a short form…). You can get all of these at once
(<emphasis>lots</emphasis> of output) by using
<option>-v5</option>, or most of them with
- <option>-v4</option>. Some of the most useful ones
- are:</para>
+ <option>-v4</option>. You can prevent them from clogging up
+ your standard output by passing <option>-ddump-to-file</option>.
+ Some of the most useful ones are:</para>
<variablelist>
<varlistentry>
<varlistentry>
<term>
- <option>-ddump-tc</option>:
- <indexterm><primary><option>-ddump-tc</option></primary></indexterm>
- </term>
- <listitem>
- <para>typechecker output</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term>
<option>-ddump-splices</option>:
<indexterm><primary><option>-ddump-splices</option></primary></indexterm>
</term>
<indexterm><primary><option>-ddump-rules</option></primary></indexterm>
</term>
<listitem>
- <para>dumps all rewrite rules (including those generated
- by the specialisation pass)</para>
+ <para>dumps all rewrite rules specified in this module;
+ see <xref linkend="controlling-rules"/>.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-ddump-rule-firings</option>:
+ <indexterm><primary><option>-ddump-rule-firings</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>dumps the names of all rules that fired in this module</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-ddump-rule-rewrites</option>:
+ <indexterm><primary><option>-ddump-rule-rewrites</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>dumps detailed information about all rules that fired in
+ this module
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-ddump-vect</option>:
+ <indexterm><primary><option>-ddump-vect</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>dumps the output of the vectoriser.
+ </para>
</listitem>
</varlistentry>
<varlistentry>
<term>
- <option>-ddump-workwrap</option>:
- <indexterm><primary><option>-ddump-workwrap</option></primary></indexterm>
+ <option>-ddump-worker-wrapper</option>:
+ <indexterm><primary><option>-ddump-worker-wrapper</option></primary></indexterm>
</term>
<listitem>
<para>worker/wrapper split output</para>
<varlistentry>
<term>
+ <option>-ddump-simpl-phases</option>:
+ <indexterm><primary><option>-ddump-simpl-phases</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Show the output of each run of the simplifier. Used when even
+ <option>-dverbose-core2core</option> doesn't cut it.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
<option>-ddump-simpl-iterations</option>:
<indexterm><primary><option>-ddump-simpl-iterations</option></primary></indexterm>
</term>
<listitem>
<para>Show the output of each <emphasis>iteration</emphasis>
of the simplifier (each run of the simplifier has a maximum
- number of iterations, normally 4). Used when even
- <option>-dverbose-simpl</option> doesn't cut it.</para>
+ number of iterations, normally 4). This outputs even more information
+ than <option>-ddump-simpl-phases</option>.</para>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
- <term>
+ <term>
<option>-ddump-tc-trace</option>
<indexterm><primary><option>-ddump-tc-trace</option></primary></indexterm>
</term>
- <listitem>
- <para>Make the type checker be *real* chatty about what it is
- upto.</para>
- </listitem>
+ <listitem>
+ <para>Make the type checker be *real* chatty about what it is
+ upto.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-ddump-vt-trace</option>
+ <indexterm><primary><option>-ddump-tv-trace</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Make the vectoriser be *real* chatty about what it is
+ upto.</para>
+ </listitem>
</varlistentry>
<varlistentry>
of output!) So: when we're really desperate:</para>
<screen>
-% ghc -noC -O -ddump-simpl -dverbose-simpl -dcore-lint Foo.hs
+% ghc -noC -O -ddump-simpl -dverbose-core2core -dcore-lint Foo.hs
</screen>
</listitem>
<varlistentry>
<term>
+ <option>-ddump-core-stats</option>
+ <indexterm><primary><option>-ddump-core-stats</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Print a one-line summary of the size of the Core program
+ at the end of the optimisation pipeline.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
<option>-dfaststring-stats</option>
<indexterm><primary><option>-dfaststring-stats</option></primary></indexterm>
</term>
style.</para>
</listitem>
</varlistentry>
+ </variablelist>
+ </sect2>
+
+ <sect2 id="formatting dumps">
+ <title>Formatting dumps</title>
+ <indexterm><primary>formatting dumps</primary></indexterm>
+
+ <variablelist>
<varlistentry>
<term>
<option>-dppr-user-length</option>
<para>In error messages, expressions are printed to a
certain “depth”, with subexpressions beyond the
depth replaced by ellipses. This flag sets the
- depth.</para>
+ depth. Its default value is 5.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-dppr-colsNNN</option>
+ <indexterm><primary><option>-dppr-colsNNN</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Set the width of debugging output. Use this if your code is wrapping too much.
+ For example: <option>-dppr-cols200</option>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
- <option>-dshow-unused-imports</option>
- <indexterm><primary><option>-dshow-unused-imports</option></primary></indexterm>
+ <option>-dppr-case-as-let</option>
+ <indexterm><primary><option>-dppr-case-as-let</option></primary></indexterm>
</term>
<listitem>
- <para>Have the renamer report what imports does not
- contribute.</para>
+ <para>Print single alternative case expressions as though they were strict
+ let expressions. This is helpful when your code does a lot of unboxing.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-dno-debug-output</option>
+ <indexterm><primary><option>-dno-debug-output</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Suppress any unsolicited debugging output. When GHC
+ has been built with the <literal>DEBUG</literal> option it
+ occasionally emits debug output of interest to developers.
+ The extra output can confuse the testing framework and
+ cause bogus test failures, so this flag is provided to
+ turn it off.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ </sect2>
+
+ <sect2 id="supression">
+ <title>Suppressing unwanted information</title>
+
+ <indexterm><primary>suppression</primary></indexterm>
+
+ Core dumps contain a large amount of information. Depending on what you are doing, not all of it will be useful.
+ Use these flags to suppress the parts that you are not interested in.
+
+ <variablelist>
+ <varlistentry>
+ <term>
+ <option>-dsuppress-all</option>
+ <indexterm><primary><option>-dsuppress-all</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Suppress everything that can be suppressed, except for unique ids as this often
+ makes the printout ambiguous. If you just want to see the overall structure of
+ the code, then start here.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-dsuppress-uniques</option>
+ <indexterm><primary><option>-dsuppress-uniques</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Suppress the printing of uniques. This may make
+ the printout ambiguous (e.g. unclear where an occurrence of 'x' is bound), but
+ it makes the output of two compiler runs have many fewer gratuitous differences,
+ so you can realistically apply <command>diff</command>. Once <command>diff</command>
+ has shown you where to look, you can try again without <option>-dsuppress-uniques</option></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-dsuppress-idinfo</option>
+ <indexterm><primary><option>-dsuppress-idinfo</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Suppress extended information about identifiers where they are bound. This includes
+ strictness information and inliner templates. Using this flag can cut the size
+ of the core dump in half, due to the lack of inliner templates</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-dsuppress-module-prefixes</option>
+ <indexterm><primary><option>-dsuppress-module-prefixes</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Suppress the printing of module qualification prefixes.
+ This is the <constant>Data.List</constant> in <constant>Data.List.length</constant>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-dsuppress-type-signatures</option>
+ <indexterm><primary><option>-dsuppress-type-signatures</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Suppress the printing of type signatures.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-dsuppress-type-applications</option>
+ <indexterm><primary><option>-dsuppress-type-applications</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Suppress the printing of type applications.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <option>-dsuppress-coercions</option>
+ <indexterm><primary><option>-dsuppress-coercions</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>Suppress the printing of type coercions.</para>
</listitem>
</varlistentry>
</variablelist>
of platform-specific code that needs to be written in order to get
unregisterised compilation going is usually fairly small.</para>
- <variablelist>
- <varlistentry>
- <term>
- <option>-unreg</option>:
- <indexterm><primary><option>-unreg</option></primary></indexterm>
- </term>
- <listitem>
- <para>Compile via vanilla ANSI C only, turning off
- platform-specific optimisations. NOTE: in order to use
- <option>-unreg</option>, you need to have a set of libraries
- (including the RTS) built for unregisterised compilation.
- This amounts to building GHC with way "u" enabled.</para>
- </listitem>
- </varlistentry>
- </variablelist>
+ <para>Unregisterised compilation cannot be selected at
+ compile-time; you have to build GHC with the appropriate options
+ set. Consult the GHC Building Guide for details.</para>
</sect2>
</sect1>
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