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

src/arm64/builtins-arm64.cc

 // Copyright 2013 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_ARM64
 
 #include "src/arm64/frames-arm64.h"
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
@@ skipping 709 matching lines @@
                       kLRHasNotBeenSaved, kDontSaveFPRegs);
 
   // Store resume mode into generator object.
   __ Str(x2, FieldMemOperand(x1, JSGeneratorObject::kResumeModeOffset));
 
   // Load suspended function and context.
   __ Ldr(cp, FieldMemOperand(x1, JSGeneratorObject::kContextOffset));
   __ Ldr(x4, FieldMemOperand(x1, 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());
   __ Mov(x10, Operand(step_in_enabled));
   __ Ldrb(x10, MemOperand(x10));
-  __ CompareAndBranch(x10, Operand(0), eq, &skip_flooding);
-  {
-    FrameScope scope(masm, StackFrame::INTERNAL);
-    __ Push(x1, x2, x4);
-    __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
-    __ Pop(x2, x1);
-    __ Ldr(x4, FieldMemOperand(x1, JSGeneratorObject::kFunctionOffset));
-  }
-  __ bind(&skip_flooding);
+  __ CompareAndBranch(x10, Operand(0), ne, &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());
+  __ Mov(x10, Operand(debug_suspended_generator));
+  __ Ldr(x10, MemOperand(x10));
+  __ CompareAndBranch(x10, Operand(x1), eq,
+                      &prepare_step_in_suspended_generator);
+  __ Bind(&stepping_prepared);
 
   // Push receiver.
   __ Ldr(x5, FieldMemOperand(x1, JSGeneratorObject::kReceiverOffset));
   __ Push(x5);
 
   // ----------- S t a t e -------------
   //  -- x1      : the JSGeneratorObject to resume
   //  -- x2      : the resume mode (tagged)
   //  -- x4      : generator function
   //  -- cp      : generator context
@@ skipping 67 matching lines @@
     __ Ldr(x10, FieldMemOperand(x10, SharedFunctionInfo::kCodeOffset));
     __ Add(x10, x10, Code::kHeaderSize - kHeapObjectTag);
     __ Ldrsw(x11,
         UntagSmiFieldMemOperand(x1, JSGeneratorObject::kContinuationOffset));
     __ Add(x10, x10, x11);
     __ Mov(x12, Smi::FromInt(JSGeneratorObject::kGeneratorExecuting));
     __ Str(x12, FieldMemOperand(x1, JSGeneratorObject::kContinuationOffset));
     __ Move(x0, x1);  // Continuation expects generator object in x0.
     __ Br(x10);
   }
+
+  __ Bind(&prepare_step_in_if_stepping);
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    __ Push(x1, x2, x4);
+    __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
+    __ Pop(x2, x1);
+    __ Ldr(x4, FieldMemOperand(x1, JSGeneratorObject::kFunctionOffset));
+  }
+  __ B(&stepping_prepared);
+
+  __ Bind(&prepare_step_in_suspended_generator);
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    __ Push(x1, x2);
+    __ CallRuntime(Runtime::kDebugPrepareStepInSuspendedGenerator);
+    __ Pop(x2, x1);
+    __ Ldr(x4, FieldMemOperand(x1, JSGeneratorObject::kFunctionOffset));
+  }
+  __ B(&stepping_prepared);
 }
 
 enum IsTagged { kArgcIsSmiTagged, kArgcIsUntaggedInt };
 
 
 // Clobbers x10, x15; preserves all other registers.
 static void Generate_CheckStackOverflow(MacroAssembler* masm, Register argc,
                                         IsTagged argc_is_tagged) {
   // Check the stack for overflow.
   // We are not trying to catch interruptions (e.g. debug break and
@@ skipping 2046 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM