https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94618
--- Comment #11 from CVS Commits ---
The releases/gcc-9 branch has been updated by Jakub Jelinek
:
https://gcc.gnu.org/g:dea597314f4503228e23e887ddbb773cbf197093
commit r9-8881-gdea597314f4503228e23e887ddbb773cbf197093
Author: Jakub Jelinek
Date: Fri Apr 17 10:33:27 2020 +0200
Fix -fcompare-debug issue in delete_insn_and_edges [PR94618]
delete_insn_and_edges calls purge_dead_edges whenever deleting the last
insn
in a bb, whatever it is. If it called it only for mandatory last insns
in the basic block (that may not be followed by DEBUG_INSNs, dunno if that
is control_flow_insn_p or something more complex), that wouldn't be a
problem, but as it calls it on any last insn and can actually do something
in the bb, if such an insn is followed by one more more DEBUG_INSNs and
nothing else in the same bb, we don't call purge_dead_edges with -g and do
call it with -g0.
On the testcase, there are two reg-to-reg moves with REG_EH_REGION notes
(previously memory accesses but simplified and yet not optimized), and the
second is followed by DEBUG_INSNs; the second move is delete_insn_and_edges
and after removing it, for -g0 purge_dead_edges removes the REG_EH_REGION
from the now last insn in the bb (the first reg-to-reg move), while
for -g it isn't called and things diverge from that quickly on.
Fixed by calling purdge_dead_edges even if we remove the last real insn
followed only by DEBUG_INSNs in the same bb.
2020-04-17 Jakub Jelinek
PR rtl-optimization/94618
* cfgrtl.c (delete_insn_and_edges): Set purge not just when
insn is the BB_END of its block, but also when it is only followed
by DEBUG_INSNs in its block.
* g++.dg/opt/pr94618.C: New test.
(cherry picked from commit c41884a09206be0e21cad7eea71b9754daa969d4)
