This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [GOOGLE] LIPO resolved node handling for inline clone references


Ok, with minor fix to the comments:

1) Before possibly cloning --> Before possibly creating a new
2) It is not clear from the comments that the remaining references are
from call statements in ipa cp clones that have not been fixed up.
Possibly add a 3 line example to show the call statements calling the
original function --> after fixup it will be calling the callee's
clone?

thanks,

David

On Tue, Jul 1, 2014 at 7:06 AM, Teresa Johnson <tejohnson@google.com> wrote:
> This patch addresses an issue with looking up the resolved node
> rebuilding cgraph references during clone materialization. It is
> possible that in ipa-cp cases the resolved node was eliminated during
> inlining and indirect call promotion, but the clone still exists as a
> function call argument in an inline virtual clone. The clones would be
> removed later when we actually do the inline transformation, but in
> the meantime during clone materialization the cgraph references are
> rebuilt, and the temporary reference on the call still exists in the
> IR. Handle this by skipping such references in inline clones.
>
> Passes regression tests. Ok for google/4_9?
>
> Teresa
>
> 2014-07-01  Teresa Johnson  <tejohnson@google.com>
>
>         Google ref b/15411384.
>         * cgraphbuild.c (mark_address): Skip resolved node lookup
>         in inline copies.
>
> Index: cgraphbuild.c
> ===================================================================
> --- cgraphbuild.c       (revision 211957)
> +++ cgraphbuild.c       (working copy)
> @@ -389,8 +389,28 @@ mark_address (gimple stmt, tree addr, tree, void *
>    addr = get_base_address (addr);
>    if (TREE_CODE (addr) == FUNCTION_DECL)
>      {
> +      /* Before possibly cloning the node in cgraph_get_create_node,
> +         save the current cgraph node for addr.  */
> +      struct cgraph_node *first_clone = cgraph_get_node (addr);
>        struct cgraph_node *node = cgraph_get_create_node (addr);
> -      if (L_IPO_COMP_MODE && cgraph_pre_profiling_inlining_done)
> +      /* In LIPO mode we use the resolved node. However, there is
> +         a possibility that it may not exist at this point. This
> +         can happen in cases of ipa-cp, where this is a reference
> +         that will eventually go away during inline_transform when we
> +         invoke cgraph_redirect_edge_call_stmt_to_callee to rewrite
> +         the call_stmt and skip some arguments. It is possible
> +         that earlier during inline_call the references to the original
> +         non-cloned resolved node were all eliminated, and it was removed.
> +         However, virtual clones may stick around until inline_transform,
> +         due to references in other virtual clones, at which point they
> +         will all be removed. In between inline_call and inline_transform,
> +         however, we will materialize clones which would rebuild references
> +         and end up here upon still seeing the reference on the call.
> +         Handle this by skipping the resolved node lookup when the first
> +         clone was marked global.inlined_to (i.e. it is a virtual clone,
> +         the original is gone).  */
> +      if (L_IPO_COMP_MODE && cgraph_pre_profiling_inlining_done
> +          && first_clone && !first_clone->global.inlined_to)
>          node = cgraph_lipo_get_resolved_node (addr);
>
>        cgraph_mark_address_taken_node (node);
>
>
> --
> Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]