spec2k comparison of gcc 4.1 and 4.2 on AMD K8

[Serge Belyshev <belyshev at depni dot sinp dot msu dot ru>]

I have compared 4.1.2 release (r121943) with three revisions of 4.2 on spec2k
on an 2GHz AMD Athlon64 box (in 64bit mode), detailed results are below.

In short, current 4.2 performs just as good as 4.1 on this target
with the exception of huge 80% win on 178.galgel. All other difference
lies almost in the noise.

results:

first number in each column is a runtime difference in %
between corresponding 4.2 revision and 4.1.2 (+ is better, - is worse).

second number is a +- confidence interval, i.e. according to my results,
current 4.2 does (82.0+-1.7)% better than 4.1.2 on 178.galgel.

(note some results are clearly noisy, but I've tried hard to avoid this --
I did three runs on a completely idle machine, wasting 14 hours of machine time in total).

r117890 -- 4.2 just before DannyB's aliasing fixes
r117891 -- 4.2 with aliasing fixes.
r122236 -- 4.2 current.

CINT2000         r117890         r117891         r122236

164.gzip        -4.2 1.7        -4.2 1.2        -4.0 1.3
175.vpr          1.7 2.6         1.4 2.3         1.1 2.5
176.gcc         -0.5 0.8        -0.8 1.1        -1.2 4.0
181.mcf         -0.4 2.0        -0.1 2.1        -0.6 2.7
186.crafty      -0.4 6.4        -1.3 7.0         0.8 4.4
197.parser       0.7 1.3         0.8 1.5        -0.3 1.6
252.eon          8.8 3.7        10.6 9.4         6.9 4.7
253.perlbmk      2.7 1.0         3.4 1.4         3.0 1.9
254.gap         -0.6 0.5        -0.5 0.4        -0.4 0.6
255.vortex       1.3 0.9         1.2 1.2         1.4 1.1
256.bzip2        0.6 1.6         0.9 1.6         0.4 1.7
300.twolf        0.1 4.5         0.8 1.4        -0.6 2.0


CFP2000

168.wupwise      0.2 22.0        0.1 22.1        2.2 13.6
171.swim        -0.1 0.7        -0.3 0.1        -0.3 0.2
172.mgrid       -6.3 0.4        -6.1 0.4        -6.6 0.3
173.applu       -0.1 0.8         0.1 0.9        -0.4 0.1
177.mesa         6.9 15.1        7.2 15.1        3.9 5.3
178.galgel      80.8 1.7        80.9 2.0        82.0 1.7
179.art          0.8 8.9        -1.6 8.1        -0.3 5.1
183.equake      -0.9 1.0        -0.8 0.9        -0.9 0.9
187.facerec      2.7 0.7         2.9 0.8         3.0 0.6
188.ammp        -0.4 0.5        -0.1 1.0        -0.5 0.7
189.lucas       -0.8 0.5        -0.7 0.6        -0.4 0.6
191.fma3d        1.1 2.1        -0.9 2.3        -1.0 2.2
200.sixtrack    -0.7 0.4        -0.7 0.5        -1.3 0.4
301.apsi        -3.0 1.4        -2.7 1.1        -3.1 0.3


remarks:

1. big jump on 178.galgel can be seen here too:
   http://www.suse.de/~aj/SPEC/amd64/CFP/sandbox-britten/178_galgel_big.png

2. even though I did three runs, most of the difference is noise,
   which means that one should treat single-run spec results with a *big* grain of salt.

3. on this AMD K8 machine the difference between 4.2 with aliasing fixes and 4.2 w/o
   aliasing fixes lies completely in the noise (modulo small 2% 191.fma3d regression).