<sect2 id="replacing-phases">
<title>Replacing the program for one or more phases</title>
<indexterm><primary>phases, changing</primary></indexterm>
-
+
<para>You may specify that a different program be used for one
of the phases of the compilation system, in place of whatever
the <command>ghc</command> has wired into it. For example, you
<varlistentry>
<term>
- <option>-pgmm</option> <replaceable>cmd</replaceable>
- <indexterm><primary><option>-pgmm</option></primary></indexterm>
- </term>
- <listitem>
- <para>Use <replaceable>cmd</replaceable> as the
- mangler.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term>
<option>-pgms</option> <replaceable>cmd</replaceable>
<indexterm><primary><option>-pgms</option></primary></indexterm>
</term>
for Windows, <literal>solaris</literal>, etc.).</para>
</listitem>
</varlistentry>
-
+
<varlistentry>
<term>
<constant><replaceable>arch</replaceable>_HOST_ARCH=1</constant>
<programlisting>strmod = "\
\ p \
\ "</programlisting>
-
+
<para>don't work with <option>-cpp</option>;
<filename>/usr/bin/cpp</filename> elides the backslash-newline
pairs.</para>
<sect2 id="pre-processor">
<title>Options affecting a Haskell pre-processor</title>
-
+
<indexterm><primary>pre-processing: custom</primary></indexterm>
<indexterm><primary>Pre-processor options</primary></indexterm>
</term>
<listitem>
<para>Use GHC's native code generator rather than
- compiling via C. This will compile faster (up to twice as
- fast), but may produce code that is slightly slower than
- compiling via C. <option>-fasm</option> is the default.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term>
- <option>-fvia-C</option>
- <indexterm><primary><option>-fvia-C</option></primary></indexterm>
- </term>
- <listitem>
- <para>Compile via C instead of using the native code
- generator. This is the default on architectures for which GHC
- doesn't have a native code generator.</para>
+ compiling via LLVM.
+ <option>-fasm</option> is the default.</para>
</listitem>
</varlistentry>
<listitem>
<para>Compile via LLVM instead of using the native code
generator. This will generally take slightly longer than the
- native code generator to compile but quicker than compiling
- via C. Produced code is generally the same speed or faster
+ native code generator to compile.
+ Produced code is generally the same speed or faster
than the other two code generators. Compiling via LLVM
requires LLVM version 2.7 or later to be on the path.</para>
</listitem>
However, if all the modules are otherwise up to date, you may need to force
recompilation both of the module where the new "main" is, and of the
module where the "main" function used to be;
- <literal>ghc</literal> is not clever
+ <literal>ghc</literal> is not clever
enough to figure out that they both need recompiling. You can
force recompilation by removing the object file, or by using the
<option>-fforce-recomp</option> flag.
- </para>
+ </para>
</listitem>
</varlistentry>
<para>The threaded runtime system provides the following
benefits:</para>
- <itemizedlist>
+ <itemizedlist>
<listitem>
<para>Parallelism<indexterm><primary>parallelism</primary></indexterm> on a multiprocessor<indexterm><primary>multiprocessor</primary></indexterm><indexterm><primary>SMP</primary></indexterm> or multicore<indexterm><primary>multicore</primary></indexterm>
machine. See <xref linkend="using-smp" />.</para>
on the command line or via the <envar>GHCRTS</envar> environment variable.
There are three possibilities:
</para>
- <itemizedlist>
- <listitem>
- <option>-rtsopts=none</option> disables all processing of RTS options.
- Passing <option>+RTS</option> anywhere on the command line causes the program
- to abort with an error message. Setting the <envar>GHCRTS</envar> environment
- variable causes a warning is printed before the main Haskell program runs.
- </listitem>
- <listitem>
- <option>-rtsopts=some</option> enables only the "safe" RTS options on the
- command line. (Currently only <option>-?</option> and <option>--info</option>.)
- Any other RTS options on the command line abort the program with an error
- message. All RTS options in the <envar>GHCRTS</envar> environment variable are
- processed as normal. This is the default setting.
- </listitem>
- <listitem>
- <option>-rtsopts=all</option> (or just <option>-rtsopts</option>) enables
- <emphasis>all</emphasis> RTS option processing, both on the command line and
- through the <envar>GHCRTS</envar> environment variable.
- </listitem>
- </itemizedlist>
+ <variablelist>
+ <varlistentry>
+ <term><option>-rtsopts=none</option></term>
+ <listitem>
+ <para>
+ Disable all processing of RTS options.
+ If <option>+RTS</option> appears anywhere on the command
+ line, then the program will abort with an error message.
+ If the <envar>GHCRTS</envar> environment variable is
+ set, then the program will emit a warning message,
+ <envar>GHCRTS</envar> will be ignored, and the program
+ will run as normal.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>-rtsopts=some</option></term>
+ <listitem>
+ <para>[this is the default setting] Enable
+ only the "safe" RTS options: (Currently
+ only <option>-?</option>
+ and <option>--info</option>.) Any other RTS options
+ on the command line or in the <envar>GHCRTS</envar>
+ environment variable causes the program with to abort
+ with an error message.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>-rtsopts=all</option>, or
+ just <option>-rtsopts</option></term>
+ <listitem>
+ <para>
+ Enable <emphasis>all</emphasis> RTS option
+ processing, both on the command line and through
+ the <envar>GHCRTS</envar> environment variable.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
<para>
- Prior to GHC 7.0, the default was to process all RTS options. However, since
- RTS options can be used to write logging data to arbitrary files under the
- security context of the running program, there is a potential security problem.
- For this reason, GHC 7.0 defaults to <option>-rtsops=some</option>.
+ In GHC 6.12.3 and earlier, the default was to process all
+ RTS options. However, since RTS options can be used to
+ write logging data to arbitrary files under the security
+ context of the running program, there is a potential
+ security problem. For this reason, GHC 7.0.1 and later
+ default to <option>-rtsops=some</option>.
</para>
</listitem>
</varlistentry>
<para>
This option allows you to set the default RTS options at link-time. For example,
<option>-with-rtsopts="-H128m"</option> sets the default heap size to 128MB.
- This will now always be the default heap size, unless the user overrides it.
+ This will always be the default heap size for this program, unless the user overrides it.
(Depending on the setting of the <option>-rtsopts</option> option, the user might
- not have the ability to change RTS options at run-time, in which case
+ not have the ability to change RTS options at run-time, in which case
<option>-with-rtsopts</option> would be the <emphasis>only</emphasis> way to set
them.)
</para>
<listitem>
<para>On Windows, GHC normally generates a
<firstterm>manifest</firstterm><indexterm><primary>manifest</primary>
- </indexterm>file when linking a binary. The
+ </indexterm> file when linking a binary. The
manifest is placed in the file
<literal><replaceable>prog</replaceable>.exe.manifest</literal>
where <replaceable>prog.exe</replaceable> is the name of the
system using the security control panel, but GHC by default
generates binaries that don't depend on the user having disabled
installer detection.</para>
-
+
<para>The <option>-fno-gen-manifest</option> disables generation of
the manifest file. One reason to do this would be if you had
a manifest file of your own, for example.</para>
<option>-fno-embed-manifest</option>, see below.</para>
</listitem>
</varlistentry>
-
+
<varlistentry>
<term>
<option>-fno-embed-manifest</option>
</indexterm>; to see exactly what GHC does to embed the manifest,
use the <option>-v</option> flag. A GHC installation comes with
its own copy of <literal>windres</literal> for this reason.</para>
-
+
<para>See also <option>-pgmwindres</option> (<xref
- linkend="replacing-phases" />) and
+ linkend="replacing-phases" />) and
<option>-optwindres</option> (<xref
linkend="forcing-options-through"
/>).</para>
</listitem>
</varlistentry>
-
+
<varlistentry>
<term>
<option>-fno-shared-implib</option>
disk-space cost of creating this import library, which can be substantial - it
might require as much space as the code itself, as Haskell DLLs tend to export
lots of symbols.</para>
-
+
<para>As long as you are happy to only be able to link to the DLL using
<literal>GetProcAddress</literal> and friends, you can supply the
<option>-fno-shared-implib</option> flag to disable the creation of the import
projects / ghc-hetmet.git / blobdiff