Re: [Qemu-devel] [PATCH] translate: optimize gen_intermediate_code_internal

[li guang]

在 2013-04-09二的 10:11 +0200，Paolo Bonzini写道：
> Il 09/04/2013 10:05, 陳韋任 (Wei-Ren Chen) ha scritto:
> > Hi liguang,
> > 
> >   Just to be curious, how much performance improvement this patch can get?
> 
> I think zero.  It is indeed making the code a tiny bit more readable in
> the 2nd/3rd/5th/6th hunks.

I think maybe a little greater than 0,
for it optimizes a variable 'lj' increment.

> 
> But the 1st and 4th hunks, which do
> 
> -    num_insns = 0;
> 
> are wrong.  I'm surprised the compiler doesn't report usage of an
> uninitialized variable.  liguang, how did you test them?

I do normal compile and run guest OS for TCG,
I think 'max_insns = tb->cflags & CF_COUNT_MASK;' is enough
to feed compiler.

> 
> Paolo
> 
> 
> > Regards,
> > chenwj
>