Track ascii-ness of data in externalized strings.

test/mjsunit/string-externalize.js

Index: test/mjsunit/string-externalize.js
diff --git a/test/mjsunit/string-externalize.js b/test/mjsunit/string-externalize.js
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+++ b/test/mjsunit/string-externalize.js
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+// Copyright 2010 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: --expose-externalize-string
+
+var size = 1024;
+
+function test() {
+  var str = "";
+
+  // Build an ascii cons string.
+  for (var i = 0; i < size; i++) {
+      str += String.fromCharCode(i & 0x7f);
+  }
+  assertTrue(isAsciiString(str));
+
+  var twoByteExternalWithAsciiData =
+      "AA" + (function() { return "A"; })();
+  externalizeString(twoByteExternalWithAsciiData, true /* force two-byte */);
+  assertFalse(isAsciiString(twoByteExternalWithAsciiData));
+
+  var realTwoByteExternalString =
+      "\u1234\u1234" + (function() { return "\u1234"; })();
+  externalizeString(realTwoByteExternalString);
+  assertFalse(isAsciiString(realTwoByteExternalString));
+
+  assertTrue(isAsciiString(["a", twoByteExternalWithAsciiData].join("")));
+
+  // Appending a two-byte string that contains only ascii chars should
+  // still produce an ascii cons.
+  var str1 = str + twoByteExternalWithAsciiData;
+  assertTrue(isAsciiString(str1));
+
+  // Force flattening of the string.
+  var old_length = str1.length - twoByteExternalWithAsciiData.length;
+  for (var i = 0; i < old_length; i++) {
+    assertEquals(String.fromCharCode(i & 0x7f), str1[i]);
+  }
+  for (var i = old_length; i < str1.length; i++) {
+    assertEquals("A", str1[i]);
+  }
+
+  // Flattened string should still be ascii.
+  assertTrue(isAsciiString(str1));
+
+  // Lower-casing an ascii string should produce ascii.
+  assertTrue(isAsciiString(str1.toLowerCase()));
+
+  assertFalse(isAsciiString(["a", realTwoByteExternalString].join("")));
+
+  // Appending a real two-byte string should produce a two-byte cons.
+  var str2 = str + realTwoByteExternalString;
+  assertFalse(isAsciiString(str2));
+
+  // Force flattening of the string.
+  old_length = str2.length - realTwoByteExternalString.length;
+  for (var i = 0; i < old_length; i++) {
+    assertEquals(String.fromCharCode(i & 0x7f), str2[i]);
+  }
+  for (var i = old_length; i < str.length; i++) {
+    assertEquals("\u1234", str2[i]);
+  }
+
+  // Flattened string should still be two-byte.
+  assertFalse(isAsciiString(str2));
+}
+
+// Run the test many times to ensure IC-s don't break things.
+for (var i = 0; i < 10; i++) {
+  test();
+}