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From: Richard Henderson <richard.henderson@linaro.org>
To: David Gibson <david@gibson.dropbear.id.au>,
	"Bruno Larsen (billionai)" <bruno.larsen@eldorado.org.br>
Cc: qemu-devel@nongnu.org, lagarcia@br.ibm.com,
	lucas.araujo@eldorado.org.br, fernando.valle@eldorado.org.br,
	qemu-ppc@nongnu.org, andre.silva@eldorado.org.br,
	matheus.ferst@eldorado.org.br, luis.pires@eldorado.org.br
Subject: Re: [PATCH 2/4] target/ppc: added solutions for building with disable-tcg
Date: Mon, 12 Apr 2021 08:40:47 -0700	[thread overview]
Message-ID: <26d5b8e4-693d-f747-3b7f-d984a43f0209@linaro.org> (raw)
In-Reply-To: <YHPV19l06sgXCNEj@yekko.fritz.box>

On 4/11/21 10:08 PM, David Gibson wrote:
> Not directly related to what you're trying to accomplish here, but the
> whole vscr_sat thing looks really weird.  I have no idea why we're
> splitting out the storage of VSCR[SAT] for the TCG case at all.  If
> you wanted to clean that up as a preliminary, I'd be grateful.

That's about efficiently implementing the vector saturation instructions in 
TCG.  See GEN_VXFORM_SAT in translate/vmx-impl.c.inc.

The SAT bit is represented as a vector that e.g. compares the result of 
addition with the result of saturating addition.  We don't need to resolve that 
to a single bit until the VSCR register is read.


r~


  reply	other threads:[~2021-04-12 15:42 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-09 15:19 [RFC PATCH 0/4] target/ppc: add disable-tcg option Bruno Larsen (billionai)
2021-04-09 15:19 ` [PATCH 1/4] target/ppc: Code motion required to build disabling tcg Bruno Larsen (billionai)
2021-04-09 19:48   ` Fabiano Rosas
2021-04-12  4:34     ` David Gibson
2021-04-09 15:19 ` [PATCH 2/4] target/ppc: added solutions for building with disable-tcg Bruno Larsen (billionai)
2021-04-09 20:40   ` Fabiano Rosas
2021-04-12  5:08   ` David Gibson
2021-04-12 15:40     ` Richard Henderson [this message]
2021-04-13  6:42       ` David Gibson
2021-04-09 15:19 ` [PATCH 3/4] target/ppc: Add stubs for tcg functions, so it builds Bruno Larsen (billionai)
2021-04-19  5:28   ` David Gibson
2021-04-09 15:19 ` [PATCH 4/4] target/ppc: updated build rules for disable-tcg option Bruno Larsen (billionai)
2021-04-09 15:57 ` [RFC PATCH 0/4] target/ppc: add " no-reply
2021-04-12  5:13   ` David Gibson
2021-04-12  4:32 ` David Gibson

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