160 lines
5.1 KiB
Text
160 lines
5.1 KiB
Text
Tiny C Compiler - C Scripting Everywhere - The Smallest ANSI C compiler
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-----------------------------------------------------------------------
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Features:
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--------
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- SMALL! You can compile and execute C code everywhere, for example on
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rescue disks (25KB for x86 executable).
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- FAST! tcc generates optimized x86 code. No byte code overhead.
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- UNLIMITED! Any C dynamic library can be used directly. TCC is
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heading torward full ANSI C compliance. TCC can of course compile
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itself.
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- Compile and execute C source directly. No linking or assembly
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necessary. Full C preprocessor included.
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- C script supported : just add '#!/usr/local/bin/tcc' at the first
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line of your C source, and execute it directly from the command
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line.
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Documentation:
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-------------
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1) Installation
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***TCC currently only work on Linux x86***.
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Type 'make install' to compile and install tcc in /usr/local and
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/usr/local/lib/tcc.
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2) Introduction
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We assume here that you know ANSI C. Look at the example ex1.c to know
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what the programs look like.
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The main limitation of tcc is that you cannot use floats.
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The include file <tcclib.h> can be used if you want a small basic libc
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include support (especially useful for floppy disks). Of course, you
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can also use standard headers, although they are slower to compile.
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You can begin your C script with '#!/usr/local/bin/tcc' on the first
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line and set its execute bits (chmod a+x your_script). Then, you can
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launch the C code as a shell or perl script :-) The command line
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arguments are put in 'argc' and 'argv' of the main functions, as in
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ANSI C.
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3) Invokation
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'-Idir' : specify an additionnal include path. The
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default ones are: /usr/include, /usr/lib/tcc, /usr/local/lib/tcc.
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'-Dsym' : define preprocessor symbol 'sym' to 1.
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'-lxxx' : dynamically link your program with library
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libxxx.so. Standard library paths are checked, including those
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specificed with LD_LIBRARY_PATH.
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Only one source code can be compiled. If you have multiple source
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files, add one which includes all your sources.
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4) Examples
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ex1.c: simplest example (hello world). Can also be launched directly
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as a script: ./ex2.c.
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ex2.c: more complicated example: find a number with the four
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operations given a list of numbers (benchmark).
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ex3.c: compute fibonacci numbers (benchmark).
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ex4.c: more complicated: X11 program. Very complicated test in fact
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because standard headers are being used ! Currently slow because
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parsing does not use hash tables.
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ex5.c: 'hello world' with standard glibc headers.
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tcc.c: TCC can compile itself. Used to check the code generator.
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prog.c: auto test for TCC which tests many subtle possible bugs. Used
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when doing 'make test'.
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Exact differences with ANSI C:
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-----------------------------
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1) Preprocessor
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- the preprocessor tokens are the same as C. It means that in some
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rare cases, preprocessed numbers are not handled exactly as in ANSI
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C. This approach has the advantage of being simpler and FAST!
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- __LINE__, __FILE__, __DATE__, __TIME__ are currently not handled.
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- #line not handled
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2) C language
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- Parsing: variables cannot be initialized ('int a = 1' or 'int tab[2] =
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{1, 2}' not supported).
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- Cannot pass struct/union as value. Cannot assign struct/union (use
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memcpy instead).
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- Types: floating point numbers are not supported.
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- (BUG) 'char' and 'short' casts do not truncate correctly.
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- 'sizeof' may not work if too complex expression is given.
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Supported C extensions:
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----------------------
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- 'inline' keyword is ignored.
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Technical Description:
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---------------------
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This is not my first C compiler (see my 'fbcc' compiler) but it
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contains the first C preprocessor I wrote. The project started as a
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joke to make the smallest C compiler. Then I expanded it torward ANSI
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compliance. This C compiler is particular because each feature was
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added while trying to be as simple and compact as possible. For
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example, no intermediate structure is used to store code or
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expressions.
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The TCC code generator directly generates linked binary code. It is
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rather unusual these days (see gcc for example which generates text
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assembly), but it allows to be very fast and surprisingly not so
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complicated.
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The TCC code generator is register based. It means that it could even
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generate good code for RISC processors. On x86, three temporary
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registers are used. When more registers are needed, one register is
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flushed in a new local variable.
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Constant propagation is done for all operations. Multiplications and
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divisions are optimized to shifts when appropriate. Logical operators
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are optimized by maintaining a special cache for the processor
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flags. &&, || and ! are optimized by maintaining a special 'jmp
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target' value. No other jmp optimization is currently performed
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because it would require to store the code in a more abstract fashion.
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The types and values descriptions are stored in a single 'int'
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variable (see VT_xxx constants). It was choosen in the first stages of
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development when tcc was much simpler. Now, it may not be the best
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solution.
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License:
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-------
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TCC is distributed under the GNU Generic Public License (see COPYING
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file).
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I accept only patches where you give your copyright explictely to me
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to simplify licensing issues.
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Fabrice Bellard - Nov 11, 2001.
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