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Subject: Re: [Qemu-devel] [PATCH 2/3] Get rid of temporary variable cache.
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From: Paul Brook <paul@codesourcery.com>
Date: Mon, 29 Jun 2009 19:34:55 +0100
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To: qemu-devel@nongnu.org
Cc: Filip Navara <filip.navara@gmail.com>

On Monday 29 June 2009, Filip Navara wrote:
> The temporary variable cache actually hurts TCG more than it helps.
> Empirical results show that when running the Dhrystone benchmark with this
> patch improves the speed by about 2%.

I find it hard to believe this patch has any significant effect on runtime, 
other than random variation. My guess is it spends almost all of its time in a 
few guest loops, and no time doing translation. I'd expect the generated code 
should be the same before and after.

I'm not saying this patch is a bad idea (new_tmp/dead_tmp predate 
tcg_temp_free and are now redundant), just that I don't believe your benchmark 
results.

Paul