Implement [Generator].prototype.return.

src/full-codegen/ia32/full-codegen-ia32.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_IA32
 
 #include "src/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 1820 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(ebx);
+      __ cmp(ebx, Immediate(Smi::FromInt(JSGeneratorObject::RETURN)));
+      __ j(not_equal, &resume);
+      __ push(result_register());
+      EmitCreateIteratorResult(true);
+      EmitUnwindBeforeReturn();
+      EmitReturnSequence();
 
       __ bind(&suspend);
       VisitForAccumulatorValue(expr->generator_object());
       DCHECK(continuation.pos() > 0 && Smi::IsValid(continuation.pos()));
       __ mov(FieldOperand(eax, JSGeneratorObject::kContinuationOffset),
              Immediate(Smi::FromInt(continuation.pos())));
       __ mov(FieldOperand(eax, JSGeneratorObject::kContextOffset), esi);
       __ mov(ecx, esi);
       __ RecordWriteField(eax, JSGeneratorObject::kContextOffset, ecx, edx,
                           kDontSaveFPRegs);
       __ lea(ebx, Operand(ebp, StandardFrameConstants::kExpressionsOffset));
       __ cmp(esp, ebx);
       __ j(equal, &post_runtime);
       __ push(eax);  // generator object
       __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
       __ mov(context_register(),
              Operand(ebp, StandardFrameConstants::kContextOffset));
       __ bind(&post_runtime);
       __ pop(result_register());
       EmitReturnSequence();
 
       __ bind(&resume);
       context()->Plug(result_register());
       break;
     }
 
     case Yield::kFinal: {
       VisitForAccumulatorValue(expr->generator_object());
-      __ mov(FieldOperand(result_register(),
-                          JSGeneratorObject::kContinuationOffset),
-             Immediate(Smi::FromInt(JSGeneratorObject::kGeneratorClosed)));
       // 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(eax);                                       // result
       int handler_index = NewHandlerTableEntry();
       EnterTryBlock(handler_index, &l_catch);
       const int try_block_size = TryCatch::kElementCount * kPointerSize;
       __ push(eax);                                      // result
 
       __ jmp(&l_suspend);
       __ bind(&l_continuation);
       __ RecordGeneratorContinuation();
+      __ pop(ebx);
+      // 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.
       __ jmp(&l_resume);
 
       __ bind(&l_suspend);
       const int generator_object_depth = kPointerSize + try_block_size;
       __ mov(eax, Operand(esp, generator_object_depth));
       __ push(eax);                                      // g
       __ push(Immediate(Smi::FromInt(handler_index)));   // handler-index
       DCHECK(l_continuation.pos() > 0 && Smi::IsValid(l_continuation.pos()));
       __ mov(FieldOperand(eax, JSGeneratorObject::kContinuationOffset),
              Immediate(Smi::FromInt(l_continuation.pos())));
@@ skipping 115 matching lines @@
   if (resume_mode == JSGeneratorObject::NEXT) {
     Label slow_resume;
     __ cmp(edx, Immediate(0));
     __ j(not_zero, &slow_resume);
     __ mov(edx, FieldOperand(edi, JSFunction::kCodeEntryOffset));
     __ mov(ecx, FieldOperand(ebx, JSGeneratorObject::kContinuationOffset));
     __ SmiUntag(ecx);
     __ add(edx, ecx);
     __ mov(FieldOperand(ebx, JSGeneratorObject::kContinuationOffset),
            Immediate(Smi::FromInt(JSGeneratorObject::kGeneratorExecuting)));
+    __ Push(Smi::FromInt(resume_mode));  // Consumed in continuation.
     __ jmp(edx);
     __ 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);
   __ sub(edx, Immediate(1));
   __ j(carry, &call_resume);
   __ push(ecx);
   __ jmp(&push_operand_holes);
   __ bind(&call_resume);
+  __ Push(Smi::FromInt(resume_mode));  // Consumed in continuation.
   __ push(ebx);
   __ push(result_register());
   __ Push(Smi::FromInt(resume_mode));
   __ CallRuntime(Runtime::kResumeJSGeneratorObject);
   // Not reached: the runtime call returns elsewhere.
   __ Abort(kGeneratorFailedToResume);
 
   __ bind(&done);
   context()->Plug(result_register());
 }
@@ skipping 2641 matching lines @@
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32