Reasoning:
1. Majority of code assumes the usage of `Intrinsic` and related types, which is derived from the JSON structure of the ARM intrinsics JSON source file
2. Further commits will start with extracting common parts of the code (eg: Create C/Rust file, Build C/Rust file, etc)
This reverts commit e907456b2e10622ccd854a3bba8d02ce170b5dbb.
This is due to a CI failure (technically broken HTML with duplicate IDs)
caused by this commit (visibly fine but invalid per the HTML specification
and detected by the LinkCheck tool on the Rust CI process).
The author independently working on a rustdoc enhancement to enable writing
multiple references to a single footnote. Once that change makes it to the
stage0 compiler (the next beta), the original change will be acceptable
again (postponed for possibly the version 1.89 cycle).
Since there's no architectural feature detection on RISC-V (unlike `CPUID`
on x86 architectures and some system registers on Arm/AArch64), runtime
feature detection entirely depends on the platform-specific facility.
As a result, availability of each feature heavily depends on the platform
and its version.
To help users make a decision for feature checking on a RISC-V system, this
commit adds a platform guide with minimum supported platform versions.
Note:
It intentionally omits the description of the reverse implication related
to *extension groups* (such like implication of `B` *from* its members:
`Zba`, `Zbb` and `Zbs` extensions) because it currently does not synchronize
well with the `-Ctarget-feature` compiler option (due to missing reverse
implication checks using `cfg` and due to constraints of the current Rust's
feature handling).
Instead, it only describes forward implications (like `D` implying `F`) due
to the fact that it relatively synchronizes well between Rust and `stdarch`
for this kind of feature handling (not fully synchronized though).
Still, an extension group is considered "supported" once the
platform/version supports runtime detection of all members in it.
