Enable preaging of code objects when --optimize-for-size.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index b3a264e79831963d91b91818db9634ef4400244a..19c1457c476bad4bcc549a82965774f1961befab 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -10438,6 +10438,12 @@ void Code::MakeCodeAgeSequenceYoung(byte* sequence, Isolate* isolate) {
 }
 
 
+void Code::MarkCodeAsExecuted(byte* sequence, Isolate* isolate) {
+  PatchPlatformCodeAge(isolate, sequence, kExecutedOnceCodeAge,
+      NO_MARKING_PARITY);
+}
+
+
 void Code::MakeOlder(MarkingParity current_parity) {
   byte* sequence = FindCodeAgeSequence();
   if (sequence != NULL) {
@@ -10455,12 +10461,8 @@ void Code::MakeOlder(MarkingParity current_parity) {
 
 
 bool Code::IsOld() {
-  byte* sequence = FindCodeAgeSequence();
-  if (sequence == NULL) return false;
-  Age age;
-  MarkingParity parity;
-  GetCodeAgeAndParity(sequence, &age, &parity);
-  return age >= kSexagenarianCodeAge;
+  Age age = GetAge();
+  return age >= kIsOldCodeAge;
 }
 
 
@@ -10474,7 +10476,7 @@ byte* Code::FindCodeAgeSequence() {
 }
 
 
-int Code::GetAge() {
+Code::Age Code::GetAge() {
   byte* sequence = FindCodeAgeSequence();
   if (sequence == NULL) {
     return Code::kNoAge;
@@ -10506,6 +10508,20 @@ void Code::GetCodeAgeAndParity(Code* code, Age* age,
   }
   CODE_AGE_LIST(HANDLE_CODE_AGE)
 #undef HANDLE_CODE_AGE
+  stub = *builtins->MarkCodeAsExecutedOnce();
+  if (code == stub) {
+    // Treat that's never been executed as old immediatly.
+    *age = kIsOldCodeAge;
+    *parity = NO_MARKING_PARITY;
+    return;
+  }
+  stub = *builtins->MarkCodeAsExecutedTwice();
+  if (code == stub) {
+    // Pre-age code that has only been executed once.
+    *age = kPreAgedCodeAge;
+    *parity = NO_MARKING_PARITY;
+    return;
+  }
   UNREACHABLE();
 }
 
@@ -10522,6 +10538,14 @@ Code* Code::GetCodeAgeStub(Isolate* isolate, Age age, MarkingParity parity) {
     }
     CODE_AGE_LIST(HANDLE_CODE_AGE)
 #undef HANDLE_CODE_AGE
+    case kNotExecutedCodeAge: {
+      ASSERT(parity == NO_MARKING_PARITY);
+      return *builtins->MarkCodeAsExecutedOnce();
+    }
+    case kExecutedOnceCodeAge: {
+      ASSERT(parity == NO_MARKING_PARITY);
+      return *builtins->MarkCodeAsExecutedTwice();
+    }
     default:
       UNREACHABLE();
       break;