Reuse ZoneList memory if possible.

src/hydrogen.cc

 // Copyright 2013 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 "hydrogen.h"
 
 #include <algorithm>
 
 #include "v8.h"
 #include "allocation-site-scopes.h"
@@ skipping 10497 matching lines @@
   ASSERT(globals_.is_empty());
   AstVisitor::VisitDeclarations(declarations);
   if (!globals_.is_empty()) {
     Handle<FixedArray> array =
        isolate()->factory()->NewFixedArray(globals_.length(), TENURED);
     for (int i = 0; i < globals_.length(); ++i) array->set(i, *globals_.at(i));
     int flags = DeclareGlobalsEvalFlag::encode(current_info()->is_eval()) |
         DeclareGlobalsNativeFlag::encode(current_info()->is_native()) |
         DeclareGlobalsStrictMode::encode(current_info()->strict_mode());
     Add<HDeclareGlobals>(array, flags);
-    globals_.Clear();
+    globals_.Rewind(0);
   }
 }
 
 
 void HOptimizedGraphBuilder::VisitVariableDeclaration(
     VariableDeclaration* declaration) {
   VariableProxy* proxy = declaration->proxy();
   VariableMode mode = declaration->mode();
   Variable* variable = proxy->var();
   bool hole_init = mode == LET || mode == CONST || mode == CONST_LEGACY;
@@ skipping 1266 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal