Hi,
On Mon, Jul 27 2020, Richard Biener via Gcc-patches wrote:
> On Sat, Jul 25, 2020 at 8:35 PM Sergei Trofimovich via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
>>
>> From: Sergei Trofimovich <siarh...@google.com>
>>
>> In PR ipa/96291 the test contained an SCC with one
>> unoptimized function. This tricked ipa-cp into NULL dereference.
>>
>> has_undead_caller_from_outside_scc_p() did not take into account
>> that unoptimized funtions don't have IPA summary analysis. and
>> dereferenced NULL pointer causing an ICE.
>
> Can you create a single-unit testcase with a SCC with one function
> having the no_ipa attribute?
This bug is LTO specific because otherwise a summary (although marked as
quite useless) will be left over from the summary building stage.
So Sergei, if you can afford to spend an extra while providing a
testcase, you'll need to add three files into gcc/testsuite/gcc.dg/lto,
with either the second or third (numbered _1 or _2)) having
/* { dg-lto-options { { -flto -O0 } } } */
in them.
Thanks,
Martin
>
>> PR ipa/96291
>> * ipa-cp.c (has_undead_caller_from_outside_scc_p): Consider
>> unoptimized callers as undead.
>> ---
>> gcc/ipa-cp.c | 12 +++++++++---
>> 1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/gcc/ipa-cp.c b/gcc/ipa-cp.c
>> index b0c8f405260..d5082576962 100644
>> --- a/gcc/ipa-cp.c
>> +++ b/gcc/ipa-cp.c
>> @@ -5666,9 +5666,15 @@ has_undead_caller_from_outside_scc_p (struct
>> cgraph_node *node,
>> && cs->caller->call_for_symbol_thunks_and_aliases
>> (has_undead_caller_from_outside_scc_p, NULL, true))
>> return true;
>> - else if (!ipa_edge_within_scc (cs)
>> - && !IPA_NODE_REF (cs->caller)->node_dead)
>> - return true;
>> + else if (!ipa_edge_within_scc (cs))
>> + {
>> + /* Unoptimized callers don't have IPA information.
>> + Conservatively assume callers are undead. */
>> + if (!IPA_NODE_REF (cs->caller))
>> + return true;
>> + if (!IPA_NODE_REF (cs->caller)->node_dead)
>> + return true;
>> + }
>> return false;
>> }
>>
>> --
>> 2.27.0
>>
