[PATCH] Emulate clock and other stubs on nvptx

Joel Sherrill joel@rtems.org
Thu Aug 19 12:59:16 GMT 2021

Should these be in a machine directory or a libgloss directory? If you ran
a different run-time/OS on the CPU, at least some of these wouldn't make
sense to be there.


On Wed, Aug 18, 2021, 11:43 AM Roger Sayle <roger@nextmovesoftware.com>

> 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
> them for me that would be much appreciated (as I don't have repository
> access).
> Likewise, these changes should be obvious enough to not require a copyright
> assignment, but to avoid any objections, I'm happy to put them in the
> public
> domain.
> 2021-08-18  Roger Sayle  <roger@nextmovesoftware.com>
> newlib/
>         configure.host: Add -DCLOCK_PROVIDED to newlib_cflags on nvptx*.
> newlib/libc/machine/nvptx
>         Makefile.am: Add clock.c to lib_a_SOURCES.
>         clock.c: New source file to implement/approximate clock().
>         misc.c: Add stubs for fstat, isatty, open, sync and unlink.
>         Makefile.in: Regenerate.
> Many thanks in advance,
> Roger
> --
> Roger Sayle
> NextMove Software Limited
> Cambridge, UK

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