Re: GCSE store motion

[Roger Sayle <roger@eyesopen.com>]

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
http://gcc.gnu.org/ml/gcc-patches/2002-01/msg01142.html, it
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
--
Roger Sayle,                         E-mail: roger@eyesopen.com
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