Bootstrappable TCC/TinyCC -- Tiny C Compiler's bootstrappable fork
------------------------------------------------------------------

Bootstrappable TCC is a fork from mainline TCC development, that
started spring 2017 from

    commit 307b7b183d4ee56e74090b0e525d6a587840e31f
    Author: Aron BARATH <baratharon@caesar.elte.hu>
    Date:   Tue May 16 07:03:26 2017 +0200

        the R_X86_64_GOTOFF64 relocation was missing

and can be compiled by MesCC (https://gnu.org/s/mes).

Initially the plan was to make TinyCC itself "bootstrappable"
(https://bootstrappable.org).

The best way to do so would be to gradually simplify the
implementation of TinyCC by restricting the use of language constructs
to a well-defined subset of C.  In bootstrapping each stage or
compiler adds functionality; a compiler that is written in itself --a
so-called `self-hosting' compiler--is not considered to be
bootstrappable.

At the time this vision was not received with much enthousiasm

    https://lists.nongnu.org/archive/html/tinycc-devel/2017-09/msg00019.html

so I decided to fork TinyCC and instead grow MesCC (a bootstrappable
sub-C compiler in a subset of Guile Scheme) into a full C99 compiler.

Currently, the Reduced Binary Seed Bootstrap of the GNU Guix System
uses bootstrappable-tinycc.  See
    https://guix.gnu.org/en/blog/2020/guix-further-reduces-bootstrap-seed-to-25/
    https://guix.gnu.org/blog/2019/guix-reduces-bootstrap-seed-by-50/

The fork consists of about 30 patches

    ff2210b3 build: Add support for ARM.
    f8c8caaf ARM: allow fake asm in functions.
    d9ecdebc bootstrappable: ARM: Force eabi header.
    82b822c3 bootstrappable: HAVE_LONG_LONG, part 3.
    77ae03e8 bootstrappable: ARM: HAVE_FLOAT?
    82678555 bootstrappable: ARM: generate __memcpy, __memmove, __memset.
    0688c1f5 bootstrappable: ARM: HAVE_SETJMP.
    35c9c246 bootstrappable: HAVE_LONG_LONG_STUB.
    bdec98dd bootstrappable: HAVE_LONG_LONG, part 2.
    2556e105 bootstrappable: ARM: HAVE_FLOAT.
    fcb48635 bootstrappable: ARM: Avoid ternary.
    d0608d0d bootstrappable: ARM: Avoid ternary in argument.
    f7e98b52 bootstrappable: ARM: HAVE_FLOAT.
    e23023ec bootstrappable: HAVE_FLOAT, part 2.
    907479d7 bootstrappable: Avoid function modulo.
    33403a40 bootstrappable: Avoid using __clear_cache.
    94fa1710 bootstrappable: Use tmp initialization instead of for struct assigment.
    35ccd609 bootstrappable: Support libtcc1-mes.a.
    cee58e09 build: Support building from bootstrap-mes.
    39de3568 bootstrappable: Force static link.
    2b6271d1 bootstrappable: Work around MesCC bug.
    379c62d6 bootstrappable: add tcc.h include guards to include location.
    6ae9aa40 bootstrappable: Skip tidy_section_headers.
    a130ce17 bootstrappable: HAVE_FLOAT.
    de906df4 bootstrappable: HAVE_BITFIELD.
    540ba0b4 bootstrappable: HAVE_LONG_LONG.
    306f6779 bootstrappable: Work around Nyacc-0.80.42 bug.
    9c97705c build: bootstrap build scripts.
    584478fc bootstrappable: Remove non-free grep test.

that work around bugs and missing C language features in MesCC.  Only
three of these are really interesting: the HAVE_* patches that allow
for stepwise introduction of bitfields, doubles/floats and long longs.

In time, I hope we can remove the need for this fork; either by
upstreaming some bootstrappable work or else by maturing MesCC.

At the time of writing, mainline (non-bootstrappable) tinycc lives
here

    https://repo.or.cz/tinycc.git
    https://lists.nongnu.org/mailman/listinfo/tinycc-devel

-- 
janneke


Tiny C Compiler - C Scripting Everywhere - The Smallest ANSI C compiler
-----------------------------------------------------------------------

Features:
--------

- SMALL! You can compile and execute C code everywhere, for example on
  rescue disks.

- FAST! tcc generates optimized x86 code. No byte code
  overhead. Compile, assemble and link about 7 times faster than 'gcc
  -O0'.

- UNLIMITED! Any C dynamic library can be used directly. TCC is
  heading torward full ISOC99 compliance. TCC can of course compile
  itself.

- SAFE! tcc includes an optional memory and bound checker. Bound
  checked code can be mixed freely with standard code.

- Compile and execute C source directly. No linking or assembly
  necessary. Full C preprocessor included. 

- C script supported : just add '#!/usr/local/bin/tcc -run' at the first
  line of your C source, and execute it directly from the command
  line.

Documentation:
-------------

1) Installation on a i386/x86_64/arm Linux/OSX/FreeBSD host

   ./configure
   make
   make test
   make install

   Notes: For OSX and FreeBSD, gmake should be used instead of make.
   For Windows read tcc-win32.txt.

makeinfo must be installed to compile the doc.  By default, tcc is
installed in /usr/local/bin.  ./configure --help  shows configuration
options.


2) Introduction

We assume here that you know ANSI C. Look at the example ex1.c to know
what the programs look like.

The include file <tcclib.h> can be used if you want a small basic libc
include support (especially useful for floppy disks). Of course, you
can also use standard headers, although they are slower to compile.

You can begin your C script with '#!/usr/local/bin/tcc -run' on the first
line and set its execute bits (chmod a+x your_script). Then, you can
launch the C code as a shell or perl script :-) The command line
arguments are put in 'argc' and 'argv' of the main functions, as in
ANSI C.

3) Examples

ex1.c: simplest example (hello world). Can also be launched directly
as a script: './ex1.c'.

ex2.c: more complicated example: find a number with the four
operations given a list of numbers (benchmark).

ex3.c: compute fibonacci numbers (benchmark).

ex4.c: more complicated: X11 program. Very complicated test in fact
because standard headers are being used ! As for ex1.c, can also be launched
directly as a script: './ex4.c'.

ex5.c: 'hello world' with standard glibc headers.

tcc.c: TCC can of course compile itself. Used to check the code
generator.

tcctest.c: auto test for TCC which tests many subtle possible bugs. Used
when doing 'make test'.

4) Full Documentation

Please read tcc-doc.html to have all the features of TCC.

Additional information is available for the Windows port in tcc-win32.txt.

License:
-------

TCC is distributed under the GNU Lesser General Public License (see
COPYING file).

Fabrice Bellard.
