Sam Elliott c8136da26c

[RISCV] Correctly Decode Unsigned Immediates with Ranges (#128584) ...

We currently have two operands upstream that are an unsigned immediate
with a range constraint - `uimm8ge32` (for `cm.jalt`) and `uimm5gt3`
(for `qc.shladd`).

Both of these were using `decodeUImmOperand<N>` for decoding. For `Zcmt`
this worked, because the generated decoder automatically checked for
`cm.jt` first because the 8 undefined bits in `cm.jalt` are `000?????`
in `cm.jt` (this is to do with the range lower-bound being a
power-of-two). For Zcmt, this patch is NFC.

We have less luck with `Xqciac` - `qc.shladd` is being decoded where the
`uimm5` field is 3 or lower. This patch fixes this by introducing a
`decodeUImmOperandGE<Width, LowerBound>` helper, which will corretly
return `MCDisassembler::Fail` when the immediate is below the lower
bound.

I have added a test to show the encoding where `uimm5` is equal to 3 is
no longer disassembled as `qc.shladd`.

2025-02-25 11:12:08 -08:00

..

CMakeLists.txt

…

RISCVDisassembler.cpp

[RISCV] Correctly Decode Unsigned Immediates with Ranges (#128584)

2025-02-25 11:12:08 -08:00