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<title>LLDB FAQ</title>
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Troubleshooting <strong>LLDB</strong>
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<h1 class ="postheader">File and line breakpoints are not getting hit</h1>
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<p>First you must make sure that your source files were compiled with
debug information. Typically this means passing <code>-g</code> to the
compiler when compiling your source file.
<p>When setting breakpoints in <b>implementation</b> source files
(.c, cpp, cxx, .m, .mm, etc), LLDB by default will only search for compile units whose filename matches. If your
code does tricky things like using <font color=purple>#include</font> to include source files:
<code><pre><tt>% <b>cat foo.c</b>
<font color=purple>#include</font> "bar.c"
<font color=purple>#include</font> "baz.c"
<p> This will cause breakpoints in "bar.c" to be inlined into the compile unit for "foo.c".
If your code does this, or if your build system combines multiple files in some way such
that breakpoints from one implementation file will be compiled into another implementation file,
you will need to tell LLDB to always search for inlined breakpoint locations
by adding the following line to your <code>~/.lldbinit</code> file:
<code><pre><tt>% <b>echo "settings set target.inline-breakpoint-strategy always" >> ~/.lldbinit</b></tt></pre></code>
<p> This tells LLDB to always look in all compile units and search for breakpoint
locations by file and line even if the implementation file doesn't match. Setting breakpoints
in header files always searches all compile units because inline functions are commonly defined
in header files and often cause multiple breakpoints to have source line information that matches
many header file paths.
<p> If you set a file and line breakpoint using a full path to the source file, like Xcode does when setting a
breakpoint in its GUI on Mac OS X when you click in the gutter of the source view, this path must match
the full paths in the debug information. If the paths mismatch, possibly due to
passing in a resolved source file path that doesn't match an unresolved path in the debug
information, this can cause breakpoints to not be resolved. Try setting breakpoints using the file
basename only.
<p> If you are using an IDE and you move your project in your file system and build again, sometimes doing a
clean then build will solve the issue.This will fix the issue if some .o files didn't get rebuilt
after the move as the .o files in the build folder might still contain stale debug information with
the old source locations.
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<h1 class ="postheader">How do I check if I have debug symbols?</h1>
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<p> Checking if a module has any compile units (source files) is a good way to check
if there is debug information in a module:
(lldb) <b>file /tmp/a.out</b>
(lldb) <b>image list</b>
[ 0] 71E5A649-8FEF-3887-9CED-D3EF8FC2FD6E 0x0000000100000000 /tmp/a.out
[ 1] 6900F2BA-DB48-3B78-B668-58FC0CF6BCB8 0x00007fff5fc00000 /usr/lib/dyld
(lldb) <b>script['/tmp/a.out'].GetNumCompileUnits()</b>
(lldb) <b>script['/usr/lib/dyld'].GetNumCompileUnits()</b>
<p> Above we can see that "/tmp/a.out" does have a compile unit, and "/usr/lib/dyld" does not.
<p> We can also list the full paths to all compile units for a module using python:
(lldb) <b>script</b>
Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
>>> <b>m =['a.out']</b>
>>> <b>for i in range(m.GetNumCompileUnits()):</b>
... <b>cu = m.GetCompileUnitAtIndex(i).file.fullpath</b>
<p> This can help to show the actual full path to the source files. Sometimes IDEs will set breakpoints by full paths where the path doesn't match the full path in the debug info and this can cause LLDB to not resolve breakpoints. You can use the breakpoint list command with the --verbose option to see the full paths for any source file and line breakpoints that the IDE set using:
(lldb) <b>breakpoint list --verbose</b>
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