131 lines
5.2 KiB
HTML
131 lines
5.2 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
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<HTML>
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<HEAD>
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<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
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<META NAME="AUTHOR" CONTENT="pme@sources.redhat.com (Phil Edwards)">
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<META NAME="KEYWORDS" CONTENT="libgcc.a, rebuild">
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<META NAME="DESCRIPTION" CONTENT="How to automatically rebuild libgcc.a.">
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<META NAME="GENERATOR" CONTENT="vi and eight fingers">
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<TITLE>How to automatically rebuild libgcc.a.</TITLE>
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<LINK REL="home" HREF="http://sources.redhat.com/libstdc++/">
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<LINK REL=StyleSheet HREF="lib3styles.css">
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<!-- $Id: gccrebuild.html,v 1.4 2000/07/07 21:13:27 pme Exp $ -->
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</HEAD>
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<BODY>
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<H2 CLASS="centered"><TT>--enable-libgcc-rebuild</TT></H2>
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<P><B>NOTA BENE</B>: If using the <TT>--enable-libstdcxx-v3</TT> approach
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to configuring, the std namespace will be turned on for you, without
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going this route. Only use this flag if you'd like to experiment
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with yet more binary incompatibilities, as discussed below.
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</P>
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<HR>
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<P>If you build libstdc++ using certain flags (e.g., -fnew-abi), then
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programs that use some of the new C++ language features (like namespace
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std and RTTI) will only link if the compiler's libgcc is built using
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the same flags. Other extralinguistic flags (like -fsquangle to change
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the name mangling algorithm) will have the same effect.
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</P>
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<P>Passing --enable-libgcc-rebuild to libstdc++'s configure script
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means that when you type 'make' next, after libstdc++ is built,
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then libgcc will also be rebuilt. If you've given other
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--enable/--with switches to libstdc++ that would require a core
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library rebuild, then those compiler options will be automatically
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used when compiling libgcc, such that both libraries will always be
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built with the same options.
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</P>
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<P>The argument to this enable switch is the path to the GCC build
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directory. The GCC configuration documentation refers to this directory
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as <EM>objdir</EM>; here it will be called <EM>GCCobjdir</EM>.
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</P>
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<P>This was required for a few busy months of development, but was
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always acknowledged a kludge. After the library sources were merged into
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the compiler sources, this was commented out. If you must re-enable
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it, you amy do so by uncommenting the GLIBCPP_ENABLE_RELIBGCC line in
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configure.in and regenerating.
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</P>
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<HR>
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<H3>If you kept your <EM>GCCobjdir</EM></H3>
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<P>Easy as pi, er, pie. Just pass the pathname to the --enable switch
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(absolute pathnames are best), and build libstdc++ as you normally
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would. When it is finished, 'make' will go over to <EM>GCCobjdir</EM>
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and build a new libgcc.a for you.
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</P>
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<P>Once that's done, skip down to "Installing the new libgcc.a."
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</P>
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<H3>If you deleted your <EM>GCCobjdir</EM>, or never had one</H3>
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<P>Aaargggghhh, you had to make things difficult. Okay, note for future
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reference: if you plan on experimenting with weird features, you'll want
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to keep your build directories around. If you're having to re-unpack
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the GCC source for this step, the same thing applies.
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</P>
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<P>We don't put a whole lot of effort into supporting this, so you might
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just have to go the long way 'round if you run into difficulties.
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</P>
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<P>You'll have to trick the configure script into believing that libgcc.a
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has been previously built. You'll also have to build the libraries that
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libgcc.a needs. The steps are these:
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<OL>
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<LI>Unpack the GCC sources. Call this directory <EM>GCCsrcdir</EM>.
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<LI>"<TT>mkdir <EM>GCCobjdir</EM> && cd <EM>GCCobjdir</EM> &&
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<EM>GCCsrcdir</EM>/configure --whatever</TT>"
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<BR>Configure GCC like you normally would. See
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<A HREF="http://gcc.gnu.org/install/configure.html">the GCC
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configuration instructions</A> for all the possible values
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of <TT>--whatever</TT>.
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<LI>"<TT>cd libiberty && make</TT>"
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<LI>"<TT>cd ../gcc; touch libgcc2.ready</TT>"
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</OL>
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Now go back to "If you kept your GCCobjdir" and proceed from there.
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</P>
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<H3>Installing the new libgcc.a</H3>
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<P>The reckless method is
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<PRE>
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cd GCCobjdir/gcc
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make install-libgcc</PRE>
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This will copy in the new libgcc.a on top of the old one.
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</P>
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<P>The wiser method is to keep the old one around under a different name,
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and install the new one under another different name, and then make
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libgcc.a be a hard or soft link to one of the two real libraries. Or
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copy one of them by a new name into a directory searched by the linker,
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and use -l (dash ell) to pick it up before finding the default
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<EM>other</EM> library.
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</P>
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<HR>
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<P>If you're <B>really</B> interested in using a particular flag (say,
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-fhonor-std) under <B>all</B> conditions, then you can edit
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<EM>GCCsrcdir</EM>/gcc/cp/decl2.c and change the initialization of the
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appropriate <TT>flag_</TT> variable to 1. This will turn that flag
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on by default, which means that libgcc.a, libstdc++.a, libstdc++.so,
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and everything else you ever do will be built with that feature
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unless you specifically turn it <EM>off</EM>.
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</P>
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<!-- ####################################################### -->
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<HR>
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<P CLASS="fineprint"><EM>
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$Id: gccrebuild.html,v 1.4 2000/07/07 21:13:27 pme Exp $
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</EM></P>
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