[turbofan] Introduce CheckPoint common operator.

src/compiler/verifier.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/verifier.h"
 
 #include <algorithm>
 #include <deque>
 #include <queue>
 #include <sstream>
@@ skipping 402 matching lines @@
       CHECK_EQ(0, value_count);
       CHECK_EQ(1, control_count);
       Node* control = NodeProperties::GetControlInput(node, 0);
       CHECK_EQ(effect_count, control->op()->ControlInputCount());
       CHECK_EQ(input_count, 1 + effect_count);
       break;
     }
     case IrOpcode::kGuard:
       // TODO(bmeurer): what are the constraints on these?
       break;
+    case IrOpcode::kCheckPoint:
+      // Type is empty.
+      CheckNotTyped(node);
+      break;
     case IrOpcode::kBeginRegion:
       // TODO(rossberg): what are the constraints on these?
       break;
     case IrOpcode::kFinishRegion: {
       // TODO(rossberg): what are the constraints on these?
       // Type must be subsumed by input type.
       if (typing == TYPED) {
         Node* val = NodeProperties::GetValueInput(node, 0);
         CHECK(NodeProperties::GetType(val)->Is(NodeProperties::GetType(node)));
       }
@@ skipping 929 matching lines @@
          replacement->op()->EffectOutputCount() > 0);
   DCHECK(!NodeProperties::IsFrameStateEdge(edge) ||
          replacement->opcode() == IrOpcode::kFrameState);
 }
 
 #endif  // DEBUG
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8