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Ted Kremenekb24b0f82010-02-09 23:42:00 +0000[diff] [blame]19
20<h1>Clang Static Analyzer</h1>
21
Ted Kremenek250f67b2010-02-19 17:33:38 +0000[diff] [blame]22<p>The Clang Static Analyzer is source code analysis tool that find bugs in C
23and Objective-C programs.</p>
Ted Kremenek8bebc6e2010-02-09 23:05:59 +0000[diff] [blame]24
Ted Kremenek250f67b2010-02-19 17:33:38 +0000[diff] [blame]25<p>Currently it can be run either as a <a href="/scan-build.html">standalone
26tool</a> or <a href="/xcode.html">within Xcode</a>. The standalone tool is
27invoked from the command-line, and is intended to be run in tandem with a build
28of a codebase.</p>
Ted Kremenek591b9072009-06-08 21:21:24 +0000[diff] [blame]29
Ted Kremenek3ff9da42010-03-12 16:46:36 +0000[diff] [blame]30<p>The analyzer is 100% open source and is part of the <a
Ted Kremenek250f67b2010-02-19 17:33:38 +0000[diff] [blame]31href="http://clang.llvm.org">Clang</a> project. Like the rest of Clang, the
32analyzer is implemented as a C++ library that can be used by other tools and
33applications.</p>
34
35<h2>Download</h2>
Ted Kremenek51667ee2010-02-08 22:12:48 +0000[diff] [blame]36
Ted Kremenek591b9072009-06-08 21:21:24 +0000[diff] [blame]37<!-- Generated from: http://www.spiffycorners.com/index.php -->
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Ted Kremenek8bebc6e2010-02-09 23:05:59 +0000[diff] [blame]90<div style="padding:0px; font-size: 90%">
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Ted Kremenek250f67b2010-02-19 17:33:38 +0000[diff] [blame]99 <h3 style="margin:0px;padding:0px">Mac OS X</h3>
Ted Kremenek591b9072009-06-08 21:21:24 +0000[diff] [blame]100 <ul>
Ted Kremenek250f67b2010-02-19 17:33:38 +0000[diff] [blame]101 <li>Latest build (Universal binary, 10.5+):<br>
Ted Kremenek591b9072009-06-08 21:21:24 +0000[diff] [blame]102 <!--#include virtual="latest_checker.html.incl"-->
103 </li>
Ted Kremenek250f67b2010-02-19 17:33:38 +0000[diff] [blame]104 <li>Can be used both from the command line and within Xcode</li>
Ted Kremenek591b9072009-06-08 21:21:24 +0000[diff] [blame]105 <li><a href="/installation.html">Installation</a> and <a
106 href="/scan-build.html">usage</a></li>
107 </ul>
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127 <h3 style="margin:0px;padding:0px">Other Platforms</h3>
Ted Kremenek591b9072009-06-08 21:21:24 +0000[diff] [blame]128 <p>For other platforms, please follow the instructions for <a
129 href="/installation#OtherPlatforms">building the analyzer</a> from
130 source code.<p>
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Ted Kremenek250f67b2010-02-19 17:33:38 +0000[diff] [blame]141
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Ted Kremenekcf98c3f2010-02-10 06:43:43 +0000[diff] [blame]143<a href="images/analyzer_xcode.png"><img src="images/analyzer_xcode.png" width="450x" border=0></a>
Ted Kremenek8bebc6e2010-02-09 23:05:59 +0000[diff] [blame]144<center><b>Viewing static analyzer results in Xcode 3.2</b></center>
Ted Kremenekcf98c3f2010-02-10 06:43:43 +0000[diff] [blame]145<a href="images/analyzer_html.png"><img src="images/analyzer_html.png" width="450px" border=0></a>
Ted Kremenek8bebc6e2010-02-09 23:05:59 +0000[diff] [blame]146<center><b>Viewing static analyzer results in a web browser</b></center>
147</td></tr></table>
148
Ted Kremenek591b9072009-06-08 21:21:24 +0000[diff] [blame]149<h2 id="StaticAnalysis">What is Static Analysis?</h2>
150
151<p>The term &quot;static analysis&quot; is conflated, but here we use it to mean
152a collection of algorithms and techniques used to analyze source code in order
153to automatically find bugs. The idea is similar in spirit to compiler warnings
154(which can be useful for finding coding errors) but to take that idea a step
155further and find bugs that are traditionally found using run-time debugging
156techniques such as testing.</p>
157
158<p>Static analysis bug-finding tools have evolved over the last several decades
159from basic syntactic checkers to those that find deep bugs by reasoning about
160the semantics of code. The goal of the Clang Static Analyzer is to provide a
161industrial-quality static analysis framework for analyzing C and Objective-C
162programs that is freely available, extensible, and has a high quality of
163implementation.</p>
164
165<h3 id="Clang">Part of Clang and LLVM</h3>
166
167<p>As its name implies, the Clang Static Analyzer is built on top of <a
168href="http://clang.llvm.org">Clang</a> and <a href="http://llvm.org">LLVM</a>.
169Strictly speaking, the analyzer is part of Clang, as Clang consists of a set of
170reusable C++ libraries for building powerful source-level tools. The static
171analysis engine used by the Clang Static Analyzer is a Clang library, and has
172the capability to be reused in different contexts and by different clients.</p>
173
174<h2>Important Points to Consider</h2>
175
176<p>While we believe that the static analyzer is already very useful for finding
177bugs, we ask you to bear in mind a few points when using it.</p>
178
179<h3>Work-in-Progress</h3>
180
181<p>The analyzer is a continuous work-in-progress.
182There are many planned enhancements to improve both the precision and scope of
183its analysis algorithms as well as the kinds bugs it will find. While there are
184fundamental limitations to what static analysis can do, we have a long way to go
185before hitting that wall.</p>
186
187<h3>Slower than Compilation</h3>
188
189<p>Operationally, using static analysis to
190automatically find deep program bugs is about trading CPU time for the hardening
191of code. Because of the deep analysis performed by state-of-the-art static
192analysis tools, static analysis can be much slower than compilation.</p>
193
194<p>While the Clang Static Analyzer is being designed to be as fast and
195light-weight as possible, please do not expect it to be as fast as compiling a
196program (even with optimizations enabled). Some of the algorithms needed to find
197bugs require in the worst case exponential time.</p>
198
199<p>The Clang Static Analyzer runs in a reasonable amount of time by both
200bounding the amount of checking work it will do as well as using clever
201algorithms to reduce the amount of work it must do to find bugs.</p></li>
202
203<h3>False Positives</h3>
204
205<p>Static analysis is not perfect. It can falsely flag bugs in a program where
206the code behaves correctly. Because some code checks require more analysis
207precision than others, the frequency of false positives can vary widely between
208different checks. Our long-term goal is to have the analyzer have a low false
209positive rate for most code on all checks.</p>
210
211<p>Please help us in this endeavor by <a href="filing_bugs.html">reporting false
212positives</a>. False positives cannot be addressed unless we know about
213them.</p>
214
215<h3>More Checks</h3>
216
Zhongxing Xu0c3a16d2009-06-15 13:22:32 +0000[diff] [blame]217<p>Static analysis is not magic; a static analyzer can only find bugs that it
218has been specifically engineered to find. If there are specific kinds of bugs
219you would like the Clang Static Analyzer to find, please feel free to
220file <a href="filing_bugs.html">feature requests</a> or contribute your own
221patches.</p>
Ted Kremenek591b9072009-06-08 21:21:24 +0000[diff] [blame]222
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