[debugger] infrastructure for side-effect-free debug-evaluate.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index d695d0ed901e2570e5dc3773d483a4dffc17d454..f179a3718ab24aedcb3ef24156735a60594ee66d 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -4314,13 +4314,12 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
 void MacroAssembler::FloodFunctionIfStepping(Register fun, Register new_target,
                                              const ParameterCount& expected,
                                              const ParameterCount& actual) {
-  Label skip_flooding;
-  ExternalReference last_step_action =
-      ExternalReference::debug_last_step_action_address(isolate());
-  Operand last_step_action_operand = ExternalOperand(last_step_action);
-  STATIC_ASSERT(StepFrame > StepIn);
-  cmpb(last_step_action_operand, Immediate(StepIn));
-  j(less, &skip_flooding);
+  Label skip_hook;
+  ExternalReference debug_hook_active =
+      ExternalReference::debug_hook_on_function_call_address(isolate());
+  Operand debug_hook_active_operand = ExternalOperand(debug_hook_active);
+  cmpb(debug_hook_active_operand, Immediate(0));
+  j(equal, &skip_hook);
   {
     FrameScope frame(this,
                      has_frame() ? StackFrame::NONE : StackFrame::INTERNAL);
@@ -4337,7 +4336,7 @@ void MacroAssembler::FloodFunctionIfStepping(Register fun, Register new_target,
     }
     Push(fun);
     Push(fun);
-    CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
+    CallRuntime(Runtime::kDebugOnFunctionCall);

[jgruber, 2017/01/10 12:46:38]

Can we use this in builtins-x64.cc (Generate_ResumeGeneratorTrampoline) as well
and remove DebugPrepareStepInIfStepping?

[Yang, 2017/01/10 14:14:07]

We probably can. Let me think this through.

[Yang, 2017/01/11 10:32:10]

Done.

     Pop(fun);
     if (new_target.is_valid()) {
       Pop(new_target);
@@ -4351,7 +4350,7 @@ void MacroAssembler::FloodFunctionIfStepping(Register fun, Register new_target,
       SmiToInteger64(expected.reg(), expected.reg());
     }
   }
-  bind(&skip_flooding);
+  bind(&skip_hook);
 }
 
 void MacroAssembler::StubPrologue(StackFrame::Type type) {