For use in both the Fortran front-end and in libgfortran, it would be really nice to have __builtin_signbit() be type-generic. It makes sense from the C point of view too, because it’s the only built-in from the C99 type-generic floating-point macros that is not type-generic.
So far, I have built a compiler with the trivial change attached (marking the built-in type-generic in gcc/builtins.def) on x86_64-apple-darwin14, where I can confirm that the built-in is correctly expanded (without function call) on all floating-point types. Is there something more to do (apart from adjusting the documentation)? Joseph, I’m CC’ing you because of a 7-year old comment in PR 36757, where you said: > It's necessary to avoid the type-generic signbit expanding to call a library > function that may not exist, but as all currently supported floating-point > formats do have a sign bit specified in signbit_ro I believe the case > of failing to expand inline can be made into an abort. I can confirm that even in 2015, the only format which has (signbit_ro < 0) is real_internal_format, which I think doesn’t matter here. So: should I, in addition to the change in gcc/builtins.def, add some aborts() or sorry() in gcc/builtins.c if we can’t expand (which should never happen)? Thanks in advance for your help, FX
signbit.diff
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