8eb92e6052
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
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.