Use range information to omit checks in TRUNCDIV/MOD operations.

tests/language/modulo_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // Dart test optimization of modulo operator on Smi.
 // VMOptions=--optimization-counter-threshold=10 --no-use-osr
 
 import "package:expect/expect.dart";
 
 
 main() {
   // Prime IC cache.
   noDom(1);
   noDom(-1);
   for (int i = -30; i < 30; i++) {
     Expect.equals(i % 256, foo(i));
     Expect.equals(i % -256, boo(i));
     Expect.throws(() => hoo(i), (e) => e is IntegerDivisionByZeroException);
     
     Expect.equals(i ~/ 254 + i % 254, fooTwo(i));
     Expect.equals(i ~/ -254 + i % -254, booTwo(i));
     Expect.throws(() => hooTwo(i), (e) => e is IntegerDivisionByZeroException);
     if (i > 0) {
       Expect.equals(i % 10, noDom(i));
     } else {
       Expect.equals(i ~/ 10, noDom(i));
     }
     Expect.equals((i ~/ 10) + (i ~/ 10) + (i % 10), threeOp(i));
     Expect.equals((i ~/ 10) + (i ~/ 12) + (i % 10) + (i % 12), fourOp(i));
+    
+    // Zero test is done outside the loop.
+    if (i < 0) {
+      Expect.equals(i % -i, foo2(i));
+      Expect.equals(i ~/ -i + i % -i, fooTwo2(i));
+    } else if (i > 0) {
+      Expect.equals(i % i, foo2(i));
+      Expect.equals(i ~/ i + i % i, fooTwo2(i));
+    }
   }
+  Expect.throws(() => foo2(0), (e) => e is IntegerDivisionByZeroException);
+  Expect.throws(() => fooTwo2(0), (e) => e is IntegerDivisionByZeroException);
 }
 
 foo(i) => i % 256;  // This will get optimized to AND instruction.
 boo(i) => i % -256;
 hoo(i) => i % 0;
 
 fooTwo(i) => i ~/ 254 + i % 254;
 booTwo(i) => i ~/ -254 + i % -254;
 hooTwo(i) => i ~/ 0 + i % 0;
 
@@ skipping 14 matching lines @@
   return x + y + z;
 }
 
 
 fourOp(a) {
   var x0 = a ~/ 10;
   var x1 = a ~/ 12;
   var y0 = a % 10; 
   var y1 = a % 12;
   return x0 + x1 + y0 + y1;
-}
+}
+
+foo2(i) {
+  // Make sure x has a range computed. 
+  var x = 0;
+  if (i < 0) {
+    x = -i;
+  } else {
+    x = i;
+  }
+  return i % x;
+}
+
+
+fooTwo2(i) {
+  // Make sure x has a range computed. 
+  var x = 0;
+  if (i < 0) {
+    x = -i;
+  } else {
+    x = i;
+  }
+  return i ~/ x + i % x;
+}