[Bug target/27827] gcc 4 produces worse x87 code on all platforms than gcc 3

["whaley at cs dot utsa dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #17 from whaley at cs dot utsa dot edu  2006-06-25 13:17 -------
OK, thanks for the reply.  I will assume gcc 4 won't be fixed in the near
future.  My guess is this will make icc an easier compiler for users, which I
kind of hate, which is why I worked as much as I did on this report . . .

I hope you will consider adding the mmbench4s.tar.gz attachment above (the one
that runs both single and double precision) to the gcc regression tests. 
Notice that it caught this problem between 3 and 4, as well as a similar fp
performance drop between gcc 2 and 3 (bugzilla 4991).  The kernel here is
typical of those used in ATLAS, which is used by hundreds of thousands of
people worldwide.  I believe these kernels are also typical of pretty much any
register blocked fp code, so having them in the regression tests may help other
open source fp packages (eg, fftw, etc) as well.  Notice that closed-source
alternatives that ship binaries do not face this challenge, so that having the
compiler drop between releases gives them an advantage, and can drive HPC users
(where performance dictates everything) to proprietary solutions.

Thanks,
Clint


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27827