docs/HowToSubmitABug.html - fp2-dev/platform/external/llvm - Gitiles

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 <tr><td>&nbsp; <font size=+3 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>How to submit an LLVM bug report</b></font></td>
 </tr></table>

 <table border=0 width=100%>
 <tr><td valign=top>
 <p><font size=+1>
 <ol>
   <li><a href="#introduction">Introduction - Got bugs?</a>
   <li><a href="#crashers">Crashing Bugs</a>
     <ul>
     <li><a href="#front-end">Front-end bugs</a>
     <li><a href="#gccas">GCCAS bugs</a>
     <li><a href="#gccld">GCCLD bugs</a>
     <li><a href="#passes">Bugs in LLVM passes</a>
     </ul>
   <li><a href="#miscompilations">Miscompilations</a>

   <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><p>
 </ol><p></font>
 </td><td valign=top align=right>
 <img src="Debugging.gif" width=444 height=314>
 </td></tr>
 </table>


 <!-- *********************************************************************** -->
 <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
 <a name="introduction">Introduction - Got bugs?
 </b></font></td></tr></table><ul>
 <!-- *********************************************************************** -->

 If you're working with LLVM and run into a bug, we definitely want to know about
 it.  This document describes what you can do to increase the odds of getting it
 fixed quickly.<p>

 Basically you have to do two things at a minimum.  First, decide whether the bug
 <a href="#crashers">crashes the compiler</a> (or an LLVM pass), or if the
 compiler is <a href="#miscompilations">miscompiling</a> the program.  Based on
 what type of bug it is, follow the instructions in the linked section to narrow
 down the bug so that the person who fixes it will be able to find the problem
 more easily.<p>

 Once you have a reduced test-case, email information about the bug to: <a
 href="mailto:llvmbugs@cs.uiuc.edu">llvmbugs@cs.uiuc.edu</a>.  This should
 include all of the information necessary to reproduce the problem, including
 where you got the LLVM tree from (if you're not working out of CVS).<p>

 Thanks for helping us make LLVM better!<p>


 <!-- *********************************************************************** -->
 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
 <a name="crashers">Crashing Bugs
 </b></font></td></tr></table><ul>
 <!-- *********************************************************************** -->

 More often than not, bugs in the compiler cause it to crash - often due to an
 assertion failure of some sort.  If you are running <tt><b>opt</b></tt> or
 <tt><b>analyze</b></tt> directly, and something crashes, jump to the section on
 <a href="#passes">bugs in LLVM passes</a>.  Otherwise, the most important
 piece of the puzzle is to figure out if it is the GCC-based front-end that is
 buggy or if it's one of the LLVM tools that has problems.<p>

 To figure out which program is crashing (the front-end, <tt><b>gccas</b></tt>,
 or <tt><b>gccld</b></tt>), run the <tt><b>llvm-gcc</b></tt> command line as you
 were when the crash occurred, but add a <tt>-v</tt> option to the command line.
 The compiler will print out a bunch of stuff, and should end with telling you
 that one of <tt><b>cc1</b></tt>, <tt><b>gccas</b></tt>, or <tt><b>gccld</b></tt>
 crashed.<p>

 <ul>
 <li>If <tt><b>cc1</b></tt> crashed, you found a problem with the front-end.
 Jump ahead to the section on <a href="#front-end">front-end bugs</a>.
 <li>If <tt><b>gccas</b></tt> crashed, you found a bug in <a href="#gccas">one of
 the passes in <tt><b>gccas</b></tt></a>.
 <li>If <tt><b>gccld</b></tt> crashed, you found a bug in <a href="#gccld">one
 of the passes in <tt><b>gccld</b></tt></a>.
 <li>Otherwise, something really weird happened.  Email the list with what you
 have at this point.
 </ul><p>


 <!-- ======================================================================= -->
 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
 <tr><td>&nbsp;</td><td width="100%">&nbsp;
 <font color="#EEEEFF" face="Georgia,Palatino"><b>
 <a name="front-end">Front-end bugs
 </b></font></td></tr></table><ul>

 If the problem is in the front-end, you should re-run the same
 <tt>llvm-gcc</tt> command that resulted in the crash, but add the
 <tt>-save-temps</tt> option.  The compiler will crash again, but it
 will leave behind a <tt><i>foo</i>.i</tt> file (containing preprocessed
 C source code) and possibly <tt><i>foo</i>.s</tt> (containing LLVM
 assembly code), for each compiled <tt><i>foo</i>.c</tt> file. Send us
 the <tt><i>foo</i>.i</tt> file, along with a brief description of the
 error it caused.<p>

 <!-- ======================================================================= -->
 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
 <tr><td>&nbsp;</td><td width="100%">&nbsp;
 <font color="#EEEEFF" face="Georgia,Palatino"><b>
 <a name="gccas">GCCAS bugs
 </b></font></td></tr></table><ul>

 If you find that a bug crashes in the <tt><b>gccas</b></tt> stage of
 compilation, compile your test-case to a <tt>.s</tt> file with the
 <tt>-save-temps</tt> option to <tt><b>llvm-gcc</b></tt>. Then run:<p>

 <pre>
   <b>gccas</b> -debug-pass=Arguments &lt; /dev/null -o - &gt; /dev/null
 </pre><p>

 ... which will print a list of arguments, indicating the list of passes that
 <tt><b>gccas</b></tt> runs.  Once you have the input file and the list of
 passes, go to the section on <a href="#passes">debugging bugs in LLVM
 passes</a>.<p>


 <!-- ======================================================================= -->
 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
 <tr><td>&nbsp;</td><td width="100%">&nbsp;
 <font color="#EEEEFF" face="Georgia,Palatino"><b>
 <a name="gccld">GCCLD bugs
 </b></font></td></tr></table><ul>

 If you find that a bug crashes in the <tt><b>gccld</b></tt> stage of
 compilation, gather all of the <tt>.o</tt> bytecode files and libraries that are
 being linked together (the "<tt><b>llvm-gcc</b> -v</tt>" output should include
 the full list of objects linked).  Then run:<p>

 <pre>
   <b>as</b> &lt; /dev/null &gt; null.bc
   <b>gccld</b> -debug-pass=Arguments null.bc
 </pre><p>

 ... which will print a list of arguments, indicating the list of passes that
 <tt><b>gccld</b></tt> runs.  Once you have the input files and the list of
 passes, go to the section on <a href="#passes">debugging bugs in LLVM
 passes</a>.<p>

 <!-- ======================================================================= -->
 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
 <tr><td>&nbsp;</td><td width="100%">&nbsp;
 <font color="#EEEEFF" face="Georgia,Palatino"><b>
 <a name="passes">Bugs in LLVM passes
 </b></font></td></tr></table><ul>

 At this point, you should have some number of LLVM assembly files or bytecode
 files and a list of passes which crash when run on the specified input.  In
 order to reduce the list of passes (which is probably large) and the input to
 something tractable, use the <tt><b>bugpoint</b></tt> tool as follows:<p>

 <pre>
   <b>bugpoint</b> &lt;input files&gt; &lt;list of passes&gt;
 </pre><p>

 <tt><b>bugpoint</b></tt> will print a bunch of output as it reduces the
 test-case, but it should eventually print something like this:<p>

 <pre>
   ...
   Emitted bytecode to 'bugpoint-reduced-simplified.bc'

   *** You can reproduce the problem with: opt bugpoint-reduced-simplified.bc -licm
 </pre><p>

 Once you complete this, please send the LLVM bytecode file and the command line
 to reproduce the problem to the llvmbugs mailing list.<p>


 <!-- *********************************************************************** -->
 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
 <a name="miscompilations">Miscompilations
 </b></font></td></tr></table><ul>
 <!-- *********************************************************************** -->

 Fortunately we haven't had too many miscompilations.  Because of this, this
 section is a TODO.  Basically, use bugpoint to track down the problem.<p>


 <!-- *********************************************************************** -->
 </ul>
 <!-- *********************************************************************** -->

 <hr><font size-1>
 <address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
 <!-- Created: Tue Aug  6 15:00:33 CDT 2002 -->
 <!-- hhmts start -->
 Last modified: Fri May 23 09:48:53 CDT 2003
 <!-- hhmts end -->
 </font></body></html>
	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
	<html><head><title>How to submit an LLVM bug report</title></head>

	<body bgcolor=white>

	<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
	<tr><td>  <font size=+3 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>How to submit an LLVM bug report</b></font></td>
	</tr></table>

	<table border=0 width=100%>
	<tr><td valign=top>
	<p><font size=+1>
	<ol>
	<li><a href="#introduction">Introduction - Got bugs?</a>
	<li><a href="#crashers">Crashing Bugs</a>
	<ul>
	<li><a href="#front-end">Front-end bugs</a>
	<li><a href="#gccas">GCCAS bugs</a>
	<li><a href="#gccld">GCCLD bugs</a>
	<li><a href="#passes">Bugs in LLVM passes</a>
	</ul>
	<li><a href="#miscompilations">Miscompilations</a>

	<p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><p>
	</ol><p></font>
	</td><td valign=top align=right>
	<img src="Debugging.gif" width=444 height=314>
	</td></tr>
	</table>


	<!-- *********************************************************************** -->
	<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
	<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
	<a name="introduction">Introduction - Got bugs?
	</b></font></td></tr></table><ul>
	<!-- *********************************************************************** -->

	If you're working with LLVM and run into a bug, we definitely want to know about
	it. This document describes what you can do to increase the odds of getting it
	fixed quickly.<p>

	Basically you have to do two things at a minimum. First, decide whether the bug
	<a href="#crashers">crashes the compiler</a> (or an LLVM pass), or if the
	compiler is <a href="#miscompilations">miscompiling</a> the program. Based on
	what type of bug it is, follow the instructions in the linked section to narrow
	down the bug so that the person who fixes it will be able to find the problem
	more easily.<p>

	Once you have a reduced test-case, email information about the bug to: <a
	href="mailto:llvmbugs@cs.uiuc.edu">llvmbugs@cs.uiuc.edu</a>. This should
	include all of the information necessary to reproduce the problem, including
	where you got the LLVM tree from (if you're not working out of CVS).<p>

	Thanks for helping us make LLVM better!<p>


	<!-- *********************************************************************** -->
	</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
	<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
	<a name="crashers">Crashing Bugs
	</b></font></td></tr></table><ul>
	<!-- *********************************************************************** -->

	More often than not, bugs in the compiler cause it to crash - often due to an
	assertion failure of some sort. If you are running <tt><b>opt</b></tt> or
	<tt><b>analyze</b></tt> directly, and something crashes, jump to the section on
	<a href="#passes">bugs in LLVM passes</a>. Otherwise, the most important
	piece of the puzzle is to figure out if it is the GCC-based front-end that is
	buggy or if it's one of the LLVM tools that has problems.<p>

	To figure out which program is crashing (the front-end, <tt><b>gccas</b></tt>,
	or <tt><b>gccld</b></tt>), run the <tt><b>llvm-gcc</b></tt> command line as you
	were when the crash occurred, but add a <tt>-v</tt> option to the command line.
	The compiler will print out a bunch of stuff, and should end with telling you
	that one of <tt><b>cc1</b></tt>, <tt><b>gccas</b></tt>, or <tt><b>gccld</b></tt>
	crashed.<p>

	<ul>
	<li>If <tt><b>cc1</b></tt> crashed, you found a problem with the front-end.
	Jump ahead to the section on <a href="#front-end">front-end bugs</a>.
	<li>If <tt><b>gccas</b></tt> crashed, you found a bug in <a href="#gccas">one of
	the passes in <tt><b>gccas</b></tt></a>.
	<li>If <tt><b>gccld</b></tt> crashed, you found a bug in <a href="#gccld">one
	of the passes in <tt><b>gccld</b></tt></a>.
	<li>Otherwise, something really weird happened. Email the list with what you
	have at this point.
	</ul><p>


	<!-- ======================================================================= -->
	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
	<tr><td> </td><td width="100%">
	<font color="#EEEEFF" face="Georgia,Palatino"><b>
	<a name="front-end">Front-end bugs
	</b></font></td></tr></table><ul>

	If the problem is in the front-end, you should re-run the same
	<tt>llvm-gcc</tt> command that resulted in the crash, but add the
	<tt>-save-temps</tt> option. The compiler will crash again, but it
	will leave behind a <tt><i>foo</i>.i</tt> file (containing preprocessed
	C source code) and possibly <tt><i>foo</i>.s</tt> (containing LLVM
	assembly code), for each compiled <tt><i>foo</i>.c</tt> file. Send us
	the <tt><i>foo</i>.i</tt> file, along with a brief description of the
	error it caused.<p>

	<!-- ======================================================================= -->
	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
	<tr><td> </td><td width="100%">
	<font color="#EEEEFF" face="Georgia,Palatino"><b>
	<a name="gccas">GCCAS bugs
	</b></font></td></tr></table><ul>

	If you find that a bug crashes in the <tt><b>gccas</b></tt> stage of
	compilation, compile your test-case to a <tt>.s</tt> file with the
	<tt>-save-temps</tt> option to <tt><b>llvm-gcc</b></tt>. Then run:<p>

	<pre>
	<b>gccas</b> -debug-pass=Arguments < /dev/null -o - > /dev/null
	</pre><p>

	... which will print a list of arguments, indicating the list of passes that
	<tt><b>gccas</b></tt> runs. Once you have the input file and the list of
	passes, go to the section on <a href="#passes">debugging bugs in LLVM
	passes</a>.<p>


	<!-- ======================================================================= -->
	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
	<tr><td> </td><td width="100%">
	<font color="#EEEEFF" face="Georgia,Palatino"><b>
	<a name="gccld">GCCLD bugs
	</b></font></td></tr></table><ul>

	If you find that a bug crashes in the <tt><b>gccld</b></tt> stage of
	compilation, gather all of the <tt>.o</tt> bytecode files and libraries that are
	being linked together (the "<tt><b>llvm-gcc</b> -v</tt>" output should include
	the full list of objects linked). Then run:<p>

	<pre>
	<b>as</b> < /dev/null > null.bc
	<b>gccld</b> -debug-pass=Arguments null.bc
	</pre><p>

	... which will print a list of arguments, indicating the list of passes that
	<tt><b>gccld</b></tt> runs. Once you have the input files and the list of
	passes, go to the section on <a href="#passes">debugging bugs in LLVM
	passes</a>.<p>

	<!-- ======================================================================= -->
	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
	<tr><td> </td><td width="100%">
	<font color="#EEEEFF" face="Georgia,Palatino"><b>
	<a name="passes">Bugs in LLVM passes
	</b></font></td></tr></table><ul>

	At this point, you should have some number of LLVM assembly files or bytecode
	files and a list of passes which crash when run on the specified input. In
	order to reduce the list of passes (which is probably large) and the input to
	something tractable, use the <tt><b>bugpoint</b></tt> tool as follows:<p>

	<pre>
	<b>bugpoint</b> <input files> <list of passes>
	</pre><p>

	<tt><b>bugpoint</b></tt> will print a bunch of output as it reduces the
	test-case, but it should eventually print something like this:<p>

	<pre>
	...
	Emitted bytecode to 'bugpoint-reduced-simplified.bc'

	*** You can reproduce the problem with: opt bugpoint-reduced-simplified.bc -licm
	</pre><p>

	Once you complete this, please send the LLVM bytecode file and the command line
	to reproduce the problem to the llvmbugs mailing list.<p>


	<!-- *********************************************************************** -->
	</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
	<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
	<a name="miscompilations">Miscompilations
	</b></font></td></tr></table><ul>
	<!-- *********************************************************************** -->

	Fortunately we haven't had too many miscompilations. Because of this, this
	section is a TODO. Basically, use bugpoint to track down the problem.<p>


	<!-- *********************************************************************** -->
	</ul>
	<!-- *********************************************************************** -->

	<hr><font size-1>
	<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
	<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
	<!-- hhmts start -->
	Last modified: Fri May 23 09:48:53 CDT 2003
	<!-- hhmts end -->
	</font></body></html>