Implement [Generator].prototype.return.

src/full-codegen/mips/full-codegen-mips.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_MIPS
 
 // Note on Mips implementation:
 //
 // The result_register() for mips is the 'v0' register, which is defined
 // by the ABI to contain function return values. However, the first
@@ skipping 1908 matching lines @@
     case Yield::kSuspend:
       // Pop value from top-of-stack slot; box result into result register.
       EmitCreateIteratorResult(false);
       __ push(result_register());
       // Fall through.
     case Yield::kInitial: {
       Label suspend, continuation, post_runtime, resume;
 
       __ jmp(&suspend);
       __ 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();
-      __ jmp(&resume);
+      __ pop(a1);
+      __ Branch(&resume, ne, a1,
+                Operand(Smi::FromInt(JSGeneratorObject::RETURN)));
+      __ push(result_register());
+      EmitCreateIteratorResult(true);
+      EmitUnwindBeforeReturn();
+      EmitReturnSequence();
 
       __ bind(&suspend);
       VisitForAccumulatorValue(expr->generator_object());
       DCHECK(continuation.pos() > 0 && Smi::IsValid(continuation.pos()));
       __ li(a1, Operand(Smi::FromInt(continuation.pos())));
       __ sw(a1, FieldMemOperand(v0, JSGeneratorObject::kContinuationOffset));
       __ sw(cp, FieldMemOperand(v0, JSGeneratorObject::kContextOffset));
       __ mov(a1, cp);
       __ RecordWriteField(v0, JSGeneratorObject::kContextOffset, a1, a2,
                           kRAHasBeenSaved, kDontSaveFPRegs);
       __ Addu(a1, fp, Operand(StandardFrameConstants::kExpressionsOffset));
       __ Branch(&post_runtime, eq, sp, Operand(a1));
       __ push(v0);  // generator object
       __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
       __ lw(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());
-      __ li(a1, Operand(Smi::FromInt(JSGeneratorObject::kGeneratorClosed)));
-      __ sw(a1, 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 24 matching lines @@
       __ bind(&l_try);
       __ pop(a0);                                        // result
       int handler_index = NewHandlerTableEntry();
       EnterTryBlock(handler_index, &l_catch);
       const int try_block_size = TryCatch::kElementCount * kPointerSize;
       __ push(a0);                                       // result
 
       __ jmp(&l_suspend);
       __ bind(&l_continuation);
       __ RecordGeneratorContinuation();
+      __ pop(a1);
+      // 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.
       __ mov(a0, v0);
       __ jmp(&l_resume);
 
       __ bind(&l_suspend);
       const int generator_object_depth = kPointerSize + try_block_size;
       __ lw(a0, MemOperand(sp, generator_object_depth));
       __ push(a0);                                       // g
       __ Push(Smi::FromInt(handler_index));              // handler-index
       DCHECK(l_continuation.pos() > 0 && Smi::IsValid(l_continuation.pos()));
       __ li(a1, Operand(Smi::FromInt(l_continuation.pos())));
@@ skipping 119 matching lines @@
   // in directly.
   if (resume_mode == JSGeneratorObject::NEXT) {
     Label slow_resume;
     __ Branch(&slow_resume, ne, a3, Operand(zero_reg));
     __ lw(a3, FieldMemOperand(t0, JSFunction::kCodeEntryOffset));
     __ lw(a2, FieldMemOperand(a1, JSGeneratorObject::kContinuationOffset));
     __ SmiUntag(a2);
     __ Addu(a3, a3, Operand(a2));
     __ li(a2, Operand(Smi::FromInt(JSGeneratorObject::kGeneratorExecuting)));
     __ sw(a2, FieldMemOperand(a1, JSGeneratorObject::kContinuationOffset));
+    __ Push(Smi::FromInt(resume_mode));  // Consumed in continuation.
     __ Jump(a3);
     __ bind(&slow_resume);
   }
 
   // Otherwise, we push holes for the operand stack and call the runtime to fix
   // up the stack and the handlers.
   Label push_operand_holes, call_resume;
   __ bind(&push_operand_holes);
   __ Subu(a3, a3, Operand(1));
   __ Branch(&call_resume, lt, a3, Operand(zero_reg));
   __ push(a2);
   __ Branch(&push_operand_holes);
   __ bind(&call_resume);
+  __ Push(Smi::FromInt(resume_mode));  // Consumed in continuation.
   DCHECK(!result_register().is(a1));
   __ Push(a1, result_register());
   __ Push(Smi::FromInt(resume_mode));
   __ CallRuntime(Runtime::kResumeJSGeneratorObject);
   // Not reached: the runtime call returns elsewhere.
   __ stop("not-reached");
 
   __ bind(&done);
   context()->Plug(result_register());
 }
@@ skipping 2635 matching lines @@
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS