-*- org -*-
#+TITLE: Hacking GNU Mes

* SETUP
    guix shell #64 bit + 32bit

    CC=i686-unknown-linux-gnu-gcc ./configure
    CC=arm-unknown-linux-gnueabihf-gcc ./configure

or
    ./configure

The 64bit bootstrap is not supported; MesCC needs work to be able to
compile a functional tinycc.

* BUILD

GNU Guile can be used as a replacement for Mes.  It's faster and has
much better error handling.

   #+BEGIN_SRC bash
   make MES=guile
   make check MES=guile
   #+END_SRC

Configure to compile with Tiny CC

   #+BEGIN_SRC bash
   ./configure CC=tcc --host=i686-unknown-linux-gnu --with-courage
   #+END_SRC

* DEBUG
  MES_DEBUG=<level> mes
** Levels
  1) Informational:
     - MODULEDIR
     - included SCM modules and sources
     - result of program
     - gc stats at exit
  2) opened files
  3) runtime gc stats
  4) detailed info
     - parsed, expanded program
     - list of builtins
     - list of symbol
     - opened input strings
     - gc details
  5) lots of data
     - usage of opened input strings
     - bytes read
  6) globals

* TESTING
** make check recheck=true TESTS="tests/base lib/tests/scaffold/t.c"
** mescc

*** To skip MES tests, in "./check.sh", comment-out check-boot.sh, check-mes.sh.

*** Running individual tests
#+BEGIN_SRC bash
cd gcc-lib
V=2 CC=i686-unknown-linux-gnu-gcc ../pre-inst-env test-c.sh ../lib/tests/scaffold/t.c
#+END_SRC

#+BEGIN_SRC bash
cd mescc-lib
V=2 CC=mescc ../pre-inst-env test-c.sh ../lib/tests/scaffold/t.c
#+END_SRC

* Bugs
** mes: performance, Mes is now 2-10x slower than Guile.
** mes/mescc lack support for fork/exec on the Hurd.
** mes: gcc-x86_64 compiled mes segfaults with small arena, or gc_up_arena.
** mes: gcc-x86 compiled, tests/srfi-13.test number->string INT-MIN fails:
test: number->string INT-MIN: fail
expected: -2147483648
actual: -./,),(-*,(
** tcc: tcc-built lib/libc+tcc.c segfaults with mes, with tcc.
** mes: remove pmatch-car/pmatch-cdr hack.
** mescc: softcode stack frame size, now hardcoded and very large
** mes+mescc: parse tcc.c->tcc.E works, compile tcc.E -> tcc.M1 segfaults.
  time GUILE_LOAD_PATH=/home/janneke/src/nyacc/module:$GUILE_LOAD_PATH ../mes/scripts/mescc -E -o tcc.E -I . -I ../mes/lib -I ../mes/include -D 'CONFIG_TCCDIR="usr/lib/tcc"' -D 'CONFIG_TCC_CRTPREFIX="usr/lib:{B}/lib:."' -D 'CONFIG_TCC_ELFINTERP="/gnu/store/70jxsnpffkl7fdb7qv398n8yi1a3w5nx-glibc-2.26.105-g0890d5379c/lib/ld-linux.so.2"' -D 'CONFIG_TCC_LIBPATHS="/home/janneke/src/tinycc/usr/lib:{B}/lib:."' -D 'CONFIG_TCC_SYSINCLUDEPATHS="../mes/include:usr/include:{B}/include"' -D CONFIG_USE_LIBGCC=1 -D 'TCC_LIBGCC="/home/janneke/src/tinycc/usr/lib/libc+tcc-gcc.mlibc-o"' -D CONFIG_TCC_STATIC=1 -D ONE_SOURCE=yes -D TCC_TARGET_I386=1 -D BOOTSTRAP=1 tcc.c
  time GUILE_LOAD_PATH=/home/janneke/src/nyacc/module:$GUILE_LOAD_PATH MES_ARENA=200000000 ../mes/scripts/mescc -c -o tcc.M1 tcc.E
** mescc: 64 bit compiled mes loses top 4 bytes
*** 64 bit mescc-compiled mes:
  #x100000000 => 0
  (modulo 1 #x100000000) => divide-by-zero
*** 64 bit gcc-compiled mes:
  #x100000000 => 0
  (modulo 1 #x100000000) => 1
** mescc: 7n-struct-struct-array.c:  struct file f = {"first.h"};
** test/match.test ("nyacc-simple"): hygiene problem in match
* OLD: Booting from LISP-1.5 into Mes

Mes started out experimenting with booting from a hex-coded minimal
LISP-1.5 (prototype in mes.c), into an almost-RRS Scheme.

When EOF is read, the LISP-1.5 machine calls loop2 from loop2.mes,
which reads the rest of stdin and takes over control.  The functions
readenv, eval and apply-env in mes.mes introduced define, define-macro
quasiquote and macro expansion.

While this works, it's amazingly slow.  We implemented a full reader
in mes.c, which makes running mes:apply-env mes:eval somewhat
bearable, still over 1000x slower than running mes.c.

Bootstrapping has been removed and mes.c implements enough of RRS to
run a macro-based define-syntax and syntax-rules.

loop.mes and mes.mes are unused and lagging behind.  Probably it's not
worth considering this route without a VM.  GNU Epsilon is taking the
more usual VM-route to provide multiple personas.  While that sounds
neat, Lisp/Scheme, bootstrapping and trusted binaries are probably not
in scope as there is no mention of such things; only ML is mentioned
while Guile is used for bootstrapping.

* Assorted ideas and info
** Using GDB on assembly/a.out
info registers
p/x $eax
p/x $edx
set disassemble-next-line on
gdb-display-disassembly-buffer
b *0x804a79d
** Create memory dump with 32 bit Gcc compiled Mes
make out/i686-unknown-linux-gnu-mes
out/i686-unknown-linux-gnu-mes --dump < module/mes/read-0.mes > module/mes/read-0-32.mo

x/s *((char **)($rsp+8))

** C parser/compiler
*** [[https://savannah.gnu.org/projects/nyacc][nyacc]]
*** PEG: [[https://piumarta.com/software/peg/][parse C using PEG]]
*** [[https://en.wikipedia.org/wiki/Tiny_C_Compiler][Tiny C Compiler]]
*** [[https://www.t3x.org/subc/index.html][Sub C]]
*** [[https://groups.google.com/forum/#!topic/comp.lang.lisp/VPuX0VsjTTE][C intepreter in LISP/Scheme/Python]]

** C assembler/linker
*** [[https://www.tldp.org/HOWTO/Assembly-HOWTO/linux.html][Assembly HOWTO]]
*** ELF
7f 45 4c 46
*** [[https://www.muppetlabs.com/~breadbox/software/tiny/][Small ELF programs]]
*** [[https://www.cirosantilli.com/elf-hello-world/][Elf hello world]]
** SC - c as s-expressions
sc: https://sph.mn/content/3d3
** RNRS
*** [[https://www.scheme-reports.org/][Scheme Reports]]
*** [[ftp://publications.ai.mit.edu/ai-publications/pdf/AIM-349.pdf][Scheme - Report on Scheme]]
*** [[ftp://publications.ai.mit.edu/ai-publications/pdf/AIM-452.pdf][RRS - Revised Report on Scheme]]

** tiny schemes
https://forum.osdev.org/viewtopic.php?f=15&t=19937

https://www.stripedgazelle.org/joey/dreamos.html
https://armpit.sourceforge.net/
https://common-lisp.net/project/movitz/movitz.html

<civodul> janneke: https://github.com/namin/inc looks interesting  [15:18]
** Orians Jeremiah
<OriansJ> janneke: also, if you look at
          https://github.com/oriansj/stage0/tree/master/stage2/High_level_prototypes
          [the garbage collected lisp I implemented], if there are any pieces
          I could add to finish off your mes lisp bootstrap just let me know
          because I would be more than happy to do that :D
<janneke> OriansJ: that's what I'm hoping for, that our efforts can be
          complementary and we can work together
*** lfam (~lfam@2601:47:4180:2ffb:7c05:17de:cf5f:23ef) has quit: Ping timeout:
    246 seconds  [00:22]
<janneke> exciting times!  [00:23]
<janneke> OriansJ: i looked a few times and saw 'LISP empty', so thanks for
          the pointer!  [00:24]
<civodul> OriansJ, janneke: from that page, there's also:
          https://web.archive.org/web/20160604035203fw_/https://homepage.ntlworld.com/edmund.grimley-evans/bcompiler.html

** C4/C500
https://web.archive.org/web/20160604041431/https://homepage.ntlworld.com/edmund.grimley-evans/cc500/cc500.c
https://github.com/rswier/c4/blob/master/c4.c
** Compilers for free
https://codon.com/compilers-for-free
** Small lisps
*** [[https://www.mirrorservice.org/sites/www.bitsavers.org/bits/TI/Explorer/zeta-c/][ZETA-C]]
** Small C compilers
*** tinycc
*** [[https://github.com/rui314/8cc][8cc]] -- a C11 compiler, but simple
8cc is a compiler for the C programming language. It's intended to
support all C11 language features while keeping the code as small and
simple as possible.
*** pcc
*** early GCC?
https://miyuki.github.io/2017/10/04/gcc-archaeology-1.html
*** [[https://tack.sourceforge.net/][ack]]
<rain1> it may be possible to compile like this:  mes |> ack |> pcc |> tcc |>
        gcc 4.7.4 |> gcc later version... up to modern
*** [[https://web.archive.org/web/20160402225843/https://homepage.ntlworld.com/edmund.grimley-evans/cc500/][cc500]]
** rain1's Bootstrapping Wiki: https://bootstrapping.miraheze.org/wiki/Main_Page
** rain1's hex86
https://notabug.org/rain1/hex86/src/master/tests/hex0b3.hex86
** <pdewacht> janneke, have you ever tried testing mescc with csmith?  [10:55]
** <pdewacht> e.g. as described here
           https://jamey.thesharps.us/2016/07/15/testing-strategies-for-corrode/
           ("Randomized testing with Csmith and C-Reduce")  [10:58]
** linux syscalls: https://fedora.juszkiewicz.com.pl/syscalls.html
* legalese

Copyright © 2016,2017,2018,2019,2021,2022 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>

  Copying and distribution of this file, with or without modification,
  are permitted in any medium without royalty provided the copyright
  notice and this notice are preserved.