(out-of-band) performance with gcc3

[Marc-Antoine Parent]

Le 04-01-19, 
 12:34, duchier at ps.uni-sb.de a ‚crit :

> kost at sics.se (Konstantin Popov) writes:
>
>> The good news is that I managed to find the "right" option(s) to boost
>> the Mozart's performance with gcc3: one got to compile the emulator
>> with '-fno-guess-branch-probability' (which brings 'PC' back into a
>> [hardware] register),

I was curious re what the effect would be on Darwin-ppc.
I am using CVS head, and I introduced that flag 
(-fno-guess-branch-probability) in the Makefile.
FYI, I am using gcc version 3.3 20030304 (Apple Computer, Inc. build 
1495)
and the other flags are -O3 -fstrict-aliasing -fschedule-insns2 
-fomit-frame-pointer
(adding  -finline-limit=500 on the emulator)

The results (using Deny's benchmark) are... mixed, mostly negative 
actually:
(But the variance on the results is scary, to be honest)

With -fno-guess-branch-probability
Bridge: 3940
Compiler: 3110
Diff: 3650
FD: 5650
Knights: 2730
Nrev: 5010
Port: 4930
Rec: 5240
Tak: 3750
Tak Thread: 2160

Without -fno-guess-branch-probability
Bridge: 3720
Compiler: 2920
Diff: 3310
FD: 5490
Knights: 2700
Nrev: 5170
Port: 4820
Rec: 5240
Tak: 3710
Tak Thread: 2720

Marc-Antoine

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