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Re: [PATCH][AArch64] Improve aarch64_case_values_threshold setting

From: Evandro Menezes <e dot menezes at samsung dot com>
To: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>, Jim Wilson <jim dot wilson at linaro dot org>, James Greenhalgh <James dot Greenhalgh at arm dot com>
Cc: nd <nd at arm dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, "philipp dot tomsich at theobroma-systems dot com" <philipp dot tomsich at theobroma-systems dot com>, "benedikt dot huber at theobroma-systems dot com" <benedikt dot huber at theobroma-systems dot com>, "pinskia at gmail dot com" <pinskia at gmail dot com>
Date: Tue, 24 May 2016 10:11:45 -0500
Subject: Re: [PATCH][AArch64] Improve aarch64_case_values_threshold setting
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On 05/24/16 07:08, Wilco Dijkstra wrote:

Jim Wilson wrote:

It looks like a slight lose on qdf24xx on SPEC CPU2006 at -O3.  I see
about a 0.37% loss on the integer benchmarks, and no significant
change on the FP benchmarks.  The integer loss is mainly due to
458.sjeng which drops 2%.  We had tried various values for
max_case_values earlier, and didn't see any performance improvement
from setting it, so we are using the default value.

That's interesting as sjeng shows ~2% gain on Cortex-A72 due to the
hot switches being badly laid out... I wonder whether the loss you see is
due to code alignment or some other secondary effect.

I always thought that this patch, that lays out the branch tree moreoptimally, deserved to be revisited:https://gcc.gnu.org/ml/gcc-patches/2008-04/msg02197.html


Cheers,

--
Evandro Menezes

References:
- Re: [PATCH][AArch64] Improve aarch64_case_values_threshold setting
  - From: Wilco Dijkstra
- Re: [PATCH][AArch64] Improve aarch64_case_values_threshold setting
  - From: James Greenhalgh
- Re: [PATCH][AArch64] Improve aarch64_case_values_threshold setting
  - From: Jim Wilson
- Re: [PATCH][AArch64] Improve aarch64_case_values_threshold setting
  - From: Wilco Dijkstra

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