On Sun, May 19, 2024 at 10:58 AM Jeff Law <j...@ventanamicro.com> wrote: > > perl has some internal bitmap code. One of its implementation > properties is that if you ask it to set a bit, the bit is first cleared. > > > Unfortunately this is fairly hard to see in gimple/match due to type > changes in the IL. But it is easy to see in the code we get from > combine. So we just match the relevant cases.
So looking into this from a gimple point of view, we can see the issue on x86_64 if you used explicitly `unsigned char`. We have: ``` c_8 = (unsigned char) _1; _2 = *a_10(D); c.0_3 = (signed char) _1; _4 = ~c.0_3; _12 = (unsigned char) _4; `` So for this, we could push the no_op cast from `signed char` to `unsigned char` past the `bit_not` and I think it will fix the issue on the gimple level. So something like: ``` /* Push no_op conversion past the bit_not expression if it was single use. */ (simplify (convert (bit_not:s @0)) (if (tree_nop_conversion_p (type, TREE_TYPE (@0))) (bit_not (convert @0)))) ``` Thanks, Andrew Pinski > > > > Regression tested in Ventana's CI system as well as my own. Waiting on > the Rivos CI system before moving forward. > > > > Jeff
