Paul Eggert wrote: > > On NetBSD, I apparently did not locate the right source code of the mbsinit > > function, due to the complexity of the citrus code. And did not want to > > debug > > it, because debugging in libc code without debugging information is often > > a waste of time. > > I looked into it. I think it's due to the funky business with struct > _RuneStatePriv. There's a pointer's worth of data before the data that > the converters see, and until recently there was another character that > ended up perhaps needing another pointer's worth of padding. Two > pointers (8 bytes each), plus the 12 bytes we already saw, would explain > the 28 bytes you observed.
In a 64-bit world, yes. It doesn't explain why 28 bytes is also the minimum needed in 32-bit NetBSD 8: In this situation, with the ZERO_SIZE set to 24, I get an 'assertion "mbsinit (&iter->state)" failed'. Anyway, this is not a high priority platform. > I fixed mbcel.h for that by installing the attached patch into > diffutils. Thanks for pointing it out. > + /* These platforms have 128-byte mbstate_t. What were they thinking? They were probably afraid of having to break binary compatibility when needing to increase mbstate_t's size. > >> This macro is not used anywhere. How about adding a comment explaining > >> why it's defined but not used? Or if it's not needed we can remove it. > > > > It's needed, namely as lower bound for _GL_MBSTATE_ZERO_SIZE: > > 0 < _GL_MBSTATE_INIT_SIZE <= _GL_MBSTATE_ZERO_SIZE <= sizeof (mbstate_t). > > That's merely documentation, right? That is, only comments use the lower > bound. Right. > One thing I noticed on NetBSD 9.3 x86-64 (it has GCC 7), is that it > didn't optimize memset calls away. Strange. For me, it does. I tried gcc 7.5.0 both on a Linux+glibc system, as well as on NetBSD 9.3 x86_64, and 'nm' of the executable does not reference 'memset'. If you can reproduce it, feel free to change memset (ps, 0, _GL_MBSTATE_ZERO_SIZE); to # if defined __GNUC__ && __GNUC__ >= 3 __builtin_memset (ps, 0, _GL_MBSTATE_ZERO_SIZE); # else memset (ps, 0, _GL_MBSTATE_ZERO_SIZE); # endif (__builtin_memset was already documented for GCC 3.0.4: https://gcc.gnu.org/onlinedocs/gcc-3.0.4/gcc_5.html#SEC114 ) Bruno
