Optimize num::~/, num::>> and num::<< for some cases.

sdk/lib/_internal/compiler/implementation/ssa/codegen.dart

 // Copyright (c) 2012, 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.
 
 part of ssa;
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
 
@@ skipping 1231 matching lines @@
   visitDivide(HDivide node)         => visitInvokeBinary(node, '/');
   visitMultiply(HMultiply node)     => visitInvokeBinary(node, '*');
   visitSubtract(HSubtract node)     => visitInvokeBinary(node, '-');
   visitBitAnd(HBitAnd node)         => visitBitInvokeBinary(node, '&');
   visitBitNot(HBitNot node)         => visitBitInvokeUnary(node, '~');
   visitBitOr(HBitOr node)           => visitBitInvokeBinary(node, '|');
   visitBitXor(HBitXor node)         => visitBitInvokeBinary(node, '^');
   visitShiftLeft(HShiftLeft node)   => visitBitInvokeBinary(node, '<<');
   visitShiftRight(HShiftRight node) => visitBitInvokeBinary(node, '>>>');
 
+  visitTruncatingDivide(HTruncatingDivide node) {

[floitsch, 2013/12/10 15:45:16]

Maybe add an assert that left and right are of the right size?
This makes it clear what the preconditions are, and might even catch
regressions.

[ngeoffray, 2013/12/10 15:48:15]

Done.

+    use(node.left);
+    js.Expression jsLeft = pop();
+    use(node.right);
+    push(new js.Binary('/', jsLeft, pop()), node);
+    push(new js.Binary('|', pop(), new js.LiteralNumber("0")), node);
+  }
+
   visitNegate(HNegate node)         => visitInvokeUnary(node, '-');
 
   visitLess(HLess node)                 => visitRelational(node, '<');
   visitLessEqual(HLessEqual node)       => visitRelational(node, '<=');
   visitGreater(HGreater node)           => visitRelational(node, '>');
   visitGreaterEqual(HGreaterEqual node) => visitRelational(node, '>=');
 
   visitBoolify(HBoolify node) {
     assert(node.inputs.length == 1);
     use(node.inputs[0]);
@@ skipping 1398 matching lines @@
     if (left.isConstantNull() || right.isConstantNull() ||
         (left.isPrimitive(compiler) &&
          left.instructionType == right.instructionType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }