Re: [PATCH 2/n] OpenMP 4.0 offloading infrastructure: LTO streaming

[Thomas Schwinge <thomas@codesourcery.com>]

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Hi!

As just discussed for the libgcc changes in
<http://news.gmane.org/find-root.php?message_id=%3C87d2ad73ze.fsf%40schwinge.name%3E>,
just some suggestions regarding the terminology, where I think that the
term »target« might be confusing in comments or symbols' names.  That is,
in the following, »target« should possibly be replaced by »offload[ing]«
or similar:

On Mon, 29 Sep 2014 21:37:04 +0400, Ilya Verbin <iverbin@gmail.com> wrote:
> --- a/gcc/lto-cgraph.c
> +++ b/gcc/lto-cgraph.c
> @@ -321,6 +321,11 @@ referenced_from_other_partition_p (symtab_node *node, lto_symtab_encoder_t encod
>  
>    for (i = 0; node->iterate_referring (i, ref); i++)
>      {
> +      /* Ignore references from non-target nodes while streaming NODE into
> +	 offload target section.  */
> +      if (!ref->referring->need_lto_streaming)
> +	continue;
> +
>        if (ref->referring->in_other_partition
>            || !lto_symtab_encoder_in_partition_p (encoder, ref->referring))
>  	return true;
> @@ -339,9 +344,16 @@ reachable_from_other_partition_p (struct cgraph_node *node, lto_symtab_encoder_t
>    if (node->global.inlined_to)
>      return false;
>    for (e = node->callers; e; e = e->next_caller)
> -    if (e->caller->in_other_partition
> -	|| !lto_symtab_encoder_in_partition_p (encoder, e->caller))
> -      return true;
> +    {
> +      /* Ignore references from non-target nodes while streaming NODE into
> +	 offload target section.  */
> +      if (!e->caller->need_lto_streaming)
> +	continue;
> +
> +      if (e->caller->in_other_partition
> +	  || !lto_symtab_encoder_in_partition_p (encoder, e->caller))
> +	return true;
> +    }
>    return false;
>  }

> --- a/gcc/lto-section-names.h
> +++ b/gcc/lto-section-names.h
> @@ -25,6 +25,11 @@ along with GCC; see the file COPYING3.  If not see
>     name for the functions and static_initializers.  For other types of
>     sections a '.' and the section type are appended.  */
>  #define LTO_SECTION_NAME_PREFIX ".gnu.lto_"
> +#define OMP_SECTION_NAME_PREFIX ".gnu.target_lto_"

What about:

    #define OFFLOAD_SECTION_NAME_PREFIX ".gnu.offload_lto_"

> --- a/gcc/omp-low.c
> +++ b/gcc/omp-low.c
> @@ -8337,6 +8345,11 @@ expand_omp_target (struct omp_region *region)
>        push_cfun (child_cfun);
>        cgraph_edge::rebuild_edges ();
>  
> +      /* Prevent IPA from removing child_fn as unreachable, since there are no
> +	 refs from the parent function to the target side child_fn.  */
> +      node = cgraph_node::get (child_fn);
> +      node->mark_force_output ();
> +
>        /* Some EH regions might become dead, see PR34608.  If
>  	 pass_cleanup_cfg isn't the first pass to happen with the
>  	 new child, these dead EH edges might cause problems.


Grüße,
 Thomas

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