[Bug target/27855] reassociation pass produces ~30% slower matrix multiplication code

[ubizjak at gmail dot com]

------- Comment #13 from ubizjak at gmail dot com  2007-03-02 15:34 -------
Any news about this problem?
Current mainline still has severe problems:

-msse3 -O2 -mfpmath=sse -ffast-math
GCC 4.3 -ffast-math double performance:
ALGORITHM     NB   REPS        TIME      MFLOPS
=========  =====  =====  ==========  ==========
atlasmm       60   1000       0.288     1499.91

-msse3 -O2 -mfpmath=sse
GCC 4.3 double performance:
ALGORITHM     NB   REPS        TIME      MFLOPS
=========  =====  =====  ==========  ==========
atlasmm       60   1000       0.192     2249.86

-msse3 -O2 -mfpmath=sse -ffast-math
GCC 4.3 -ffast-math single performance:
ALGORITHM     NB   REPS        TIME      MFLOPS
=========  =====  =====  ==========  ==========
atlasmm       60   1000       0.304     1420.96

-msse3 -O2 -mfpmath=sse
GCC 4.3 single performance:
ALGORITHM     NB   REPS        TIME      MFLOPS
=========  =====  =====  ==========  ==========
atlasmm       60   1000       0.172     2511.48

Please consider the fact that all benchmarks are using -ffast-math nowadays. ;)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27855