[Bug other/31477] New: [libgcc] miscompiled trapping arithmetic routines

[Bug other/31477] New: [libgcc] miscompiled trapping arithmetic routines

[rth at gcc dot gnu dot org]

At least some of the trapping arithmetic routines (__absvsi2, etc), are
being compiled *without* the abort that would, in general, be required.
These routines are falling foul of the signed-arithmetic-doesn't-overflow
coding trap.  We need to either compile them with -fwrapv, or rewrite 
them to use unsigned arithmetic.

Further, it would be A Good Idea if these routines were actually tested...


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           Summary: [libgcc] miscompiled trapping arithmetic routines
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31477

[Bug other/31477] [libgcc] miscompiled trapping arithmetic routines

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2007-04-05 00:08 -------
An even better idea is to have them being called with simple programs :).
See PR 19020 for that issue.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31477

[Bug other/31477] [libgcc] miscompiled trapping arithmetic routines

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2007-04-09 18:45 -------
comment #5 in PR19020 mentions several reasons why -ftrapv doesn't really work
right now.  I'd be in favor of removing it rather than trying to fix it...


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-04-09 18:45:22
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31477

[Bug other/31477] [libgcc] miscompiled trapping arithmetic routines

[jsm28 at gcc dot gnu dot org]

------- Comment #3 from jsm28 at gcc dot gnu dot org  2010-05-22 17:29 -------
I believe I fixed this with:

r132815 | jsm28 | 2008-03-02 13:11:19 +0000 (Sun, 02 Mar 2008) | 4 lines

        * libgcc2.c (__addvSI3, __addvsi3, __addvDI3, __subvSI3,
        __subvsi3, __subvDI3, __negvSI2, __negvsi2, __negvDI2, __absvSI2,
        __absvsi2, __absvDI2): Use unsigned arithmetic.

(whether or not -ftrapv actually works properly).


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jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31477