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<a name="Debugging-Options"></a>
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<p>
Next: <a href="Directory-Options.html#Directory-Options" accesskey="n" rel="next">Directory Options</a>, Previous: <a href="Error-and-Warning-Options.html#Error-and-Warning-Options" accesskey="p" rel="prev">Error and Warning Options</a>, Up: <a href="Invoking-GNU-Fortran.html#Invoking-GNU-Fortran" accesskey="u" rel="up">Invoking GNU Fortran</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Options-for-debugging-your-program-or-GNU-Fortran"></a>
<h3 class="section">2.5 Options for debugging your program or GNU Fortran</h3>
<a name="index-options_002c-debugging"></a>
<a name="index-debugging-information-options"></a>

<p>GNU Fortran has various special options that are used for debugging
either your program or the GNU Fortran compiler.
</p>
<dl compact="compact">
<dt><code>-fdump-fortran-original</code></dt>
<dd><a name="index-fdump_002dfortran_002doriginal"></a>
<p>Output the internal parse tree after translating the source program
into internal representation.  Only really useful for debugging the
GNU Fortran compiler itself.
</p>
</dd>
<dt><code>-fdump-fortran-optimized</code></dt>
<dd><a name="index-fdump_002dfortran_002doptimized"></a>
<p>Output the parse tree after front-end optimization.  Only really
useful for debugging the GNU Fortran compiler itself.
</p>
</dd>
<dt><code>-fdump-parse-tree</code></dt>
<dd><a name="index-fdump_002dparse_002dtree"></a>
<p>Output the internal parse tree after translating the source program
into internal representation.  Only really useful for debugging the
GNU Fortran compiler itself.  This option is deprecated; use
<code>-fdump-fortran-original</code> instead.
</p>
</dd>
<dt><code>-ffpe-trap=<var>list</var></code></dt>
<dd><a name="index-ffpe_002dtrap_003dlist"></a>
<p>Specify a list of floating point exception traps to enable.  On most
systems, if a floating point exception occurs and the trap for that
exception is enabled, a SIGFPE signal will be sent and the program
being aborted, producing a core file useful for debugging.  <var>list</var>
is a (possibly empty) comma-separated list of the following
exceptions: &lsquo;<samp>invalid</samp>&rsquo; (invalid floating point operation, such as
<code>SQRT(-1.0)</code>), &lsquo;<samp>zero</samp>&rsquo; (division by zero), &lsquo;<samp>overflow</samp>&rsquo;
(overflow in a floating point operation), &lsquo;<samp>underflow</samp>&rsquo; (underflow
in a floating point operation), &lsquo;<samp>inexact</samp>&rsquo; (loss of precision
during operation), and &lsquo;<samp>denormal</samp>&rsquo; (operation performed on a
denormal value).  The first five exceptions correspond to the five
IEEE 754 exceptions, whereas the last one (&lsquo;<samp>denormal</samp>&rsquo;) is not
part of the IEEE 754 standard but is available on some common
architectures such as x86.
</p>
<p>The first three exceptions (&lsquo;<samp>invalid</samp>&rsquo;, &lsquo;<samp>zero</samp>&rsquo;, and
&lsquo;<samp>overflow</samp>&rsquo;) often indicate serious errors, and unless the program
has provisions for dealing with these exceptions, enabling traps for
these three exceptions is probably a good idea.
</p>
<p>Many, if not most, floating point operations incur loss of precision
due to rounding, and hence the <code>ffpe-trap=inexact</code> is likely to
be uninteresting in practice.
</p>
<p>By default no exception traps are enabled.
</p>
</dd>
<dt><code>-ffpe-summary=<var>list</var></code></dt>
<dd><a name="index-ffpe_002dsummary_003dlist"></a>
<p>Specify a list of floating-point exceptions, whose flag status is printed
to <code>ERROR_UNIT</code> when invoking <code>STOP</code> and <code>ERROR STOP</code>.
<var>list</var> can be either &lsquo;<samp>none</samp>&rsquo;, &lsquo;<samp>all</samp>&rsquo; or a comma-separated list
of the following exceptions: &lsquo;<samp>invalid</samp>&rsquo;, &lsquo;<samp>zero</samp>&rsquo;, &lsquo;<samp>overflow</samp>&rsquo;,
&lsquo;<samp>underflow</samp>&rsquo;, &lsquo;<samp>inexact</samp>&rsquo; and &lsquo;<samp>denormal</samp>&rsquo;. (See
<samp>-ffpe-trap</samp> for a description of the exceptions.)
</p>
<p>By default, a summary for all exceptions but &lsquo;<samp>inexact</samp>&rsquo; is shown.
</p>
</dd>
<dt><code>-fno-backtrace</code></dt>
<dd><a name="index-fno_002dbacktrace"></a>
<a name="index-backtrace"></a>
<a name="index-trace"></a>
<p>When a serious runtime error is encountered or a deadly signal is
emitted (segmentation fault, illegal instruction, bus error,
floating-point exception, and the other POSIX signals that have the
action &lsquo;<samp>core</samp>&rsquo;), the Fortran runtime library tries to output a
backtrace of the error. <code>-fno-backtrace</code> disables the backtrace
generation. This option only has influence for compilation of the
Fortran main program.
</p>
</dd>
</dl>

<p>See <a href="http://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html#Debugging-Options">Options for Debugging Your Program or GCC</a> in <cite>Using the GNU Compiler Collection (GCC)</cite>, for more information on
debugging options.
</p>
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Next: <a href="Directory-Options.html#Directory-Options" accesskey="n" rel="next">Directory Options</a>, Previous: <a href="Error-and-Warning-Options.html#Error-and-Warning-Options" accesskey="p" rel="prev">Error and Warning Options</a>, Up: <a href="Invoking-GNU-Fortran.html#Invoking-GNU-Fortran" accesskey="u" rel="up">Invoking GNU Fortran</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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