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

src/x64/builtins-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/code-factory.h"
 #include "src/codegen.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 462 matching lines @@
                       kDontSaveFPRegs);
 
   // Store resume mode into generator object.
   __ movp(FieldOperand(rbx, JSGeneratorObject::kResumeModeOffset), rdx);
 
   // Load suspended function and context.
   __ movp(rsi, FieldOperand(rbx, JSGeneratorObject::kContextOffset));
   __ movp(rdi, FieldOperand(rbx, 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());
   Operand step_in_enabled_operand = masm->ExternalOperand(step_in_enabled);
   __ cmpb(step_in_enabled_operand, Immediate(0));
-  __ j(equal, &skip_flooding);
-  {
-    FrameScope scope(masm, StackFrame::INTERNAL);
-    __ Push(rbx);
-    __ Push(rdx);
-    __ Push(rdi);
-    __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
-    __ Pop(rdx);
-    __ Pop(rbx);
-    __ movp(rdi, FieldOperand(rbx, 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());
+  Operand debug_suspended_generator_operand =
+      masm->ExternalOperand(debug_suspended_generator);
+  __ cmpp(rbx, debug_suspended_generator_operand);
+  __ j(equal, &prepare_step_in_suspended_generator);
+  __ bind(&stepping_prepared);
 
   // Pop return address.
   __ PopReturnAddressTo(rax);
 
   // Push receiver.
   __ Push(FieldOperand(rbx, JSGeneratorObject::kReceiverOffset));
 
   // ----------- S t a t e -------------
   //  -- rax    : return address
   //  -- rbx    : the JSGeneratorObject to resume
@@ skipping 79 matching lines @@
     __ movp(rdx, FieldOperand(rdi, JSFunction::kSharedFunctionInfoOffset));
     __ movp(rdx, FieldOperand(rdx, SharedFunctionInfo::kCodeOffset));
     __ SmiToInteger64(
         rcx, FieldOperand(rbx, JSGeneratorObject::kContinuationOffset));
     __ leap(rdx, FieldOperand(rdx, rcx, times_1, Code::kHeaderSize));
     __ Move(FieldOperand(rbx, JSGeneratorObject::kContinuationOffset),
             Smi::FromInt(JSGeneratorObject::kGeneratorExecuting));
     __ movp(rax, rbx);  // Continuation expects generator object in rax.
     __ jmp(rdx);
   }
+
+  __ bind(&prepare_step_in_if_stepping);
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    __ Push(rbx);
+    __ Push(rdx);
+    __ Push(rdi);
+    __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
+    __ Pop(rdx);
+    __ Pop(rbx);
+    __ movp(rdi, FieldOperand(rbx, JSGeneratorObject::kFunctionOffset));
+  }
+  __ jmp(&stepping_prepared);
+
+  __ bind(&prepare_step_in_suspended_generator);
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    __ Push(rbx);
+    __ Push(rdx);
+    __ CallRuntime(Runtime::kDebugPrepareStepInSuspendedGenerator);
+    __ Pop(rdx);
+    __ Pop(rbx);
+    __ movp(rdi, FieldOperand(rbx, JSGeneratorObject::kFunctionOffset));
+  }
+  __ jmp(&stepping_prepared);
 }
 
 static void LeaveInterpreterFrame(MacroAssembler* masm, Register scratch1,
                                   Register scratch2) {
   Register args_count = scratch1;
   Register return_pc = scratch2;
 
   // Get the arguments + receiver count.
   __ movp(args_count,
           Operand(rbp, InterpreterFrameConstants::kBytecodeArrayFromFp));
@@ skipping 2311 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64