Maintain a FixedArray for the optimized code map.

src/objects.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/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <sstream>
 
@@ skipping 11039 matching lines @@
       isolate->builtins()->builtin(Builtins::kCompileOptimizedConcurrent));
   // No write barrier required, since the builtin is part of the root set.
 }
 
 
 void SharedFunctionInfo::AddSharedCodeToOptimizedCodeMap(
     Handle<SharedFunctionInfo> shared, Handle<Code> code) {
   Isolate* isolate = shared->GetIsolate();
   if (isolate->serializer_enabled()) return;
   DCHECK(code->kind() == Code::OPTIMIZED_FUNCTION);
-  Handle<Object> value(shared->optimized_code_map(), isolate);
-  if (value->IsSmi()) return;  // Empty code maps are unsupported.
-  Handle<FixedArray> code_map = Handle<FixedArray>::cast(value);
-  code_map->set(kSharedCodeIndex, *code);
+  // Empty code maps are unsupported.
+  if (shared->OptimizedCodeMapIsCleared()) return;
+  shared->optimized_code_map()->set(kSharedCodeIndex, *code);
 }
 
 
 void SharedFunctionInfo::AddToOptimizedCodeMap(
     Handle<SharedFunctionInfo> shared, Handle<Context> native_context,
     Handle<HeapObject> code, Handle<LiteralsArray> literals,
     BailoutId osr_ast_id) {
   Isolate* isolate = shared->GetIsolate();
   if (isolate->serializer_enabled()) return;
   DCHECK(*code == isolate->heap()->undefined_value() ||
          !shared->SearchOptimizedCodeMap(*native_context, osr_ast_id).code);
   DCHECK(*code == isolate->heap()->undefined_value() ||
          Code::cast(*code)->kind() == Code::OPTIMIZED_FUNCTION);
   DCHECK(native_context->IsNativeContext());
   STATIC_ASSERT(kEntryLength == 4);
   Handle<FixedArray> new_code_map;
-  Handle<Object> value(shared->optimized_code_map(), isolate);
   int entry;
-  if (value->IsSmi()) {
-    // No optimized code map.
-    DCHECK_EQ(0, Smi::cast(*value)->value());
+  if (shared->OptimizedCodeMapIsCleared()) {
     new_code_map = isolate->factory()->NewFixedArray(kInitialLength, TENURED);
     entry = kEntriesStart;
   } else {
-    Handle<FixedArray> old_code_map = Handle<FixedArray>::cast(value);
+    Handle<FixedArray> old_code_map(shared->optimized_code_map(), isolate);
     entry = shared->SearchOptimizedCodeMapEntry(*native_context, osr_ast_id);
     if (entry > kSharedCodeIndex) {
       // Found an existing context-specific entry, it must not contain any code.
       DCHECK_EQ(isolate->heap()->undefined_value(),
                 old_code_map->get(entry + kCachedCodeOffset));
       // Just set the code and literals to the entry.
       old_code_map->set(entry + kCachedCodeOffset, *code);
       old_code_map->set(entry + kLiteralsOffset, *literals);
       return;
     }
 
     // Copy old optimized code map and append one new entry.
     new_code_map = isolate->factory()->CopyFixedArrayAndGrow(
         old_code_map, kEntryLength, TENURED);
     // TODO(mstarzinger): Temporary workaround. The allocation above might have
     // flushed the optimized code map and the copy we created is full of holes.
     // For now we just give up on adding the entry and pretend it got flushed.
-    if (shared->optimized_code_map()->IsSmi()) return;
+    if (shared->OptimizedCodeMapIsCleared()) return;
     entry = old_code_map->length();
   }
   new_code_map->set(entry + kContextOffset, *native_context);
   new_code_map->set(entry + kCachedCodeOffset, *code);
   new_code_map->set(entry + kLiteralsOffset, *literals);
   new_code_map->set(entry + kOsrAstIdOffset, Smi::FromInt(osr_ast_id.ToInt()));
 
 #ifdef DEBUG
   for (int i = kEntriesStart; i < new_code_map->length(); i += kEntryLength) {
     DCHECK(new_code_map->get(i + kContextOffset)->IsNativeContext());
     Object* code = new_code_map->get(i + kCachedCodeOffset);
     if (code != isolate->heap()->undefined_value()) {
       DCHECK(code->IsCode());
       DCHECK(Code::cast(code)->kind() == Code::OPTIMIZED_FUNCTION);
     }
     DCHECK(new_code_map->get(i + kLiteralsOffset)->IsFixedArray());
     DCHECK(new_code_map->get(i + kOsrAstIdOffset)->IsSmi());
   }
 #endif
 
   // Zap any old optimized code map.
-  if (!shared->optimized_code_map()->IsSmi()) {
-    FixedArray* old_code_map = FixedArray::cast(shared->optimized_code_map());
+  if (!shared->OptimizedCodeMapIsCleared()) {
+    FixedArray* old_code_map = shared->optimized_code_map();
     old_code_map->FillWithHoles(0, old_code_map->length());
   }
 
   shared->set_optimized_code_map(*new_code_map);
 }
 
 
 void SharedFunctionInfo::ClearOptimizedCodeMap() {
   // Zap any old optimized code map.
-  if (!optimized_code_map()->IsSmi()) {
-    FixedArray* old_code_map = FixedArray::cast(optimized_code_map());
+  FixedArray* cleared_map = GetHeap()->cleared_optimized_code_map();
+  if (optimized_code_map() != cleared_map) {

[Michael Starzinger, 2015/11/13 12:14:22]

suggestion: Not sure this optimization is worth it. I would vote for using the
OptimizedCodeMapIsCleared() predicate here as well for readability. Decision is
up to you.

[mvstanton, 2015/11/17 20:32:12]

Done.

+    FixedArray* old_code_map = optimized_code_map();
     old_code_map->FillWithHoles(0, old_code_map->length());
   }
 
-  set_optimized_code_map(Smi::FromInt(0));
+  set_optimized_code_map(cleared_map, SKIP_WRITE_BARRIER);
 }
 
 
 void SharedFunctionInfo::EvictFromOptimizedCodeMap(Code* optimized_code,
                                                    const char* reason) {
   DisallowHeapAllocation no_gc;
-  if (optimized_code_map()->IsSmi()) return;
+  if (OptimizedCodeMapIsCleared()) return;
 
   Heap* heap = GetHeap();
-  FixedArray* code_map = FixedArray::cast(optimized_code_map());
+  FixedArray* code_map = optimized_code_map();
   int dst = kEntriesStart;
   int length = code_map->length();
   for (int src = kEntriesStart; src < length; src += kEntryLength) {
     DCHECK(code_map->get(src)->IsNativeContext());
     if (code_map->get(src + kCachedCodeOffset) == optimized_code) {
       BailoutId osr(Smi::cast(code_map->get(src + kOsrAstIdOffset))->value());
       if (FLAG_trace_opt) {
         PrintF("[evicting entry from optimizing code map (%s) for ", reason);
         ShortPrint();
         if (osr.IsNone()) {
@@ skipping 38 matching lines @@
                                                            length - dst);
     if (code_map->length() == kEntriesStart &&
         code_map->get(kSharedCodeIndex)->IsUndefined()) {
       ClearOptimizedCodeMap();
     }
   }
 }
 
 
 void SharedFunctionInfo::TrimOptimizedCodeMap(int shrink_by) {
-  FixedArray* code_map = FixedArray::cast(optimized_code_map());
+  FixedArray* code_map = optimized_code_map();
   DCHECK(shrink_by % kEntryLength == 0);
   DCHECK(shrink_by <= code_map->length() - kEntriesStart);
   // Always trim even when array is cleared because of heap verifier.
   GetHeap()->RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>(code_map,
                                                               shrink_by);
   if (code_map->length() == kEntriesStart &&
       code_map->get(kSharedCodeIndex)->IsUndefined()) {
     ClearOptimizedCodeMap();
   }
 }
@@ skipping 1121 matching lines @@
     set_opt_count(0);
     set_deopt_count(0);
   }
 }
 
 
 int SharedFunctionInfo::SearchOptimizedCodeMapEntry(Context* native_context,
                                                     BailoutId osr_ast_id) {
   DisallowHeapAllocation no_gc;
   DCHECK(native_context->IsNativeContext());
-  Object* value = optimized_code_map();
-  if (!value->IsSmi()) {
-    FixedArray* optimized_code_map = FixedArray::cast(value);
+  if (!OptimizedCodeMapIsCleared()) {
+    FixedArray* optimized_code_map = this->optimized_code_map();
     int length = optimized_code_map->length();
     Smi* osr_ast_id_smi = Smi::FromInt(osr_ast_id.ToInt());
     for (int i = kEntriesStart; i < length; i += kEntryLength) {
       if (optimized_code_map->get(i + kContextOffset) == native_context &&
           optimized_code_map->get(i + kOsrAstIdOffset) == osr_ast_id_smi) {
         return i;
       }
     }
     Object* shared_code = optimized_code_map->get(kSharedCodeIndex);
     if (shared_code->IsCode() && osr_ast_id.IsNone()) {
       return kSharedCodeIndex;
     }
   }
   return -1;
 }
 
 
 CodeAndLiterals SharedFunctionInfo::SearchOptimizedCodeMap(
     Context* native_context, BailoutId osr_ast_id) {
   CodeAndLiterals result = {nullptr, nullptr};
   int entry = SearchOptimizedCodeMapEntry(native_context, osr_ast_id);
   if (entry != kNotFound) {
-    FixedArray* code_map = FixedArray::cast(optimized_code_map());
+    FixedArray* code_map = optimized_code_map();
     if (entry == kSharedCodeIndex) {
       result = {Code::cast(code_map->get(kSharedCodeIndex)), nullptr};
 
     } else {
       DCHECK_LE(entry + kEntryLength, code_map->length());
       Object* code = code_map->get(entry + kCachedCodeOffset);
       result = {code->IsUndefined() ? nullptr : Code::cast(code),
                 LiteralsArray::cast(code_map->get(entry + kLiteralsOffset))};
     }
   }
-  if (FLAG_trace_opt && !optimized_code_map()->IsSmi() &&
+  if (FLAG_trace_opt && !OptimizedCodeMapIsCleared() &&
       result.code == nullptr) {
     PrintF("[didn't find optimized code in optimized code map for ");
     ShortPrint();
     PrintF("]\n");
   }
   return result;
 }
 
 
 #define DECLARE_TAG(ignore1, name, ignore2) name,
@@ skipping 5508 matching lines @@
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 
 }  // namespace internal
 }  // namespace v8