope.
Variable* var = LocalLookup(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 != NULL) {
*binding_kind = BOUND;
return var;
}
// We did not find a variable locally. Check against the function variable,
// if any. We can do this for all scopes, since the function variable is
// only present - if at all - for function scopes.
*binding_kind = UNBOUND;
var = LookupFunctionVar(name, factory);
if (var != NULL) {
*binding_kind = BOUND;
} else if (outer_scope_ != NULL) {
var = outer_scope_->LookupRecursive(name, binding_kind, factory);
if (*binding_kind == BOUND && (is_function_scope() || is_with_scope())) {
var->ForceContextAllocation();
}
} else {
ASSERT(is_global_scope());
}
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).
*binding_kind = DYNAMIC_LOOKUP;
return NULL;
} else if (calls_non_strict_eval()) {
// A variable binding may have been found in an outer scope, but the current
// scope makes a non-strict '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.
if (*binding_kind == BOUND) {
*binding_kind = BOUND_EVAL_SHADOWED;
} else if (*binding_kind == UNBOUND) {
*binding_kind = UNBOUND_EVAL_SHADOWED;
}
}
return var;
}
void Scope::ResolveVariable(Scope* global_scope,
VariableProxy* proxy,
AstNodeFactory<AstNullVisitor>* factory) {
ASSERT(global_scope == NULL || global_scope->is_global_scope());
// If the proxy is already resolved there's nothing to do
// (functions and consts may be resolved by the parser).
if (proxy->var() != NULL) return;
// Otherwise, try to resolve the variable.
BindingKind binding_kind;
Variable* var = LookupRecursive(proxy->name(), &binding_kind, factory);
switch (binding_kind) {
case BOUND:
// We found a variable binding.
break;
case BOUND_EVAL_SHADOWED:
// We found a variable variable binding that might be shadowed
// by 'eval' introduced variable bindings.
if (var->is_global()) {
var = NonLocal(proxy->name(), DYNAMIC_GLOBAL);
} else {
Variable* invalidated = var;
var = NonLocal(proxy->name(), DYNAMIC_LOCAL);
var->set_local_if_not_shadowed(invalidated);
}
break;
case UNBOUND:
// No binding has been found. Declare a variable in global scope.
ASSERT(global_scope != NULL);
var = global_scope->DeclareGlobal(proxy->name());
break;
case UNBOUND_EVAL_SHADOWED:
// No binding has been found. But some scope makes a
// non-strict 'eval' call.
var = NonLocal(proxy->name(), DYNAMIC_GLOBAL);
break;
case DYNAMIC_LOOKUP:
// The variable could not be resolved statically.
var = NonLocal(proxy->name(), DYNAMIC);
break;
}
ASSERT(var != NULL);
proxy->BindTo(var);
}
void Scope::ResolveVariablesRecursively(
Scope* global_scope,
AstNodeFactory<AstNullVisitor>* factory) {
ASSERT(global_scope == NULL || global_scope->is_global_scope());
// Resolve unresolved variables for this scope.
for (int i = 0; i < unresolved_.length(); i++) {
ResolveVariable(global_scope, unresolved_[i], factory);
}
// Resolve unresolved variables for inner scopes.
for (int i = 0; i < inner_scopes_.length(); i++) {
inner_scopes_[i]->ResolveVariablesRecursively(global_scope, factory);
}
}
bool Scope::PropagateScopeInfo(bool outer_scope_calls_non_strict_eval ) {
if (outer_scope_calls_non_strict_eval) {
outer_scope_calls_non_strict_eval_ = true;
}
bool calls_non_strict_eval =
this->calls_non_strict_eval() || outer_scope_calls_non_strict_eval_;
for (int i = 0; i < inner_scopes_.length(); i++) {
Scope* inner_scope = inner_scopes_[i];
if (inner_scope->PropagateScopeInfo(calls_non_strict_eval)) {
inner_scope_calls_eval_ = true;
}
if (inner_scope->force_eager_compilation_) {
force_eager_compilation_ = true;
}
}
return scope_calls_eval_ || inner_scope_calls_eval_;
}
bool Scope::MustAllocate(Variable* var) {
// 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->name()->length() > 0) &&
(var->has_forced_context_allocation() ||
scope_calls_eval_ ||
inner_scope_calls_eval_ ||
scope_contains_with_ ||
is_catch_scope() ||
is_block_scope())) {
var->set_is_used(true);
}
// Global variables do not need to be allocated.
return !var->is_global() && 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: temporary variables are never allocated in a context;
// catch-bound variables are always allocated in a context.
if (var->mode() == TEMPORARY) return false;
if (is_catch_scope() || is_block_scope()) return true;
return var->has_forced_context_allocation() ||
scope_calls_eval_ ||
inner_scope_calls_eval_ ||
scope_contains_with_ ||
var->is_global();
}
bool Scope::HasArgumentsParameter() {
for (int i = 0; i < params_.length(); i++) {
if (params_[i]->name().is_identical_to(
isolate_->factory()->arguments_symbol())) {
return true;
}
}
return false;
}
void Scope::AllocateStackSlot(Variable* var) {
var->AllocateTo(Variable::LOCAL, num_stack_slots_++);
}
void Scope::AllocateHeapSlot(Variable* var) {
var->AllocateTo(Variable::CONTEXT, num_heap_slots_++);
}
void Scope::AllocateParameterLocals() {
ASSERT(is_function_scope());
Variable* arguments = LocalLookup(isolate_->factory()->arguments_symbol());
ASSERT(arguments != NULL); // functions have 'arguments' declared implicitly
bool uses_nonstrict_arguments = false;
if (MustAllocate(arguments) && !HasArgumentsParameter()) {
// '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.
// We are using 'arguments'. Tell the code generator that is needs to
// allocate the arguments object by setting 'arguments_'.
arguments_ = arguments;
// In strict mode 'arguments' does not alias formal parameters.
// Therefore in strict mode we allocate parameters as if 'arguments'
// were not used.
uses_nonstrict_arguments = is_classic_mode();
}
// 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 = params_.length() - 1; i >= 0; --i) {
Variable* var = params_[i];
ASSERT(var->scope() == this);
if (uses_nonstrict_arguments) {
// Force context allocation of the parameter.
var->ForceContextAllocation();
}
if (MustAllocate(var)) {
if (MustAllocateInContext(var)) {
ASSERT(var->IsUnallocated() || var->IsContextSlot());
if (var->IsUnallocated()) {
AllocateHeapSlot(var);
}
} else {
ASSERT(var->IsUnallocated() || var->IsParameter());
if (var->IsUnallocated()) {
var->AllocateTo(Variable::PARAMETER, i);
}
}
}
}
}
void Scope::AllocateNonParameterLocal(Variable* var) {
ASSERT(var->scope() == this);
ASSERT(!var->IsVariable(isolate_->factory()->result_symbol()) ||
!var->IsStackLocal());
if (var->IsUnallocated() && MustAllocate(var)) {
if (MustAllocateInContext(var)) {
AllocateHeapSlot(var);
} else {
AllocateStackSlot(var);
}
}
}
void Scope::AllocateNonParameterLocals() {
// All variables that have no rewrite yet are non-parameter locals.
for (int i = 0; i < temps_.length(); i++) {
AllocateNonParameterLocal(temps_[i]);
}
for (VariableMap::Entry* p = variables_.Start();
p != NULL;
p = variables_.Next(p)) {
Variable* var = reinterpret_cast<Variable*>(p->value);
AllocateNonParameterLocal(var);
}
// 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_ != NULL) {
AllocateNonParameterLocal(function_->var());
}
}
void Scope::AllocateVariablesRecursively() {
// Allocate variables for inner scopes.
for (int i = 0; i < inner_scopes_.length(); i++) {
inner_scopes_[i]->AllocateVariablesRecursively();
}
// If scope is already resolved, we still need to allocate
// variables in inner scopes which might not had been resolved yet.
if (already_resolved()) return;
// The number of slots required for variables.
num_stack_slots_ = 0;
num_heap_slots_ = Context::MIN_CONTEXT_SLOTS;
// Allocate variables for this scope.
// Parameters must be allocated first, if any.
if (is_function_scope()) AllocateParameterLocals();
AllocateNonParameterLocals();
// 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.
bool must_have_context = is_with_scope() ||
(is_function_scope() && calls_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.
ASSERT(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS);
}
int Scope::StackLocalCount() const {
return num_stack_slots() -
(function_ != NULL && function_->var()->IsStackLocal() ? 1 : 0);
}
int Scope::ContextLocalCount() const {
if (num_heap_slots() == 0) return 0;
return num_heap_slots() - Context::MIN_CONTEXT_SLOTS -
(function_ != NULL && function_->var()->IsContextSlot() ? 1 : 0);
}
} } // namespace v8::internal