From: lkcl Date: Mon, 21 Dec 2020 18:53:58 +0000 (+0000) Subject: (no commit message) X-Git-Tag: convert-csv-opcode-to-binary~1074 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=65a22eb47fc652612752ce648ebb14975931ffb7;p=libreriscv.git --- diff --git a/openpower/sv/svp_rewrite/svp64.mdwn b/openpower/sv/svp_rewrite/svp64.mdwn index e658a0f0b..b7a483cfa 100644 --- a/openpower/sv/svp_rewrite/svp64.mdwn +++ b/openpower/sv/svp_rewrite/svp64.mdwn @@ -49,7 +49,9 @@ An interesting side-effect of this decision is that the OE flag is now free for SV is primarily designed for use as an efficient hybrid 3D GPU / VPU / CPU ISA. -As mentioned above, OE=1 is not applicable in SV, freeing this bit for alternative uses. Additionally, Vectorisation of the VSX SIMD system likewise makes no sense whatsoever: SV replaces VSX and provides, at the very minimum, predication (which VSX was not designed to incorporate). Thus all VSX Major Opcodes - all of them - are "unused" and raise illegal instruction exceptions in SV Prefix Mode. +As mentioned above, OE=1 is not applicable in SV, freeing this bit for alternative uses. Additionally, Vectorisation of the VSX SIMD system likewise makes no sense whatsoever: SV replaces VSX and provides, at the very minimum, predication (which VSX was designed without). Thus all VSX Major Opcodes - all of them - are "unused" and must raise illegal instruction exceptions in SV Prefix Mode. + +Likewise, `lq` (Load Quad), and Load/Store Multiple make no sense to have because they are not only provided by SV, the SV alternatives may be predicated as well, making them far better suited to use in function calls and context-switching. This leaves several Major Opcodes free for use by SV to fit alternative instructions: Vector Product, Vector Normalise, [[sv/mv.swizzle]], Texture LD/ST operations, and others critical to an efficient, effective 3D GPU and VPU ISA. With such instructions being included as standard in other commercially-successful GPU ISAs it is likewise critical that a 3D GPU/VPU based on svp64 also have such instructions.