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11      The <strong>LLDB</strong> Debugger
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21				<h1 class ="postheader">What is LLDB?</h1>
22				<div class="postcontent">
23                    <p>LLDB is a next generation, high-performance debugger. It is built as a set
24                        of reusable components which highly leverage existing libraries in the
25                        larger LLVM Project, such as the Clang expression parser and LLVM
26                        disassembler.</p>
27                    <p>LLDB is the default debugger in Xcode on Mac OS X and supports
28                        debugging C, Objective-C and C++ on the desktop and iOS devices and simulator.</p>
29
30                    <p>All of the code in the LLDB project is available under the standard
31                        <a href="http://llvm.org/docs/DeveloperPolicy.html#license">LLVM
32                        License</a>, an open source "BSD-style" license.</p>
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38				<h1 class ="postheader">Why a new debugger?</h1>
39				<div class="postcontent">
40					  <p>In order to achieve our goals we decided to start with a fresh architecture
41					     that would support modern multi-threaded programs, handle debugging symbols
42					     in an efficient manner, use compiler based code knowledge and have plug-in
43					     support for functionality and extensions. Additionally we want the debugger
44					     capabilities to be available to other analysis tools, be they scripts or
45					     compiled programs, without requiring them to be GPL.</p>
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51				<h1 class ="postheader">Compiler Integration Benefits</h1>
52				<div class="postcontent">
53						<p>LLDB currently converts debug information into clang types so that
54						it can leverage the clang compiler infrastructure.
55						This allows LLDB to support the latest C, C++, Objective C and Objective C++
56						language features and runtimes in expressions without having to reimplement <b>any</b> 
57						of this functionality. It also leverages the compiler to take care of all ABI
58						details when making functions calls for expressions, when disassembling
59						instructions and extracting instruciton details, and much more. 
60				   	<p>The major benefits include:</p>
61				   	<ul>
62					   	<li>Up to date language support for C, C++, Objective C</li>
63					   	<li>Multi-line expressions that can declare local variables and types</li>
64					   	<li>Utilitize the JIT for expressions when supported</li>
65					   	<li>Evaluate expression Intermediate Representation (IR) when JIT can't be used</li>
66				    </ul>
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71				<h1 class ="postheader">Reusability</h1>
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73				   	<p>The LLDB debugger APIs are exposed as a C++ object oriented interface in a shared library. 
74					The <b>lldb</b> command line tool links to, and uses this public API. On Mac OS X the shared library
75					is exposed as a framework named <b>LLDB.framework</b>, and unix systems expose it as <b>lldb.so</b>.
76					The entire API is also then exposed through Python script bindings which allow the API to be used
77					within the LLDB embedded script interpreter, and also in any python script that loads the <b>lldb.py</b>
78					module in standard python script files. See the <a href="python-reference.html">Python Reference</a> page for more details on how 
79					and where Python can be used with the LLDB API.</p>
80					<p>Sharing the LLDB API allows LLDB to not only be used for debugging, but also for symbolication,
81						disassembly, object and symbol file introspection, and much more.
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86				<h1 class ="postheader">Platform Support</h1>
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88
89				   	<p>LLDB is known to work on the following platforms, but ports to new
90				       platforms are welcome:</p>
91				   	<ul>
92					   	<li>Mac OS X desktop user space debugging for i386 and x86-64</li>
93					   	<li>iOS simulator debugging on i386</li>
94					   	<li>iOS device debugging on ARM</li>
95					   	<li>Linux local user-space debugging for i386 and x86-64</li>
96					   	<li>FreeBSD local user-space debugging for i386 and x86-64</li>
97				    </ul>
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104				<h1 class ="postheader">Get it and get involved!</h1>
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106
107				    <p>To check out the code, use:</p>
108
109				    <ul>
110				        <li>svn co http://llvm.org/svn/llvm-project/lldb/trunk lldb</li>
111				    </ul>
112
113				    <p>Note that LLDB generally builds from top-of-trunk on Mac OS X with
114				        Xcode and on Linux (with clang and libstdc++/libc++). </p>
115
116				    <p>Discussions about LLDB should go to the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev">lldb-dev</a> mailing
117				        list.  Commit messages for the lldb SVN module are automatically sent to the
118				        <a  href="http://lists.cs.uiuc.edu/mailman/listinfo/lldb-commits">lldb-commits</a>
119				        mailing list, and this is also the preferred mailing list for patch
120				        submissions.</p>
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