[debug] implement intuitive semantics for stepping over await call.

src/ia32/builtins-ia32.cc

Index: src/ia32/builtins-ia32.cc
diff --git a/src/ia32/builtins-ia32.cc b/src/ia32/builtins-ia32.cc
index e17fb70baa57d034ee6862daf5c8205d7e0f7925..41780679307e0424e7808fe491b77bb989b9d388 100644
--- a/src/ia32/builtins-ia32.cc
+++ b/src/ia32/builtins-ia32.cc
@@ -407,22 +407,19 @@ void Builtins::Generate_ResumeGeneratorTrampoline(MacroAssembler* masm) {
   __ mov(edi, FieldOperand(ebx, JSGeneratorObject::kFunctionOffset));
 
   // Flood function if we are stepping.
-  Label skip_flooding;
+  Label prepare_step_in_if_stepping, prepare_step_in_suspended_generator;
+  Label stepping_prepared;
   ExternalReference step_in_enabled =
       ExternalReference::debug_step_in_enabled_address(masm->isolate());
   __ cmpb(Operand::StaticVariable(step_in_enabled), Immediate(0));
-  __ j(equal, &skip_flooding);
-  {
-    FrameScope scope(masm, StackFrame::INTERNAL);
-    __ Push(ebx);
-    __ Push(edx);
-    __ Push(edi);
-    __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
-    __ Pop(edx);
-    __ Pop(ebx);
-    __ mov(edi, FieldOperand(ebx, JSGeneratorObject::kFunctionOffset));
-  }
-  __ bind(&skip_flooding);
+  __ j(not_equal, &prepare_step_in_if_stepping);
+
+  // Flood function if we need to continue stepping in the suspended generator.
+  ExternalReference debug_suspended_generator =
+      ExternalReference::debug_suspended_generator_address(masm->isolate());
+  __ cmp(ebx, Operand::StaticVariable(debug_suspended_generator));
+  __ j(equal, &prepare_step_in_suspended_generator);
+  __ bind(&stepping_prepared);
 
   // Pop return address.
   __ PopReturnAddressTo(eax);
@@ -518,6 +515,31 @@ void Builtins::Generate_ResumeGeneratorTrampoline(MacroAssembler* masm) {
     __ mov(eax, ebx);  // Continuation expects generator object in eax.
     __ jmp(edx);
   }
+
+  __ bind(&prepare_step_in_if_stepping);
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    __ Push(ebx);
+    __ Push(edx);
+    __ Push(edi);
+    __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
+    __ Pop(edx);
+    __ Pop(ebx);
+    __ mov(edi, FieldOperand(ebx, JSGeneratorObject::kFunctionOffset));
+  }
+  __ jmp(&stepping_prepared);
+
+  __ bind(&prepare_step_in_suspended_generator);
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    __ Push(ebx);
+    __ Push(edx);
+    __ CallRuntime(Runtime::kDebugPrepareStepInSuspendedGenerator);
+    __ Pop(edx);
+    __ Pop(ebx);
+    __ mov(edi, FieldOperand(ebx, JSGeneratorObject::kFunctionOffset));
+  }
+  __ jmp(&stepping_prepared);
 }
 
 static void LeaveInterpreterFrame(MacroAssembler* masm, Register scratch1,