Cache WeakCell for optimized code.

BUG=

Review URL: https://codereview.chromium.org/873233002

Cr-Commit-Position: refs/heads/master@{#26274}

src/arm/lithium-codegen-arm.cc

@@ -944,6 +944,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
   } else {
     data->SetSharedFunctionInfo(Smi::FromInt(0));
   }
+  data->SetWeakCellCache(Smi::FromInt(0));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);

src/arm64/lithium-codegen-arm64.cc

@@ -941,6 +941,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
   } else {
     data->SetSharedFunctionInfo(Smi::FromInt(0));
   }
+  data->SetWeakCellCache(Smi::FromInt(0));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);

src/ia32/lithium-codegen-ia32.cc

@@ -913,6 +913,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
   } else {
     data->SetSharedFunctionInfo(Smi::FromInt(0));
   }
+  data->SetWeakCellCache(Smi::FromInt(0));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);

src/mips/lithium-codegen-mips.cc

@@ -908,6 +908,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
   } else {
     data->SetSharedFunctionInfo(Smi::FromInt(0));
   }
+  data->SetWeakCellCache(Smi::FromInt(0));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);

src/mips64/lithium-codegen-mips64.cc

@@ -858,6 +858,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
   } else {
     data->SetSharedFunctionInfo(Smi::FromInt(0));
   }
+  data->SetWeakCellCache(Smi::FromInt(0));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);

src/objects.cc

@@ -11033,6 +11033,29 @@ const char* Code::Kind2String(Kind kind) {
 }
 
 
+Handle<WeakCell> Code::WeakCellFor(Handle<Code> code) {
+  DCHECK(code->kind() == OPTIMIZED_FUNCTION);
+  WeakCell* raw_cell = code->CachedWeakCell();
+  if (raw_cell != NULL) return Handle<WeakCell>(raw_cell);
+  Handle<WeakCell> cell = code->GetIsolate()->factory()->NewWeakCell(code);
+  DeoptimizationInputData::cast(code->deoptimization_data())
+      ->SetWeakCellCache(*cell);
+  return cell;
+}
+
+
+WeakCell* Code::CachedWeakCell() {
+  DCHECK(kind() == OPTIMIZED_FUNCTION);
+  Object* weak_cell_cache =
+      DeoptimizationInputData::cast(deoptimization_data())->WeakCellCache();
+  if (weak_cell_cache->IsWeakCell()) {
+    DCHECK(this == WeakCell::cast(weak_cell_cache)->value());
+    return WeakCell::cast(weak_cell_cache);
+  }
+  return NULL;
+}
+
+
 #ifdef ENABLE_DISASSEMBLER
 
 void DeoptimizationInputData::DeoptimizationInputDataPrint(

src/objects.h

@@ -4852,7 +4852,8 @@ class DeoptimizationInputData: public FixedArray {
   static const int kOsrPcOffsetIndex = 4;
   static const int kOptimizationIdIndex = 5;
   static const int kSharedFunctionInfoIndex = 6;
-  static const int kFirstDeoptEntryIndex = 7;
+  static const int kWeakCellCacheIndex = 7;
+  static const int kFirstDeoptEntryIndex = 8;
 
   // Offsets of deopt entry elements relative to the start of the entry.
   static const int kAstIdRawOffset = 0;
@@ -4877,6 +4878,7 @@ class DeoptimizationInputData: public FixedArray {
   DEFINE_ELEMENT_ACCESSORS(OsrPcOffset, Smi)
   DEFINE_ELEMENT_ACCESSORS(OptimizationId, Smi)
   DEFINE_ELEMENT_ACCESSORS(SharedFunctionInfo, Object)
+  DEFINE_ELEMENT_ACCESSORS(WeakCellCache, Object)
 
 #undef DEFINE_ELEMENT_ACCESSORS
 
@@ -5407,6 +5409,9 @@ class Code: public HeapObject {
 
   static inline bool IsWeakObjectInOptimizedCode(Object* object);
 
+  static Handle<WeakCell> WeakCellFor(Handle<Code> code);
+  WeakCell* CachedWeakCell();
+
   // Max loop nesting marker used to postpose OSR. We don't take loop
   // nesting that is deeper than 5 levels into account.
   static const int kMaxLoopNestingMarker = 6;

src/x64/lithium-codegen-x64.cc

@@ -823,6 +823,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
   } else {
     data->SetSharedFunctionInfo(Smi::FromInt(0));
   }
+  data->SetWeakCellCache(Smi::FromInt(0));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);

src/x87/lithium-codegen-x87.cc

@@ -1195,6 +1195,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
   } else {
     data->SetSharedFunctionInfo(Smi::FromInt(0));
   }
+  data->SetWeakCellCache(Smi::FromInt(0));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);