[Lightning] sparc port of lightning-2.0

[Paulo César Pereira de Andrade]

  Just to let you know development is still active :-)

  I got an account in the gcc build farm, so I am making a sparc port there.
After a few days reading assembly manuals and coding the port, it is
now executing some code. One example from the test cases:

---%<---
$ cat add.tst
.data   32
fmt:
.c      "%d + %d = %d\n"

.code
        jmpi main

        name test
test:
        prolog
        arg $i0
        arg $i1
        getarg %r0 $i0
        getarg %r1 $i1
        addr %r0 %r0 %r1
        retr %r0
        epilog

        name main
main:
        prolog
        prepare
                pushargi 5
                pushargi 4
        finishi test
        retval %r0
        prepare
                pushargi fmt
                ellipsis
                pushargi 5
                pushargi 4
                pushargr %r0
        finishi @printf
        ret
        epilog
---%<---

and what I see in my ssh to the sparc computer:

---%<---
(gdb) r -v2 add.tst
Starting program: /home/pcpa/lightning-2.0/check/.libs/lt-lightning -v2 add.tst

    jmpi L3
        #name test
L0:
        #note add.tst:9
L1: %i0 %i1 /* prolog */
        arg 0x0
        arg 0x1
        movr %g2 %i0
        movr %g3 %i1
        addr %g2 %g2 %g3
        movr %i0 %g2
L2: /* epilog */
        #name main
L3:
        #note add.tst:20
L4: %g2 /* prolog */
        movi %o0 0x5
        movi %o1 0x4
    calli L0
        movr %g2 %o0
        movi %o0 0x3dfe8
        movi %o1 0x5
        movi %o2 0x4
        movr %o3 %g2
    calli 0x70301900
L5: /* epilog */
  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        0x7041a000      sethi  %hi(0x7041a000), %g2
        0x7041a004      or  %g2, 0x30, %g2      ! 0x7041a030 main:add.tst:20
        0x7041a008      jmp  %g2
        0x7041a00c      nop
# test:add.tst:9
        0x7041a010      save  %sp, -112, %sp
        0x7041a014      mov  %i0, %g2
        0x7041a018      mov  %i1, %g3
        0x7041a01c      add  %g2, %g3, %g2
        0x7041a020      mov  %g2, %i0
        0x7041a024      restore
        0x7041a028      retl
        0x7041a02c      nop
# main:add.tst:20
        0x7041a030      save  %sp, -112, %sp
        0x7041a034      mov  5, %o0
        0x7041a038      mov  4, %o1
        0x7041a03c      sethi  %hi(0x7041a000), %g3
        0x7041a040      or  %g3, 0x10, %g3      ! 0x7041a010 test:add.tst:9
        0x7041a044      call  %g3
        0x7041a048      nop
        0x7041a04c      mov  %o0, %g2
        0x7041a050      sethi  %hi(0x3dc00), %o0
        0x7041a054      or  %o0, 0x3e8, %o0     ! 0x3dfe8
        0x7041a058      mov  5, %o1
        0x7041a05c      mov  4, %o2
        0x7041a060      mov  %g2, %o3
        0x7041a064      call  0x70301900
        0x7041a068      nop
        0x7041a06c      restore
        0x7041a070      retl
        0x7041a074      nop
  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
5 + 4 = 9

Program exited normally.
---%<---

There is still plently to be done to pass all test cases, and several
backend specific optimizations could be done. Particularly, sparc
benefits from knowing if the current function is a leaf function, and
this is information is easy to gather. Not so easy is to use annulled
delay slots or do optimal delay slot usage, but at least some of
it should be used (at first only when it can be readily done, that
is, not have an optimization pass reordering the assembly output).

Thanks,
Paulo