Quoting Rémi Denis-Courmont (2024-07-26 18:32:19) > The absolute value of a floating point value is easier to calculate than > that of an integer: it is obtained by either clearing the sign or xoring it > with itself. Accordingly, Arm, LoongArch, RISC-V have dedicated instructions > to manipulate float sign bits. x86-64 has ANDPS. > > As per C11 appendix F, FFABS() is not quite the same as fabs() however, > due to differing NaN handling. GCC is able to optimise the current FFABS > definition to match fabs() anyway with just -fno-signed-zeros. But Clang is > evidently not doing so and inserts a comparison with 0 and a conditional > select or branch. Now that we have C11, this is easy to fix properly. > (Another option is to manually audit which of the ~880 FFABS/FFNABS use > sites involve floating point values.) > > Note that this still preserves the old definitions for C++ and pre-C11 > compilers since the 2 macros are public (even though they start with FF). > --- > libavutil/common.h | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/libavutil/common.h b/libavutil/common.h > index 3b830daf30..48761885fb 100644 > --- a/libavutil/common.h > +++ b/libavutil/common.h > @@ -71,7 +71,14 @@ > * as with *abs() > * @see FFNABS() > */ > +#if !defined (__cplusplus) && __STDC_VERSION__ >= 201112L
Is __STDC_VERSION__ defined for C++? -- Anton Khirnov _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
