forked from OSchip/llvm-project
Update information about the new DEBUG_TYPE macro
llvm-svn: 7496
This commit is contained in:
Chris Lattner
parent
fea54c2511
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5a0c4c6aa5
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@ -24,6 +24,10 @@
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<tt>dyn_cast<></tt> templates</a>
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<li><a href="#DEBUG">The <tt>DEBUG()</tt> macro &
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<tt>-debug</tt> option</a>
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<ul>
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<li><a href="#DEBUG_TYPE">Fine grained debug info with
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<tt>DEBUG_TYPE</tt> and the <tt>-debug-only</tt> option</a/>
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</ul>
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<li><a href="#Statistic">The <tt>Statistic</tt> template &
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<tt>-stats</tt> option</a>
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<!--
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@ -324,12 +328,11 @@ Naturally, because of this, you don't want to delete the debug printouts, but
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you don't want them to always be noisy. A standard compromise is to comment
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them out, allowing you to enable them if you need them in the future.<p>
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The "<tt><a
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href="/doxygen/Statistic_8h-source.html">Support/Statistic.h</a></tt>"
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file provides a macro named <tt>DEBUG()</tt> that is a much nicer solution to
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this problem. Basically, you can put arbitrary code into the argument of the
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<tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' is run with the
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'<tt>-debug</tt>' command line argument:
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The "<tt><a href="/doxygen/Debug_8h-source.html">Support/Debug.h</a></tt>" file
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provides a macro named <tt>DEBUG()</tt> that is a much nicer solution to this
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problem. Basically, you can put arbitrary code into the argument of the
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<tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' (or any other
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tool) is run with the '<tt>-debug</tt>' command line argument:
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<pre>
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...
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@ -347,7 +350,7 @@ Then you can run your pass like this:<p>
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$
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</pre><p>
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Using the <tt>DEBUG()</tt> macro instead of a home brewed solution allows you to
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Using the <tt>DEBUG()</tt> macro instead of a home-brewed solution allows you to
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now have to create "yet another" command line option for the debug output for
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your pass. Note that <tt>DEBUG()</tt> macros are disabled for optimized builds,
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so they do not cause a performance impact at all (for the same reason, they
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@ -359,6 +362,62 @@ enable or disable it directly in gdb. Just use "<tt>set DebugFlag=0</tt>" or
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program hasn't been started yet, you can always just run it with
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<tt>-debug</tt>.<p>
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<!-- _______________________________________________________________________ -->
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</ul><h4><a name="DEBUG_TYPE"><hr size=0>Fine grained debug info with
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<tt>DEBUG_TYPE()</tt> and the <tt>-debug-only</tt> option</a> </h4><ul>
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Sometimes you may find yourself in a situation where enabling <tt>-debug</tt>
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just turns on <b>too much</b> information (such as when working on the code
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generator). If you want to enable debug information with more fine-grained
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control, you define the <tt>DEBUG_TYPE</tt> macro and the <tt>-debug</tt> only
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option as follows:<p>
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<pre>
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...
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DEBUG(std::cerr << "No debug type\n");
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#undef DEBUG_TYPE
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#define DEBUG_TYPE "foo"
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DEBUG(std::cerr << "'foo' debug type\n");
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#undef DEBUG_TYPE
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#define DEBUG_TYPE "bar"
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DEBUG(std::cerr << "'bar' debug type\n");
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#undef DEBUG_TYPE
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#define DEBUG_TYPE ""
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DEBUG(std::cerr << "No debug type (2)\n");
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...
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</pre><p>
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Then you can run your pass like this:<p>
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<pre>
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$ opt < a.bc > /dev/null -mypass
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<no output>
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$ opt < a.bc > /dev/null -mypass -debug
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No debug type
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'foo' debug type
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'bar' debug type
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No debug type (2)
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$ opt < a.bc > /dev/null -mypass -debug-only=foo
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No debug type
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'foo' debug type
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No debug type (2)
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$ opt < a.bc > /dev/null -mypass -debug-only=bar
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No debug type
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'bar' debug type
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No debug type (2)
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$
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</pre><p>
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Of course, in practice, you should only set <tt>DEBUG_TYPE</tt> at the top of a
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file, to specify the debug type for the entire module (if you do this before you
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<tt>#include "Support/Debug.h"</tt>, you don't have to insert the ugly
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<tt>#undef</tt>'s). Also, you should use names more meaningful that "foo" and
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"bar", because there is no system in place to ensure that names do not conflict:
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if two different modules use the same string, they will all be turned on when
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the name is specified. This allows all, say, instruction scheduling debug
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information to be enabled with <tt>-debug-type=InstrSched</tt>, even if the
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source lives in multiple files.<p>
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<!-- ======================================================================= -->
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</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
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@ -1734,6 +1793,6 @@ pointer to the parent Function.
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<a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
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<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
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<!-- hhmts start -->
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Last modified: Wed Apr 23 11:21:57 CDT 2003
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Last modified: Fri Aug 1 16:40:37 CDT 2003
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<!-- hhmts end -->
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</font></body></html>
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