[Libre-soc-dev] change sv ld/st to allow non-zero immediates for unit-strided load/store

[lkcl]

that's the "splat" mode.
https://libre-soc.org/openpower/sv/ldst/

    else
      # standard scalar mode (but predicated)
      # no stride multiplier means VSPLAT mode
      srcbase = ireg[RA]
      offs = immed




On October 11, 2022 9:47:35 PM GMT+01:00, Jacob Lifshay <programmerjake at gmail.com> wrote:
>On Tue, Oct 11, 2022, 02:51 lkcl <luke.leighton at gmail.com> wrote:
>
>> On Tue, Oct 11, 2022 at 10:28 AM Jacob Lifshay
><programmerjake at gmail.com>
>> wrote:
>> >
>> > this will be very common in spill code or other code with vectors
>stored
>> in a struct or on stack:
>> > sv.ld/unitstrided *r120, -32(r1) # load from local stack var in
>redzone
>> > sv.ld/unitstrided *r32, 64(r1) # load from function arguments
>> > sv.ld/unitstrided *r64, 32(r3) # load from struct member that
>starts at
>> offset 32
>>
>
>to be clear, I'm *not* proposing post-increment (which is what your
>reply
>seem to be entirely about), i'm proposing unit-strided, no-update, with
>non-zero immediates, e.g.:
>
>sv.ld/unitstrided *r32, 64(r1)
>
>equivalent code:
>for i in range(VL):
>    ea = 64 + regs[1]
>    regs[i + 32] = mem(ea)
>
>Jacob