Generator objects can suspend

src/ia32/full-codegen-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1865 matching lines @@
     case NAMED_PROPERTY:
       EmitNamedPropertyAssignment(expr);
       break;
     case KEYED_PROPERTY:
       EmitKeyedPropertyAssignment(expr);
       break;
   }
 }
 
 
+void FullCodeGenerator::VisitYield(Yield* expr) {
+  Comment cmnt(masm_, "[ Yield");
+  // Evaluate yielded value first; the initial iterator definition depends on
+  // this.  It stays on the stack while we update the iterator.
+  VisitForStackValue(expr->expression());
+  VisitForStackValue(expr->generator_object());
+
+  if (expr->kind() == Yield::FINAL) {

[Michael Starzinger, 2013/04/17 13:43:48]

For the record: I think it will be best to just pass the yield kind as a second
parameter to the suspend runtime functions, because we will have different state
transitions depending on the kind. But let's not worry about that now for the
purpose of this CL.

+    // TODO(wingo): Mark the iterator as closed.
+  } else {
+    __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
+    __ mov(context_register(),
+           Operand(ebp, StandardFrameConstants::kContextOffset));
+  }
+
+  Label resume;
+  __ CompareRoot(result_register(), Heap::kTheHoleValueRootIndex);
+  __ j(not_equal, &resume);
+  switch (expr->kind()) {
+    case Yield::INITIAL:
+      __ pop(result_register());
+      break;
+    case Yield::SUSPEND:
+      // TODO(wingo): Box into { value: VALUE, done: false }.
+      __ pop(result_register());
+      break;
+    case Yield::FINAL:
+      // TODO(wingo): Box into { value: VALUE, done: true }.
+      __ pop(result_register());
+      break;
+    case Yield::DELEGATING:
+      UNIMPLEMENTED();
+  }
+  EmitReturnSequence();
+
+  __ bind(&resume);
+  context()->Plug(result_register());
+}
+
+
 void FullCodeGenerator::EmitNamedPropertyLoad(Property* prop) {
   SetSourcePosition(prop->position());
   Literal* key = prop->key()->AsLiteral();
   ASSERT(!key->handle()->IsSmi());
   __ mov(ecx, Immediate(key->handle()));
   Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
   CallIC(ic, RelocInfo::CODE_TARGET, prop->PropertyFeedbackId());
 }
 
 
@@ skipping 2662 matching lines @@
   *stack_depth = 0;
   *context_length = 0;
   return previous_;
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32