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Re: Add znver2 scheduler model

From: Jan Hubicka <hubicka at ucw dot cz>
To: gcc-patches at gcc dot gnu dot org
Date: Tue, 30 Jul 2019 11:28:57 +0200
Subject: Re: Add znver2 scheduler model
References: <20190723094134.6uz2x7fyb346cv3q@kam.mff.cuni.cz>

> Hi,
> this patch adds znver2 scheduler model. Znver2 is close enough to znver1
> that I have decided to implement it in one automaton.  The main
> difference is extra AGU unit that seems to be used for store only
> (according to CPU diagram), the fact that 256bit vector operations are
> no longer split (and thus they behave like 128bit) and reduced latency
> of fp multiply and conversion operations.
> 
> The patch seems to have very little effect on overall performance but
> since we do not model the out of order core and thus we think that the
> CPU is mostly starved by not having enough parallelism to exectue.
> Still it is better to be precise.
> 
> Bootstrapped/regtested x86_64-linux, commited.
> 
> 	* common/config/i386/i386-common.c: Use PROCESSOR_ZNVER2 scheduler for
> 	znver2.
> 	* config/i386/znver1.md: Enable patterns for znver2 and add store
> 	variants which use extra AGU unit.

Hello,
I have backported this patch to gcc 9 branch now too.

Honza

References:
- Add znver2 scheduler model
  - From: Jan Hubicka

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