Custom call IC-s for String.prototype.{charAt,charCodeAt}.

test/mjsunit/string-charat.js

 // Copyright 2008 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:
 //
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 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 // 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.
 
 var s = "test";
 
-assertEquals("t", s.charAt());
-assertEquals("t", s.charAt("string"));
-assertEquals("t", s.charAt(null));
-assertEquals("t", s.charAt(void 0));
-assertEquals("t", s.charAt(false));
-assertEquals("e", s.charAt(true));
-assertEquals("", s.charAt(-1));
-assertEquals("", s.charAt(4));
-assertEquals("t", s.charAt(0));
-assertEquals("t", s.charAt(3));
-assertEquals("t", s.charAt(NaN));
+var slowIndex1 = { valueOf: function() { return 1; } };
+var slowIndex2 = { toString: function() { return "2"; } };
+var slowIndexOutOfRange = { valueOf: function() { return -1; } };
 
-assertEquals(116, s.charCodeAt());
-assertEquals(116, s.charCodeAt("string"));
-assertEquals(116, s.charCodeAt(null));
-assertEquals(116, s.charCodeAt(void 0));
-assertEquals(116, s.charCodeAt(false));
-assertEquals(101, s.charCodeAt(true));
-assertEquals(116, s.charCodeAt(0));
-assertEquals(116, s.charCodeAt(3));
-assertEquals(116, s.charCodeAt(NaN));
-assertTrue(isNaN(s.charCodeAt(-1)));
-assertTrue(isNaN(s.charCodeAt(4)));
+function basicTest() {
+  assertEquals("t", s.charAt());
+  assertEquals("t", s.charAt("string"));
+  assertEquals("t", s.charAt(null));
+  assertEquals("t", s.charAt(void 0));
+  assertEquals("t", s.charAt(false));
+  assertEquals("e", s.charAt(true));
+  assertEquals("", s.charAt(-1));
+  assertEquals("", s.charAt(4));
+  assertEquals("", s.charAt(slowIndexOutOfRange));
+  assertEquals("t", s.charAt(0));
+  assertEquals("t", s.charAt(-0.0));
+  assertEquals("t", s.charAt(0.4));
+  assertEquals("e", s.charAt(slowIndex1));
+  assertEquals("s", s.charAt(slowIndex2));
+  assertEquals("t", s.charAt(3));
+  assertEquals("t", s.charAt(3.4));
+  assertEquals("t", s.charAt(NaN));
+
+  assertEquals(116, s.charCodeAt());
+  assertEquals(116, s.charCodeAt("string"));
+  assertEquals(116, s.charCodeAt(null));
+  assertEquals(116, s.charCodeAt(void 0));
+  assertEquals(116, s.charCodeAt(false));
+  assertEquals(101, s.charCodeAt(true));
+  assertEquals(116, s.charCodeAt(0));
+  assertEquals(116, s.charCodeAt(-0.0));
+  assertEquals(116, s.charCodeAt(0.4));
+  assertEquals(101, s.charCodeAt(slowIndex1));
+  assertEquals(115, s.charCodeAt(slowIndex2));
+  assertEquals(116, s.charCodeAt(3));
+  assertEquals(116, s.charCodeAt(3.4));
+  assertEquals(116, s.charCodeAt(NaN));
+  assertTrue(isNaN(s.charCodeAt(-1)));
+  assertTrue(isNaN(s.charCodeAt(4)));
+  assertTrue(isNaN(s.charCodeAt(slowIndexOutOfRange)));
+}
+basicTest();
 
 // Make sure enough of the one-char string cache is filled.
 var alpha = ['@'];
 for (var i = 1; i < 128; i++) {
   var c = String.fromCharCode(i);
   alpha[i] = c.charAt(0);
 }
 var alphaStr = alpha.join("");
 
 // Now test chars.
 for (var i = 1; i < 128; i++) {
   assertEquals(alpha[i], alphaStr.charAt(i));
   assertEquals(String.fromCharCode(i), alphaStr.charAt(i));
 }
+
+// Test stealing String.prototype.{charAt,charCodeAt}.
+var o = {
+  charAt: String.prototype.charAt,
+  charCodeAt: String.prototype.charCodeAt,
+  toString: function() { return "012"; },
+  valueOf: function() { return "should not be called"; }
+};
+
+function stealTest() {
+  assertEquals("0", o.charAt(0));
+  assertEquals("1", o.charAt(1));
+  assertEquals("1", o.charAt(1.4));
+  assertEquals("1", o.charAt(slowIndex1));
+  assertEquals("2", o.charAt(2));
+  assertEquals("2", o.charAt(slowIndex2));
+  assertEquals(48, o.charCodeAt(0));
+  assertEquals(49, o.charCodeAt(1));
+  assertEquals(49, o.charCodeAt(1.4));
+  assertEquals(49, o.charCodeAt(slowIndex1));
+  assertEquals(50, o.charCodeAt(2));
+  assertEquals(50, o.charCodeAt(slowIndex2));
+  assertEquals("", o.charAt(-1));
+  assertEquals("", o.charAt(-1.4));
+  assertEquals("", o.charAt(10));
+  assertEquals("", o.charAt(slowIndexOutOfRange));
+  assertTrue(isNaN(o.charCodeAt(-1)));
+  assertTrue(isNaN(o.charCodeAt(-1.4)));
+  assertTrue(isNaN(o.charCodeAt(10)));
+  assertTrue(isNaN(o.charCodeAt(slowIndexOutOfRange)));
+}
+stealTest();
+
+// Test custom string IC-s.
+for (var i = 0; i < 20; i++) {
+  basicTest();
+  stealTest();
+}
+
+var badToString = function() { return []; };
+
+function testBadToString_charAt() {
+  var goodToString = o.toString;
+  var hasCaught = false;
+  var numCalls = 0;
+  var result;
+  try {
+    for (var i = 0; i < 20; i++) {
+      if (i == 10) o.toString = o.valueOf = badToString;
+      result = o.charAt(1);
+      numCalls++;
+    }
+  } catch (e) {
+    hasCaught = true;
+  } finally {
+    o.toString = goodToString;
+  }
+  assertTrue(hasCaught);
+  assertEquals("1", result);
+  assertEquals(10, numCalls);
+}
+testBadToString_charAt();
+
+function testBadToString_charCodeAt() {
+  var goodToString = o.toString;
+  var hasCaught = false;
+  var numCalls = 0;
+  var result;
+  try {
+    for (var i = 0; i < 20; i++) {
+      if (i == 10) o.toString = o.valueOf = badToString;
+      result = o.charCodeAt(1);
+      numCalls++;
+    }
+  } catch (e) {
+    hasCaught = true;
+  } finally {
+    o.toString = goodToString;
+  }
+  assertTrue(hasCaught);
+  assertEquals(49, result);
+  assertEquals(10, numCalls);
+}
+testBadToString_charCodeAt();
+
+var badIndex = {
+  toString: badToString,
+  valueOf: badToString
+};
+
+function testBadIndex_charAt() {
+  var index = 1;
+  var hasCaught = false;
+  var numCalls = 0;
+  var result;
+  try {
+    for (var i = 0; i < 20; i++) {
+      if (i == 10) index = badIndex;
+      result = o.charAt(index);
+      numCalls++;
+    }
+  } catch (e) {
+    hasCaught = true;
+  }
+  assertTrue(hasCaught);
+  assertEquals("1", result);
+  assertEquals(10, numCalls);
+}
+testBadIndex_charAt();
+
+function testBadIndex_charCodeAt() {
+  var index = 1;
+  var hasCaught = false;
+  var numCalls = 0;
+  var result;
+  try {
+    for (var i = 0; i < 20; i++) {
+      if (i == 10) index = badIndex;
+      result = o.charCodeAt(index);
+      numCalls++;
+    }
+  } catch (e) {
+    hasCaught = true;
+  }
+  assertTrue(hasCaught);
+  assertEquals(49, result);
+  assertEquals(10, numCalls);
+}
+testBadIndex_charCodeAt();
+
+function testPrototypeChange_charAt() {
+  var result, oldResult;
+  for (var i = 0; i < 20; i++) {
+    if (i == 10) {
+      oldResult = result;
+      String.prototype.charAt = function() { return "%"; };
+    }
+    result = s.charAt(1);
+  }
+  assertEquals("%", result);
+  assertEquals("e", oldResult);
+  delete String.prototype.charAt;  // Restore the default.
+}
+testPrototypeChange_charAt();
+
+function testPrototypeChange_charCodeAt() {
+  var result, oldResult;
+  for (var i = 0; i < 20; i++) {
+    if (i == 10) {
+      oldResult = result;
+      String.prototype.charCodeAt = function() { return 42; };
+    }
+    result = s.charCodeAt(1);
+  }
+  assertEquals(42, result);
+  assertEquals(101, oldResult);
+  delete String.prototype.charCodeAt;  // Restore the default.
+}
+testPrototypeChange_charCodeAt();