Hi,
since r278669 (fix for PR ipa/91956), IPA-SRA makes sure that the clone
it creates is put into the same same_comdat as the original cgraph_node,
so that it can call private comdats (such as the ipa-split bits of a
comdat that is private).
However, that means that if there is non-comdat caller of a public
comdat that is modified by IPA-SRA, it now finds itself calling a
private comdat, which call graph verifier does not like (and for a
reason, in theory it can disappear and since it is private it would not
be available from other CUs).
The patch fixes this by performing the fix for PR 91956 only when the
node in question actually calls a local comdat and when it does, also
making sure that no callers come from a different same_comdat (disabling
IPA-SRA if both conditions are true), so that it plays by the rules in
both modes, does not violate the private comdat calling rule and at the
same time does not disable the transformation unnecessarily.
The patch also fixes up the calls_comdat_local of callers of the
modified node, despite that not triggering any known issues. It has
passed LTO-bootstrap and testing. What do you think?
Thanks,
Martin
2019-12-16 Martin Jambor <mjam...@suse.cz>
PR ipa/92676
* ipa-sra.c (struct caller_issues): New fields candidate and
call_from_outside_comdat.
(check_for_caller_issues): Check for calls from outsied of
candidate's same_comdat_group.
(check_all_callers_for_issues): Set up issues.candidate, check result
of the new check.
(process_isra_node_results): Set calls_comdat_local of callers if
appropriate.
---
gcc/ipa-sra.c | 27 +++++++++++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/gcc/ipa-sra.c b/gcc/ipa-sra.c
index 421c0899e11..8612c8fc920 100644
--- a/gcc/ipa-sra.c
+++ b/gcc/ipa-sra.c
@@ -2895,10 +2895,14 @@ ipa_sra_ipa_function_checks (cgraph_node *node)
struct caller_issues
{
+ /* The candidate being considered. */
+ cgraph_node *candidate;
/* There is a thunk among callers. */
bool thunk;
/* Call site with no available information. */
bool unknown_callsite;
+ /* Call from outside the the candidate's comdat group. */
+ bool call_from_outside_comdat;
/* There is a bit-aligned load into one of non-gimple-typed arguments. */
bool bit_aligned_aggregate_argument;
};
@@ -2920,6 +2924,13 @@ check_for_caller_issues (struct cgraph_node *node, void
*data)
thunks. */
return true;
}
+ if (issues->candidate->calls_comdat_local
+ && issues->candidate->same_comdat_group
+ && !issues->candidate->in_same_comdat_group_p (cs->caller))
+ {
+ issues->call_from_outside_comdat = true;
+ return true;
+ }
isra_call_summary *csum = call_sums->get (cs);
if (!csum)
@@ -2942,6 +2953,7 @@ check_all_callers_for_issues (cgraph_node *node)
{
struct caller_issues issues;
memset (&issues, 0, sizeof (issues));
+ issues.candidate = node;
node->call_for_symbol_and_aliases (check_for_caller_issues, &issues, true);
if (issues.unknown_callsite)
@@ -2960,6 +2972,13 @@ check_all_callers_for_issues (cgraph_node *node)
node->dump_name ());
return true;
}
+ if (issues.call_from_outside_comdat)
+ {
+ if (dump_file)
+ fprintf (dump_file, "Function would become private comdat called "
+ "outside of its comdat group.\n");
+ return true;
+ }
if (issues.bit_aligned_aggregate_argument)
{
@@ -3759,8 +3778,12 @@ process_isra_node_results (cgraph_node *node,
= node->create_virtual_clone (callers, NULL, new_adjustments, "isra",
suffix_counter);
suffix_counter++;
- if (node->same_comdat_group)
- new_node->add_to_same_comdat_group (node);
+ if (node->calls_comdat_local && node->same_comdat_group)
+ {
+ new_node->add_to_same_comdat_group (node);
+ for (cgraph_edge *cs = new_node->callers; cs; cs = cs->next_caller)
+ cs->caller->calls_comdat_local = true;
+ }
new_node->calls_comdat_local = node->calls_comdat_local;
if (dump_file)
--
2.24.0
