Correctly set kCanBeDivByZero flag for HMathFloorOfDiv.

After r13289 the divisor can be non-constant, so we should check for zero.

BUG=171641
R=yangguo@chromium.org

Review URL: https://chromiumcodereview.appspot.com/12047050

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13479 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.h

@@ -3111,6 +3111,9 @@ class HMathFloorOfDiv: public HBinaryOperation {
     set_representation(Representation::Integer32());
     SetFlag(kUseGVN);
     SetFlag(kCanOverflow);
+    if (!right->IsConstant()) {
+      SetFlag(kCanBeDivByZero);
+    }
   }
 
   virtual HValue* EnsureAndPropagateNotMinusZero(BitVector* visited);

test/mjsunit/regress/regress-171641.js

+// 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.
+
+// Flags: --allow-natives-syntax
+
+function foo(k, p) {
+  for (var i = 0; i < 1; i++) {
+    p = Math.min(p, i);
+  }
+  m = Math.floor((k | 0) / p);
+}
+
+foo(0, 1);
+foo(0, 1);
+%OptimizeFunctionOnNextCall(foo);
+foo(0, 1);