On 12/28/2021 3:21 AM, Jakub Jelinek wrote:
Hi!
In the following testcase we have a -fcompare-debug failure, because
can_move_invariant_reg doesn't ignore DEBUG_INSNs in its decisions.
In the testcase we have due to uninitialized variable:
loop_header
debug_insn using pseudo84
pseudo84 = invariant
insn using pseudo84
end loop
and with -g decide not to move the pseudo84 = invariant before the
loop header; in this case not resetting the debug insns might be fine.
But, we could have also:
pseudo84 = whatever
loop_header
debug_insn using pseudo84
pseudo84 = invariant
insn using pseudo84
end loop
and in that case not resetting the debug insns would result in wrong-debug.
And, we don't really have generally a good substitution on what pseudo84
contains, it could inherit various values from different paths.
So, the following patch ignores DEBUG_INSNs in the decisions, and if there
are any that previously prevented the optimization, resets them before
return true.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2021-12-28 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/103837
* loop-invariant.c (can_move_invariant_reg): Ignore DEBUG_INSNs in
the decisions whether to return false or continue and right before
returning true reset those debug insns that previously caused
returning false.
* gcc.dg/pr103837.c: New test.
OK
jeff
