From 5fb0eebad2f8cf3d018d5c96b9d72b4d90ee2312 Mon Sep 17 00:00:00 2001 From: lkcl Date: Fri, 10 Jun 2022 13:24:23 +0100 Subject: [PATCH] --- openpower/sv/mv.vec.mdwn | 46 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 45 insertions(+), 1 deletion(-) diff --git a/openpower/sv/mv.vec.mdwn b/openpower/sv/mv.vec.mdwn index ac7dec62b..de40ddf0a 100644 --- a/openpower/sv/mv.vec.mdwn +++ b/openpower/sv/mv.vec.mdwn @@ -92,5 +92,49 @@ mv.zip, RA!=0, RB!=0 # REMAP concept for pack/unpack It may be possible to use one standard mv instruction to perform packing -and unpacking. At the very least a predicate mask potentially can +and unpacking: Matrix allows for both reordering and offsets. At the very least a predicate mask potentially can be used. + +* If a single src-dest mv is used, then it potentially requires + two separate REMAP and two separate sv.mvs: remap-even, sv.mv, + remap-odd, sv.mv +* If adding twin-src and twin-dest that is a lot of instructions, + particularly if triple is added as well. FPR mv, GPR mv +* Unless twin or triple is added, how is it possible to determine + the extra register(s) to be merged (or split)? + +How about instead relying on the implicit RS=MAXVL+RT trick and +extending that to RS=MAXVL+RA as a source? One spare bit in the +EXTRA RM area says whether the sv.mv is a pack (RS-as-src=RA+MAXVL) +or unpack (RS-as-dest=RT+MAXVL) + +Alternatively, given that Matrix is up to 3 Dimensions, not even +be concerned about RS, just simply use one of those dimensions to +span the packing: + +Example 1: + +* RA set to linear +* RT set to YX, ydim=2, xdim=4 +* VL=MAXVL=8 + + | RA | (0 1) (2 3) (4 5) (6 7) | + | RT | 0 2 4 8 1 3 5 7 | + +This results in a 2-element "unpack" + +Example 2: + +* RT set to linear +* RT set to YX, ydim=3, xdim=3 +* VL=MAXVL=9 + + | RA | 0 1 2 3 4 5 6 7 8 | + | RT | (0 3 6) (1 4 7) (2 5 8) | + +This results in a 3-element "pack" + +Both examples become particularly fun when Twin Predication is thrown +into the mix. + + -- 2.30.2