[wwwdocs] My GCC 4.2 changes

[Paolo Bonzini <paolo dot bonzini at lu dot unisi dot ch>]

This patch documents the visible changes that I'm more or less 
responsible for.  These include the reload changes to support SSE math 
(PR/19653), the bashjar script, toplevel bootstrap and --with-target-tools.

I don't remember exactly the speed-up for the x86 change, but I'm doing 
a reportable run of SPECfp2000 (-O2 vs. -mfpmath=sse -msse2 -O2).  When 
committing the patch I will adjust it from 5% to whatever I find.

Tested with the W3C validator, which only complains about a missing 
DOCTYPE (without and with the patch).  Ok to commit?

Paolo

Index: changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-4.2/changes.html,v
retrieving revision 1.10
diff -p -u -r1.10 changes.html
--- changes.html        5 Jun 2006 18:37:15 -0000       1.10
+++ changes.html        4 Jul 2006 08:04:47 -0000
@@ -86,10 +86,28 @@
          http://gcc.gnu.org/wiki/Statically%20linking%20libgcj
      </a>
    </li>
+
+    <li>
+      <tt>fastjar</tt> is not bundled anymore with GCC.  To build libgcj,
+      you will need either InfoZIP (both <tt>zip</tt> and <tt>unzip</tt>)
+      or an external <tt>jar</tt> program.  In the former case, the GCC
+      build will install a <tt>jar</tt> shell script that uses InfoZIP
+      to provide the functionality of <tt>jar</tt>.
  </ul>

<h2>New Targets and Target Specific Improvements</h2>

+<h3>x86/x86-64</h3>
+  <ul>
+    <li>The generated code for scalar SSE floating-point instructions
+      has been improved.  Using SSE for math on 32-bit CPUs can
+      provide speed improvements around 5\% over the x87 instruction
+      set, though the resulting binary will only run on processors
+      that implement the instructions.  To do so, use the
+      options <tt>-mfpmath=sse -msse</tt> or <tt>-mfpmath=sse
+      -msse2</tt>.</li>
+  </ul>
+
<h3>SPARC</h3>
  <ul>
    <li>The default CPU setting has been changed from V7 to V9 in 32-bit
@@ -113,5 +131,48 @@

<h2>Other significant improvements</h2>

+<h3>Build system improvements</h3>
+  <ul>
+    <li><p>All the components of the compiler are now bootstrapped by
+        default.  This improves the resilience to bugs in the system
+        compiler or binary compatibility problems, as well as providing
+        better testing of GCC 4.2 itself.  In addition, if you build
+       the compiler from a combined tree, the assembler, linker, etc.
+       will also be bootstrapped (i.e. built with themselves).</p>
+
+        <p>You can disable this behavior, and go back to
+       the pre-GCC 4.2 set up, by configuring GCC with
+       <tt>--disable-bootstrap</tt>.</p></li>
+
+    <li><p>The rules that <tt>configure</tt> follows to find target tools
+        resemble more closely the locations that the built compiler
+        will search.  In addition, you can use the new configure option
+        <tt>--with-target-tools</tt> to specify where to find the
+        target tools used during the build, without affecting what the
+        built compiler will use.</p>
+
+        <p>This can be especially useful when building packages of
+        GCC.  For example, you may want to build GCC with
+        GNU <tt>as</tt> or <tt>ld</tt>, even if the resulting compiler
+        to work with the native assembler and linker.  To do so, you
+        can use <tt>--with-target-tools</tt> to point to the native
+        tools.</p></li>
+  </ul>
+
+<h3>Incompatible changes to the build system</h3>
+  <ul>
+    <li>Front-ends external to GCC should modify their
+       <tt>Make-lang.in</tt> file to replace double-colon rules
+       (e.g. <tt>dvi::</tt>) with normal rules (like <tt>lang.dvi:</tt>).
+       Front-end makefile hooks do not use double-colon rules anymore.</li>
+
+    <li>Up to GCC 4.1, a popular way to specify the target tools used 
during
+       the build was to create directories named <tt>gas</tt>, 
<tt>binutils</tt>,
+       etc. in the build tree, and create links to the tools from there.
+       This does not work anymore when the compiler is bootstrapped.  The
+       new configure option <tt>--with-target-tools</tt> provides a better
+       way to achieve the same effect, and works for all native and cross
+       settings.</li>
+  </ul>
</body>
</html>