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

src/x64/macro-assembler-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 4296 matching lines @@
       Jump(adaptor, RelocInfo::CODE_TARGET);
     }
     bind(&invoke);
   }
 }
 
 
 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);
     if (expected.is_reg()) {
       Integer32ToSmi(expected.reg(), expected.reg());
       Push(expected.reg());
     }
     if (actual.is_reg()) {
       Integer32ToSmi(actual.reg(), actual.reg());
       Push(actual.reg());
     }
     if (new_target.is_valid()) {
       Push(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);
     }
     if (actual.is_reg()) {
       Pop(actual.reg());
       SmiToInteger64(actual.reg(), actual.reg());
     }
     if (expected.is_reg()) {
       Pop(expected.reg());
       SmiToInteger64(expected.reg(), expected.reg());
     }
   }
-  bind(&skip_flooding);
+  bind(&skip_hook);
 }
 
 void MacroAssembler::StubPrologue(StackFrame::Type type) {
   pushq(rbp);  // Caller's frame pointer.
   movp(rbp, rsp);
   Push(Smi::FromInt(type));
 }
 
 void MacroAssembler::Prologue(bool code_pre_aging) {
   PredictableCodeSizeScope predictible_code_size_scope(this,
@@ skipping 932 matching lines @@
   movl(rax, dividend);
   shrl(rax, Immediate(31));
   addl(rdx, rax);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64