Deoptimizer support for hydrogen stubs that accept a variable number of arguments.

src/code-stubs-hydrogen.cc

Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index bb8bfe3fdc4447e90683ffc8df0cf77514ae1cd5..026e777901fa3e2e1b8bc9fae67e806c79a6d08b 100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -124,11 +124,13 @@ bool CodeStubGraphBuilderBase::BuildGraph() {
     parameters_[i] = param;
   }
 
+  HInstruction* stack_pop_count;

[danno, 2013/03/20 21:07:33]

nit: Can you define this down where you initially set its value?

[mvstanton, 2013/03/21 11:47:35]

Done.

   HInstruction* stack_parameter_count;
   if (descriptor_->stack_parameter_count_ != NULL) {
     ASSERT(descriptor_->environment_length() == (param_count + 1));
     stack_parameter_count = new(zone) HParameter(param_count,
-        HParameter::REGISTER_PARAMETER);
+                                                 HParameter::REGISTER_PARAMETER,
+                                                 Representation::Integer32());
     // it's essential to bind this value to the environment in case of deopt
     start_environment->Bind(param_count, stack_parameter_count);
     AddInstruction(stack_parameter_count);
@@ -139,6 +141,8 @@ bool CodeStubGraphBuilderBase::BuildGraph() {
     arguments_length_ = graph()->GetConstant0();
   }
 
+  stack_pop_count = stack_parameter_count;
+
   context_ = new(zone) HContext();
   AddInstruction(context_);
   start_environment->BindContext(context_);
@@ -146,13 +150,25 @@ bool CodeStubGraphBuilderBase::BuildGraph() {
   AddSimulate(BailoutId::StubEntry());
 
   HValue* return_value = BuildCodeStub();
+
+  // We might have extra expressions to pop from the stack in addition to the
+  // arguments above
+  if (descriptor_->acting_as_js_function_) {
+    HInstruction* amount = graph()->GetConstant1();
+    stack_pop_count = AddInstruction(
+        HAdd::New(zone, context_, stack_parameter_count, amount));
+    stack_pop_count->ChangeRepresentation(Representation::Integer32());
+    stack_pop_count->ClearFlag(HValue::kCanOverflow);
+  }
+
   HReturn* hreturn_instruction = new(zone) HReturn(return_value,
                                                    context_,
-                                                   stack_parameter_count);
+                                                   stack_pop_count);
   current_block()->Finish(hreturn_instruction);
   return true;
 }
 
+
 template <class Stub>
 class CodeStubGraphBuilder: public CodeStubGraphBuilderBase {
  public: