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Re: [PATCH 00/27] tcg: Simplify temporary usage


From: Emilio Cota
Subject: Re: [PATCH 00/27] tcg: Simplify temporary usage
Date: Wed, 1 Mar 2023 07:11:48 -0500

On Wed, Feb 15, 2023 at 20:15:37 -1000, Richard Henderson wrote:
> On 2/10/23 02:35, Emilio Cota wrote:
> > I ran yesterday linux-user SPEC06 benchmarks from your tcg-life branch.
> > I do see perf regressions for two workloads (sjeng and xalancbmk).
> > With perf(1) I see liveness_pass* are at 0.00%, so I wonder: is it
> > possible that the emitted code isn't quite the same?
> 
> Everything that I checked by hand was the same, but it's possible.
> It's a tedious process.  You'd definitely want to turn off ASR.

I've checked with -jitdump and perf whether there was any difference
in the generated code before vs. after for the most common TBs.
They were identical.

Benchmarking without ASR didn't make a difference, unfortunately.

> My current branch has __attribute__((noreturn)) added to all of the liveness
> passes, so that they don't get folded into tcg_gen_code.  But I still would
> expect 0%.

I'll bisect the series in the next few days see exactly where
the perf regression begins so that at least we know where to look.

Thanks,
                Emilio



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