Re: [PATCH] libffi: fix handling of homogeneous float128 structs [PR109447]

[Jakub Jelinek <jakub@redhat.com>]

On Thu, May 04, 2023 at 02:29:34PM -0500, Peter Bergner wrote:
> I'd like to pull in Dan's upstream libffi commit into trunk to fix a
> wrong code bug/testsuite failure on powerpc64le-linux with long double
> defaulting to ieee128.  This passed bootstrap and regtesting with no
> regressions.  Ok for trunk?
> 
> This bug is also on the GCC 12 and GCC 11 release branches. Ok there too
> assuming testing is clean?  I can wait to push the gcc12 backport until
> after the release.
> 
> Peter
> 
> 
> If there is a homogeneous struct with float128 members, they should be
> copied to vector register save area. The current code incorrectly copies
> only the value of the first member, not increasing the pointer with each
> iteration. Fix this.
> 
> Merged from upstream libffi commit: 464b4b66e3cf3b5489e730c1466ee1bf825560e0
> 
> 2023-05-03  Dan Horák <dan@danny.cz>
> 
> libffi/
> 	PR libffi/109447
> 	* src/powerpc/ffi_linux64.c (ffi_prep_args64): Update arg.f128 pointer.

Ok for 14/13.2/12.4 (i.e. after 12.3 is out)/11.4

> diff --git a/libffi/src/powerpc/ffi_linux64.c b/libffi/src/powerpc/ffi_linux64.c
> index 4d50878e402..3454dacd3d6 100644
> --- a/libffi/src/powerpc/ffi_linux64.c
> +++ b/libffi/src/powerpc/ffi_linux64.c
> @@ -680,7 +680,7 @@ ffi_prep_args64 (extended_cif *ecif, unsigned long *const stack)
>                      {
>                        if (vecarg_count < NUM_VEC_ARG_REGISTERS64
>                            && i < nfixedargs)
> -		        memcpy (vec_base.f128++, arg.f128, sizeof (float128));
> +		        memcpy (vec_base.f128++, arg.f128++, sizeof (float128));
>                        else
>  		        memcpy (next_arg.f128, arg.f128++, sizeof (float128));
>                        if (++next_arg.f128 == gpr_end.f128)

	Jakub