From c819f8562f9efd63a4591669b94582d769537cd3 Mon Sep 17 00:00:00 2001 From: lkcl Date: Sat, 8 Apr 2023 11:40:25 +0100 Subject: [PATCH] --- openpower/sv/rfc/ls012.mdwn | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/openpower/sv/rfc/ls012.mdwn b/openpower/sv/rfc/ls012.mdwn index 395863cf2..cae948fb4 100644 --- a/openpower/sv/rfc/ls012.mdwn +++ b/openpower/sv/rfc/ls012.mdwn @@ -82,6 +82,20 @@ where IEEE754 full bit-accuracy is paramount. In 3D GPU scenarios for example even 12-bit accuracy can be overkill, but for HPC Scientific scenarios 12-bit would be disastrous. +There are a **lot** of operations here, and they also bring Power ISA +up-to-date to IEEE754-2019. Fortunately the number of critical instructions +is quite low, but the caveat is that if those operations are utilised to +synthesise other IEEE754 operations (divide by `pi` for example) full bitlevel +accuracy (a hard requirement for IEEE754) is lost. + +Also worth noting that the Khronos Group defines minimum acceptable bit-accuracy +levels for 3D Graphics: these are **nowhere near* the full accuracy demanded +by IEEE754, the reason for the Khronos definitions is a massive reduction often +four-fold in power consumption and gate count when 3D Graphics simply has no need +for full accuracy. + +*For 3D GPU markets this definitely needs addressing* + ## Audio/Video Found at [[sv/av_opcodes]] these do not require Saturated variants because Saturation -- 2.30.2