On 12/19/07, Alexandre Oliva <[EMAIL PROTECTED]> wrote: > On Dec 19, 2007, "Daniel Berlin" <[EMAIL PROTECTED]> wrote: > > > Here is the easy one: > > > z_5 = a_3 + b_3 > > x_4 = z_5 + c_3 > > > DEBUG(x, x_4) > > > > Reassoc may transform this into: > > > > z_5 = c_3 + b_3 > > x_4 = z_5 + a_3 > > > DEBUG(x, x_4) > > > Now x has the wrong value. > > As Andrew said, no, it doesn't. > Yes, I corrected it later. You didn't address the other one, which is much harder and does require addressing by you.
> Now, if z_5 were present in a debug expression, then it would need > adjusting. No different from the adjusting need for any other > instruction in which z_5 was present, though. uh, but if you don't adjust in the fixed examples, DEBUG(x, x_4) will give an invalid value. You can cause this to value to change without ever changing x_4, and do so legally. How do i know i need to change this DEBUG expression.
