[turbofan] Flatten cons strings before embedding them into optimized code.

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 54 matching lines @@
 }
 
 
 Node* JSGraph::NaNConstant() {
   return CACHED(kNaNConstant,
                 NumberConstant(std::numeric_limits<double>::quiet_NaN()));
 }
 
 
 Node* JSGraph::HeapConstant(Handle<HeapObject> value) {
-  // TODO(bmeurer): Flatten cons strings here before we canonicalize them?
+  if (value->IsConsString()) {

[Yang, 2015/12/16 06:24:16]

String::Flatten already checks for cons string. No need to do it here.

[Benedikt Meurer, 2015/12/16 06:26:02]

That doesn't really help, since we'd have to test for string at least :-)

+    value = String::Flatten(Handle<String>::cast(value), TENURED);
+  }
   Node** loc = cache_.FindHeapConstant(value);
   if (*loc == nullptr) {
     *loc = graph()->NewNode(common()->HeapConstant(value));
   }
   return *loc;
 }
 
 
 Node* JSGraph::Constant(Handle<Object> value) {
   // Dereference the handle to determine if a number constant or other
@@ skipping 114 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