Do not embed function in DirectLoadGlobalFunctionPrototype.

src/ic/arm64/handler-compiler-arm64.cc

 // Copyright 2014 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/v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/ic/call-optimization.h"
 #include "src/ic/handler-compiler.h"
@@ skipping 39 matching lines @@
   __ JumpIfNotRoot(map, Heap::kHashTableMapRootIndex, miss_label);
 
   NameDictionaryLookupStub::GenerateNegativeLookup(
       masm, miss_label, &done, receiver, properties, name, scratch1);
   __ Bind(&done);
   __ DecrementCounter(counters->negative_lookups_miss(), 1, scratch0, scratch1);
 }
 
 
 void NamedLoadHandlerCompiler::GenerateDirectLoadGlobalFunctionPrototype(
-    MacroAssembler* masm, int index, Register prototype, Label* miss) {
+    MacroAssembler* masm, int index, Register prototype, Register scratch,
+    Label* miss) {
   Isolate* isolate = masm->isolate();
   // Get the global function with the given index.
-  Handle<JSFunction> function(
+  Handle<JSFunction> jsfunction(
       JSFunction::cast(isolate->native_context()->get(index)));
+  Handle<WeakCell> cell = isolate->factory()->NewWeakCell(jsfunction);
 
   // Check we're still in the same context.
-  Register scratch = prototype;
+  Register function = prototype;
   __ Ldr(scratch, GlobalObjectMemOperand());
   __ Ldr(scratch, FieldMemOperand(scratch, GlobalObject::kNativeContextOffset));
-  __ Ldr(scratch, ContextMemOperand(scratch, index));
-  __ Cmp(scratch, Operand(function));
+  __ Ldr(function, ContextMemOperand(scratch, index));
+  __ CmpWeakValue(function, cell, scratch);

[Toon Verwaest, 2014/12/03 16:22:09]

Why still embed the weak cell if all you do is miss if it's different? We'll do
a map-check on the prototype itself anyway later on if we use it, so checking
the function itself is not necessary as far as I can tell.

   __ B(ne, miss);
 
   // Load its initial map. The global functions all have initial maps.
-  __ Mov(prototype, Operand(Handle<Map>(function->initial_map())));
+  __ Ldr(scratch,
+         FieldMemOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
   // Load the prototype from the initial map.
-  __ Ldr(prototype, FieldMemOperand(prototype, Map::kPrototypeOffset));
+  __ Ldr(prototype, FieldMemOperand(scratch, Map::kPrototypeOffset));
 }
 
 
 void NamedLoadHandlerCompiler::GenerateLoadFunctionPrototype(
     MacroAssembler* masm, Register receiver, Register scratch1,
     Register scratch2, Label* miss_label) {
   __ TryGetFunctionPrototype(receiver, scratch1, scratch2, miss_label);
   // TryGetFunctionPrototype can't put the result directly in x0 because the
   // 3 inputs registers can't alias and we call this function from
   // LoadIC::GenerateFunctionPrototype, where receiver is x0. So we explicitly
@@ skipping 610 matching lines @@
   // Return the generated code.
   return GetCode(kind(), Code::FAST, name);
 }
 
 
 #undef __
 }
 }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32