Symbols for type cells.

src/x64/code-stubs-x64.cc

 // Copyright 2013 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
@@ skipping 2249 matching lines @@
 
   __ bind(&done);
   __ Integer32ToSmi(rdx, rdx);
 
   __ bind(&done_no_smi_convert);
 }
 
 
 void CallFunctionStub::Generate(MacroAssembler* masm) {
   // rbx : feedback vector
-  // rdx : (only if rbx is not undefined) slot in feedback vector (Smi)
+  // rdx : (only if rbx is not the megamorphic symbol) slot in feedback
+  //       vector (Smi)
   // rdi : the function to call
   Isolate* isolate = masm->isolate();
   Label slow, non_function, wrap, cont;
   StackArgumentsAccessor args(rsp, argc_);
 
   if (NeedsChecks()) {
     // Check that the function really is a JavaScript function.
     __ JumpIfSmi(rdi, &non_function);
 
     // Goto slow case if we do not have a function.
@@ skipping 39 matching lines @@
     __ bind(&cont);
   }
   __ InvokeFunction(rdi, actual, JUMP_FUNCTION, NullCallWrapper());
 
   if (NeedsChecks()) {
     // Slow-case: Non-function called.
     __ bind(&slow);
     if (RecordCallTarget()) {
       // If there is a call target cache, mark it megamorphic in the
       // non-function case.  MegamorphicSentinel is an immortal immovable
-      // object (undefined) so no write barrier is needed.
+      // object (megamorphic symbol) so no write barrier is needed.
       __ SmiToInteger32(rdx, rdx);
       __ Move(FieldOperand(rbx, rdx, times_pointer_size,
                            FixedArray::kHeaderSize),
               TypeFeedbackInfo::MegamorphicSentinel(isolate));
       __ Integer32ToSmi(rdx, rdx);
     }
     // Check for function proxy.
     __ CmpInstanceType(rcx, JS_FUNCTION_PROXY_TYPE);
     __ j(not_equal, &non_function);
     __ PopReturnAddressTo(rcx);
@@ skipping 31 matching lines @@
     }
     __ movp(args.GetReceiverOperand(), rax);
     __ jmp(&cont);
   }
 }
 
 
 void CallConstructStub::Generate(MacroAssembler* masm) {
   // rax : number of arguments
   // rbx : feedback vector
-  // rdx : (only if rbx is not undefined) slot in feedback vector (Smi)
+  // rdx : (only if rbx is not the megamorphic symbol) slot in feedback
+  //       vector (Smi)
   // rdi : constructor function
   Label slow, non_function_call;
 
   // Check that function is not a smi.
   __ JumpIfSmi(rdi, &non_function_call);
   // Check that function is a JSFunction.
   __ CmpObjectType(rdi, JS_FUNCTION_TYPE, rcx);
   __ j(not_equal, &slow);
 
   if (RecordCallTarget()) {
@@ skipping 2603 matching lines @@
     CreateArrayDispatch<ArrayNArgumentsConstructorStub>(masm, mode);
   } else {
     UNREACHABLE();
   }
 }
 
 
 void ArrayConstructorStub::Generate(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rax    : argc
-  //  -- rbx    : feedback vector (fixed array or undefined)
+  //  -- rbx    : feedback vector (fixed array or megamorphic symbol)
   //  -- rdx    : slot index (if ebx is fixed array)
   //  -- rdi    : constructor
   //  -- rsp[0] : return address
   //  -- rsp[8] : last argument
   // -----------------------------------
-  Handle<Object> undefined_sentinel(
-      masm->isolate()->heap()->undefined_value(),
-      masm->isolate());
+  Handle<Object> megamorphic_sentinel =
+      TypeFeedbackInfo::MegamorphicSentinel(masm->isolate());
 
   if (FLAG_debug_code) {
     // The array construct code is only set for the global and natives
     // builtin Array functions which always have maps.
 
     // Initial map for the builtin Array function should be a map.
     __ movp(rcx, FieldOperand(rdi, JSFunction::kPrototypeOrInitialMapOffset));
     // Will both indicate a NULL and a Smi.
     STATIC_ASSERT(kSmiTag == 0);
     Condition not_smi = NegateCondition(masm->CheckSmi(rcx));
     __ Check(not_smi, kUnexpectedInitialMapForArrayFunction);
     __ CmpObjectType(rcx, MAP_TYPE, rcx);
     __ Check(equal, kUnexpectedInitialMapForArrayFunction);
 
-    // We should either have undefined in rbx or a valid fixed array.
+    // We should either have the megamorphic symbol in rbx or a valid
+    // fixed array.
     Label okay_here;
     Handle<Map> fixed_array_map = masm->isolate()->factory()->fixed_array_map();
-    __ Cmp(rbx, undefined_sentinel);
+    __ Cmp(rbx, megamorphic_sentinel);
     __ j(equal, &okay_here);
     __ Cmp(FieldOperand(rbx, 0), fixed_array_map);
     __ Assert(equal, kExpectedFixedArrayInRegisterRbx);
 
-    // rdx should be a smi if we don't have undefined in rbx.
+    // rdx should be a smi if we don't have the megamorphic symbol in rbx.
     __ AssertSmi(rdx);
 
     __ bind(&okay_here);
   }
 
   Label no_info;
-  // If the feedback slot is undefined, or contains anything other than an
-  // AllocationSite, call an array constructor that doesn't use AllocationSites.
-  __ Cmp(rbx, undefined_sentinel);
+  // If the feedback slot is the megamorphic sentinel, or contains anything
+  // other than an AllocationSite, call an array constructor that doesn't use
+  // AllocationSites.
+  __ Cmp(rbx, megamorphic_sentinel);
   __ j(equal, &no_info);
   __ SmiToInteger32(rdx, rdx);
   __ movp(rbx, FieldOperand(rbx, rdx, times_pointer_size,
                             FixedArray::kHeaderSize));
   __ Integer32ToSmi(rdx, rdx);
   __ Cmp(FieldOperand(rbx, 0),
          masm->isolate()->factory()->allocation_site_map());
   __ j(not_equal, &no_info);
 
   // Only look at the lower 16 bits of the transition info.
@@ skipping 272 matching lines @@
                               return_value_operand,
                               NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64