[parser] Only lookup in entry_point->variables_ of the ScopeInfo-backed chain.

We now only cache Variable* in entry_point->variables_ so there's no point in
looking at all variables_ in the entire chain.

Change-Id: I3d1f389a9ad7d790d2e778a72cd5f7fc47880233
Reviewed-on: https://chromium-review.googlesource.com/c/1340245
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57574}

src/ast/scopes.cc

@@ -564,9 +564,7 @@ void DeclarationScope::HoistSloppyBlockFunctions(AstNodeFactory* factory) {
       // example, that does not prevent hoisting of the function in
       // `{ let e; try {} catch (e) { function e(){} } }`
       do {
-        var = query_scope->scope_info_.is_null()
-                  ? query_scope->LookupLocal(name)
-                  : query_scope->LookupInScopeInfo(name, query_scope);
+        var = query_scope->LookupInScopeOrScopeInfo(name);
         if (var != nullptr && IsLexical(var)) {
           should_hoist = false;
           break;
@@ -924,8 +922,7 @@ void Scope::ReplaceOuterScope(Scope* outer) {
 
 Variable* Scope::LookupInScopeInfo(const AstRawString* name, Scope* cache) {
   DCHECK(!scope_info_.is_null());
-  Variable* cached = cache->variables_.Lookup(name);
-  if (cached) return cached;
+  DCHECK_NULL(cache->variables_.Lookup(name));
 
   Handle<String> name_handle = name->string();
   // The Scope is backed up by ScopeInfo. This means it cannot operate in a
@@ -959,7 +956,7 @@ Variable* Scope::LookupInScopeInfo(const AstRawString* name, Scope* cache) {
     Variable* var = AsDeclarationScope()->DeclareFunctionVar(name, cache);
     DCHECK_EQ(VariableMode::kConst, var->mode());
     var->AllocateTo(VariableLocation::CONTEXT, index);
-    return variables_.Lookup(name);
+    return cache->variables_.Lookup(name);
   }
 
   VariableKind kind = NORMAL_VARIABLE;
@@ -1813,6 +1810,12 @@ template <Scope::ScopeLookupMode mode>
 Variable* Scope::Lookup(VariableProxy* proxy, Scope* scope,
                         Scope* outer_scope_end, bool force_context_allocation) {
   Scope* entry_point = scope;
+
+  if (mode == kDeserializedScope) {
+    Variable* var = entry_point->variables_.Lookup(proxy->raw_name());
+    if (var != nullptr) return var;
+  }
+
   while (true) {
     DCHECK_IMPLIES(mode == kParsedScope, !scope->is_debug_evaluate_scope_);
     // Short-cut: whenever we find a debug-evaluate scope, just look everything
@@ -1824,7 +1827,7 @@ Variable* Scope::Lookup(VariableProxy* proxy, Scope* scope,
     // the scopes in which it's evaluating.
     if (mode == kDeserializedScope &&
         V8_UNLIKELY(scope->is_debug_evaluate_scope_)) {
-      return scope->NonLocal(proxy->raw_name(), VariableMode::kDynamic);
+      return entry_point->NonLocal(proxy->raw_name(), VariableMode::kDynamic);
     }
 
     // Try to find the variable in this scope.

src/ast/scopes.h

@@ -481,11 +481,15 @@ class V8_EXPORT_PRIVATE Scope : public NON_EXPORTED_BASE(ZoneObject) {
     return false;
   }
 
+  Variable* LookupInScopeOrScopeInfo(const AstRawString* name) {
+    Variable* var = variables_.Lookup(name);
+    if (var != nullptr || scope_info_.is_null()) return var;
+    return LookupInScopeInfo(name, this);
+  }
+
   Variable* LookupForTesting(const AstRawString* name) {
     for (Scope* scope = this; scope != nullptr; scope = scope->outer_scope()) {
-      Variable* var = scope->scope_info_.is_null()
-                          ? scope->LookupLocal(name)
-                          : scope->LookupInScopeInfo(name, scope);
+      Variable* var = scope->LookupInScopeOrScopeInfo(name);
       if (var != nullptr) return var;
     }
     return nullptr;
@@ -709,7 +713,7 @@ class V8_EXPORT_PRIVATE DeclarationScope : public Scope {
 
   Variable* LookupInModule(const AstRawString* name) {
     DCHECK(is_module_scope());
-    Variable* var = LookupInScopeInfo(name, this);
+    Variable* var = variables_.Lookup(name);
     DCHECK_NOT_NULL(var);
     return var;
   }