[builtins] Add --print-builtin-size flag

Passing --print-builtin-size will print the size of all builtins on
isolate creation.

BUG=v8:5737

Review-Url: https://codereview.chromium.org/2895163002
Cr-Commit-Position: refs/heads/master@{#45605}

src/flag-definitions.h

@@ -1268,6 +1268,7 @@ DEFINE_BOOL(print_unopt_code, false,
             "printing optimized code based on it")
 DEFINE_BOOL(print_code_verbose, false, "print more information for code")
 DEFINE_BOOL(print_builtin_code, false, "print generated code for builtins")
+DEFINE_BOOL(print_builtin_size, false, "print code size for builtins")
 
 #ifdef ENABLE_DISASSEMBLER
 DEFINE_BOOL(sodium, false,

src/isolate.cc

@@ -2651,6 +2651,16 @@ void Isolate::InitializeLoggingAndCounters() {
   InitializeCounters();
 }
 
+namespace {
+void PrintBuiltinSizes(Isolate* isolate) {
+  Builtins* builtins = isolate->builtins();
+  for (int i = 0; i < Builtins::builtin_count; i++) {
+    const char* name = builtins->name(i);
+    Code* code = builtins->builtin(static_cast<Builtins::Name>(i));
+    PrintF(stdout, "%s: %d\n", name, code->instruction_size());
+  }
+}
+}  // namespace
 
 bool Isolate::Init(Deserializer* des) {
   TRACE_ISOLATE(init);
@@ -2790,6 +2800,8 @@ bool Isolate::Init(Deserializer* des) {
   delete setup_delegate_;
   setup_delegate_ = nullptr;
 
+  if (FLAG_print_builtin_size) PrintBuiltinSizes(this);
+
   // Finish initialization of ThreadLocal after deserialization is done.
   clear_pending_exception();
   clear_pending_message();