public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug rtl-optimization/57425] New: RTL alias analysis unprepared to handle stack slot sharing
@ 2013-05-26 22:52 amylaar at gcc dot gnu.org
  2013-05-26 22:53 ` [Bug rtl-optimization/57425] " amylaar at gcc dot gnu.org
                   ` (18 more replies)
  0 siblings, 19 replies; 20+ messages in thread
From: amylaar at gcc dot gnu.org @ 2013-05-26 22:52 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57425

            Bug ID: 57425
           Summary: RTL alias analysis unprepared to handle stack slot
                    sharing
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: major
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: amylaar at gcc dot gnu.org

Created attachment 30198
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30198&action=edit
testcase variant using a int / long union

I see a failures for gcc.dg/torture/pr25654.c for avr for -Os, -O2 and higher
optimization levels.  The .172r.cse1 debugging dump still looks OK, but the
.173r.fwprop1 dump shows that the second memory read to compute sum
has been eliminated by reusing the value of the first one, despite the store
that happened in the mean time.

AFAICT, this patch:
http://gcc.gnu.org/viewcvs/gcc?view=revision&revision=188667
has removed the infrastructure that was put in place to fix PR 25654, without
putting any in any replacement.

Now, what makes the avr different from the majority of tier1 targets is that
short and int are the same size.

If I change the testcase a bit to use int/long instead of short/int, it starts
failing on i686-pc-linux-gnu.  This is a 4.8 regression relative to 4.7 .
A variant of the testcase without unions also fails.  This is again at -Os /
-O2
and higher optimization levels.


^ permalink raw reply	[flat|nested] 20+ messages in thread
end of thread, other threads:[~2014-03-23 10:53 UTC | newest]

Thread overview: 20+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-05-26 22:52 [Bug rtl-optimization/57425] New: RTL alias analysis unprepared to handle stack slot sharing amylaar at gcc dot gnu.org
2013-05-26 22:53 ` [Bug rtl-optimization/57425] " amylaar at gcc dot gnu.org
2013-05-26 23:21 ` amylaar at gcc dot gnu.org
2013-05-27  7:53 ` [Bug rtl-optimization/57425] [4.8/4.9 regression] " ebotcazou at gcc dot gnu.org
2013-05-27  8:08 ` rguenth at gcc dot gnu.org
2013-05-27  8:31 ` ebotcazou at gcc dot gnu.org
2013-05-31 10:59 ` jakub at gcc dot gnu.org
2013-06-15 20:16 ` amylaar at gcc dot gnu.org
2013-10-16  9:51 ` jakub at gcc dot gnu.org
2013-10-18 16:06 ` mikpelinux at gmail dot com
2013-10-25 10:23 ` [Bug rtl-optimization/57425] [4.8 Regression] " rguenth at gcc dot gnu.org
2014-03-13  3:00 ` wschmidt at gcc dot gnu.org
2014-03-13  8:41 ` mikpelinux at gmail dot com
2014-03-13 15:01 ` wschmidt at gcc dot gnu.org
2014-03-13 18:59 ` mikpelinux at gmail dot com
2014-03-13 19:03 ` wschmidt at gcc dot gnu.org
2014-03-15 18:07 ` mikpelinux at gmail dot com
2014-03-17  9:49 ` mikpelinux at gmail dot com
2014-03-17 15:32 ` wschmidt at gcc dot gnu.org
2014-03-23 10:53 ` ebotcazou at gcc dot gnu.org

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).