Fix IsDeletable() for HStringAdd, HStringCharCodeAt, HStringCharFromCode.

test/mjsunit/compiler/dead-string-add.js

-// Copyright 2008 the V8 project authors. All rights reserved.
+// 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.
 
 function dead1(a, b) {
-    a + b; // dead
-    return a;
+    var x = "a" + "b";
+    return a; // x, "a", and "b" are dead code
 }
 
 function dead2(a, b) {
-    a | 0; // dead
-    b | 0; // dead
+    var x = a + "0";
+    var y = b + "0";
     return a; // x and y are both dead
 }
 
 function dead3(a, b) {
-    a == 2 ? a : b; // dead
-    return a;
-}
-
-function dead4(a) {
-    var z = 3;
-    for (i = 0; i < 3; i++) {
-        z + 3; // dead
-    }
-    return a;
-}
-
-function dead5(a) {
-    var z = 3;
-    for (i = 0; i < 3; i++) {
-        z + 3; // dead
-        z++;
-    }
-    var w = z + a;
-    return a; // z is dead
+    a = a ? "1" : "0";
+    b = b ? "1" : "0";
+    var x = a + "0";
+    var y = b + "0";
+    return a; // x and y are both dead
 }
 
 assertTrue(dead1(33, 32) == 33);
 assertTrue(dead2(33, 32) == 33);
-assertTrue(dead3(33, 32) == 33);
-assertTrue(dead4(33) == 33);
-assertTrue(dead5(33) == 33);
+assertTrue(dead3(33, 32) == "1");
 
-assertTrue(dead1(34, 7) == 34);
-assertTrue(dead2(34, 7) == 34);
-assertTrue(dead3(34, 7) == 34);
-assertTrue(dead4(34) == 34);
-assertTrue(dead5(34) == 34);
+assertTrue(dead1(31, 30) == 31);
+assertTrue(dead2(31, 30) == 31);
+assertTrue(dead3(31, 32) == "1");
 
-assertTrue(dead1(3.4, 0.1) == 3.4);
-assertTrue(dead2(3.4, 0.1) == 3.4);
-assertTrue(dead3(3.4, 0.1) == 3.4);
-assertTrue(dead4(3.4) == 3.4);
-assertTrue(dead5(3.4) == 3.4);
+assertTrue(dead1(0, 30) == 0);
+assertTrue(dead2(0, 30) == 0);
+assertTrue(dead3(0, 32) == "0");
+
+assertTrue(dead1(true, 0) == true);
+assertTrue(dead2(true, 0) == true);
+assertTrue(dead3(true, 0) == "1");
+
+assertTrue(dead1("true", 0) == "true");
+assertTrue(dead2("true", 0) == "true");
+assertTrue(dead3("true", 0) == "1");