-O option in gcc 2.95.1 generates internal error

[Reeves, Alastair M.]

   Using the -O optimize option results in an "internal error" message from
the gcc 2.95.1 compiler.  If the -O option is not used, the compile works
fine.  BTW, this problem with -O does not occur with the 2.8.0 compiler.
This is an example of the attempted compile:

[amr@amr.563] % gcc -O -I/usr/include/Motif1.2 -I/usr/include/X11R5
-I/opt/epak/include -I/opt/loox/include -c creation-c.c

In file included from creation-c.c:23:
/opt/loox/include/DrawingM.h:148: warning: `XmNdoubleBuffer' redefined
/opt/epak/include/Xi/XiEPakDefs.h:4222: warning: this is the location of the
previous definition
/opt/loox/include/DrawingM.h:149: warning: `XmCDoubleBuffer' redefined
/opt/epak/include/Xi/XiEPakDefs.h:5245: warning: this is the location of the
previous definition
/opt/loox/include/DrawingM.h:151: warning: `XmNgridWidth' redefined
/opt/epak/include/Xi/XiEPakDefs.h:4024: warning: this is the location of the
previous definition
creation-c.c: In function `Createform5':
creation-c.c:4006: internal error--unrecognizable insn:
(insn 42442 42441 16788 (set (reg:SI 21 %r21)
        (mult:SI (reg/v:SI 3 %r3)
            (const_int 8 [0x8]))) -1 (nil)
    (nil))

Specifics:

   The creation-c.c file is generated by the GUI building utility "BxPro"
from
ICS.  (BxPro interprets a GUI specification file, outputs C code in
creation-c.c, which is then compiled by gcc.) In addition, the program uses 
graphics libraries from Loox Inc.  (This is the source of the redefinition
warnings, but it doesn't cause any problems with the executable code.)

g++ version:      2.95.1
O/S:              HP-UX Rev 10.20
System:           B132 workstation
Installation
details:          The "configure" script was used to:
                  i)   Install the compiler in /opt/gcc-2.95.1  (/opt/gcc is
                       a symbolic link that points to this directory.)
                  ii)  Include files were re-directed from
/usr/local/include
                       to /opt/gcc-2.95.1/include
                  Other than this, installation of the compiler is standard.

   Below is a "tarred-gzipped-uuencoded" copy of creation-c.c and
creation-c.ii