std_detect: RISC-V: implement implication to "C"
Just like we implemented relatively complex rules to imply other extensions **from** "C" (and some others), this commit implements implication **to** the "C" extension from others, complying the following text in the ISA Manual (although there's no direct imply/depend references).
> The C extension is the superset of the following extensions:
>
> - Zca
> - Zcf if F is specified (RV32 only)
> - Zcd if D is specified
This is formally verified so that no other extension combinations (*not* in this implementation) can (currently) imply the "C" extension.
Note: this is a `std_detect` change and not main target feature handling.
`std_detect`: Use `rustc-std-workspace-*` to pull in `compiler-builtins`
https://github.com/rust-lang/rust/pull/145489 changed `std_detect` to no
longer depend on `cfg-if`, which meant it no longer indirectly pulled in
`rustc-std-workspace-core` via `cfg-if`. That caused it to no longer
depend on `compiler-builtins`.
Change `std_detect` to use `rustc-std-workspace-core` and
`rustc-std-workspace-alloc`, to integrate with the rustc workspace. This
also pulls in `compiler-builtins` via `rustc-std-workspace-core`.
Closes: https://github.com/rust-lang/rust/issues/145594
Add runtime detection for APX-F and AVX10
This was missed in rust-lang/rust#139534 and rust-lang/rust#139675
`@rustbot` label O-x86_64 O-x86_32 A-target-feature
r? `@Amanieu`
std_detect: RISC-V platform guide documentation
This is practically a revert of a revert, making the commit e907456b2e10622ccd854a3bba8d02ce170b5dbb on `stdarch` come around again with minor fixes, enhancements and adjustments.
An excerpt from the original commit message follows:
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.
https://github.com/rust-lang/rust/pull/145489 changed `std_detect` to no
longer depend on `cfg-if`, which meant it no longer indirectly pulled in
`rustc-std-workspace-core` via `cfg-if`. That caused it to no longer
depend on `compiler-builtins`.
Change `std_detect` to use `rustc-std-workspace-core` and
`rustc-std-workspace-alloc`, to integrate with the rustc workspace. This
also pulls in `compiler-builtins` via `rustc-std-workspace-core`.
Closes: https://github.com/rust-lang/rust/issues/145594
Just like we implemented relatively complex rules to imply other extensions
**from** "C" (and some others), this commit implements implication
**to** the "C" extension from others, complying the following text
in the ISA Manual (although there's no direct imply/depend references).
> The C extension is the superset of the following extensions:
>
> - Zca
> - Zcf if F is specified (RV32 only)
> - Zcd if D is specified
This is formally verified so that no other extension combinations
(*not* in this implementation) can (currently) imply the "C" extension.
Migrate the standard library from using the external `cfg_if` crate to
using the now-built-in `cfg_select` macro.
This does not yet eliminate the dependency from
`library/std/Cargo.toml`, because while the standard library itself no
longer uses `cfg_if`, it also incorporates the `backtrace` crate, which
does.
Migration assisted by the following vim command (after selecting the
full `cfg_if!` invocation):
```
'<,'>s/\(cfg_if::\)\?cfg_if/cfg_select/ | '<,'>s/^\( *\)} else {/\1}\r\1_ => {/c | '<,'>s/^\( *\)} else if #\[cfg(\(.*\))\] /\1}\r\1\2 => /e | '<,'>s/if #\[cfg(\(.*\))\] {/\1 => {/e
```
This is imperfect, but substantially accelerated the process. This
prompts for confirmation on the `} else {` since that can also appear
inside one of the arms. This also requires manual intervention to handle
any multi-line conditions.
This is practically a revert of a revert, making the
commit e907456b2e10622ccd854a3bba8d02ce170b5dbb on `stdarch` come around
again with minor fixes, enhancements and adjustments.
An excerpt from the original commit message follows:
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.
* Fix riscv testing. Previously the mod tests; would be looking for
src/detect/os/tests.rs.
* Replace a test with an unnamed const item. It is testing that no
warnings are emitted. It doesn't contain any checks that need to run
at runtime. Replacing the test allows removing the tidy:skip directive
for test locations.
