[Openmcl-devel] Progress toward a CCL-to-ARM64 compiler
Tim McNerney
mc at media.mit.edu
Sun Feb 25 14:50:08 PST 2024
Thanks for doing this experiment, Robert.
Gary B., to the best of my knowledge, never tackled designing register conventions or stack usage for the arm64. This is an open problem for the taking. I haven’t yet searched for CCL documentation on register and stack usage on the PPC64. But my own strategy would be to try to map one into the other with very few changes, kinda like the spirit your experiment. My current crazy plan is to write a specialized (*) ppc64 to arm64 translator and use it to convert all the subprims (once) and translate the ppc64 compiler output (on an ongoing basis). I know this isn’t what RME would do, but it seems less risky that doing “open heart surgery” on the compiler.
(*) by specialized meaning it is not a general translated, but rather designed specifically for CCL hand-written assembly language and compiler output, and knows how to rewrite register references based on knowledge of the register and stack conventions for both targets.
--Tim
> On Feb 25, 2024, at 16:05, Robert Munyer <2420506348 at munyer.com> wrote:
>
> I have made some progress toward a CCL-to-ARM64 compiler, by taking
> code from the existing CCL-to-PPC64 compiler, and modifying it to emit
> ARM64 instruction sequences that resemble ARM64 assembly code that was
> checked-in by Gary Byers before 2013-10-22.
>
> It compiles the body of this function:
>
> (defun fixnum-fibonacci (n)
> (declare (type (mod 24) n)
> (optimize (safety 0) (speed 3)))
> (do ((a 1 b)
> (b 0 (the fixnum (+ a b)))
> (n n (1- n)))
> ((zerop n) b)
> (declare (fixnum a b n))))
>
> to this ARM64 machine code:
>
> aa1e03f8 a9bf7bf9 f9402f80 eb2063ff 5400004a d4207d00 f81f8f2f
> f81f8f30 f81f8f31 f81f8f32 d2800112 d2800010 f9400f31 14000008
> f81f8f30 8b10024f f81f8f2f d1002231 f9400732 f9400330 91004339
> f100023f 54ffff01 aa1003ef f9400332 f9400731 f9400b30 a9407bf9
> aa1803fe 910043ff d65f03c0
>
> (hand-disassembled here [1]), which, when pasted into this test
> program [3], calculates "fibonacci(23) = 28657".
>
> If you have an Apple Silicon device with Linux and GCC, I think you
> should be able to run the test program on it. (Darwin might also
> work, with some tweaking.) Paste the program's code [3] into a text
> file named test-fib.s, then enter "gcc test-fib.s" and "./a.out".
>
> For comparison, here is the result of running the existing PPC64
> compiler on the same Fibonacci source code: [2].
>
> Forge resources (source code, wiki wiki, issue tracker, mailing
> lists) are available at https://ccl-arm64-2023-07.srht.site .
>
> Some disclaimers...
>
> I have not yet made any effort to make the compiled code thread-safe
> or signal-safe or garbage-collection-safe, so I wouldn't expect it to
> work correctly in a real CCL kernel.
>
> I mostly have implemented only enough of the compiler for the Fibonacci
> function above, so I wouldn't expect other functions to work correctly.
>
> I don't fully understand how GB intended ARM64 register assignments
> and stack discipline to work, so feedback in those areas would be
> especially welcome.
>
> -- Robert Munyer
>
> [1] --------
>
> fib (mov loc-pc lr)
> (stp vsp lr (:-@! sp 16))
> (ldr imm0 (:+@ rcontext 88))
> (cmp sp imm0)
> (b.ge l24)
> (brk 1000)
> l24 (str arg_z (:-@! vsp 8))
> (str save0 (:-@! vsp 8))
> (str save1 (:-@! vsp 8))
> (str save2 (:-@! vsp 8))
> (mov save2 '1)
> (mov save0 '0)
> (ldr save1 (:+@ vsp 24))
> (b l84)
> l56 (str save0 (:-@! vsp 8))
> (add arg_z save2 save0)
> (str arg_z (:-@! vsp 8))
> (sub save1 save1 '1)
> (ldr save2 (:+@ vsp 8))
> (ldr save0 (:@ vsp))
> (add vsp vsp 16)
> l84 (cmp save1 '0)
> (b.ne l56)
> (mov arg_z save0)
> (ldr save2 (:@ vsp))
> (ldr save1 (:+@ vsp 8))
> (ldr save0 (:+@ vsp 16))
> (ldp vsp lr (:@ sp))
> (mov lr loc-pc)
> (add sp sp 16)
> (ret)
>
> [2] --------
>
> 0000000000000000 <fib>:
> 00: 7d c8 02 a6 mflr loc_pc
> 04: f8 21 ff e1 stdu sp,-32(sp)
> 08: fa 01 00 08 std fn,8(sp)
> 0c: f9 c1 00 10 std loc_pc,16(sp)
> 10: f9 e1 00 18 std vsp,24(sp)
> 14: 7e 50 93 78 mr fn,nfn
> 18: e8 62 00 58 ld imm0,88(rcontext)
> 1c: 7c 41 18 88 tdllt sp,imm0
> 20: fa ef ff f9 stdu arg_z,-8(vsp)
> 24: fb ef ff f9 stdu save0,-8(vsp)
> 28: fb cf ff f9 stdu save1,-8(vsp)
> 2c: fb af ff f9 stdu save2,-8(vsp)
> 30: 3b a0 00 08 li save2,8
> 34: 3b e0 00 00 li save0,0
> 38: eb cf 00 18 ld save1,24(vsp)
> 3c: 48 00 00 20 b 5c <fib+0x5c>
> 40: fb ef ff f9 stdu save0,-8(vsp)
> 44: 7e fd fa 14 add arg_z,save2,save0
> 48: fa ef ff f9 stdu arg_z,-8(vsp)
> 4c: 3b de ff f8 addi save1,save1,-8
> 50: eb af 00 08 ld save2,8(vsp)
> 54: eb ef 00 00 ld save0,0(vsp)
> 58: 39 ef 00 10 addi vsp,vsp,16
> 5c: 2c 3e 00 00 cmpdi save1,0
> 60: 40 82 ff e0 bne 40 <fib+0x40>
> 64: 7f f7 fb 78 mr arg_z,save0
> 68: eb af 00 00 ld save2,0(vsp)
> 6c: eb cf 00 08 ld save1,8(vsp)
> 70: eb ef 00 10 ld save0,16(vsp)
> 74: e9 c1 00 10 ld loc_pc,16(sp)
> 78: e9 e1 00 18 ld vsp,24(sp)
> 7c: ea 01 00 08 ld fn,8(sp)
> 80: 7d c8 03 a6 mtlr loc_pc
> 84: 38 21 00 20 addi sp,sp,32
> 88: 4e 80 00 20 blr
> 8c: 83 a9 ff e0 lwz save2,-32(allocptr)
>
> [3] --------
>
> .global main
> .extern printf
> .text
>
> fmt: .asciz "fibonacci(23) = %ld\n"
>
> .balign 4
>
> fib: .inst 0xAA1E03F8, 0xA9BF7BF9, 0xF9402F80, 0xEB2063FF, 0x5400004A
> .inst 0xD4207D00, 0xF81F8F2F, 0xF81F8F30, 0xF81F8F31, 0xF81F8F32
> .inst 0xD2800112, 0xD2800010, 0xF9400F31, 0x14000008, 0xF81F8F30
> .inst 0x8B10024F, 0xF81F8F2F, 0xD1002231, 0xF9400732, 0xF9400330
> .inst 0x91004339, 0xF100023F, 0x54FFFF01, 0xAA1003EF, 0xF9400332
> .inst 0xF9400731, 0xF9400B30, 0xA9407BF9, 0xAA1803FE, 0x910043FF
> .inst 0xD65F03C0
>
> main: mov x0, sp
> stp fp, lr, [sp, -64]!
> mov fp, sp
> stp x24, x25, [sp, -16]!
> mov x25, x0
> sub x0, sp, 32
> stp x0, x28, [sp, -16]!
> sub x28, sp, 88
> mov x15, 23 << 3
> bl fib
> asr x1, x15, 3
> adr x0, fmt
> bl printf
> ldp x0, x28, [sp], 16
> ldp x24, x25, [sp], 16
> ldp fp, lr, [sp], 64
> mov x0, 0
> ret
More information about the Openmcl-devel
mailing list