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Kirill Smelkov 8eb92e6052 Optimize cstr_reset() to only reset string to empty, not call free() and later malloc()
A CString could be reset to empty just setting its .size to 0.

If memory was already allocated, that would be remembered in
.data_allocated and .size_allocated and on consequent string
manipulations that memory will be used without immediate need to call
malloc().

For

    $ ./tcc -B. -bench -DONE_SOURCE -DCONFIG_MULTIARCHDIR=\"i386-linux-gnu\" -c tcc.c

after the patch malloc/free are called less often:

(tcc is run in loop; perf record -a sleep 10 && perf report)
before:

 # Overhead      Command       Shared Object                                      Symbol
 # ........  ...........  ..................  ..........................................
 #
     13.89%          tcc  tcc                 [.] next_nomacro1
      4.73%          tcc  libc-2.13.so        [.] _int_malloc
      4.39%          tcc  tcc                 [.] next
      2.94%          tcc  tcc                 [.] tok_str_add2
      2.78%          tcc  tcc                 [.] macro_subst_tok
      2.75%          tcc  libc-2.13.so        [.] free
      2.74%          tcc  tcc                 [.] macro_subst
      2.63%          tcc  libc-2.13.so        [.] _int_free
      2.28%          tcc  tcc                 [.] vswap
      2.24%          tcc  tcc                 [.] next_nomacro_spc
      2.06%          tcc  libc-2.13.so        [.] realloc
      2.00%          tcc  libc-2.13.so        [.] malloc
      1.99%          tcc  tcc                 [.] unary
      1.85%          tcc  libc-2.13.so        [.] __i686.get_pc_thunk.bx
      1.76%  kworker/0:1  [kernel.kallsyms]   [k] delay_tsc
      1.70%          tcc  tcc                 [.] next_nomacro
      1.62%          tcc  tcc                 [.] preprocess
      1.41%          tcc  libc-2.13.so        [.] __memcmp_ssse3
      1.38%          tcc  [kernel.kallsyms]   [k] memset
      1.10%          tcc  tcc                 [.] g
      1.06%          tcc  tcc                 [.] parse_btype
      1.05%          tcc  tcc                 [.] sym_push2
      1.04%          tcc  libc-2.13.so        [.] _int_realloc
      1.00%          tcc  libc-2.13.so        [.] malloc_consolidate

after:

 # Overhead      Command       Shared Object                                          Symbol
 # ........  ...........  ..................  ..............................................
 #
     15.26%          tcc  tcc                 [.] next_nomacro1
      5.07%          tcc  libc-2.13.so        [.] _int_malloc
      4.62%          tcc  tcc                 [.] next
      3.22%          tcc  tcc                 [.] tok_str_add2
      3.03%          tcc  tcc                 [.] macro_subst_tok
      3.02%          tcc  tcc                 [.] macro_subst
      2.59%          tcc  tcc                 [.] next_nomacro_spc
      2.44%          tcc  tcc                 [.] vswap
      2.39%          tcc  libc-2.13.so        [.] _int_free
      2.28%          tcc  libc-2.13.so        [.] free
      2.22%          tcc  tcc                 [.] unary
      2.07%          tcc  libc-2.13.so        [.] realloc
      1.97%          tcc  libc-2.13.so        [.] malloc
      1.70%          tcc  tcc                 [.] preprocess
      1.69%          tcc  libc-2.13.so        [.] __i686.get_pc_thunk.bx
      1.68%          tcc  tcc                 [.] next_nomacro
      1.59%          tcc  [kernel.kallsyms]   [k] memset
      1.55%          tcc  libc-2.13.so        [.] __memcmp_ssse3
      1.22%          tcc  tcc                 [.] parse_comment
      1.11%          tcc  tcc                 [.] g
      1.11%          tcc  tcc                 [.] sym_push2
      1.10%          tcc  tcc                 [.] parse_btype
      1.10%          tcc  libc-2.13.so        [.] _int_realloc
      1.06%          tcc  tcc                 [.] vsetc
      0.98%          tcc  libc-2.13.so        [.] malloc_consolidate

and this gains small speedup for tcc:

    # best of 5 runs
    before: 8268 idents, 47191 lines, 1526670 bytes, 0.153 s, 307997 lines/s, 10.0 MB/s
    after:  8268 idents, 47203 lines, 1526763 bytes, 0.148 s, 319217 lines/s, 10.3 MB/s
2012-12-21 20:46:26 +04:00
examples Revert "Make ex1.c and ex4.c be executable on any systems" 2012-06-12 15:45:13 +02:00
include Remove semicolon in x86-64 va_arg definition. 2011-08-05 20:32:57 +02:00
lib build: fix VPATH builds 2012-12-18 10:06:20 +01:00
tests build: fix VPATH builds 2012-12-18 10:06:20 +01:00
tests2 build: fix VPATH builds 2012-12-18 10:06:20 +01:00
win32 win32: build-tcc.bat: get rid of hardcoded VERSION string 2012-12-20 21:20:54 +01:00
.gitignore tests: Add tests for compile/run tcc.c with tcc -b then compile tcc.c again, then run tcctest.c 2012-12-09 19:43:40 +04:00
arm-gen.c Fix OABI calling convention 2012-11-28 22:26:39 +01:00
c67-gen.c rename error/warning -> tcc_(error/warning) 2011-08-11 17:07:56 +02:00
Changelog Add support for arm hardfloat calling convention 2012-06-05 23:09:55 +02:00
coff.h C67 COFF executable format support (TK) 2004-10-05 22:33:55 +00:00
configure configure: support absolete out-of-tree builds 2012-12-21 13:57:22 +01:00
COPYING changed license to LGPL 2003-05-24 14:18:56 +00:00
elf.h Add support for R_ARM_THM_{JUMP24,CALL} relocs 2012-10-28 19:55:12 +01:00
i386-asm.c rename error/warning -> tcc_(error/warning) 2011-08-11 17:07:56 +02:00
i386-asm.h i386-asm: support "pause" opcode 2011-02-24 09:38:13 -08:00
i386-gen.c i386: We can change 'lea 0(%ebp),r' to 'mov %ebp,r' 2012-11-16 10:22:45 +04:00
i386-tok.h integrate x86_64-asm.c into i386-asm.c 2009-12-19 22:16:20 +01:00
il-gen.c rename error/warning -> tcc_(error/warning) 2011-08-11 17:07:56 +02:00
il-opcodes.h added CIL target 2002-02-10 16:14:03 +00:00
libtcc.c fix #include_next infinite loop bug, see http://savannah.nongnu.org/bugs/?31357 2012-09-20 22:12:05 +03:00
libtcc.h tccrun: another incompatible change to the tcc_relocate API 2012-09-01 11:33:34 +02:00
Makefile build: fix out-of-tree install 2012-12-21 14:23:28 +01:00
README configure: support absolete out-of-tree builds 2012-12-21 13:57:22 +01:00
stab.def added 2002-12-08 14:36:36 +00:00
stab.h added 2002-12-08 14:36:36 +00:00
tcc-doc.texi Inform user that -b only exists on i386. 2012-03-13 19:43:43 +01:00
tcc.c tcc.c: fix argv index for parse_args 2012-06-12 15:32:44 +02:00
tcc.h Optimize cstr_reset() to only reset string to empty, not call free() and later malloc() 2012-12-21 20:46:26 +04:00
tccasm.c Compile tccasm.c conditionally (TCC_CONFIG_ASM) 2012-01-06 18:34:21 +01:00
tcccoff.c rename error/warning -> tcc_(error/warning) 2011-08-11 17:07:56 +02:00
tccelf.c Generate PLT thumb stub only when necessary 2012-11-17 10:01:11 +01:00
tccgen.c Make tcc work after self-compiling with bounds-check enabled 2012-12-09 18:06:09 +04:00
tccpe.c pe: fix tcc not linking to user32 and gdi32 2012-11-02 16:59:21 +08:00
tccpp.c Optimize cstr_reset() to only reset string to empty, not call free() and later malloc() 2012-12-21 20:46:26 +04:00
tccrun.c tccrun: another incompatible change to the tcc_relocate API 2012-09-01 11:33:34 +02:00
tcctok.h tcctok.h: fix ifdef target/host confusion 2011-04-12 00:11:47 -07:00
texi2pod.pl automatic man page generation from tcc-doc.texi 2003-05-18 18:11:06 +00:00
TODO re-apply VLA by Thomas Preud'homme 2011-04-06 09:17:03 -07:00
VERSION update Changelog, bump version: 0.9.25 2009-05-11 19:01:26 +02:00
x86_64-asm.h x86-64: fix udiv, add cqto instruction 2009-12-19 22:16:19 +01:00
x86_64-gen.c x86-64: Fix call saved register restore 2012-06-10 09:01:26 +02:00

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 Linux host (for Windows read tcc-win32.txt)

   ./configure
   make
   make test
   make install

Alternatively, out-of-tree builds are supported: you may use different
directories to hold build objects, kept separate from your source tree:

   mkdir _build
   cd _build
   ../configure
   make
   make test
   make install

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.