[turbofan] Some common operators are globally shared singletons.

src/compiler/operator-properties-inl.h

 // Copyright 2013 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.
 
 #ifndef V8_COMPILER_OPERATOR_PROPERTIES_INL_H_
 #define V8_COMPILER_OPERATOR_PROPERTIES_INL_H_
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/opcodes.h"
@@ skipping 97 matching lines @@
 
 inline int OperatorProperties::GetControlInputCount(const Operator* op) {
   switch (op->opcode()) {
     case IrOpcode::kPhi:
     case IrOpcode::kEffectPhi:
     case IrOpcode::kControlEffect:
       return 1;
 #define OPCODE_CASE(x) case IrOpcode::k##x:
       CONTROL_OP_LIST(OPCODE_CASE)
 #undef OPCODE_CASE
-      return static_cast<const ControlOperator*>(op)->ControlInputCount();
+      return OpParameter<int>(op);

[Michael Starzinger, 2014/09/12 11:47:02]

This is scarily implicit, can we leave a comment here that this only works
because ControlOperator is an Operator1<int> where the parameter is the control
input count?

[Benedikt Meurer, 2014/09/12 11:59:08]

Done.

     default:
       // Operators that have write effects must have a control
       // dependency. Effect dependencies only ensure the correct order of
       // write/read operations without consideration of control flow. Without an
       // explicit control dependency writes can be float in the schedule too
       // early along a path that shouldn't generate a side-effect.
       return op->HasProperty(Operator::kNoWrite) ? 0 : 1;
   }
   return 0;
 }
@@ skipping 44 matching lines @@
          opcode == IrOpcode::kDead || opcode == IrOpcode::kLoop ||
          opcode == IrOpcode::kMerge || opcode == IrOpcode::kIfTrue ||
          opcode == IrOpcode::kIfFalse;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_OPERATOR_PROPERTIES_INL_H_