> Hi,
>
> code removing references to indirectly-inlined functions can remove a
> few too many when speculative devirtualization gets into the picture.
> Although we already handle the case when speculative devirtualization
> clones an edge with a CONST jump function by also cloning the
> appropriate reference, we do nothing when cloning a PASS_THROUGH jump
> function. However, inlining can later convert this into a CONST jump
> function and when that gets deleted, the reference is dropped (as a
> part of speculative devirtualization resolution). Eventually this
> leads to the function being removed as unreachable and missing in the
> final link. This is fixed by the following patch which increments
> controlled use counter of formal parameters when this kind of edge
> duplication.
>
> I have also attempted to add a hunk to the edge removal hook that
> would decrement the counter in these situation (dropping the edge
> after all means the call will never happen). However, I have run into
> ordering issues within indirect inlining (and speculative
> devirtualization resolution which happens as a part of making an edge
> direct). So at the moment I'm posting only this fix and will work on
> the removal hook later.
>
> Bootstrapped and tested on x86_64-linux, I have also successfully
> LTO-built Firefox with the patch (when before it was failing).
>
> Thanks,
>
> Martin
>
>
> 2014-09-19 Martin Jambor <mjam...@suse.cz>
>
> * ipa-prop.c (ipa_edge_duplication_hook): Update controlled_use_count
> when duplicating a PASS_THROUGH jump function when creating a
> speculative edge.
OK, perhaps adding a comment would be good idea?
I assume you did not manage to get a self contained testcase.
Honza
>
> diff --git a/gcc/ipa-prop.c b/gcc/ipa-prop.c
> index bbb417d..29c8681 100644
> --- a/gcc/ipa-prop.c
> +++ b/gcc/ipa-prop.c
> @@ -3643,6 +3643,21 @@ ipa_edge_duplication_hook (struct cgraph_edge *src,
> struct cgraph_edge *dst,
> dst_jf->value.constant.rdesc = dst_rdesc;
> }
> }
> + else if (dst_jf->type == IPA_JF_PASS_THROUGH
> + && src->caller == dst->caller)
> + {
> + struct cgraph_node *inline_root = dst->caller->global.inlined_to
> + ? dst->caller->global.inlined_to : dst->caller;
> + struct ipa_node_params *root_info = IPA_NODE_REF (inline_root);
> + int idx = ipa_get_jf_pass_through_formal_id (dst_jf);
> +
> + int c = ipa_get_controlled_uses (root_info, idx);
> + if (c != IPA_UNDESCRIBED_USE)
> + {
> + c++;
> + ipa_set_controlled_uses (root_info, idx, c);
> + }
> + }
> }
> }
>
