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diff --git a/cil/doc/cil001.html b/cil/doc/cil001.html new file mode 100644 index 00000000..5edc5daa --- /dev/null +++ b/cil/doc/cil001.html @@ -0,0 +1,134 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" + "http://www.w3.org/TR/REC-html40/loose.dtd"> +<HTML> +<HEAD> + + + +<META http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"> +<META name="GENERATOR" content="hevea 1.08"> + +<base target="main"> +<script language="JavaScript"> +<!-- Begin +function loadTop(url) { + parent.location.href= url; +} +// --> +</script> +<LINK rel="stylesheet" type="text/css" href="cil.css"> +<TITLE> +Introduction +</TITLE> +</HEAD> +<BODY > +<A HREF="ciltoc.html"><IMG SRC ="contents_motif.gif" ALT="Up"></A> +<A HREF="cil002.html"><IMG SRC ="next_motif.gif" ALT="Next"></A> +<HR> + +<H2 CLASS="section"><A NAME="htoc1">1</A> Introduction</H2> +New: CIL now has a Source Forge page: + <A HREF="javascript:loadTop('http://sourceforge.net/projects/cil')">http://sourceforge.net/projects/cil</A>. <BR> +<BR> +CIL (<B>C</B> <B>I</B>ntermediate <B>L</B>anguage) is a high-level representation +along with a set of tools that permit easy analysis and source-to-source +transformation of C programs.<BR> +<BR> +CIL is both lower-level than abstract-syntax trees, by clarifying ambiguous +constructs and removing redundant ones, and also higher-level than typical +intermediate languages designed for compilation, by maintaining types and a +close relationship with the source program. The main advantage of CIL is that +it compiles all valid C programs into a few core constructs with a very clean +semantics. Also CIL has a syntax-directed type system that makes it easy to +analyze and manipulate C programs. Furthermore, the CIL front-end is able to +process not only ANSI-C programs but also those using Microsoft C or GNU C +extensions. If you do not use CIL and want instead to use just a C parser and +analyze programs expressed as abstract-syntax trees then your analysis will +have to handle a lot of ugly corners of the language (let alone the fact that +parsing C itself is not a trivial task). See Section <A HREF="cil016.html#sec-simplec">16</A> for some +examples of such extreme programs that CIL simplifies for you.<BR> +<BR> +In essence, CIL is a highly-structured, “clean” subset of C. CIL features a +reduced number of syntactic and conceptual forms. For example, all looping +constructs are reduced to a single form, all function bodies are given +explicit <TT>return</TT> statements, syntactic sugar like <TT>"->"</TT> is +eliminated and function arguments with array types become pointers. (For an +extensive list of how CIL simplifies C programs, see Section <A HREF="cil004.html#sec-cabs2cil">4</A>.) +This reduces the number of cases that must be considered when manipulating a C +program. CIL also separates type declarations from code and flattens scopes +within function bodies. This structures the program in a manner more amenable +to rapid analysis and transformation. CIL computes the types of all program +expressions, and makes all type promotions and casts explicit. CIL supports +all GCC and MSVC extensions except for nested functions and complex numbers. +Finally, CIL organizes C's imperative features into expressions, instructions +and statements based on the presence and absence of side-effects and +control-flow. Every statement can be annotated with successor and predecessor +information. Thus CIL provides an integrated program representation that can +be used with routines that require an AST (e.g. type-based analyses and +pretty-printers), as well as with routines that require a CFG (e.g., dataflow +analyses). CIL also supports even lower-level representations (e.g., +three-address code), see Section <A HREF="ext.html#sec-Extension">8</A>. <BR> +<BR> +CIL comes accompanied by a number of Perl scripts that perform generally +useful operations on code: +<UL CLASS="itemize"><LI CLASS="li-itemize"> +A <A HREF="cil007.html#sec-driver">driver</A> which behaves as either the <TT>gcc</TT> or +Microsoft VC compiler and can invoke the preprocessor followed by the CIL +application. The advantage of this script is that you can easily use CIL and +the analyses written for CIL with existing make files. +<LI CLASS="li-itemize">A <A HREF="merger.html#sec-merger">whole-program merger</A> that you can use as a +replacement for your compiler and it learns all the files you compile when you +make a project and merges all of the preprocessed source files into a single +one. This makes it easy to do whole-program analysis. +<LI CLASS="li-itemize">A <A HREF="patcher.html#sec-patcher">patcher</A> makes it easy to create modified +copies of the system include files. The CIL driver can then be told to use +these patched copies instead of the standard ones. +</UL> +CIL has been tested very extensively. It is able to process the SPECINT95 +benchmarks, the Linux kernel, GIMP and other open-source projects. All of +these programs are compiled to the simple CIL and then passed to <TT>gcc</TT> and +they still run! We consider the compilation of Linux a major feat especially +since Linux contains many of the ugly GCC extensions (see Section <A HREF="cil016.html#sec-ugly-gcc">16.2</A>). +This adds to about 1,000,000 lines of code that we tested it on. It is also +able to process the few Microsoft NT device drivers that we have had access +to. CIL was tested against GCC's c-torture testsuite and (except for the tests +involving complex numbers and inner functions, which CIL does not currently +implement) CIL passes most of the tests. Specifically CIL fails 23 tests out +of the 904 c-torture tests that it should pass. GCC itself fails 19 tests. A +total of 1400 regression test cases are run automatically on each change to +the CIL sources.<BR> +<BR> +CIL is relatively independent on the underlying machine and compiler. When +you build it CIL will configure itself according to the underlying compiler. +However, CIL has only been tested on Intel x86 using the gcc compiler on Linux +and cygwin and using the MS Visual C compiler. (See below for specific +versions of these compilers that we have used CIL for.)<BR> +<BR> +The largest application we have used CIL for is +<A HREF="javascript:loadTop('../ccured/index.html')">CCured</A>, a compiler that compiles C code into +type-safe code by analyzing your pointer usage and inserting runtime checks in +the places that cannot be guaranteed statically to be type safe. <BR> +<BR> +You can also use CIL to “compile” code that uses GCC extensions (e.g. the +Linux kernel) into standard C code.<BR> +<BR> +CIL also comes accompanies by a growing library of extensions (see +Section <A HREF="ext.html#sec-Extension">8</A>). You can use these for your projects or as examples of +using CIL. <BR> +<BR> +<TT>PDF</TT> versions of <A HREF="CIL.pdf">this manual</A> and the +<A HREF="CIL-API.pdf">CIL API</A> are available. However, we recommend the +<TT>HTML</TT> versions because the postprocessed code examples are easier to +view. <BR> +<BR> +If you use CIL in your project, we would appreciate letting us know. If you +want to cite CIL in your research writings, please refer to the paper “CIL: +Intermediate Language and Tools for Analysis and Transformation of C +Programs” by George C. Necula, Scott McPeak, S.P. Rahul and Westley Weimer, +in “Proceedings of Conference on Compilier Construction”, 2002.<BR> +<BR> +<HR> +<A HREF="ciltoc.html"><IMG SRC ="contents_motif.gif" ALT="Up"></A> +<A HREF="cil002.html"><IMG SRC ="next_motif.gif" ALT="Next"></A> +</BODY> +</HTML> |