[Bug rtl-optimization/61509] New: GCC miscompilation on ARM during RTL optimization when compiled with -O3

[Bug rtl-optimization/61509] New: GCC miscompilation on ARM during RTL optimization when compiled with -O3

[quentusrex at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61509

            Bug ID: 61509
           Summary: GCC miscompilation on ARM during RTL optimization when
                    compiled with -O3
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: quentusrex at gmail dot com

C code:
if(strcasecmp(var,"a")) 
else if(strcasecmp(var, "b") 

the second call to strcasecmp is being optimized out, and the control statement
is effectively being treated as an if() else statement.

More detailed write up here: 
http://quentusrex.com/freeswitch-raspberrypi-gcc-compiler-bug.html

Debug files located here:
https://github.com/quentusrex/FS-6495/tree/master/gcc_debug_orig

The second call to strcasecmp is being removed in pass #200 during a DCE loop.

[Bug rtl-optimization/61509] GCC miscompilation on ARM during RTL optimization when compiled with -O3

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61509

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2014-06-14
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
4.6.3 is no longer supported, can you try a newer compiler?  Also can you
attach the preprocessed source?

[Bug rtl-optimization/61509] GCC miscompilation on ARM during RTL optimization when compiled with -O3

[quentusrex at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61509

--- Comment #3 from William King <quentusrex at gmail dot com> ---
Line 7945 has the strcasecmp of the gcc output 'original' pass:
https://github.com/quentusrex/FS-6495/blob/master/gcc_debug_orig/switch_core_media.c.003t.original

[Bug rtl-optimization/61509] GCC miscompilation on ARM during RTL optimization when compiled with -O3

[quentusrex at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61509

--- Comment #2 from William King <quentusrex at gmail dot com> ---
Created attachment 32939
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32939&action=edit
Source file for switch_core_media.c

Line 3356 is the strcasecmp that is being optimized out.

[Bug rtl-optimization/61509] GCC miscompilation on ARM during RTL optimization when compiled with -O3

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61509

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to William King from comment #2)
> Created attachment 32939 [details]
> Source file for switch_core_media.c

This is the source and not the preprocessed source.

[Bug rtl-optimization/61509] GCC miscompilation on ARM during RTL optimization when compiled with -O2

[quentusrex at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61509

--- Comment #5 from William King <quentusrex at gmail dot com> ---
Preprocessed file located here:
http://quentusrex.com/switch_core_media.c.preprocessed

[Bug rtl-optimization/61509] GCC miscompilation on ARM during RTL optimization when compiled with -O2

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61509

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Still waiting for reporter to try a still supported compiler which would be
GCC 4.8.3 or 4.9.0.

[Bug rtl-optimization/61509] GCC miscompilation on ARM during RTL optimization when compiled with -O2

[quentusrex at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61509

--- Comment #7 from William King <quentusrex at gmail dot com> ---
While I haven't had a chance to run through more than a handful of call
scenarios, building FreeSWITCH on the Raspberry Pi with GCC 4.9.0 does not have
the same problem.