// In Nanojit, loads and stores have a maximum displacement of 16-bits. Any // displacements larger than that should be split off into a separate // instruction that adds the displacement to the base pointer. This // program tests if this is done correctly. // // x.y ends up having a dslot offset of 79988, because of the 20000 array // elements before it. If Nanojit incorrectly stores this offset into a // 16-bit value it will truncate to 14452 (because 79988 - 65536 == 14452). // This means that the increments in the second loop will be done to one of // the array elements instead of x.y. And so x.y's final value will be // (99 + 8) instead of 1099. // // Note that setting x.y to 99 and checking its value at the end will // access the correct location because those lines are interpreted. Phew.
var x = {} for (var i = 0; i < 20000; i++)
x[i] = 0;
x.y = 99; // not traced, correctly accessed
for (var i = 0; i < 1000; ++i) {
x.y++; // traced, will access an array elem if disp was truncated
}
assertEq(x.y, 1099); // not traced, correctly accessed
Die Informationen auf dieser Webseite wurden
nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit,
noch Qualität der bereit gestellten Informationen zugesichert.
Bemerkung:
Die farbliche Syntaxdarstellung und die Messung sind noch experimentell.
