Fix IsDeletable() for HStringAdd, HStringCharCodeAt, HStringCharFromCode.

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

Index: test/mjsunit/compiler/dead-string-add.js
diff --git a/test/mjsunit/compiler/dead-code3.js b/test/mjsunit/compiler/dead-string-add.js
similarity index 66%
copy from test/mjsunit/compiler/dead-code3.js
copy to test/mjsunit/compiler/dead-string-add.js
index d05797825b9400033b148090e9cd47e8305c4ce9..4ef4adbfaf63118d0264f4f6aeca844382e1c68d 100644
--- a/test/mjsunit/compiler/dead-code3.js
+++ b/test/mjsunit/compiler/dead-string-add.js
@@ -1,4 +1,4 @@
-// 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:
@@ -26,53 +26,40 @@
 // 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(31, 30) == 31);
+assertTrue(dead2(31, 30) == 31);
+assertTrue(dead3(31, 32) == "1");
+
+assertTrue(dead1(0, 30) == 0);
+assertTrue(dead2(0, 30) == 0);
+assertTrue(dead3(0, 32) == "0");
 
-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(true, 0) == true);
+assertTrue(dead2(true, 0) == true);
+assertTrue(dead3(true, 0) == "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("true", 0) == "true");
+assertTrue(dead2("true", 0) == "true");
+assertTrue(dead3("true", 0) == "1");