[Vm-dev] VM Maker: VMMaker.oscog-eem.2602.mcz

[Henrik Sperre Johansen]

On Wed, Dec 4, 2019 at 3:33 AM <commits at source.squeak.org> wrote:

> ARMv8 has an amazingly exotic scheme for encoding bitfields as immediates
> in logical operations.  Copy LLVM's encoder.  So far this is unverified
> because I cannot make sense of
>         immN:NOT(imms)
> in
>                 len = HighestSetBit(immN:NOT(imms));
> in DecodeBitMasks on page J1-7389 of the Arm ARM.
> If you can make sense of this either consider fully implementing
> CogARMv8Compiler>>decodeBitMasksN:imms:immr: or explaining to me what is
> meant by "immN:NOT(imms)" (via email to OpenSMalltalk-VM ?).
>
> AdvThanksance.
>

Is line 91 of
https://github.com/NationalSecurityAgency/ghidra/blob/master/Ghidra/Processors/AARCH64/src/main/java/DecodeBitMasks.java
of any use?

Basically,
: -> concatenate bit fields
NOT -> ... not ;)

Cheers,
Henry
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