On Fri, Aug 26, 2022 at 6:34 PM Jeff Law <jeffreya...@gmail.com> wrote: > > > > On 8/26/2022 10:24 AM, Aldy Hernandez wrote: > > On Fri, Aug 26, 2022 at 6:08 PM Jeff Law via Gcc-patches > > <gcc-patches@gcc.gnu.org> wrote: > >> > >> > >> On 8/23/2022 4:33 AM, Aldy Hernandez via Gcc-patches wrote: > >>> For the frange implementation with endpoints I'm about to contribute, > >>> we need to set REAL_VALUE_TYPEs with negative infinity. The support > >>> is already there in real.cc, but it is awkward to get at. One could > >>> call real_inf() and then negate the value, but I've added the ability > >>> to pass the sign argument like many of the existing real.* functions. > >>> > >>> I've declared the functions in such a way to avoid changes to the > >>> existing code base: > >>> > >>> // Unchanged function returning true for either +-INF. > >>> bool real_isinf (const REAL_VALUE_TYPE *r); > >>> // New overload to be able to specify the sign. > >>> bool real_isinf (const REAL_VALUE_TYPE *r, int sign); > >>> // Replacement function for setting INF, defaults to +INF. > >>> void real_inf (REAL_VALUE_TYPE *, int sign = 0); > >>> > >>> Tested on x86-64 Linux. > >>> > >>> OK? > >>> > >>> gcc/ChangeLog: > >>> > >>> * real.cc (real_isinf): New overload. > >>> (real_inf): Add sign argument. > >>> * real.h (real_isinf): New overload. > >>> (real_inf): Add sign argument. > >> Funny in that I've fairly recently had the desire to do something a bit > >> similar. Let's consider 0.5, which we have a dconsthalf, but we don't > >> have dconstmhalf for -0.5. To get that value I create a dconsthalf > >> object and flip its sign. Similarly for a variety of other special > >> constants (particularly powers of two, but a few others as well). > > Ugh, yeah. I've been doing a lot of gymnastics in this space because > > frange's will have REAL_VALUE_TYPE endpoints. > In our case we have instructions that can make of various FP constants, > some of which may be negative. So we need to be able to recognize those > constants. Leading to having to do similar gymnastics as what you're doing.
It seems real.* needs some minor TLC. For one, a lot of these functions should be inlined. I suppose it wasn't meant to be abused the way we're about to in range-op-float.cc :-). Thanks. Aldy
