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