Generators save and restore stack handlers

src/runtime.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 2559 matching lines @@
   } else {
     MaybeObject* maybe_generator =
         isolate->heap()->AllocateJSGeneratorObject(function);
     if (!maybe_generator->To(&generator)) return maybe_generator;
   }
   generator->set_function(function);
   generator->set_context(Context::cast(frame->context()));
   generator->set_receiver(frame->receiver());
   generator->set_continuation(0);
   generator->set_operand_stack(isolate->heap()->empty_fixed_array());
+  generator->set_stack_handler_index(-1);
 
   return generator;
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_SuspendJSGeneratorObject) {
   NoHandleAllocation ha(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_CHECKED(JSGeneratorObject, generator_object, 0);
 
   JavaScriptFrameIterator stack_iterator(isolate);
   JavaScriptFrame* frame = stack_iterator.frame();
   JSFunction* function = JSFunction::cast(frame->function());
   RUNTIME_ASSERT(function->shared()->is_generator());
   ASSERT_EQ(function, generator_object->function());
 
   // We expect there to be at least two values on the operand stack: the return
   // value of the yield expression, and the argument to this runtime call.
   // Neither of those should be saved.
   int operands_count = frame->ComputeOperandsCount();
   ASSERT(operands_count >= 2);
   operands_count -= 2;
 
   if (operands_count == 0) {
     ASSERT_EQ(generator_object->operand_stack(),
               isolate->heap()->empty_fixed_array());
+    ASSERT_EQ(generator_object->stack_handler_index(), -1);
     // If there are no operands on the stack, there shouldn't be a handler
     // active either.
     ASSERT(!frame->HasHandler());
   } else {
-    if (frame->HasHandler()) {
-      // TODO(wingo): Unwind the stack handlers.
-      UNIMPLEMENTED();
-    }
-
+    int stack_handler_index = -1;
+    MaybeObject* alloc = isolate->heap()->AllocateFixedArray(operands_count);
     FixedArray* operand_stack;
-    MaybeObject* alloc = isolate->heap()->AllocateFixedArray(operands_count);
     if (!alloc->To(&operand_stack)) return alloc;
-
-    for (int i = 0; i < operands_count; i++) {
-      operand_stack->set(i, frame->GetOperand(i));
-    }
+    frame->SaveOperandStack(operand_stack, &stack_handler_index);
     generator_object->set_operand_stack(operand_stack);
+    generator_object->set_stack_handler_index(stack_handler_index);
   }
 
   // Set continuation down here to avoid side effects if the operand stack
   // allocation fails.
   intptr_t offset = frame->pc() - function->code()->instruction_start();
   ASSERT(offset > 0 && Smi::IsValid(offset));
   generator_object->set_continuation(static_cast<int>(offset));
 
   // It's possible for the context to be other than the initial context even if
   // there is no stack handler active.  For example, this is the case in the
@@ skipping 29 matching lines @@
 
   Address pc = generator_object->function()->code()->instruction_start();
   int offset = generator_object->continuation();
   ASSERT(offset > 0);
   frame->set_pc(pc + offset);
   generator_object->set_continuation(JSGeneratorObject::kGeneratorExecuting);
 
   FixedArray* operand_stack = generator_object->operand_stack();
   int operands_count = operand_stack->length();
   if (operands_count != 0) {
-    // TODO(wingo): Rewind stack handlers.  However until
-    // SuspendJSGeneratorObject unwinds them, we won't see frames with stack
-    // handlers here.
-    for (int i = 0; i < operands_count; i++) {
-      ASSERT_EQ(frame->GetOperand(i), isolate->heap()->the_hole_value());
-      Memory::Object_at(frame->GetOperandSlot(i)) = operand_stack->get(i);
-    }
+    frame->RestoreOperandStack(operand_stack,
+                               generator_object->stack_handler_index());
     generator_object->set_operand_stack(isolate->heap()->empty_fixed_array());
+    generator_object->set_stack_handler_index(-1);
   }
 
   JSGeneratorObject::ResumeMode resume_mode =
       static_cast<JSGeneratorObject::ResumeMode>(resume_mode_int);
   switch (resume_mode) {
     case JSGeneratorObject::SEND:
       return value;
     case JSGeneratorObject::THROW:
       return isolate->Throw(value);
   }
@@ skipping 10824 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal