Re: Remove support for Intel MIC offloading

[Thomas Schwinge <thomas@codesourcery.com>]

Hi Jakub, Tobias!

On 2022-10-20T13:15:43+0200, I wrote:
> I'm proposing the attached "Remove support for Intel MIC offloading"

Can you please confirm:

> --- a/gcc/config/i386/i386-options.cc
> +++ b/gcc/config/i386/i386-options.cc
> @@ -307,10 +307,6 @@ ix86_omp_device_kind_arch_isa (enum omp_device_kind_arch_isa trait,
>      case omp_device_kind:
>        return strcmp (name, "cpu") == 0;
>      case omp_device_arch:
> -#ifdef ACCEL_COMPILER
> -      if (strcmp (name, "intel_mic") == 0)
> -     return 1;
> -#endif
>        if (strcmp (name, "x86") == 0)
>       return 1;
>        if (TARGET_64BIT)

Only remove this bit as quoted, or actually remove the whole function
(used for 'gcc/config/i386/i386.cc:TARGET_OMP_DEVICE_KIND_ARCH_ISA')?
But if I do the latter, I get a few FAILs in compiler-side
'[...]/gomp/declare-variant-[...]' test cases, and
'libgomp.c/declare-variant-1.c'.

You, Jakub, had originally added that in
Subversion r277662 (Git commit 9ba66bf5b9c69e0e2bcd1b2ab88160bf9b2aa417)
"targetm.omp.device_kind_arch_isa and OpenMP declare variant kind/arch/isa handling".
Reading these emails, and the discussion in
<https://gcc.gnu.org/PR105640>
"[OpenMP] Context selectors missing for PowerPC", I infer that we
generally would like to keep this stuff, for non-offloading OpenMP use,
and thus indeed just remove the Intel MIC parts (as quoted above).

Thus:

> --- a/libgomp/libgomp.texi
> +++ b/libgomp/libgomp.texi
> @@ -4303,10 +4303,6 @@ offloading devices (it's not clear if they should be):
>
>  @multitable @columnfractions .60 .10 .25
>  @headitem @code{arch} @tab @code{kind} @tab @code{isa}
> -@item @code{intel_mic}, @code{x86}, @code{x86_64}, @code{i386}, @code{i486},
> -      @code{i586}, @code{i686}, @code{ia32}
> -      @tab @code{host}
> -      @tab See @code{-m...} flags in ``x86 Options'' (without @code{-m})
>  @item @code{amdgcn}, @code{gcn}
>        @tab @code{gpu}
>        @tab See @code{-march=} in ``AMD GCN Options''

..., I should also restore this, and only remove the Intel MIC mention.

On the other hand:

> diff --git a/gcc/config/i386/t-omp-device b/gcc/config/i386/t-omp-device
> deleted file mode 100644
| index cfb41ed71ce..00000000000
| --- gcc/config/i386/t-omp-device
| +++ /dev/null
| @@ -1,6 +0,0 @@
| -omp-device-properties-i386: $(srcdir)/config/i386/i386-options.cc
| -     echo kind: cpu > $@
| -     echo arch: intel_mic x86 x86_64 i386 i486 i586 i686 ia32 >> $@
| -     echo isa: sse4 `sed -n '/^static struct ix86_target_opts isa2\?_opts\[\] =/,/^};/p' \
| -       $(srcdir)/config/i386/i386-options.cc | \
| -       sed -n 's/",.*$$//;s/^  { "-m//p'` >> $@

Indeed remove this whole file, or just Intel MIC, again?  Here, as I
understand, this is fine to remove completely, as is only used if there
is an actual offload compiler (which now there isn't anymore); unused as
of here:

> --- a/gcc/configure.ac
> +++ b/gcc/configure.ac

> @@ -1153,10 +1147,6 @@ for tgt in `echo $enable_offload_targets | sed 's/,/ /g'`; do
>
>    enable_offloading=1
>    case "$tgt" in
> -    *-intelmic-* | *-intelmicemul-*)
> -     omp_device_property=omp-device-properties-i386
> -     omp_device_property_tmake_file="${omp_device_property_tmake_file} \$(srcdir)/config/i386/t-omp-device"
> -     ;;
>      amdgcn*)
>       omp_device_property=omp-device-properties-gcn
>       omp_device_property_tmake_file="${omp_device_property_tmake_file} \$(srcdir)/config/gcn/t-omp-device"

So I assume that is OK the way I had it prepared.


Grüße
 Thomas
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