xUNPKD821 is not that trivial so probably it may be an instruction. #37 comment says there is no usecase for it.
If unpack instructions are not too common, they probably should be implemented via shuffles and/or shifts, e.g.
ZUNPKD820 rd, rs1 => SLLI rd, rs1, 8; SRLI16 rd, rd, 8ZUNPKD832 rd, rs1 => SHFLI rd, rs1, 8; SRLI16 rd, rd, 8
same for SUNPKD8XX with SRAI16
Other unpacks may be more tricky to implement in just two insns, e.g.
ZUNPKD810 rd, rs1 => URSTSA16 rd, rs1, rs1; SHFLI rd, rd, 8
Actually it seems like ZUNPKD8XY rd, rs1 may be generalized via XPERM8 rd, rs1, rs2.
RS2 will contain the following:
So effectively any ZUNPKD is a LI + XPERM8.
While thees are very specific constants, I am still not sure if it is effective (i.e. more effective then shift + shuffle + SIMD shift).
xUNPKD821 is not that trivial so probably it may be an instruction. #37 comment says there is no usecase for it.If unpack instructions are not too common, they probably should be implemented via shuffles and/or shifts, e.g.
ZUNPKD820 rd, rs1=>SLLI rd, rs1, 8; SRLI16 rd, rd, 8ZUNPKD832 rd, rs1=>SHFLI rd, rs1, 8; SRLI16 rd, rd, 8same forSUNPKD8XXwithSRAI16Other unpacks may be more tricky to implement in just two insns, e.g.
ZUNPKD810 rd, rs1=>URSTSA16 rd, rs1, rs1; SHFLI rd, rd, 8Actually it seems like
ZUNPKD8XY rd, rs1may be generalized viaXPERM8 rd, rs1, rs2. RS2 will contain the following:So effectively any
ZUNPKDis aLI + XPERM8. While thees are very specific constants, I am still not sure if it is effective (i.e. more effective then shift + shuffle + SIMD shift).