Revert of [debugger] flood function for stepping before calling it.

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 1053a3f92e608fed933b45db40da14c0ec10ec27..fbbc0688e1ce2453a35c66d797d221059f867d6f 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -707,8 +707,8 @@
   // arguments match the expected number of arguments. Fake a
   // parameter count to avoid emitting code to do the check.
   ParameterCount expected(0);
-  GetBuiltinFunction(rdi, native_context_index);
-  InvokeFunctionCode(rdi, no_reg, expected, expected, flag, call_wrapper);
+  GetBuiltinEntry(r8, native_context_index);
+  InvokeCode(r8, no_reg, expected, expected, flag, call_wrapper);
 }
 
 
@@ -718,6 +718,15 @@
   movp(target, Operand(rsi, Context::SlotOffset(Context::GLOBAL_OBJECT_INDEX)));
   movp(target, FieldOperand(target, JSGlobalObject::kNativeContextOffset));
   movp(target, ContextOperand(target, native_context_index));
+}
+
+
+void MacroAssembler::GetBuiltinEntry(Register target,
+                                     int native_context_index) {
+  DCHECK(!target.is(rdi));
+  // Load the JavaScript builtin function from the builtins object.
+  GetBuiltinFunction(rdi, native_context_index);
+  movp(target, FieldOperand(rdi, JSFunction::kCodeEntryOffset));
 }
 
 
@@ -3998,25 +4007,25 @@
                                     const CallWrapper& call_wrapper) {
   DCHECK(function.is(rdi));
   movp(rsi, FieldOperand(function, JSFunction::kContextOffset));
-  InvokeFunctionCode(rdi, new_target, expected, actual, flag, call_wrapper);
-}
-
-
-void MacroAssembler::InvokeFunctionCode(Register function, Register new_target,
-                                        const ParameterCount& expected,
-                                        const ParameterCount& actual,
-                                        InvokeFlag flag,
-                                        const CallWrapper& call_wrapper) {
+  // Advances r8 to the end of the Code object header, to the start of
+  // the executable code.
+  movp(r8, FieldOperand(rdi, JSFunction::kCodeEntryOffset));
+  InvokeCode(r8, new_target, expected, actual, flag, call_wrapper);
+}
+
+
+void MacroAssembler::InvokeCode(Register code,
+                                Register new_target,
+                                const ParameterCount& expected,
+                                const ParameterCount& actual,
+                                InvokeFlag flag,
+                                const CallWrapper& call_wrapper) {
   // You can't call a function without a valid frame.
   DCHECK(flag == JUMP_FUNCTION || has_frame());
-  DCHECK(function.is(rdi));
+
+  // Ensure new target is passed in the correct register. Otherwise clear the
+  // appropriate register in case new target is not given.
   DCHECK_IMPLIES(new_target.is_valid(), new_target.is(rdx));
-
-  if (call_wrapper.NeedsDebugStepCheck()) {
-    FloodFunctionIfStepping(function, new_target, expected, actual);
-  }
-
-  // Clear the new.target register if not given.
   if (!new_target.is_valid()) {
     LoadRoot(rdx, Heap::kUndefinedValueRootIndex);
   }
@@ -4031,10 +4040,6 @@
                  Label::kNear,
                  call_wrapper);
   if (!definitely_mismatches) {
-    // We call indirectly through the code field in the function to
-    // allow recompilation to take effect without changing any of the
-    // call sites.
-    Operand code = FieldOperand(function, JSFunction::kCodeEntryOffset);
     if (flag == CALL_FUNCTION) {
       call_wrapper.BeforeCall(CallSize(code));
       call(code);
@@ -4114,49 +4119,6 @@
 }
 
 
-void MacroAssembler::FloodFunctionIfStepping(Register fun, Register new_target,
-                                             const ParameterCount& expected,
-                                             const ParameterCount& actual) {
-  Label skip_flooding;
-  ExternalReference debug_step_action =
-      ExternalReference::debug_last_step_action_address(isolate());
-  Operand debug_step_action_operand = ExternalOperand(debug_step_action);
-  cmpb(debug_step_action_operand, Immediate(StepIn));
-  j(not_equal, &skip_flooding);
-  {
-    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, 1);
-    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);
-}
-
-
 void MacroAssembler::StubPrologue() {
     pushq(rbp);  // Caller's frame pointer.
     movp(rbp, rsp);