On Thu, 31 Jan 2013, Richard Biener wrote:
> On Wed, 30 Jan 2013, Pat Haugen wrote:
>
> > On 01/29/2013 04:53 AM, Richard Biener wrote:
> > > I'm curious about the affect of -fno-aggressive-loop-optimizations
> > > on SPEC CPU 2006 numbers (not curious enough to try for myself
> > > though). Both on extra PASSes for official latest sources
> > > (I have no access to those) and on performance.
> > The patch/option result in both 464.h264ref and 416.gamess passing (as
> > opposed
> > to infinite loop). As for performance, I didn't see any difference outside
> > of
> > noise range for both 32-bit and 64-bit runs on PowerPC.
>
> Ok, I'll go ahead and apply the patch then.
Done. I propose the following addition to changes.html.
Ok?
Thanks,
Richard.
2013-01-31 Richard Biener <rguent...@suse.de>
* changes.html: Mention -fno-aggressive-loop-optimizations.
Index: changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-4.8/changes.html,v
retrieving revision 1.89
diff -u -r1.89 changes.html
--- changes.html 27 Jan 2013 13:44:12 -0000 1.89
+++ changes.html 31 Jan 2013 09:05:20 -0000
@@ -30,6 +30,13 @@
<p>The G++ namespace association extension, <code>__attribute
((strong))</code>,
has been deprecated. Inline namespaces should be used instead.</p>
+<p>GCC now uses more a aggressive analysis to derive an upper bound for
+the number of iterations of loops using constraints imposed by language
+standards. This may cause non-conforming programs to no longer work as
+expected, such as SPEC CPU 2006 464.h264ref and 416.gamess. A new
+option, <code>-fno-aggressive-loop-optimizations</code>, was added
+to disable this aggressive analysis.</p>
+
<p>On ARM, a bug has been fixed in GCC's implementation of the AAPCS
rules for the layout of vectors that could lead to wrong code being
generated. Vectors larger than 8 bytes in size are now by default
