[Bug target/34163] [4.3/4.4 Regression] 10% performance regression since Nov 1 on Polyhedron's "NF" on AMD64

["rob1weld at aol dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #12 from rob1weld at aol dot com  2009-01-28 03:54 -------
On the Trunk using "-O2" or "-O3" can produce slower code.

I built gcc version 4.4.0 20090126 [trunk revision 143680] for
i386-redhat-linux
and was dismayed to find that libmudflaps had a few FAILs:

Results for 4.4.0 20090126 (experimental) [trunk revision 143680] (GCC)
testsuite on i386-redhat-linux-gnu
http://gcc.gnu.org/ml/gcc-testresults/2009-01/msg02853.html


The file "libmudflap.cth/pass40-frag.c" fails with NO optimization due to:
6100 6200 WARNING: program timed out.
FAIL: libmudflap.cth/pass40-frag.c output pattern test
Since it is only completing 62% of it's task the timeout needs an appropriate
increase.


The file "libmudflap.cth/pass40-frag.c" fails with "-O2" due to:
4100 4200 4300 4400 4500 4600 4700 4800 4900 WARNING: program timed out.
FAIL: libmudflap.cth/pass40-frag.c (-O2) output pattern test
With "-O2" it only completes 49% (slower than default).


The file "libmudflap.cth/pass40-frag.c" fails with "-O3" due to:
5100 5200 5300 5400 5500 5600 5700 5800 WARNING: program timed out.
FAIL: libmudflap.cth/pass40-frag.c (-O3) output pattern test
With "-O3" it only completes 58% (slower than default, but faster than "-O2").

Rob


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34163