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Re: [Gcl-devel] Re: gcl/maxima on hppa


From: Camm Maguire
Subject: Re: [Gcl-devel] Re: gcl/maxima on hppa
Date: 01 Aug 2002 18:48:58 -0400

Greetings, and thank you for this!

At first glance, this appears to solve the gc issue on hppa!  There
may be a residual difficulty, but I won't be sure until the Debian
autobuilder finishes compiling the upload I just made.  

In any case, I would appreciate a version 'which foo can call' as you
mention below.  

Here is what the current draft looks like, which appears to work but
needs cleaning up a bit:


=============================================================================
#if defined(__hppa__)
asm(
        ".code\n\t"
        ".export GBC,entry\n\t"
        ".import GBC1,code\n\t"
        ".proc\n\t"
        ".callinfo entry_gr=18, calls, save_rp\n\t"
        ".label GBC\n\t"
        ".entry\n\t"
        "stw    %rp,-20(%sp)\n\t"
        "stwm   %r3,128(%sp)\n\t"
        "stw    %r4,-124(%sp)\n\t"
        "stw    %r5,-120(%sp)\n\t"
        "stw    %r6,-116(%sp)\n\t"
        "stw    %r7,-112(%sp)\n\t"
        "stw    %r8,-108(%sp)\n\t"
        "stw    %r9,-104(%sp)\n\t"
        "stw    %r10,-100(%sp)\n\t"
        "stw    %r11,-96(%sp)\n\t"
        "stw    %r12,-92(%sp)\n\t"
        "stw    %r13,-88(%sp)\n\t"
        "stw    %r14,-84(%sp)\n\t"
        "stw    %r15,-80(%sp)\n\t"
        "stw    %r16,-76(%sp)\n\t"
        "stw    %r17,-72(%sp)\n\t"
        "stw    %r18,-68(%sp)\n\t"
        "bl      GBC1,%rp\n\t"
        "nop\n\t"
        "ldw    -148(%sp),%rp\n\t"
        "ldw    -72(%sp),%r18\n\t"
        "ldw    -68(%sp),%r17\n\t"
        "ldw    -76(%sp),%r16\n\t"
        "ldw    -80(%sp),%r15\n\t"
        "ldw    -84(%sp),%r14\n\t"
        "ldw    -88(%sp),%r13\n\t"
        "ldw    -92(%sp),%r12\n\t"
        "ldw    -96(%sp),%r11\n\t"
        "ldw    -100(%sp),%r10\n\t"
        "ldw    -104(%sp),%r9\n\t"
        "ldw    -108(%sp),%r8\n\t"
        "ldw    -112(%sp),%r7\n\t"
        "ldw    -116(%sp),%r6\n\t"
        "ldw    -120(%sp),%r5\n\t"
        "ldw    -124(%sp),%r4\n\t"
        "bv     0(%rp)\n\t"
        "ldwm   128(%sp),%r3\n\t"

        ".exit\n\t"
        ".procend\n\t"
        ".end\n\t"
);

void
GBC1(enum type t) {
#else
void
GBC(enum type t) {
#endif
=============================================================================

Take care,

address@hidden (LaMont Jones) writes:

> On Thu, Aug 01, 2002 at 02:44:12PM -0400, Camm Maguire wrote:
> > > 16 byte alignment is certainly nicer, and may be required on hppa-linux,
> > > but I don't know.
> > What are the atomic issues with 16 byte alignment?
> 
> LDCW (load and clear word) is only defined on addresses that are 16-byte
> aligned.
> 
> > > That would be the most significant difference  sp (gr30) + 0 and beyond
> > > is off the end of the stack....
> > Does this refer to the start of the heap, ~ 0x20000 on hppa-linux?
> 
> No.  interrupts, function calls, and such eventually allocate a stack
> frame, which is done by _ADDING_ to %sp, and then storing things at
> negative offsets from the new %sp.
> 
> > Yes, this assembly is likely what I need.  I don't really care if I
> > get the state before or after the function call, as long as I can find
> > the addresses of all local variables normally intended for the stack
> > in some definiable region of memory.  Consider the following gdb
> > session.  Certain local variables cannot report their addresses under
> > gdb.  I assume this means that these addresses are also not to be
> > found on the stack, causing my garbage collector to overlook them in
> > the mark stage, and erroneously sweep them away.
> 
> OK.  I'll let willy correct me, but if you wrote a stub that spilled
> gr3-18 to the frame, and then called your garbage collector, then you
> could find the registers on the stack somewhere...
> 
> The stack layout looks like:  [old sp],register spill, local vars, args
> for function calls, [new sp].
> 
> >   (On ia64, there was
> > a special __builtin_flushrs() function which would copy these
> > registers to a defined stack area.  Adding this command and the new
> > stack area to the garbage collector completed the gcl/maxima port to
> > ia64.  I think I need something analogous here.)
> 
> Sounds like a gcc 3.0 enhancement potential....
> 
> Failing that, if you want to call foo, then call bar as below:
> 
> (As long as you have < 4 no-bigger-than-32-bit args, foo and bar have
> the same function declaration.  If you need more, holler and I can add
> that part...)
> 
> Or, if you want a function that foo can call, let me know.  Either way,
> at least some of the register vars will wind up on the stack between
> stack base and current %sp.  (foo probably spills at least one of the
> regs in it's frame...)
> 
> This stub should compile & work on hp-ux as well, if you so care...
> 
> lamont
> 
> ============================
>         .code
>         .export bar,entry
>       .import foo,code
>       .proc
>         .callinfo entry_gr=18, calls, save_rp
>       .label  bar
>       .entry
>       stw     %rp,-20(%sp)
>         stwm  %r3,128(%sp)
>       stw     %r4,-124(%sp)
>       stw     %r5,-120(%sp)
>       stw     %r6,-116(%sp)
>       stw     %r7,-112(%sp)
>       stw     %r8,-108(%sp)
>       stw     %r9,-104(%sp)
>       stw     %r10,-100(%sp)
>       stw     %r11,-96(%sp)
>       stw     %r12,-92(%sp)
>       stw     %r13,-88(%sp)
>       stw     %r14,-84(%sp)
>       stw     %r15,-80(%sp)
>       stw     %r16,-76(%sp)
>       stw     %r17,-72(%sp)
>       stw     %r18,-68(%sp)
>         bl      foo,%rp
>         nop
>       ldw     -148(%sp),%rp
>       ldw     -72(%sp),%r18
>       ldw     -68(%sp),%r17
>       ldw     -76(%sp),%r16
>       ldw     -80(%sp),%r15
>       ldw     -84(%sp),%r14
>       ldw     -88(%sp),%r13
>       ldw     -92(%sp),%r12
>       ldw     -96(%sp),%r11
>       ldw     -100(%sp),%r10
>       ldw     -104(%sp),%r9
>       ldw     -108(%sp),%r8
>       ldw     -112(%sp),%r7
>       ldw     -116(%sp),%r6
>       ldw     -120(%sp),%r5
>       ldw     -124(%sp),%r4
>       bv      0(%rp)
>         ldwm  128(%sp),%r3
> 
>       .exit
>         .procend
>       .end
> ============================
> 
> _______________________________________________
> Gcl-devel mailing list
> address@hidden
> http://mail.gnu.org/mailman/listinfo/gcl-devel
> 
> 

-- 
Camm Maguire                                            address@hidden
==========================================================================
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah



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