[turbofan] Introduce an ExternalPointer type.

src/compiler/js-graph.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/code-stubs.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/typer.h"
 
 namespace v8 {
@@ skipping 224 matching lines @@
 
 
 Node* JSGraph::Float64Constant(double value) {
   Node** loc = cache_.FindFloat64Constant(value);
   if (*loc == nullptr) {
     *loc = graph()->NewNode(common()->Float64Constant(value));
   }
   return *loc;
 }
 
+Node* JSGraph::PointerConstant(intptr_t value) {
+  Node** loc = cache_.FindPointerConstant(value);
+  if (*loc == nullptr) {
+    *loc = graph()->NewNode(common()->PointerConstant(value));
+  }
+  return *loc;
+}
 
 Node* JSGraph::ExternalConstant(ExternalReference reference) {
   Node** loc = cache_.FindExternalConstant(reference);
   if (*loc == nullptr) {
     *loc = graph()->NewNode(common()->ExternalConstant(reference));
   }
   return *loc;
 }
 
 
@@ skipping 15 matching lines @@
   for (size_t i = 0; i < arraysize(cached_nodes_); i++) {
     if (Node* node = cached_nodes_[i]) {
       if (!node->IsDead()) nodes->push_back(node);
     }
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8