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Re: GCSE store motion
- From: Roger Sayle <roger at eyesopen dot com>
- To: <gcc at gcc dot gnu dot org>
- Cc: Mark Mitchell <mark at codesourcery dot com>, "David S. Miller" <davem at redhat dot com>, Andreas Jaeger <aj at suse dot de>, Daniel Berlin <dberlin at dberlin dot org>, Richard Henderson <rth at redhat dot com>
- Date: Wed, 15 May 2002 09:29:53 -0600 (MDT)
- Subject: Re: GCSE store motion
I'm more than happy to attempt to fix GCSE store motion, but my current
understanding is that its working perfectly!
PR opt/5200 was filed by Andreas Jaeger on the supporting evidence of
PR opt/5172 and postings by Dan Berlin to gcc-patches last year.
In the review of my patch to that attempted to fix PR/5172
became clear that it was glibc at fault and not the store motion
pass at all.
Hence the only remaining claims that store motion is broken are
the comments by Dan Berlin, but as far as I am aware there are
no known examples of failing test cases. Dan also claimed that
store motion wasn't currently doing anything, but clearly PR/5172
showed that duplicate stores are being eliminated in real code.
To appease the paranoia of the pending GCC 3.1 release it was
decided to disable this optimization even without conclusive
evidence that anything was broken. Unless a failing test in
the GCC test suite starts passing, I'm against disabling a
functional optimization on the CVS mainline. Finding a failing
test case would also help the call for volunteers to fix it.
Roger Sayle, E-mail: email@example.com
OpenEye Scientific Software, WWW: http://www.eyesopen.com/
Suite 1107, 3600 Cerrillos Road, Tel: (+1) 505-473-7385
Santa Fe, New Mexico, 87507. Fax: (+1) 505-473-0833