On 07/13/2010 04:53 PM, Richard Guenther wrote:
On Tue, Jul 13, 2010 at 4:50 PM, Paolo Bonzini<bonz...@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.
Sorry, I was referring to the change in performance which I justified by
better register allocation. PRE is indeed a good candidate for the
compilation time fixes. Could the changes to PRE cause different code
to be generated?
Paolo
