unreviewed testsuite patch for profile-directed optimizations

[Janis Johnson <janis187 at us dot ibm dot com>]

Last week I submitted a testsuite patch for which I have received no
feedback: http://gcc.gnu.org/ml/gcc-patches/2001-08/msg01798.html.   
It adds testsuite/lib/profopt.exp and some tests in gcc.misc-tests to
demonstrate its use.  This new script supports checking that profile-
directed optimizations do not break anything.  There's also support for
checking that a profile-directed optimization does not degrade
performance.

Those of you working on such optimizations might find this functionality
useful for adding regression tests when you fix bugs that only show up
when the profile-directed optimization is used, since as far as I can
tell there is currently no way to do this in the test suite.

I have plans for improvements for profopt.exp; I now know how to handle
XFAIL, and perhaps for the performance checks it can get an acceptable
performance degradation percentage from a test's .x file.  In the
meantime I'd appreciate hearing whether this script is worthwhile and
whether the performance checks seem reasonable in testing environments.

Thanks,
  
Janis