[Libre-soc-bugs] [Bug 755] add grev instruction (OP_GREV)

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=755

--- Comment #44 from Jacob Lifshay <programmerjake at gmail.com> ---
(In reply to Luke Kenneth Casson Leighton from comment #43)
> (In reply to Jacob Lifshay from comment #42)
> > I think we should use primary opcode 9 for the new second opcode for
> > bitmanip instructions...but only for experimentation since it's marked as
> > reserved because stuff used to be there. primary opcode 0 should't be used
> > since it's reserved for implementation-dependent use and the `attn` opcode.
> 
> the official sandbox is EXT022.  the only reason for moving ternlogi
> and grevlogi to a separate opcode is because they're completely nuts
> on bit-allocation, and were putting design pressure on the bitmanip space
> which is pretty heavily loaded.
> 
> ternlogi has to move from EXT05 if grevlogi is to be on EXT09, they're
> allocated as a pair.

nope, grevlogi would still be in opcode 5. everything else (that're
conveniently not implemented or not completed (grev[w][i][.]) yet) will move to
opcode 9.

opcode 22 is currently used by setvl and friends and iirc you didn't want to
move them until you're back in working-on-SV mode, so I picked other opcodes
meanwhile.

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