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

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
diff --git a/src/x64/builtins-x64.cc b/src/x64/builtins-x64.cc
index df6acb6f0c02e61a6807cc9cd2df3719b963eff2..2f5e0c1b9634792c4af4480c1c40b3a3eda82218 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -627,6 +627,42 @@ CODE_AGE_LIST(DEFINE_CODE_AGE_BUILTIN_GENERATOR)
 #undef DEFINE_CODE_AGE_BUILTIN_GENERATOR
 
 
+void Builtins::Generate_MarkCodeAsExecutedOnce(MacroAssembler* masm) {
+  // For now, as in GenerateMakeCodeYoungAgainCommon, we are relying on the fact
+  // that make_code_young doesn't do any garbage collection which allows us to
+  // save/restore the registers without worrying about which of them contain
+  // pointers.
+  __ Pushad();
+  __ movq(arg_reg_2, ExternalReference::isolate_address(masm->isolate()));
+  __ movq(arg_reg_1, Operand(rsp, kNumSafepointRegisters * kPointerSize));
+  __ subq(arg_reg_1, Immediate(Assembler::kShortCallInstructionLength));
+  {  // NOLINT
+    FrameScope scope(masm, StackFrame::MANUAL);
+    __ PrepareCallCFunction(1);
+    __ CallCFunction(
+        ExternalReference::get_mark_code_as_executed_function(masm->isolate()),
+        1);
+  }
+  __ Popad();
+
+  // Perform prologue operations usually performed by the young code stub.
+  __ pop(r10);   // Pop return address into scratch register.
+  __ push(rbp);  // Caller's frame pointer.
+  __ movq(rbp, rsp);
+  __ push(rsi);  // Callee's context.
+  __ push(rdi);  // Callee's JS Function.
+  __ push(r10);  // Push return address after frame prologue.
+
+  // Jump to point after the code-age stub.
+  __ ret(0);
+}
+
+
+void Builtins::Generate_MarkCodeAsExecutedTwice(MacroAssembler* masm) {
+  GenerateMakeCodeYoungAgainCommon(masm);
+}
+
+
 void Builtins::Generate_NotifyStubFailure(MacroAssembler* masm) {
   // Enter an internal frame.
   {