[turbofan] Introduce explicit loop exits markers.

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 377 matching lines @@
     }
     case IrOpcode::kEffectPhi: {
       // EffectPhi input count matches parent control node.
       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::kLoopExit: {
+      CHECK_EQ(2, control_count);
+      Node* loop = NodeProperties::GetControlInput(node, 1);
+      CHECK_EQ(IrOpcode::kLoop, loop->opcode());
+      break;
+    }
+    case IrOpcode::kLoopExitValue: {
+      CHECK_EQ(1, control_count);
+      Node* loop_exit = NodeProperties::GetControlInput(node, 0);
+      CHECK_EQ(IrOpcode::kLoopExit, loop_exit->opcode());
+      break;
+    }
+    case IrOpcode::kLoopExitEffect: {
+      CHECK_EQ(1, control_count);
+      Node* loop_exit = NodeProperties::GetControlInput(node, 0);
+      CHECK_EQ(IrOpcode::kLoopExit, loop_exit->opcode());
+      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.
@@ skipping 1078 matching lines @@
          replacement->op()->EffectOutputCount() > 0);
   DCHECK(!NodeProperties::IsFrameStateEdge(edge) ||
          replacement->opcode() == IrOpcode::kFrameState);
 }
 
 #endif  // DEBUG
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8