wip-bootstrap updated

[Jan Nieuwenhuizen]

I've updated the wip-bootstrap branch[0] for Mes[1] 0.13.  It has new
mes-boot and tcc-boot packages.  mes-boot is a bootstrap version of
Mes; it only depends on mescc-tools and a previously compiled mes.M1
seed.  Likewise, tcc-boot depends on a precompiled tcc-seed.  Also,
tcc-boot uses a heavily patched version of the tcc sources.

Mes 0.13 is the first release that can bootstrap a fairly functional
tcc-boot.  This bootstrapped tcc passes 67/68 C tests that were created
for MesCC.  It can compile a version if itself where float, long long
and bitfield are patched out...but linking fails.  This amazing compiler
can now be played with by doing something like

--8<---------------cut here---------------start------------->8---
git checkout wip-bootstrap
make
./pre-inst-env guix build tcc-boot # may take ~2h
./pre-inst-env guix environment --ad-hoc tcc-boot
mes-tcc --help  #duck and run
--8<---------------cut here---------------end--------------->8---

The next big effort will be to make this mes-tcc fully functional and
integrate this with GuixSD.  To give you a taste of that,
here's latest bug I'm currently looking at (pretty printed comments
are only added when Guile runs MesCC, the problem is in LEA)

--8<---------------cut here---------------start------------->8---
$ diff -u ../mes-seed/mes.M1 src/mes.M1
--- ../mes-seed/mes.M1  2018-05-01 18:49:37.312162270 +0200
+++ src/mes.M1  2018-05-01 19:49:40.774770406 +0200
@@ -35805,12 +33091,11 @@
        call32 %strcpy
        add____$i8,%esp !0x8
        test___%eax,%eax
-                                       # strcpy(buf + strlen(buf), "/mes/"); 
-       push___$i32 &_string_reader_read_list_266
+       push___$i32 &_string_reader_read_list_265
        mov____%ebp,%eax
-       add____$i32,%eax %0x-200
+       add____$i32,%eax %0x-800
        push___%eax
-       lea____0x32(%ebp),%eax %0x-200
+       lea____0x32(%ebp),%eax %0x-800
        push___%eax
        call32 %strlen
        add____$i8,%esp !0x4
--8<---------------cut here---------------end--------------->8---

We also need to remove some shortcuts that we took, most notably:
mes-seed[3].  This seed consists of 1MB of M1 code.  mes.M1 is
produced by compiling mes.c using MesCC, the C compiler written in
(Guile) Scheme that comes with Mes.  Although that's really terrible,
it's probably a big step forward: currently GuixSD uses ~250MB of
binary seed: the bootstrap binaries.

The plan is to replace the mes.M1 seed with mes.M2 and compile this
new mes.M2 seed using the brand new M2-Planet[2].  M2 is basically
simple C with structs, without preprocessor.  This will reduce the
seed size by a factor of 10 while making it much more readable.

An excerpt of the TODO I keep in Mes' BOOTSTRAP document

--8<---------------cut here---------------start------------->8---
* TODO
** have tcc-boot's mes-tcc compile a fully functional tcc
*** mescc: fix unknown bug.
*** mescc: support function-static.
*** mescc: support/grok global static.
*** mescc: support unsigned comparison, arithmetic.
*** mescc: support long long (do we need long long to get long long in tcc)?
*** mescc: support bitfield (do we need bitfield to get bitfield in tcc)?
*** mescc: support float (do we need float to get float in tcc)?
** have bootstrapped tcc compile gcc-4.7
** remove or upstream patches from tcc-boot
** prepare src/mes.c for M2-Planet[2] transpiler
** integrate with GuixSD
** x86_64, arm, the Hurd
--8<---------------cut here---------------end--------------->8---

Greetings,
janneke

[0] http://git.savannah.gnu.org/cgit/guix.git/log/?h=wip-bootstrap
[1] https://gitlab.com/janneke/mes
[2] https://github.com/oriansj/m2-planet
[3] https://gitlab.com/janneke/mes-seed

-- 
Jan Nieuwenhuizen <address@hidden> | GNU LilyPond http://lilypond.org
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