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     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 // Flags: --always-opt --nocompilation-cache
     29 
     30 // Given a binary operation string and an ordered array of leaf
     31 // strings, return an array of all binary tree strings with the leaves
     32 // (in order) as the fringe.
     33 function makeTrees(op, leaves) {
     34   var len = leaves.length;
     35   if (len == 1) {
     36     // One leaf is a leaf.
     37     return leaves;
     38   } else {
     39     // More than one leaf requires an interior node.
     40     var result = [];
     41     // Split the leaves into left and right subtrees in all possible
     42     // ways.  For each split recursively compute all possible subtrees.
     43     for (var i = 1; i < len; ++i) {
     44       var leftTrees = makeTrees(op, leaves.slice(0, i));
     45       var rightTrees = makeTrees(op, leaves.slice(i, len));
     46       // Adjoin every possible left and right subtree.
     47       for (var j = 0; j < leftTrees.length; ++j) {
     48         for (var k = 0; k < rightTrees.length; ++k) {
     49           var string = "(" + leftTrees[j] + op + rightTrees[k] + ")";
     50           result.push(string);
     51         }
     52       }
     53     }
     54     return result;
     55   }
     56 }
     57 
     58 // All 429 possible bitwise OR trees with eight leaves.
     59 var identifiers = ['a','b','c','d','e','f','g','h'];
     60 var or_trees = makeTrees("|", identifiers);
     61 var and_trees = makeTrees("&", identifiers);
     62 
     63 // Set up leaf masks to set 8 least-significant bits.
     64 var a = 1 << 0;
     65 var b = 1 << 1;
     66 var c = 1 << 2;
     67 var d = 1 << 3;
     68 var e = 1 << 4;
     69 var f = 1 << 5;
     70 var g = 1 << 6;
     71 var h = 1 << 7;
     72 
     73 for (var i = 0; i < or_trees.length; ++i) {
     74   for (var j = 0; j < 8; ++j) {
     75     var or_fun = new Function("return " + or_trees[i]);
     76     if (j == 0) assertEquals(255, or_fun());
     77 
     78     // Set the j'th variable to a string to force a bailout.
     79     eval(identifiers[j] + "+= ''");
     80     assertEquals(255, or_fun());
     81     // Set it back to a number for the next iteration.
     82     eval(identifiers[j] + "= +" + identifiers[j]);
     83   }
     84 }
     85 
     86 // Set up leaf masks to clear 8 least-significant bits.
     87 a ^= 255;
     88 b ^= 255;
     89 c ^= 255;
     90 d ^= 255;
     91 e ^= 255;
     92 f ^= 255;
     93 g ^= 255;
     94 h ^= 255;
     95 
     96 for (i = 0; i < and_trees.length; ++i) {
     97   for (var j = 0; j < 8; ++j) {
     98     var and_fun = new Function("return " + and_trees[i]);
     99     if (j == 0) assertEquals(0, and_fun());
    100 
    101     // Set the j'th variable to a string to force a bailout.
    102     eval(identifiers[j] + "+= ''");
    103     assertEquals(0, and_fun());
    104     // Set it back to a number for the next iteration.
    105     eval(identifiers[j] + "= +" + identifiers[j]);
    106   }
    107 }
    108