On Thu, Aug 28, 2014 at 1:40 PM, Xinliang David Li <davi...@google.com> wrote:
>
> Do you know why the previous check is not enough ?
>
> cgraph_can_remove_if_no_direct_calls_and_refs_p (struct cgraph_node *node)
This will return true for the external node, but it also returns true
for the non-external node. The non-external node is a COMDAT, as as
the comments in that routine indicate, COMDATs can be removed even if
they are externally_visible.
Teresa
>
> David
>
>
> On Thu, Aug 28, 2014 at 1:29 PM, Teresa Johnson <tejohn...@google.com>
> wrote:
>>
>> This patch fixes up varpool nodes after LIPO linking as we were doing
>> for cgraph node references. While, here I made some fixes to the
>> cgraph fixup as well (mark address taken as appropriate) and removed
>> old references. The latter exposed an issue with resolved cgraph nodes
>> getting eliminated when they were only referenced from vtables and the
>> LIPO linking selected an external copy as the resolved node. Addressed
>> this by forcing the LIPO linking to prefer the non-external copy.
>>
>> Passes regression testing, internal benchmark testing in progress. Ok
>> for google/4_9 if that succeeds?
>>
>> Teresa
>>
>> 2014-08-28 Teresa Johnson <tejohn...@google.com>
>>
>> Google ref b/17038802.
>> * l-ipo.c (resolve_cgraph_node): Pick non-external node.
>> (fixup_reference_list): Fixup varpool references, remove old
>> references, mark cgraph nodes as address taken as needed.
>>
>> Index: l-ipo.c
>> ===================================================================
>> --- l-ipo.c (revision 213975)
>> +++ l-ipo.c (working copy)
>> @@ -1564,6 +1564,15 @@ resolve_cgraph_node (struct cgraph_sym **slot, str
>> (*slot)->rep_decl = decl2;
>> return;
>> }
>> + /* Similarly, pick the non-external symbol, since external
>> + symbols may be eliminated by symtab_remove_unreachable_nodes
>> + after ipa inlining (see process_references). */
>> + if (DECL_EXTERNAL (decl1) && !DECL_EXTERNAL (decl2))
>> + {
>> + (*slot)->rep_node = node;
>> + (*slot)->rep_decl = decl2;
>> + return;
>> + }
>>
>> has_prof1 = has_profile_info (decl1);
>> bool is_aux1 = cgraph_is_auxiliary (decl1);
>> @@ -2304,31 +2313,44 @@ fixup_reference_list (struct varpool_node *node)
>> int i;
>> struct ipa_ref *ref;
>> struct ipa_ref_list *list = &node->ref_list;
>> - vec<cgraph_node_ptr> new_refered;
>> + vec<symtab_node *> new_refered;
>> vec<int> new_refered_type;
>> - struct cgraph_node *c;
>> + struct symtab_node *sym_node;
>> enum ipa_ref_use use_type = IPA_REF_LOAD;
>>
>> new_refered.create (10);
>> new_refered_type.create (10);
>> for (i = 0; ipa_ref_list_reference_iterate (list, i, ref); i++)
>> {
>> - if (!is_a <cgraph_node> (ref->referred))
>> - continue;
>> -
>> - struct cgraph_node *cnode = ipa_ref_node (ref);
>> - struct cgraph_node *r_cnode
>> - = cgraph_lipo_get_resolved_node (cnode->decl);
>> - if (r_cnode != cnode)
>> + if (is_a <cgraph_node> (ref->referred))
>> {
>> + struct cgraph_node *cnode = ipa_ref_node (ref);
>> + struct cgraph_node *r_cnode
>> + = cgraph_lipo_get_resolved_node (cnode->decl);
>> new_refered.safe_push (r_cnode);
>> use_type = ref->use;
>> new_refered_type.safe_push ((int) use_type);
>> + gcc_assert (use_type != IPA_REF_ADDR
>> + || cnode->global.inlined_to
>> + || cnode->address_taken);
>> + if (use_type == IPA_REF_ADDR)
>> + cgraph_mark_address_taken_node (r_cnode);
>> }
>> + else if (is_a <varpool_node> (ref->referred))
>> + {
>> + struct varpool_node *var = ipa_ref_varpool_node (ref);
>> + struct varpool_node *r_var = real_varpool_node (var->decl);
>> + new_refered.safe_push (r_var);
>> + use_type = ref->use;
>> + new_refered_type.safe_push ((int) use_type);
>> + }
>> + else
>> + gcc_assert (false);
>> }
>> - for (i = 0; new_refered.iterate (i, &c); ++i)
>> + ipa_remove_all_references (&node->ref_list);
>> + for (i = 0; new_refered.iterate (i, &sym_node); ++i)
>> {
>> - ipa_record_reference (node, c,
>> + ipa_record_reference (node, sym_node,
>> (enum ipa_ref_use) new_refered_type[i],
>> NULL);
>> }
>> }
>>
>>
>> --
>> Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
>
>
--
Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
