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Unified Diff: src/scopes.cc

Issue 1136073002: Resolve references to "this" the same way as normal variables (Closed) Base URL: https://chromium.googlesource.com/v8/v8@master
Patch Set: "this" should never be looked up dynamically Created 5 years, 7 months ago
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Index: src/scopes.cc
diff --git a/src/scopes.cc b/src/scopes.cc
index 8b623f90ce908ac548bfd8ea46bdcf088121bbcf..a2d2ccf5a5dca654b6f7cc76626ebdb19e932556 100644
--- a/src/scopes.cc
+++ b/src/scopes.cc
@@ -309,22 +309,16 @@ void Scope::Initialize() {
scope_inside_with_ = is_with_scope();
}
- // Declare convenience variables.
- // Declare and allocate receiver (even for the script scope, and even
- // if naccesses_ == 0).
- // NOTE: When loading parameters in the script 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
+ // Declare convenience variables and the receiver.
if (is_declaration_scope()) {
DCHECK(!subclass_constructor || is_function_scope());
- Variable* var = variables_.Declare(
- this, ast_value_factory_->this_string(),
- subclass_constructor ? CONST : VAR, Variable::THIS,
- subclass_constructor ? kNeedsInitialization : kCreatedInitialized);
- var->AllocateTo(Variable::PARAMETER, -1);
- receiver_ = var;
+ if (has_this_declaration()) {
+ Variable* var = variables_.Declare(
+ this, ast_value_factory_->this_string(),
+ subclass_constructor ? CONST : VAR, Variable::THIS,
+ subclass_constructor ? kNeedsInitialization : kCreatedInitialized);
+ receiver_ = var;
+ }
if (subclass_constructor) {
new_target_ =
@@ -333,9 +327,6 @@ void Scope::Initialize() {
new_target_->AllocateTo(Variable::PARAMETER, -2);
new_target_->set_is_used();
}
- } else {
- DCHECK(outer_scope() != NULL);
- receiver_ = outer_scope()->receiver();
}
if (is_function_scope() && !is_arrow_scope()) {
@@ -1049,7 +1040,11 @@ Variable* Scope::LookupRecursive(VariableProxy* proxy,
DCHECK(is_script_scope());
}
- if (is_with_scope()) {
+ // "this" can't be shadowed by "eval"-introduced bindings or by "with" scopes.
+ // TODO(wingo): There are other variables in this category; add them.
+ bool name_can_be_shadowed = var == nullptr || !var->is_this();
+
+ if (is_with_scope() && name_can_be_shadowed) {
DCHECK(!already_resolved());
// 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
@@ -1060,7 +1055,7 @@ Variable* Scope::LookupRecursive(VariableProxy* proxy,
if (var != NULL && proxy->is_assigned()) var->set_maybe_assigned();
*binding_kind = DYNAMIC_LOOKUP;
return NULL;
- } else if (calls_sloppy_eval()) {
+ } else if (calls_sloppy_eval() && name_can_be_shadowed) {
// 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).
@@ -1415,24 +1410,40 @@ void Scope::AllocateParameterLocals(Isolate* isolate) {
// Force context allocation of the parameter.
var->ForceContextAllocation();
}
+ AllocateParameter(var, i);
+ }
+}
- 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(Variable::PARAMETER, i);
- }
+
+void Scope::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(Variable::PARAMETER, index);
}
}
}
}
+void Scope::AllocateReceiver() {
+ DCHECK_NOT_NULL(receiver());
+ DCHECK_EQ(receiver()->scope(), this);
+
+ if (has_forced_context_allocation()) {
+ // Force context allocation of the receiver.
+ receiver()->ForceContextAllocation();
+ }
+ AllocateParameter(receiver(), -1);
+}
+
+
void Scope::AllocateNonParameterLocal(Isolate* isolate, Variable* var) {
DCHECK(var->scope() == this);
DCHECK(!var->IsVariable(isolate->factory()->dot_result_string()) ||
@@ -1502,6 +1513,7 @@ void Scope::AllocateVariablesRecursively(Isolate* isolate) {
// Allocate variables for this scope.
// Parameters must be allocated first, if any.
if (is_function_scope()) AllocateParameterLocals(isolate);
+ if (has_this_declaration()) AllocateReceiver();
AllocateNonParameterLocals(isolate);
// Force allocation of a context for this scope if necessary. For a 'with'
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