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).
Consider making the "sign" argument a boolean. It's defined as a single
bit bitfield in the real_value structure. We don't want folks to pass
in values outside [0..1] for the sign if we can easily avoid it:-)
jeff
