[turbofan] Sparse representation for state values

src/compiler/simplified-lowering.cc

 // Copyright 2014 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.
 
 #include "src/compiler/simplified-lowering.h"
 
 #include <limits>
 
 #include "src/address-map.h"
 #include "src/base/bits.h"
@@ skipping 992 matching lines @@
         MachineRepresentation rep = input_type->IsInhabited()
                                         ? input_info->representation()
                                         : MachineRepresentation::kNone;
         MachineType machine_type(rep, DeoptValueSemanticOf(input_type));
         DCHECK(machine_type.representation() !=
                    MachineRepresentation::kWord32 ||
                machine_type.semantic() == MachineSemantic::kInt32 ||
                machine_type.semantic() == MachineSemantic::kUint32);
         (*types)[i] = machine_type;
       }
-      NodeProperties::ChangeOp(node,
-                               jsgraph_->common()->TypedStateValues(types));
+      uint32_t mask = OpParameter<uint32_t>(node);

[Jarin, 2016/12/07 08:56:20]

Descriptive name, please.

You should not use OpParameter directly, please, define an accessor in
common-operator.*.

OpParamater is very dangerous because if you decide to change the parameter type
(in CommonOperatorBuilder::StateValues), compiler will not complain about type
mismatch and you will start seeing random "mask". We already had serious bugs
here.

[Leszek Swirski, 2016/12/08 15:44:30]

Done, throughout. Interesting point about the type mismatch, I'm not sure I see
how the accessors in common-operator (which are just wrappers around
OpParameter) help with this?

+      NodeProperties::ChangeOp(
+          node, jsgraph_->common()->TypedStateValues(types, mask));
     }
     SetOutput(node, MachineRepresentation::kTagged);
   }
 
   void VisitObjectState(Node* node) {
     if (propagate()) {
       for (int i = 0; i < node->InputCount(); i++) {
         Node* input = node->InputAt(i);
         Type* input_type = TypeOf(input);
         // TODO(turbofan): Special treatment for ExternalPointer here,
@@ skipping 2421 matching lines @@
         isolate(), graph()->zone(), callable.descriptor(), 0, flags,
         Operator::kNoProperties);
     to_number_operator_.set(common()->Call(desc));
   }
   return to_number_operator_.get();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8