aarch64-nintendo-switch-freestanding - Enable CPU features that are always available in a live system (crypto instructions, plus explicit NEON).

[pantsman0]

While some NEON and crypto features may not be supported on the Nintendo Switch at boot (e.g. on the a53 cores) and this has not been tested, the features will always be available if running as a sysmodule or homebrew application under Horizon/Atmosphere. EDIT: the a53 cores are fused out, these features are always available.

This has been tested with local tools personally, as well as building emuiibo as it uses both sha and aes primitives. This was tested using inline assembly in previous versions, and in current versions by using the aes, ctr, hmac, and sha2 crates.

r? @jam1garner

This ended up being much delayed from our discussions about updating this. I tested a number of individual features such as the aes and sha2 target-features directly to avoid a warning message with the crypto feature, but that appears to be caused by #96472 and is not actually an issue.

There is also a decision to make here about explicitly enabling the neon feature. I am in favor of it to be explicit, but it is not necessary as it is already enabled by the v8a and crypto features. I will defer to your decision as it does not change the actual instructions available for codegen.

[rustbot]

Failed to set assignee to jam1garner: invalid assignee

Note: Only org members with at least the repository "read" role, users with write permissions, or people who have commented on the PR may be assigned.

[rustbot]

These commits modify compiler targets.
(See the Target Tier Policy.)

[pantsman0]

The crc features has also been added, as it is always available on the T210.

[jam1garner]

Looks good to me! Good catch, these features should've been included in the first place