[PATCH] Emulate clock and other stubs on nvptx

Corinna Vinschen vinschen@redhat.com
Thu Aug 19 10:22:23 GMT 2021

Hi Roger,

On Aug 18 17:43, Roger Sayle wrote:
> Please be gentle, this is my first patch to newlib.
> This patch to the libc/machine/nvptx port of newlib implements an
> approximation of "clock" and provides some additional stub routines.
> These changes not only reduce the number of (link) failures in the GCC
> testsuite when targeting nvptx-none, but also allow the NIST scimark4
> benchmark to compile and run without modification.
> newlib already contains support for backends to provide their own
> clock implementations via -DCLOCK_PROVIDED.  That functionality is
> used here to return an approximate elapsed time based on the NVidia
> GPU's clock64 cycle counter.  Although not great, this is better than
> the current behaviour of link error from the unresolved symbol
> _times_r.
> The other part of the patch is to add a small number of stub functions
> to nvptx's misc.c.  Adding isatty, for example, resolves linking
> problems in libc from the dependency in __smakebuf_r, and the sync
> stub, for example, fixes the failure with GCC's
> testsuite/gfortran.dg/ISO_Fortran_binding_14.f90 [which simply tests
> that gfortran can call a/any C function].
> Hopefully, these changes are acceptable.  If so, if someone could
> please commit

They are, but your patch submission is a bit weird and more work to
apply than necessary.

Please commit your patches to your local git repo, including a nice
commit message, create a git patch file via `git format-patch' and send
it via `git send-email --to="newlib@..." to this mailing list.  Note
that providing Makefile.in is nice, but you don't *have* to provide
Makefile.in.  We'll regenerate that as required.

Another point:  Given the HW support for a monotonic clock tick,
wouldn't it make more sense to implement clock_gettime() with support
for CLOCK_REALTIME and CLOCK_MONOTONIC, and implement clock() by calling


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