[Bug tree-optimization/42108] [4.4/4.5 Regression] 50% performance regression

[rguenth at gcc dot gnu dot org]

------- Comment #43 from rguenth at gcc dot gnu dot org  2009-12-19 19:29 -------
Btw, with the patch from comment #33 LIM will now hoist the division
properly and the performance regression would be fixed(?).  The patch
will though likely cause verification issues with -fnon-call-exceptions
for one and infrastructure-wise is still a hack.

Now testing the orginal testcase on i?86 doesn't show a performance improvement
though (but it's marginally faster than with 4.3).  Interestingly with
-mfpmath=sse -march=native trunk is a lot slower than 4.3 (but 4.3 isn't
much faster than trunk w/o that options).  The patch from comment #33
seems to recover that.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42108