在 2013-04-09二的 17:20 +0800，陳韋任 (Wei-Ren Chen)写道： > Hi liguang, > > On Tue, Apr 09, 2013 at 04:21:10PM +0800, li guang wrote: > > 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. > > As Peter said, only profiling can show if there is a performance > improvement. > > > > 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. > > num_insns and max_insns are two different variables, right? So this > assignment does not do anything with num_insns.
Yes, you're right. Thanks! > > Regards, > chenwj >
