On 05.04.2013 14:10, Olivier Hainque wrote:
On Apr 5, 2013, at 10:13 , Eric Botcazou <ebotca...@adacore.com> wrote:
We do have regressions on the 4.7 branch in the scheduler (CCed Olivier who
has more information).
Right: we do see a SEGV while compiling the attached monitor.i (preprocessed
output from a qemu tree) with -O2 -g.
./cc1 -m32 -O2 -g -quiet monitor.i
.../monitor.c: In function ‘memory_dump’:
.../monitor.c:1109:1: internal compiler error: Segmentation fault
As already mentioned upthread, this is triggered by a call to
flush_pending_lists with a DEBUG_INSN. We get into:
if (for_write)
{
add_dependence_list_and_free (deps, insn, &deps->pending_read_insns,
1, REG_DEP_ANTI);
if (!deps->readonly)
{
free_EXPR_LIST_list (&deps->pending_read_mems);
deps->pending_read_list_length = 0;
}
}
add_dependence_list_and_free doesn't free *LISTP when
operating on DEBUG_INSNs, so we end up with pending_read_mems freed together
with pending_read_insns not freed.
This was cured on mainline by:
Author: mkuvyrkov
Date: Mon Aug 27 22:11:48 2012 +0000
* sched-deps.c (add_dependence_list_and_free): Simplify.
(flush_pending_list_and_free): Fix a hack that was fixing a hack. Free
lists when add_dependence_list_and_free doesn't free them.
(svn+ssh://gcc.gnu.org/svn/gcc/trunk@190733)
http://gcc.gnu.org/ml/gcc-patches/2012-08/msg01625.html
I don't know whether backporting this would be better than reverting
the offending change as just done on 4.7.
I'd say for 4.6 the best way is to revert. PR 56077 is not that important,
and this 4.6 release will be the last one. For 4.7, we can additionally
backport Maxim's patch or revert this one. I'm fine with both options, but
I'll test 4.7 backport too just to be ready for that.
Andrey
