Age code to allow reclaiming old unexecuted functions

src/x64/builtins-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 588 matching lines @@
 
     // Tear down internal frame.
   }
 
   // Do a tail-call of the compiled function.
   __ lea(rax, FieldOperand(rax, Code::kHeaderSize));
   __ jmp(rax);
 }
 
 
+static void GenerateMakeCodeYoungAgainCommon(MacroAssembler* masm) {
+  // For now, 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. We also don't build an
+  // internal frame to make the code faster, since we shouldn't have to do stack
+  // crawls in MakeCodeYoung. This seems a bit fragile.
+
+  // Re-execute the code that was patched back to the young age when
+  // the stub returns.
+  __ subq(Operand(rsp, 0), Immediate(5));
+  __ Pushad();
+#ifdef _WIN64
+  __ movq(rcx, Operand(rsp, kNumSafepointRegisters * kPointerSize));
+#else
+  __ movq(rdi, Operand(rsp, kNumSafepointRegisters * kPointerSize));
+#endif
+  {  // NOLINT
+    FrameScope scope(masm, StackFrame::MANUAL);
+    __ PrepareCallCFunction(1);
+    __ CallCFunction(
+        ExternalReference::get_make_code_young_function(masm->isolate()), 1);
+  }
+  __ Popad();
+  __ ret(0);
+}
+
+
+#define DEFINE_CODE_AGE_BUILTIN_GENERATOR(C)                 \
+void Builtins::Generate_Make##C##CodeYoungAgainEvenMarking(  \
+    MacroAssembler* masm) {                                  \
+  GenerateMakeCodeYoungAgainCommon(masm);                    \
+}                                                            \
+void Builtins::Generate_Make##C##CodeYoungAgainOddMarking(   \
+    MacroAssembler* masm) {                                  \
+  GenerateMakeCodeYoungAgainCommon(masm);                    \
+}
+CODE_AGE_LIST(DEFINE_CODE_AGE_BUILTIN_GENERATOR)
+#undef DEFINE_CODE_AGE_BUILTIN_GENERATOR
+
+
 static void Generate_NotifyDeoptimizedHelper(MacroAssembler* masm,
                                              Deoptimizer::BailoutType type) {
   // Enter an internal frame.
   {
     FrameScope scope(masm, StackFrame::INTERNAL);
 
     // Pass the deoptimization type to the runtime system.
     __ Push(Smi::FromInt(static_cast<int>(type)));
 
     __ CallRuntime(Runtime::kNotifyDeoptimized, 1);
@@ skipping 1157 matching lines @@
   Deoptimizer::EntryGenerator generator(masm, Deoptimizer::OSR);
   generator.Generate();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64