From d58798aea71724ff7bf809f6a5160ca91bcc8d25 Mon Sep 17 00:00:00 2001 From: lkcl Date: Tue, 8 Dec 2020 23:42:01 +0000 Subject: [PATCH] --- openpower/sv/svp_rewrite/svp64/discussion.mdwn | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/openpower/sv/svp_rewrite/svp64/discussion.mdwn b/openpower/sv/svp_rewrite/svp64/discussion.mdwn index 23c8cdb76..89e8b343a 100644 --- a/openpower/sv/svp_rewrite/svp64/discussion.mdwn +++ b/openpower/sv/svp_rewrite/svp64/discussion.mdwn @@ -10,3 +10,18 @@ totals: 22 bits leaving 2 spare for further modes. http://lists.libre-soc.org/pipermail/libre-soc-dev/2020-December/001434.html + +# Notes about Swizzle + +Basically, there isn't enough room to try to fit two src src1/2 swizzle, and SV, even into 64 bit. + +therefore the strategy proposed is: + +* design 16bit scalar ops +* use the 11 bit old SV prefix to create 32bit insns +* when those are embedded into v3.1B 64 prefix, the 24 bits are entirely allocated to swizzle. + +with 2x12 this would mean no need to have complex encoding of swizzle. + +if we really do need 2 bits spare then the complex encoder of swizzle could be deployed. + -- 2.30.2