They were introduced back when std_detect was a standalone crate
published to crates.io. The motivation for std_detect_dlsym_getauxval
was to allow using getauxval without dlopen when statically linking
musl, which we now unconditionally do for musl. And for
std_detect_file_io to allow no_std usage, which std_detect now supports
even with that feature enabled as it directly uses libc. This also
prevents accidentally disabling runtime feature detection when using
cargo build -Zbuild-std -Zbuild-std-features=
Stabilize 29 RISC-V target features (`riscv_ratified_v2`)
This commit stabilizes RISC-V target features with following constraints:
* Describes a ratified extension.
* Implemented on Rust 1.88.0 or before.
Waiting for four+ version cycles seems sufficient.
* Does not disrupt current rustc's target feature (cf. rust-lang/rust#140570) + ABI (cf. rust-lang/rust#132618) handling.
It excludes `E` and all floating point-arithmetic extensions. The `Zfinx` family does not involve floating point registers but not stabilizing for now to avoid possible confusion between the `F` extension family.
* Not vector-related (floating point and integer).
While integer vector subsets should not cause any ABI issues (as they don't use ABI-dependent floating point registers), we need to discuss before stabilizing them.
* Supported by the lowest LLVM version supported by rustc (LLVM 20).
List of target features to be stabilized:
1. `b`
2. `za64rs` (no-RT)
3. `za128rs` (no-RT)
4. `zaamo`
5. `zabha`
6. `zacas`
7. `zalrsc`
8. `zama16b` (no-RT)
9. `zawrs`
10. `zca`
11. `zcb`
12. `zcmop`
13. `zic64b` (no-RT)
14. `zicbom`
15. `zicbop` (no-RT)
16. `zicboz`
17. `ziccamoa` (no-RT)
18. `ziccif` (no-RT)
19. `zicclsm` (no-RT)
20. `ziccrse` (no-RT)
21. `zicntr`
22. `zicond`
23. `zicsr`
24. `zifencei`
25. `zihintntl`
26. `zihintpause`
27. `zihpm`
28. `zimop`
29. `ztso`
Of which, 20 of them (29 minus 9 "no-RT" target features) support runtime detection through `std::arch::is_riscv_feature_detected!()`.
Corresponding PR for the Reference: rust-lang/reference#1987
stdarch subtree update
Subtree update of `stdarch` to 61119062fb.
Created using https://github.com/rust-lang/josh-sync.
r? `@sayantn`
My first josh sync, it lgtm, but let me know if I missed something.
I'm especially looking forward to the amd GPU module, which we want to use for the offload project.
std-detect: improve detect macro docs
Specifically, document that the detect macros expand to `true` when the feature is statically enabled.
Now that we have a bunch of these macros, perhaps we should streamline further how they are documented?
r? ``@Amanieu``
This commit stabilizes RISC-V target features with following constraints:
* Describes a ratified extension.
* Implemented on Rust 1.88.0 or before.
Waiting for four+ version cycles seems sufficient.
* Does not disrupt current rustc's target feature + ABI handling.
It excludes "E" and all floating point-arithmetic extensions.
"Zfinx" family does not involve floating point registers but
not stabilizing for now to avoid possible confusion between
the "F" extension family.
* Not vector-related (floating point and integer).
While integer vector subsets should not cause any ABI issues
(as they don't use ABI-dependent floating point registers),
we need to discuss before stabilizing them.
* Supported by the lowest LLVM version supported by rustc (LLVM 20).
List of target features to be stabilized:
1. "b"
2. "za64rs" (no-RT)
3. "za128rs" (no-RT)
4. "zaamo"
5. "zabha"
6. "zacas"
7. "zalrsc"
8. "zama16b" (no-RT)
9. "zawrs"
10. "zca"
11. "zcb"
12. "zcmop"
13. "zic64b" (no-RT)
14. "zicbom"
15. "zicbop" (no-RT)
16. "zicboz"
17. "ziccamoa" (no-RT)
18. "ziccif" (no-RT)
19. "zicclsm" (no-RT)
20. "ziccrse" (no-RT)
21. "zicntr"
22. "zicond"
23. "zicsr"
24. "zifencei"
25. "zihintntl"
26. "zihintpause"
27. "zihpm"
28. "zimop"
29. "ztso"
Of which, 20 of them (29 minus 9 "no-RT" target features) support
runtime detection through `std::arch::is_riscv_feature_detected!()`.
Now that this feature has a standard identifier, Darwin has started exposing it accordingly, in addition to the existing less-standard way. Check both, and enable the `crc` feature if either identifier for it is present to ensure backwards and forwards compatibility.
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.
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.
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.
