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Re: [PATCH] Enhance reload_cse_move2add
On 07/09/2010 06:58 PM, Jie Zhang wrote:
> I just tested idctrn01 on my pentium-m laptop. My patch does not change
> the performance of idctrn01 on i386. I did some investigation. It's
> because i386 can directly use "symbol_ref + offset" as the address in
> load instructions. So there is no optimization opportunity that my patch
> can utilize. That's the difference between RISC and CISC.
[...]
> I collected the code size data from SPEC2000 on AMD64. My patch does not
> change code size for any test whether -O2 or -O3, except
>
> Code Size
> =========
> Test -O2 Before After Change
> ----------------------------------------------
> 172.mgrid 14962 14976 14
>
> Code Size
> Test -O3 Before After Change
> ----------------------------------------------
> 171.swim 19231 19247 16
So what kinds of changes are there that would explain a 1.48% drop on
179.art? If you can verify that the code is in fact identical, and the
performance change is noise, the patch is ok.
Bernd