src/share/vm/opto/parse2.cpp

*** 103,116 ****
  
    // Do the range check
    if (GenerateRangeChecks && need_range_check) {
      // Range is constant in array-oop, so we can use the original state of mem
      Node* len = load_array_length(ary);
      // Test length vs index (standard trick using unsigned compare)
      Node* chk = _gvn.transform( new (C, 3) CmpUNode(idx, len) );
      BoolTest::mask btest = BoolTest::lt;
!     Node* tst = _gvn.transform( new (C, 2) BoolNode(chk, btest) );
      // Branch to failure if out of bounds
      { BuildCutout unless(this, tst, PROB_MAX);
        if (C->allow_range_check_smearing()) {
          // Do not use builtin_throw, since range checks are sometimes
          // made more stringent by an optimistic transformation.
--- 103,125 ----
  
    // Do the range check
    if (GenerateRangeChecks && need_range_check) {
      // Range is constant in array-oop, so we can use the original state of mem
      Node* len = load_array_length(ary);
+     Node* tst;
+     if (sizetype->_hi <= 0) {
+       // If the greatest array bound is negative, we can conclude that we're
+       // compiling unreachable code, but the unsigned compare trick used below 
+       // only works with non-negative lengths.  Instead, hack "tst" to be zero so 
+       // the uncommon_trap path will always be taken.
+       tst = _gvn.intcon(0);
+     } else {
        // Test length vs index (standard trick using unsigned compare)
        Node* chk = _gvn.transform( new (C, 3) CmpUNode(idx, len) );
        BoolTest::mask btest = BoolTest::lt;
!       tst = _gvn.transform( new (C, 2) BoolNode(chk, btest) );
!     }
      // Branch to failure if out of bounds
      { BuildCutout unless(this, tst, PROB_MAX);
        if (C->allow_range_check_smearing()) {
          // Do not use builtin_throw, since range checks are sometimes
          // made more stringent by an optimistic transformation.