Don't use StoreIC_ArrayLength on frozen arrays

The code previously assumed that an array with fast properties must have
a writable length property. But Object.freeze() now exposes a way to make
length read-only without moving the object into slow mode. This patch
simply adds a !is_frozen check to the IC code. Any future optimizations
to attribute-setting on JSArrays will need to make similar accomodations.

R=danno
BUG=v8:2711,259548

Review URL: https://chromiumcodereview.appspot.com/19115002
Patch from Adam Klein <adamk@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15651 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

diff --git a/src/ic.cc b/src/ic.cc
index a15863e..f84b3b9 100644 (file)
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -1662,12 +1662,14 @@ MaybeObject* StoreIC::Store(State state,
 
   // Use specialized code for setting the length of arrays with fast
   // properties. Slow properties might indicate redefinition of the length
-  // property.
+  // property. Note that when redefined using Object.freeze, it's possible
+  // to have fast properties but a read-only length.
   if (FLAG_use_ic &&
       receiver->IsJSArray() &&
       name->Equals(isolate()->heap()->length_string()) &&
       Handle<JSArray>::cast(receiver)->AllowsSetElementsLength() &&
-      receiver->HasFastProperties()) {
+      receiver->HasFastProperties() &&
+      !receiver->map()->is_frozen()) {
     Handle<Code> stub =
         StoreArrayLengthStub(kind(), strict_mode).GetCode(isolate());
     set_target(*stub);

diff --git a/test/mjsunit/regress/regress-2711.js b/test/mjsunit/regress/regress-2711.js
new file mode 100644 (file)
index 0000000..a58e789
--- /dev/null
+++ b/test/mjsunit/regress/regress-2711.js
@@ -0,0 +1,33 @@
+// 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.
+
+// Test that frozen arrays don't let their length change
+var a = Object.freeze([1]);
+a.push(2);
+assertEquals(1, a.length);
+a.push(2);
+assertEquals(1, a.length);