Implement [Generator].prototype.return.

src/full-codegen/arm64/full-codegen-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/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 4337 matching lines @@
       __ Push(result_register());
       // Fall through.
     case Yield::kInitial: {
       Label suspend, continuation, post_runtime, resume;
 
       __ B(&suspend);
       // TODO(jbramley): This label is bound here because the following code
       // looks at its pos(). Is it possible to do something more efficient here,
       // perhaps using Adr?
       __ Bind(&continuation);
+      // When we arrive here, the stack top is the resume mode and
+      // result_register() holds the input value (the argument given to the
+      // respective resume operation).
       __ RecordGeneratorContinuation();
-      __ B(&resume);
+      __ Pop(x1);
+      __ Cmp(x1, Smi::FromInt(JSGeneratorObject::RETURN));
+      __ B(ne, &resume);
+      __ Push(result_register());
+      EmitCreateIteratorResult(true);
+      EmitUnwindBeforeReturn();
+      EmitReturnSequence();
 
       __ Bind(&suspend);
       VisitForAccumulatorValue(expr->generator_object());
       DCHECK((continuation.pos() > 0) && Smi::IsValid(continuation.pos()));
       __ Mov(x1, Smi::FromInt(continuation.pos()));
       __ Str(x1, FieldMemOperand(x0, JSGeneratorObject::kContinuationOffset));
       __ Str(cp, FieldMemOperand(x0, JSGeneratorObject::kContextOffset));
       __ Mov(x1, cp);
       __ RecordWriteField(x0, JSGeneratorObject::kContextOffset, x1, x2,
                           kLRHasBeenSaved, kDontSaveFPRegs);
       __ Add(x1, fp, StandardFrameConstants::kExpressionsOffset);
       __ Cmp(__ StackPointer(), x1);
       __ B(eq, &post_runtime);
       __ Push(x0);  // generator object
       __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
       __ Ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
       __ Bind(&post_runtime);
       __ Pop(result_register());
       EmitReturnSequence();
 
       __ Bind(&resume);
       context()->Plug(result_register());
       break;
     }
 
     case Yield::kFinal: {
       VisitForAccumulatorValue(expr->generator_object());
-      __ Mov(x1, Smi::FromInt(JSGeneratorObject::kGeneratorClosed));
-      __ Str(x1, FieldMemOperand(result_register(),
-                                 JSGeneratorObject::kContinuationOffset));
       // Pop value from top-of-stack slot, box result into result register.
       EmitCreateIteratorResult(true);
       EmitUnwindBeforeReturn();
       EmitReturnSequence();
       break;
     }
 
     case Yield::kDelegating: {
       VisitForStackValue(expr->generator_object());
 
@@ skipping 26 matching lines @@
       EnterTryBlock(handler_index, &l_catch);
       const int try_block_size = TryCatch::kElementCount * kPointerSize;
       __ Push(x0);                                       // result
 
       __ B(&l_suspend);
       // TODO(jbramley): This label is bound here because the following code
       // looks at its pos(). Is it possible to do something more efficient here,
       // perhaps using Adr?
       __ Bind(&l_continuation);
       __ RecordGeneratorContinuation();
+      __ pop(x1);
+      // TODO(neis): Ignoring the resume mode here is clearly wrong.  Currently,
+      // return is not supported for yield*.  The planned desugaring of yield*
+      // using do-expressions will naturally solve this.
       __ B(&l_resume);
 
       __ Bind(&l_suspend);
       const int generator_object_depth = kPointerSize + try_block_size;
       __ Peek(x0, generator_object_depth);
       __ Push(x0);                                       // g
       __ Push(Smi::FromInt(handler_index));              // handler-index
       DCHECK((l_continuation.pos() > 0) && Smi::IsValid(l_continuation.pos()));
       __ Mov(x1, Smi::FromInt(l_continuation.pos()));
       __ Str(x1, FieldMemOperand(x0, JSGeneratorObject::kContinuationOffset));
@@ skipping 127 matching lines @@
     Label slow_resume;
     __ Cbnz(operand_stack_size, &slow_resume);
     __ Ldr(x10, FieldMemOperand(function, JSFunction::kCodeEntryOffset));
     __ Ldrsw(x11,
              UntagSmiFieldMemOperand(generator_object,
                                      JSGeneratorObject::kContinuationOffset));
     __ Add(x10, x10, x11);
     __ Mov(x12, Smi::FromInt(JSGeneratorObject::kGeneratorExecuting));
     __ Str(x12, FieldMemOperand(generator_object,
                                 JSGeneratorObject::kContinuationOffset));
+    __ Push(Smi::FromInt(resume_mode));  // Consumed in continuation.
     __ Br(x10);
 
     __ Bind(&slow_resume);
   }
 
   // Otherwise, we push holes for the operand stack and call the runtime to fix
   // up the stack and the handlers.
   __ PushMultipleTimes(the_hole, operand_stack_size);
 
   __ Mov(x10, Smi::FromInt(resume_mode));
+  __ Push(Smi::FromInt(resume_mode));  // Consumed in continuation.
   __ Push(generator_object, result_register(), x10);
   __ CallRuntime(Runtime::kResumeJSGeneratorObject);
   // Not reached: the runtime call returns elsewhere.
   __ Unreachable();
 
   __ Bind(&done);
   context()->Plug(result_register());
 }
 
 
@@ skipping 232 matching lines @@
   }
 
   return INTERRUPT;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64