[Bug c/25791] New: -O2 execution fails using 3.4.4, -O and -g work

["dick_guertin at yahoo dot com" <gcc-bugzilla@gcc.gnu.org>]

~> which gcc
/usr/pubsw/bin/gcc

elaine:~> gcc -v
Reading specs from
/afs/ir.stanford.edu/systems/@sys/pubsw/package/Languages/gcc-3.4.4/sun4x_58/bin/../lib/gcc/sparc-sun-solaris2.8/3.4.4/specs
Configured with: ../../gcc-3.4.4/configure --datadir=/lib --libexecdir=/lib
--sharedstatedir=/lib --prefix=/usr/pubsw --enable-threads --with-gnu-as
--with-as=/usr/pubsw/bin/as --with-gnu-ld --with-ld=/usr/pubsw/bin/ld
--with-libintl-

prefix=/usr/pubsw --with-libiconv-prefix=/usr/pubsw
Thread model: posix
gcc version 3.4.4

vine:~> gcc -v
Reading specs from
/afs/ir.stanford.edu/systems/i386_linux24/pubsw/package/Languages/gcc-3.4.4/i386_linux24/bin/../lib/gcc/i686-pc-linux-gnu/3.4.4/specs
Configured with: ../../gcc-3.4.4/configure --datadir=/lib --libexecdir=/lib
--sharedstatedir=/lib --prefix=/usr/pubsw --enable-threads --with-gnu-as
--with-as=/usr/pubsw/bin/as --with-gnu-ld --with-ld=/usr/pubsw/bin/ld
--with-libintl-

prefix=/usr/pubsw --with-libiconv-prefix=/usr/pubsw
Thread model: posix
gcc version 3.4.4

This 'bug' appeared with the introduction of version 3.4.4.  On all
other platforms, the code compiles and executes properly.  This includes
Mac OSX on a G3 and G4, RedHat Linux on i386, and Solaris on Sun's
sparc.  This code is also shared between another i486 and sparc machine,
as shown above.

I deleted all objects (.o), and created a new Makefile using 'xmkmf'
with an Imakefile.  I then compile and built the target program with
'make'.  The Makefile had -O2 optimization by default (created by xmkmf).

When I tried to execute the target program, it failed, as follows:

(gdb) run
Starting program: /afs/ir.stanford.edu/users/g/u/guertin/wylsrc/wylbur.ge

Program received signal SIGSEGV, Segmentation fault.
0x00000000 in ?? ()
(gdb) where
#0  0x00000000 in ?? ()
#1  0x0021ff6c in rlookup ()
#2  0x0021fbd8 in nscan ()
#3  0x00223778 in NSCAN ()
#4  0x00026d9c in EDTBASE ()
#5  0x000277c0 in EDTCOM ()
#6  0x00224348 in signon ()
#7  0x0001c418 in startpw ()
#8  0x00102070 in main ()

I started over, deleted all objects, and changed -O2 to -O in the
Makefile.  This version compiled and executed properly.  The same was
true when I tried -g in place of -O or -O2.  So -O2 code fails to
execute properly, but -O code works just fine.  This same behaviour
occurred on BOTH the i486 and sparc machines.

The program is rather large:
   subdirectory 1:   1 .c,   1 .h
   subdirectory 2:  16 .c,  22 .h
   subdirectory 3:   6 .c,  11 .h
   maindir:         58 .c, 142 .h

The program is 3353608 bytes in size on sparc.
The program is 2928714 bytes in size on i486.

An example of where -O2 code compiles and executes PROPERLY is:

liblin1 $ gcc -v
Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/3.2.3/specs
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--disable-checking --with-system-zlib --enable-__cxa_atexit
--host=i386-redhat-linux
Thread model: posix
gcc version 3.2.3 20030502 (Red Hat Linux 3.2.3-39)

But on the i486 and sparc machines listed at the beginning,
-O2 code fails to execute properly.


-- 
           Summary: -O2 execution fails using 3.4.4, -O and -g work
           Product: gcc
           Version: 3.4.4
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dick_guertin at yahoo dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25791