Make non-Module generators only context allocate parameters.

src/ast/scopes.cc

 // 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/ast/ast.h"
@@ skipping 330 matching lines @@
 
   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;
+  force_context_allocation_for_parameters_ = false;
 
   is_declaration_scope_ = false;
 
   must_use_preparsed_scope_data_ = false;
 }
 
 bool Scope::HasSimpleParameters() {
   DeclarationScope* scope = GetClosureScope();
   return !scope->is_function_scope() || scope->has_simple_parameters();
 }
@@ skipping 1825 matching lines @@
       var->set_is_used();
       var->set_maybe_assigned();
       var->ForceContextAllocation();
     }
     AllocateParameter(var, i);
   }
 }
 
 void DeclarationScope::AllocateParameter(Variable* var, int index) {
   if (MustAllocate(var)) {
-    if (MustAllocateInContext(var)) {
+    if (has_forced_context_allocation_for_parameters() ||
+        MustAllocateInContext(var)) {

[neis, 2017/05/24 10:39:36]

This should be moved into MustAllocateInContext(var). Or does that function not
know whether var is a parameter?

[Jarin, 2017/05/24 12:32:21]

I do not know this code well enough to say whether it is good idea to move it
there. Perhaps Adam can help?

[adamk, 2017/05/24 13:04:00]

Indeed the problem is that MustAllocateInContext doesn't know the variable is a
parameter. So this seemed the simpler option than giving MustAllocateInContext a
second argument.

       DCHECK(var->IsUnallocated() || var->IsContextSlot());
       if (var->IsUnallocated()) {
         AllocateHeapSlot(var);
       }
     } else {
       DCHECK(var->IsUnallocated() || var->IsParameter());
       if (var->IsUnallocated()) {
         var->AllocateTo(VariableLocation::PARAMETER, index);
       }
     }
@@ skipping 155 matching lines @@
   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 -
          (is_function_var_in_context ? 1 : 0);
 }
 
 }  // namespace internal
 }  // namespace v8