deref_puc_assign,21164a on RH51/alpha

[Stefan Schroepfer]

It seems to me like I discovered a bug common to egcs-1.0.2 (as
shipped with RH 5.1 PowerTools CD set) and egcs-1.0.3a. Trying to
build egcs-19980727 lead to an error on my Linux/Alpha system.

Hardware / Software:
PC164 / 21164a
RH 5.1 from PowerTools CD set
glibc*-2.0.7-19.alpha.rpm from RH updates directory

Compiler options affecting code generation used:
-O2 -mcpu=21164a -Wa,-m21164a

--------------------
sample code
--------------------

int main ()
{
    unsigned char   uc;
    unsigned char   *puc;

    puc = &uc;
    *puc = 0x00;

    return ((int) uc);
}

--------------------
sample session (comments start with '#', newlines added)
--------------------

# gdb will show that SIGILL is thrown in return statement while
# in a real world example this happens in assignment
# "*([pointer_to_unsigned_char]) = 0x00"

scr@scr02 1010 c_c++ $ gcc -g -O2 -mcpu=21164a -Wa,-m21164a
egcs_sigill.cpp -o egcs_sigill

scr@scr02 1011 c_c++ $ ./egcs_sigill 
Illegal Instruction (core dumped)

scr@scr02 1012 c_c++ $ gdb egcs_sigill core
GNU gdb 4.17
[...]
This GDB was configured as "alpha-redhat-linux"...
Core was generated by `./egcs_sigill'.
Program terminated with signal 4, Illegal Instruction.
find_solib: Can't read pathname for load map: Input/output error

#0  main () at egcs_sigill.cpp:13
13          return ((int) uc);
(gdb) quit

# Can't figure out what this "find_solib" message of gdb is all
# about ...

scr@scr02 1014 c_c++ $ gcc -v
Reading specs from
/usr/local/lib/gcc-lib/alphaev5-unknown-linux-gnu/egcs-2.90.2
9/specs
gcc version egcs-2.90.29 980515 (egcs-1.0.3 release)

# egcs-2.90.27 980315 (egcs-1.0.2 release) as shipped with RH 51
# PowerTools produces an identical executable, assembler output
# differs only by .ident version string.

scr@scr02 1017 c_c++ $ gcc -S -O2 -mcpu=21164a -Wa,-m21164a
egcs_sigill.cpp

scr@scr02 1019 c_c++ $ cat egcs_sigill.s
        .file   1 "egcs_sigill.cpp"
        .version        "01.01"
        .set noat
gcc2_compiled.:
__gnu_compiled_cplusplus:
.text
        .align 3
        .globl main
        .ent main
main:
$main..ng:
        lda $30,-16($30)
        .frame $30,16,$26,0
        .prologue 0
        stb $31,0($30)
        bis $31,$31,$0
        addq $30,16,$30
        ret $31,($26),1
        .end main
        .ident  "GCC: (GNU) egcs-2.90.29 980515 (egcs-1.0.3 release)"

--------------------
end of provided samples
--------------------

Hope this helps in further development of egcs (and that I did
not make trivial mistakes).

Regards,
Stefan Schroepfer
scr@iis.fhg.de