On 5/19/22 17:02, Jan Hubicka wrote:
>> Similarly to cgraph_nodes, it may happen that body_removed is set
>> during merging of symbols.
>>
>> PR ipa/105600
>>
>> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>>
>> Ready to be installed?
>> Thanks,
>> Martin
>>
>> gcc/ChangeLog:
>>
>> * ipa-icf.cc (sem_item_optimizer::filter_removed_items):
>> Skip variables with body_removed.
>> ---
>> gcc/ipa-icf.cc | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/gcc/ipa-icf.cc b/gcc/ipa-icf.cc
>> index 765ae746745..6528a7a10b2 100644
>> --- a/gcc/ipa-icf.cc
>> +++ b/gcc/ipa-icf.cc
>> @@ -2411,10 +2411,11 @@ sem_item_optimizer::filter_removed_items (void)
>> {
>> /* Filter out non-readonly variables. */
>> tree decl = item->decl;
>> - if (TREE_READONLY (decl))
>> - filtered.safe_push (item);
>> - else
>> + varpool_node *vnode = static_cast <sem_variable
>> *>(item)->get_node ();
>> + if (!TREE_READONLY (decl) || vnode->body_removed)
>> remove_item (item);
>> + else
>> + filtered.safe_push (item);
>
> So the situation here is that we merge symbols but keep syntactic alias
> because the declarations are not compatible (have different attributes
> perhaps because of fortify source)?
The test-case is more about a constexpr symbol or so, I'm not familiar enough
with these modern C++.
cgraph_node looks like:
(gdb) p item->node->debug()
_ZN8nlohmann6detail12static_constINS0_10to_json_fnEE5valueE/10 (value)
@0x7ffff7fb3200
Type: variable
Body removed by symtab_remove_unreachable_nodes
Visibility: externally_visible semantic_interposition preempted_reg external
public weak comdat
comdat_group:_ZN8nlohmann6detail12static_constINS0_10to_json_fnEE5valueE
one_only
References:
Referring:
_Z7to_jsonRN8nlohmann10basic_jsonISt3mapSt6vectorNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEblmiSaNS_14adl_serializerES2_IhSaIhEEEERK8Settings/1
(addr)
_Z7to_jsonRN8nlohmann10basic_jsonISt3mapSt6vectorNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEblmiSaNS_14adl_serializerES2_IhSaIhEEEERK8Settings/1
(addr)
Read from file: a.o
Availability: not_available
Varpool flags: initialized read-only
>
> Will ICF still see through the aliases and do merging?
No.
> I think you can
> craft a testcase by triggering the attribute mismatch and see what
> happens. At the time we implemented ICF these aliases did not exists,
> so maybe some TLC is needed here.
Please come up with such test case :)
Thanks,
Martin
>
> Honza
