testcase for hppa64 gcc bug

[John David Anglin]

> I think I know what's going on here.  The root of the problem is that
> pa-64.h defines an ARG_POINTER_REGNUM that isn't a fixed reg, and isn't
> eliminable.  The arg_pointer isn't even a call-saved reg.  That breaks a
> number of places in the compiler.
> 
> So I went down the path of trying to fix things properly by defining
> ELIMINABLE_REGS and so on, but I ended in a maze of twisty little passages
> labelled "Unrecognizable instruction", like this one:
> 
> /src/parisc/gcc/gcc/libgcc2.c: In function `__moddi3':
> /src/parisc/gcc/gcc/libgcc2.c:601: Unrecognizable insn:
> (insn 1289 209 1298 (set (reg:SI 50 %fr22)
>         (subreg:SI (plus:DI (reg:DI 30 %r30)
>                 (const_int -272 [0xfffffef0])) 0)) -1 (nil)
>     (nil))
> /src/parisc/gcc/gcc/libgcc2.c:601: Internal compiler error in
> extract_insn, at recog.c:2134

I am making progress in trying to make the arg_pointer register eliminable.
I have fixed the above problem.  What was happening was that reload_as_needed
was incorrectly trying to eliminate the return from millicode calls which
is also register r29.  I have figured out how to hide it from reload with
unspec.

However, the compiler is now too good at eliminating the arg_pointer.  At
-O3, it completely eliminates the arg_pointer.  However, as I read the ABI,
the call must always set the arg_pointer before calls.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)