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Re: Compilation time in gcc-4.4.0
On Tue, Jul 13, 2010 at 4:50 PM, Paolo Bonzini <bonzini@gnu.org> wrote:
> On 07/08/2010 10:58 PM, Maxiwell Garcia wrote:
>>
>> Hi,
>>
>> I am writing a paper about instruction-set architecture simulators. In
>> first time, I used gcc-4.4.0 and the compilation time reached 33
>> minutes (with -O3) for my simulator and the performance reached 270
>> MIPS (Million instruction per second). When I used the gcc-4.4.4, in
>> the same code, the compilation time reached 39 seconds and the
>> performance reached 600 MIPS. My code have many "switchs" with 512
>> "cases" and the library<systemc.h> ?is in use.
>> How to explain this behavior in the compilation and performance in my
>> paper?
>
> Try -ftime-report, it should explain the compilation time change. ?Such a
> dramatic performance change is usually due to better register allocation,
> but this is just a guess.
I would guess it was the various backports of tree PRE fixes actually.
Richard.
> Paolo
>