arm64/disassem.c: add extended register instruction definitions

[koliagogsadze_gmail.com]

Summary

Add disassembly support for the following extended register instructions:

• add
• adds
• sub
• subs
• cmp
• cmn

Test Plan

https://github.com/toor1245/freebsd-src/pull/3

[mhorne]

Looks good overall, this is definitely the appropriate time to use TYPE_04.

sys/arm64/arm64/disassem.c

76

So these are extend types, not register names. This array needs a better name...

279

Ordering is not super important, but you put add before cmn, why not sub before cmp?

434

Regarding LSL logic, I see only the following:

If "Rn" is '11111' (WSP) and "option" is '010' then LSL is preferred, but may be omitted when "imm3" is '000'. In all other cases <extend> is required and must be UXTW when "option" is '010'.

Why do you have rd == 31 ?

474–493

I think it is just fine to have these expanded inline rather than add new helper functions.

[koliagogsadze_gmail.com]

sorry, forgot to send refs to review:
ADD (extended register): https://developer.arm.com/documentation/ddi0596/2020-12/Base-Instructions/ADD--extended-register---Add--extended-register--
ADDS (extended register): https://developer.arm.com/documentation/ddi0596/2020-12/Base-Instructions/ADDS--extended-register---Add--extended-register---setting-flags-
CMN (extended register): https://developer.arm.com/documentation/ddi0596/2020-12/Base-Instructions/CMN--extended-register---Compare-Negative--extended-register---an-alias-of-ADDS--extended-register--
CMP (extended register): https://developer.arm.com/documentation/ddi0596/2020-12/Base-Instructions/CMP--extended-register---Compare--extended-register---an-alias-of-SUBS--extended-register--
SUB (extended register): https://developer.arm.com/documentation/ddi0596/2020-12/Base-Instructions/SUB--extended-register---Subtract--extended-register--
SUBS (extended register): https://developer.arm.com/documentation/ddi0596/2020-12/Base-Instructions/SUBS--extended-register---Subtract--extended-register---setting-flags-

[koliagogsadze_gmail.com]

sys/arm64/arm64/disassem.c

434

there are two cases:

OP <RD>, <RN|SP>, <RM> {, <extend> { #<amount> } }
OP <RN|SP>, <RM>, {, <extend> { #<amount> } }

example: https://developer.arm.com/documentation/ddi0596/2020-12/Base-Instructions/SUB--extended-register---Subtract--extended-register--

SUB <Xd|SP>, <Xn|SP>, <R><m>{, <extend> {#<amount>}}

If "Rd" or "Rn" is '11111' (WSP) and "option" is '010' then LSL is preferred, but may be omitted when "imm3" is '000'. In all other cases <extend> is required and must be UXTW when "option" is '010'.

474–493

ok, will update

[koliagogsadze_gmail.com]

sys/arm64/arm64/disassem.c

76

I agree with you, I think I was too focused on the "OP (extended register)" :)

279

there is no explanation, for consistency I will update

[koliagogsadze_gmail.com]

Removed helper functions and fixed naming and order of definitions

[mhorne]

Thanks, I will commit this today!