[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 --- Comment #11 from Richard Guenther rguenth at gcc dot gnu.org 2012-07-06 09:25:51 UTC --- Author: rguenth Date: Fri Jul 6 09:25:46 2012 New Revision: 189314 URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=189314 Log: 2012-07-06 Richard Guenther rguent...@suse.de Backport from mainline 2012-03-30 Richard Guenther rguent...@suse.de PR middle-end/52786 * double-int.c (rshift_double): Remove not needed cast. 2012-03-28 Richard Guenther rguent...@suse.de PR middle-end/50708 * double-int.h (rshift_double): Remove. * double-int.c (lshift_double): Use absu_hwi to make count positive. (rshift_double): Make static, take unsigned count argument, remove handling of negative count argument. (double_int_rshift): Dispatch to lshift_double. Modified: branches/gcc-4_7-branch/gcc/ChangeLog branches/gcc-4_7-branch/gcc/double-int.c branches/gcc-4_7-branch/gcc/double-int.h
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 Richard Guenther rguenth at gcc dot gnu.org changed: What|Removed |Added Known to work||4.7.2 Target Milestone|4.8.0 |4.7.2 Known to fail||4.7.1 --- Comment #12 from Richard Guenther rguenth at gcc dot gnu.org 2012-07-06 09:27:34 UTC --- 4.7.2 even.
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 Richard Guenther rguenth at gcc dot gnu.org changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution||FIXED Target Milestone|--- |4.8.0 --- Comment #10 from Richard Guenther rguenth at gcc dot gnu.org 2012-07-05 14:55:41 UTC --- Anyway, fixed for 4.8.
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 --- Comment #8 from Richard Guenther rguenth at gcc dot gnu.org 2012-03-29 08:27:16 UTC --- Author: rguenth Date: Thu Mar 29 08:27:04 2012 New Revision: 185951 URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=185951 Log: 2012-03-29 Richard Guenther rguent...@suse.de PR middle-end/50708 * double-int.h (rshift_double): Remove. * double-int.c (lshift_double): Use absu_hwi to make count positive. (rshift_double): Make static, take unsigned count argument, remove handling of negative count argument. (double_int_rshift): Dispatch to lshift_double. Modified: trunk/gcc/ChangeLog trunk/gcc/double-int.c trunk/gcc/double-int.h
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 Richard Guenther rguenth at gcc dot gnu.org changed: What|Removed |Added Known to work||4.8.0 --- Comment #9 from Richard Guenther rguenth at gcc dot gnu.org 2012-03-29 09:21:17 UTC --- Fixed on trunk sofar.
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 Richard Guenther rguenth at gcc dot gnu.org changed: What|Removed |Added CC||borut.razem at gmail dot ||com --- Comment #6 from Richard Guenther rguenth at gcc dot gnu.org 2012-03-28 14:23:40 UTC --- *** Bug 52653 has been marked as a duplicate of this bug. ***
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 Richard Guenther rguenth at gcc dot gnu.org changed: What|Removed |Added Status|NEW |ASSIGNED AssignedTo|unassigned at gcc dot |rguenth at gcc dot gnu.org |gnu.org | --- Comment #7 from Richard Guenther rguenth at gcc dot gnu.org 2012-03-28 14:24:15 UTC --- Mine.
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 --- Comment #5 from Mikael Pettersson mikpe at it dot uu.se 2011-10-30 20:35:03 UTC --- The regression started with r158372: http://gcc.gnu.org/ml/gcc-cvs/2010-04/msg00478.html Here's what seems to have happened: 1. Anatoly Sokolov suggested to add a bunch of double_int_ functions: http://gcc.gnu.org/ml/gcc-patches/2010-04/msg00482.html. 2. Eric Botcazou replied about the added double_int_rshift (a wrapper around rshift_double) that the comment about the COUNT parameter was wrong, and that rshift_double requires it to be positive (double_int_rshift stated that a negative COUNT turned it into a left-shift): http://gcc.gnu.org/ml/gcc-patches/2010-04/msg00557.html. 3. In the final version of Anatoly's patch committed in r158360: http://gcc.gnu.org/ml/gcc-cvs/2010-04/msg00466.html, the comment above rshift_double was changed to allow a negative COUNT as meaning a left-shift. However, the code in rshift_double was not changed, and still assumed that COUNT would be positive. 4. Richard Guenther followed up with a cleanup patch to move rshift_double and other related functions from fold-const.c to double-int.c in r158372: http://gcc.gnu.org/ml/gcc-cvs/2010-04/msg00478.html. However, rshift_double was not copied verbatim, as a check for a negative COUNT was added at the beginning followed by a conditional call to lshift_double with -COUNT. This made the code consistent with the comment, but also caused the loop on HWI32 platforms. I suspect that r158360 shouldn't have allowed for a negative COUNT to rshift_double or double_int_rshift. Removing the check for negative COUNT from the start of rshift_double does fix the test case on i686 with gcc-4.6. However, I'm worried that parts of gcc now depend on the extended semantics of rshift_double and double_int_rshift, so reverting that may be problematic. Instead we can robustify rshift_double a bit: if COUNT 0, check if COUNT equals INTTYPE_MINIMUM (HOST_WIDE_INT), and if so don't negate COUNT and call lshift_double but instead set COUNT to 2 * HOST_BITS_PER_WIDE_INT. The following code will then handle this like other too-large shifts. This fixes the test case too with no testsuite regressions on i686 with gcc-4.6. gcc-4.7 doesn't have the issue on i686 because i686 is now HWI64 (right?), but other HWI32 platforms like m68k and arm-oabi still have the problem. I'm currently testing the 2nd patch with gcc-4.7 on i686 and x86_64.
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 Mikael Pettersson mikpe at it dot uu.se changed: What|Removed |Added CC||mikpe at it dot uu.se --- Comment #3 from Mikael Pettersson mikpe at it dot uu.se 2011-10-29 13:29:20 UTC --- The reduced test case throws 4.6.1 and 4.6-20111021 in a loop on i686-linux, but 4.4/4.5/4.7 don't loop. On m68k-linux both 4.6-20111021 and 4.7-20111022 loop. I haven't been able to reproduce the loop on armv5tel-linux-gnueabi with any of 4.4/4.5/4.6/4.7.
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 --- Comment #4 from Ryan Mansfield rmansfield at qnx dot com 2011-10-29 14:28:57 UTC --- (In reply to comment #3) I haven't been able to reproduce the loop on armv5tel-linux-gnueabi with any of 4.4/4.5/4.6/4.7. arm eabi targets force 64bit HOST_WIDE_INT which is why the reduced testcase didn't fail.
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708
--- Comment #2 from Ryan Mansfield rmansfield at qnx dot com 2011-10-29
01:16:37 UTC ---
My large testcase reduced to:
void
foo ()
{
unsigned int a = 1 0x8000;
}
[Bug middle-end/50708] Infinite loop between rshift_double and lshift_double if count is LONG_MIN
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50708 Richard Guenther rguenth at gcc dot gnu.org changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2011-10-13 Ever Confirmed|0 |1 --- Comment #1 from Richard Guenther rguenth at gcc dot gnu.org 2011-10-13 09:26:28 UTC --- Confirmed. Not very likely, but ...
