[PATCH v2 07/19] arm64: insn: Add encoder for bitwise operations using litterals

[Peter Maydell]

On 11 December 2017 at 14:49, Marc Zyngier <marc.zyngier at arm.com> wrote:
> We lack a way to encode operations such as AND, ORR, EOR that take
> an immediate value. Doing so is quite involved, and is all about
> reverse engineering the decoding algorithm described in the
> pseudocode function DecodeBitMasks().

Is it possible to borrow the existing tested implementation
which a compiler surely must have for this, rather than having
to reinvent this rather complicated wheel? Here's LLVM's version:

https://github.com/llvm-mirror/llvm/blob/93e6e5414ded14bcbb233baaaa5567132fee9a0c/lib/Target/AArch64/MCTargetDesc/AArch64AddressingModes.h#L209

(confirming that the LLVM license is GPLv2 compatible is
left as an exercise for the reader, but I'm pretty sure it is)

PS: typo in subject: 'literal'.

thanks
-- PMM