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

Port 8d90210a

R=yangguo@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=v8:4483
LOG=N

Review-Url: https://codereview.chromium.org/2040803003
Cr-Commit-Position: refs/heads/master@{#36750}

src/ppc/builtins-ppc.cc

@@ -723,21 +723,25 @@ void Builtins::Generate_ResumeGeneratorTrampoline(MacroAssembler* masm) {
   __ LoadP(r7, FieldMemOperand(r4, 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(ip, Operand(step_in_enabled));
   __ lbz(ip, MemOperand(ip));
   __ cmpi(ip, Operand::Zero());
-  __ beq(&skip_flooding);
-  {
-    FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
-    __ Push(r4, r5, r7);
-    __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
-    __ Pop(r4, r5);
-    __ LoadP(r7, FieldMemOperand(r4, JSGeneratorObject::kFunctionOffset));
-  }
-  __ bind(&skip_flooding);
+  __ bne(&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(ip, Operand(debug_suspended_generator));
+  __ LoadP(ip, MemOperand(ip));
+  __ cmp(ip, r4);
+  __ beq(&prepare_step_in_suspended_generator);
+  __ bind(&stepping_prepared);
 
   // Push receiver.
   __ LoadP(ip, FieldMemOperand(r4, JSGeneratorObject::kReceiverOffset));
@@ -843,6 +847,26 @@ void Builtins::Generate_ResumeGeneratorTrampoline(MacroAssembler* masm) {
       __ Jump(r6);
     }
   }
+
+  __ bind(&prepare_step_in_if_stepping);
+  {
+    FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
+    __ Push(r4, r5, r7);
+    __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
+    __ Pop(r4, r5);
+    __ LoadP(r7, FieldMemOperand(r4, JSGeneratorObject::kFunctionOffset));
+  }
+  __ b(&stepping_prepared);
+
+  __ bind(&prepare_step_in_suspended_generator);
+  {
+    FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
+    __ Push(r4, r5);
+    __ CallRuntime(Runtime::kDebugPrepareStepInSuspendedGenerator);
+    __ Pop(r4, r5);
+    __ LoadP(r7, FieldMemOperand(r4, JSGeneratorObject::kFunctionOffset));
+  }
+  __ b(&stepping_prepared);
 }
 
 void Builtins::Generate_ConstructedNonConstructable(MacroAssembler* masm) {