[heap] Unify the immortal immovable root detection mechanism.

src/compiler/code-generator.cc

 // Copyright 2013 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/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/pipeline.h"
 
@@ skipping 202 matching lines @@
       *offset_return = JavaScriptFrameConstants::kFunctionOffset;
       return true;
     }
   }
   return false;
 }
 
 
 bool CodeGenerator::IsMaterializableFromRoot(
     Handle<HeapObject> object, Heap::RootListIndex* index_return) {
-  if (linkage()->GetIncomingDescriptor()->IsJSFunctionCall()) {
-    return isolate()->heap()->GetRootListIndex(object, index_return);
+  Heap::RootListIndex index;
+  if (linkage()->GetIncomingDescriptor()->IsJSFunctionCall() &&
+      isolate()->heap()->GetRootListIndex(*object, &index) &&
+      !Heap::RootCanBeWrittenAfterInitialization(index)) {
+    *index_return = index;
+    return true;
   }
   return false;
 }
 
 
 void CodeGenerator::AssembleInstruction(Instruction* instr) {
   AssembleGaps(instr);
   AssembleSourcePosition(instr);
   // Assemble architecture-specific code for the instruction.
   AssembleArchInstruction(instr);
@@ skipping 447 matching lines @@
     : masm_(gen->masm()), next_(gen->ools_) {
   gen->ools_ = this;
 }
 
 
 OutOfLineCode::~OutOfLineCode() {}
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8