Sean D'Epagnier wrote: > > I think I found a generic problem for fixed point constant folding. > > In fold-const.c:11872 gcc tries to apply: > /* Transform (x >> c) << c into x & (-1<<c), or transform (x << > c) >> c > into x & ((unsigned)-1 >> c) for unsigned types. */ > > I attached a simple patch which fixes the problem by not applying this > optimization to fixed point types. I would like to have this > optimization because it is possible.. but the problem is fixed-point > types do not support bitwise operations like & | ^ ~.. so without > supporting these somehow internally but not allowing the user to have > them, this can't take place. > > I am open to other suggestions. For future reference should this be > posted as a bug report? It seems simple enough that it could be > included right away.. but I feel like if it's a bug report no one will > notice since fixed-point support is not widely used. > > Sean >
Thanks for finding this bug and fixing it! I think you should send your patch to gcc-patc...@gcc.gnu.org, and check in this patch to mainline and 4.3 if possible. Regards, Chao-ying
