Speed up compares with characters ie single-character strings....

test/mjsunit/bit-not.js

 // Copyright 2009 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
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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.
 
-function testBitNot(x) {
+function testBitNot(x, name) {
   // The VM constant folds so we use that to check the result.
   var expected = eval("~(" + x + ")");
   var actual = ~x;
-  assertEquals(expected, actual, "x: " + x);
+  assertEquals(expected, actual, "x: " + name);
 
   // Test the path where we can overwrite the result. Use -
   // to avoid concatenating strings.
   expected = eval("~(" + x + " - 0.01)");
   actual = ~(x - 0.01);
-  assertEquals(expected, actual, "x - 0.01: " + x);
+  assertEquals(expected, actual, "x - 0.01: " + name);
 }
 
 
-testBitNot(0);
-testBitNot(1);
-testBitNot(-1);
-testBitNot(100);
-testBitNot(0x40000000);
-testBitNot(0x7fffffff);
-testBitNot(0x80000000);
+testBitNot(0, 0);
+testBitNot(1, 1);
+testBitNot(-1, 1);
+testBitNot(100, 100);
+testBitNot(0x40000000, "0x40000000");
+testBitNot(0x7fffffff, "0x7fffffff");
+testBitNot(0x80000000, "0x80000000");
 
-testBitNot(2.2);
-testBitNot(-2.3);
-testBitNot(Infinity);
-testBitNot(NaN);
-testBitNot(-Infinity);
-testBitNot(0x40000000 + 0.12345);
-testBitNot(0x40000000 - 0.12345);
-testBitNot(0x7fffffff + 0.12345);
-testBitNot(0x7fffffff - 0.12345);
-testBitNot(0x80000000 + 0.12345);
-testBitNot(0x80000000 - 0.12345);
+testBitNot(2.2, 2.2);
+testBitNot(-2.3, -2.3);
+testBitNot(Infinity, "Infinity");
+testBitNot(NaN, "NaN");
+testBitNot(-Infinity, "-Infinity");
+testBitNot(0x40000000 + 0.12345, "float1");
+testBitNot(0x40000000 - 0.12345, "float2");
+testBitNot(0x7fffffff + 0.12345, "float3");
+testBitNot(0x7fffffff - 0.12345, "float4");
+testBitNot(0x80000000 + 0.12345, "float5");
+testBitNot(0x80000000 - 0.12345, "float6");
 
-testBitNot("0");
-testBitNot("2.3");
-testBitNot("-9.4");
+testBitNot("0", "string0");
+testBitNot("2.3", "string2.3");
+testBitNot("-9.4", "string-9.4");
 
 
 // Try to test that we can deal with allocation failures in
 // the fast path and just use the slow path instead.
 function TryToGC() {
   var x = 0x40000000;
   for (var i = 0; i < 1000000; i++) {
     assertEquals(~0x40000000, ~x);
   }
 }
 TryToGC();