Turn mark deoptimize on undefined into a proper HPhase.

src/hydrogen-mark-deoptimize.cc

+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "hydrogen-mark-deoptimize.h"
+
+namespace v8 {
+namespace internal {
+
+void HMarkDeoptimizeOnUndefinedPhase::Run() {
+  const ZoneList<HPhi*>* phi_list = graph()->phi_list();
+  for (int i = 0; i < phi_list->length(); i++) {
+    HPhi* phi = phi_list->at(i);
+    if (phi->CheckFlag(HValue::kAllowUndefinedAsNaN)) {
+      for (HUseIterator it(phi->uses()); !it.Done(); it.Advance()) {
+        HValue* use_value = it.value();
+        if (!use_value->CheckFlag(HValue::kAllowUndefinedAsNaN)) {
+          AddToWorklist(phi);
+          ProcessWorklist();
+          break;
+        }
+      }
+    }
+  }
+}
+
+
+void HMarkDeoptimizeOnUndefinedPhase::AddToWorklist(HPhi* phi) {

[Dmitry Lomov (no reviews), 2013/07/30 09:05:24]

Any reason to have AddToWorklist function at all? I would do it this way:
- Rename ProcessWorklist into ProcessPhi
- Pass phi to ProcessPhi and make worklist local to ProcessPhiTree
- Remove global worklist

[Benedikt Meurer, 2013/07/30 09:59:10]

As discussed offline: The idea is to avoid allocating a new ZoneList for every
phi with an affected use. The way its done now reuses the same ZoneList. I'll
merge the AddToWorklist and ProcessWorklist methods into a single ProcessPhi
method, using the member ZoneList as optimization.

+  ASSERT(phi->CheckFlag(HValue::kAllowUndefinedAsNaN));
+  ASSERT(!worklist_.Contains(phi));
+  phi->ClearFlag(HValue::kAllowUndefinedAsNaN);
+  worklist_.Add(phi, zone());
+}
+
+
+void HMarkDeoptimizeOnUndefinedPhase::ProcessWorklist() {
+  while (!worklist_.is_empty()) {
+    HPhi* phi = worklist_.RemoveLast();
+    for (int i = phi->OperandCount() - 1; i >= 0; --i) {
+      HValue* input = phi->OperandAt(i);
+      if (input->IsPhi() && input->CheckFlag(HValue::kAllowUndefinedAsNaN)) {
+        AddToWorklist(HPhi::cast(input));
+      }
+    }
+  }
+}
+
+} }  // namespace v8::internal