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Re: [Qemu-devel] [PATCH 0/6] Implement constant folding and copy propaga
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH 0/6] Implement constant folding and copy propagation in TCG |
Date: |
Sat, 21 May 2011 14:48:30 +0200 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
On Fri, May 20, 2011 at 09:35:08PM +0200, Aurelien Jarno wrote:
> On Fri, May 20, 2011 at 04:39:27PM +0400, Kirill Batuzov wrote:
> > This series implements some basic machine-independent optimizations. They
> > simplify code and allow liveness analysis do it's work better.
> >
> > Suppose we have following ARM code:
> >
> > movw r12, #0xb6db
> > movt r12, #0xdb6d
> >
> > In TCG before optimizations we'll have:
> >
> > movi_i32 tmp8,$0xb6db
> > mov_i32 r12,tmp8
> > mov_i32 tmp8,r12
> > ext16u_i32 tmp8,tmp8
> > movi_i32 tmp9,$0xdb6d0000
> > or_i32 tmp8,tmp8,tmp9
> > mov_i32 r12,tmp8
> >
> > And after optimizations we'll have this:
> >
> > movi_i32 r12,$0xdb6db6db
> >
> > Here are performance evaluation results on SPEC CPU2000 integer tests in
> > user-mode emulation on x86_64 host. There were 5 runs of each test on
> > reference data set. The tables below show runtime in seconds for all these
> > runs.
>
> How are the tests done? Are they done with linux-user, or running the
> executables in qemu-system-xxx?
>
Another point I forgot, the current TCG code already does a very simple
copy and constant propagation, so it might be a good idea to end the
series with cleanup this code. There is no point in doing such
optimisation twice, and it is most probably taking a non negligible
time. This way you can provide benchmarks on the whole set.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- Re: [Qemu-devel] [PATCH 4/6] Do constant folding for boolean operations., (continued)
Re: [Qemu-devel] [PATCH 0/6] Implement constant folding and copy propagation in TCG, Aurelien Jarno, 2011/05/20