[turbofan] Use RootIndexMap to speed up IsMaterializableFromRoot predicate.

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"
+#include "src/snapshot/serialize.h"  // TODO(turbofan): RootIndexMap
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 class CodeGenerator::JumpTable final : public ZoneObject {
  public:
   JumpTable(JumpTable* next, Label** targets, size_t target_count)
       : next_(next), targets_(targets), target_count_(target_count) {}
 
@@ skipping 211 matching lines @@
       return true;
     }
   }
   return false;
 }
 
 
 bool CodeGenerator::IsMaterializableFromRoot(
     Handle<HeapObject> object, Heap::RootListIndex* index_return) {
   if (linkage()->GetIncomingDescriptor()->IsJSFunctionCall()) {
-    // Check if {object} is one of the non-smi roots that cannot be written
-    // after initialization.
-    for (int i = 0; i < Heap::kSmiRootsStart; ++i) {
-      Heap::RootListIndex const index = static_cast<Heap::RootListIndex>(i);
-      if (!Heap::RootCanBeWrittenAfterInitialization(index) &&
-          *object == isolate()->heap()->root(index)) {
-        *index_return = index;
-        return true;
-      }
+    RootIndexMap map(isolate());
+    int root_index = map.Lookup(*object);
+    if (root_index != RootIndexMap::kInvalidRootIndex) {
+      *index_return = static_cast<Heap::RootListIndex>(root_index);
+      return true;
     }
   }
   return false;
 }
 
 
 void CodeGenerator::AssembleInstruction(Instruction* instr) {
   AssembleGaps(instr);
   AssembleSourcePosition(instr);
   // Assemble architecture-specific code for the instruction.
@@ skipping 448 matching lines @@
     : masm_(gen->masm()), next_(gen->ools_) {
   gen->ools_ = this;
 }
 
 
 OutOfLineCode::~OutOfLineCode() {}
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8