passes. It can be used to debug three types of failures: optimizer crashes,
miscompilations by optimizers, or bad native code generation (including problems
in the static and JIT compilers). It aims to reduce large test cases to small,
-useful ones. For example, if <tt>gccas</tt> crashes while optimizing a
+useful ones. For example, if <tt>opt</tt> crashes while optimizing a
file, it will identify the optimization (or combination of optimizations) that
causes the crash, and reduce the file down to a small example which triggers the
crash.</p>
-<p>For detailed case scenarios, such as debugging <tt>gccas</tt>,
-<tt>
gccld</tt>, or one of the LLVM code generators, see <a
+<p>For detailed case scenarios, such as debugging <tt>opt</tt>,
+<tt>
llvm-ld</tt>, or one of the LLVM code generators, see <a
href="HowToSubmitABug.html">How To Submit a Bug Report document</a>.</p>
</div>
as it can to reduce the list of passes (for optimizer crashes) and the size of
the test program. First, <tt>bugpoint</tt> figures out which combination of
optimizer passes triggers the bug. This is useful when debugging a problem
-exposed by <tt>gccas</tt>, for example, because it runs over 38 passes.</p>
+exposed by <tt>opt</tt>, for example, because it runs over 38 passes.</p>
<p>Next, <tt>bugpoint</tt> tries removing functions from the test program, to
reduce its size. Usually it is able to reduce a test program to a single
flow graph, to reduce the size of the function as much as possible. Finally,
<tt>bugpoint</tt> deletes any individual LLVM instructions whose absence does
not eliminate the failure. At the end, <tt>bugpoint</tt> should tell you what
-passes crash, give you a bytecode file, and give you instructions on how to
-reproduce the failure with <tt>opt</tt>, <tt>analyze</tt>, or <tt>llc</tt>.</p>
+passes crash, give you a bitcode file, and give you instructions on how to
+reproduce the failure with <tt>opt</tt> or <tt>llc</tt>.</p>
</div>
with the C backend (into a shared object), and one piece which it runs with
either the JIT or the static LLC compiler. It uses several techniques to
reduce the amount of code pushed through the LLVM code generator, to reduce the
-potential scope of the problem. After it is finished, it emits two bytecode
+potential scope of the problem. After it is finished, it emits two bitcode
files (called "test" [to be compiled with the code generator] and "safe" [to be
compiled with the C backend], respectively), and instructions for reproducing
the problem. The code generator debugger assumes that the C backend produces
you might try <tt>llvm-link -v</tt> on the same set of input files. If
that also crashes, you may be experiencing a linker bug.
-<li>If your program is <b>supposed</b> to crash, <tt>bugpoint</tt> will be
- confused. One way to deal with this is to cause bugpoint to ignore the exit
- code from your program, by giving it the <tt>-check-exit-code=false</tt>
- option.
+<li><tt>bugpoint</tt> is useful for proactively finding bugs in LLVM.
+ Invoking <tt>bugpoint</tt> with the <tt>-find-bugs</tt> option will cause
+ the list of specified optimizations to be randomized and applied to the
+ program. This process will repeat until a bug is found or the user
+ kills <tt>bugpoint</tt>.
</ol>
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<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
- <a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
+ <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Last modified: $Date$
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projects / oota-llvm.git / blobdiff