[turbofan] Introduce CheckPoint common operator.

src/compiler/effect-control-linearizer.cc

 // Copyright 2015 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/effect-control-linearizer.h"
 
 #include "src/code-factory.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/linkage.h"
@@ skipping 275 matching lines @@
 
   // Remove the end markers of 'atomic' allocation region because the
   // region should be wired-in now.
   if (node->opcode() == IrOpcode::kFinishRegion ||
       node->opcode() == IrOpcode::kBeginRegion) {
     // Update the value uses to the value input of the finish node and
     // the effect uses to the effect input.
     return RemoveRegionNode(node);
   }
 
+  // Special treatment for CheckPoint nodes.
+  // TODO(epertoso): Pickup the current frame state.
+  if (node->opcode() == IrOpcode::kCheckPoint) {
+    // Unlink the check point; effect uses will be updated to the incoming
+    // effect that is passed.
+    node->Kill();
+    return;
+  }
+
   if (node->opcode() == IrOpcode::kIfSuccess) {
     // We always schedule IfSuccess with its call, so skip it here.
     DCHECK_EQ(IrOpcode::kCall, node->InputAt(0)->opcode());
     // The IfSuccess node should not belong to an exceptional call node
     // because such IfSuccess nodes should only start a basic block (and
     // basic block start nodes are not handled in the ProcessNode method).
     DCHECK(!NodeProperties::IsExceptionalCall(node->InputAt(0)));
     return;
   }
 
@@ skipping 649 matching lines @@
   return jsgraph()->Int32Constant(Smi::kMaxValue);
 }
 
 Node* EffectControlLinearizer::SmiShiftBitsConstant() {
   return jsgraph()->IntPtrConstant(kSmiShiftSize + kSmiTagSize);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8