[Bug target/49211] New: MMIX: Code generation broken, when using global variables

[nils@script-solution.de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49211

           Summary: MMIX: Code generation broken, when using global
                    variables
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: nils@script-solution.de
              Host: Ubuntu on x86_64
            Target: MMIX
             Build: gcc-4.6.0 with binutils-2.21


Created attachment 24386
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24386
Contains the object-file and the executable

I hope it is no missunderstanding, but as it seems, the code generation is
wrong when using global variables (I'm wondering because it is such a basic
thing).

For example, take the following C file:
----
struct foo {
    int x,y;
};

static struct foo f;
static int x;

static void func1(int *i) {
}
static void func2(struct foo *pf) {
}

int main(void) {
    int a;
    f.x = 0;
    f.y = 1;
    x = 2;
    func1(&x);
    func1(&a);
    func2(&f);
    return 0;
}
----

I'm using the following commands to build the executable:
$ mmix-elf-escape-gcc -o test.o -c test.c
$ mmix-elf-escape-gcc -nostdlib -o test test.o

The disassembly for the main-function is:
----
0000000000000040 <main>:
  40:    27fefe10     subu $254,$254,16
  44:    affdfe08     stou $253,$254,8
  48:    23fdfe10     addu $253,$254,16
  4c:    fe000004     get $0,rJ
  50:    e3010000     setl $1,0x0
  54:    ab01fe00     sttu $1,$254,0
  58:    e3010001     setl $1,0x1
  5c:    ab01fe04     sttu $1,$254,4
  60:    e3010002     setl $1,0x2
  64:    ab01fe08     sttu $1,$254,8
  68:    2303fe08     addu $3,$254,8
  6c:    f302ffe5     pushj $2,0 <_start.>
  70:    f6040000     put rJ,$0
  74:    2701fd0c     subu $1,$253,12
  78:    c1030100     set $3,$1
  7c:    f302ffe1     pushj $2,0 <_start.>
  80:    f6040000     put rJ,$0
  84:    2303fe00     addu $3,$254,0
  88:    f302ffe6     pushj $2,20 <func2>
  8c:    f6040000     put rJ,$0
  90:    e3000000     setl $0,0x0
  94:    8dfdfe08     ldo $253,$254,8
  98:    23fefe10     addu $254,$254,16
  9c:    f8010000     pop 1,0
----

That means, the code expects, that f is located at $254, offset 0. But $254 is
the frame-pointer according to
http://www.bitrange.com/mmix/mmixfest-2001/mmixabi.html. The example shows a
few other usages, that are wrong for the same reason. Note that it is correct
for the local variable.

For the case that it helps, I've attached the object file and the executable.

I hope that the fix is easy. It would be really nice to know shortly how to
resolve that, because before that, I think one can't do anything useful with
gcc for MMIX :/