From 18c460806c78c9a85894d838d4e854ea63de2b73 Mon Sep 17 00:00:00 2001 From: lkcl Date: Sun, 30 Apr 2023 03:00:45 +0100 Subject: [PATCH] --- openpower/sv/rfc/ls012.mdwn | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/openpower/sv/rfc/ls012.mdwn b/openpower/sv/rfc/ls012.mdwn index 99fcbec2e..a31ce8c97 100644 --- a/openpower/sv/rfc/ls012.mdwn +++ b/openpower/sv/rfc/ls012.mdwn @@ -636,6 +636,11 @@ the saving in power consumption and time was definitely worthwhile, and it neatly illustrates a counter-example to trying to make one instruction do too much. +Another good example is the Integer Twin-butterfly instructions, +`((a +/- b) * c) >> sh` which require **eight** instructions and +temporary registers. Although expensive they save so many other +instructions it is hard to disregard them. + **Summary** There are many tradeoffs here, it is a huge list of considerations: any -- 2.30.2