add more s390x target features by folkertdev · Pull Request #135630 · rust-lang/rust (original) (raw)

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folkertdev

Closes #88937

tracking issue: #130869

The target feature names are, right now, just the llvm target feature names. These mostly line up well with the names of Facility Indications names. The linux kernel (and /proc/cpuinfo) uses shorter, more cryptic names. (e.g. "vector" is vx). We can deviate from the llvm names, but the CPU vendor (IBM) does not appear to use e.g. vx for what they call vector.

There are a number of implied target features between the vector facilities (based on the Facility Indications table):

The remaining facilities do not have any implied target features (that we provide):

The added target features are those that have ISA implications, can be queried at runtime, and have LLVM support. LLVM defines more target features, but I'm not sure those are useful. They can always be added later, and can already be set globally using -Ctarget-feature.

I'll also update the is_s390x_feature_supported macro (added in rust-lang/stdarch#1699, not yet on nightly, that needs an stdarch sync) to include these target features.

@Amanieu you had some reservations about the "vector" target feature name. It does appear to be the most "official" name we have. On the one hand the name is very generic, and some of the other names are rather long. For the neural-network-processing-assist even LLVM thought that was a bit much and shortened it to nnp-assist. Also for vector-packed-decimal-enhancement facility 1 the llvm naming is inconsistent. On the other hand, the cpuinfo names are very cryptic, and aren't found in the IBM documentation.

r? @Amanieu

cc @uweigand @taiki-e

@rustbot rustbot added S-waiting-on-review

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Jan 17, 2025

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@uweigand

The added target features are those that have ISA implications, can be queried at runtime, and have LLVM support. LLVM defines more target features, but I'm not sure those are useful. They can always be added later, and can already be set globally using -Ctarget-feature.

The list you've added corresponds to the list provided by /proc/cpuinfo, so I agree that's a good start. [It would be possible to check for the other features at runtime as well, but using a different mechanism (the STFLE instruction).]

Also for vector-packed-decimal-enhancement facility 1 the llvm naming is inconsistent.

Yes, unfortunately sometimes a facility gets added in one generation, and then the next generation adds a version 2 of the facility, and then the original facility is renamed as version 1 retroactively ... I didn't follow those renames in the LLVM facility names to avoid accidentally breaking existing scripts.

@folkertdev

It would be possible to check for the other features at runtime as well

I was thinking of some of the special ones, e.g. backchain is not really a facility as far as I can tell? Similarly soft-float and unaligned-symbols. Anyway if the need comes up it's quite easy to add more.

but using a different mechanism (the STFLE instruction)

Yes, rust-lang/stdarch#1699 has some prototype code for that, but as you say for now that is not needed (plus you'd need the existing approach anyway to make sure that the STFLE instruction is supported).

Yes, unfortunately sometimes a facility gets added in one generation, and then the next generation adds a version 2 of the facility, and then the original facility is renamed as version 1 retroactively ... I didn't follow those renames in the LLVM facility names to avoid accidentally breaking existing scripts.

That is unfortunate and makes sense

@uweigand

It would be possible to check for the other features at runtime as well

I was thinking of some of the special ones, e.g. backchain is not really a facility as far as I can tell? Similarly soft-float and unaligned-symbols. Anyway if the need comes up it's quite easy to add more.

I see. Yes, those are not ISA facilities, but rather compiler options. These were implemented as LLVM facilities to allow setting them per-function (via attribute, or implicitly via LTO).

but using a different mechanism (the STFLE instruction)

Yes, rust-lang/stdarch#1699 has some prototype code for that, but as you say for now that is not needed (plus you'd need the existing approach anyway to make sure that the STFLE instruction is supported).

That test shouldn't really be necessary - LLVM anyway requires the Eighth Edition of the PoP as minimum level (i.e. z10 processors, which were introduced in 2010), and STFLE has been supported since the Fifth Edition.

@Amanieu

@bors

📌 Commit 8a5bb28 has been approved by Amanieu

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors

Status: Waiting on bors to run and complete tests. Bors will change the label on completion.

and removed S-waiting-on-review

Status: Awaiting review from the assignee but also interested parties.

labels

Feb 18, 2025

workingjubilee added a commit to workingjubilee/rustc that referenced this pull request

Feb 20, 2025

@workingjubilee

…r=Amanieu

add more s390x target features

Closes rust-lang#88937

tracking issue: rust-lang#130869

The target feature names are, right now, just the llvm target feature names. These mostly line up well with the names of Facility Indications names. The linux kernel (and /proc/cpuinfo) uses shorter, more cryptic names. (e.g. "vector" is vx). We can deviate from the llvm names, but the CPU vendor (IBM) does not appear to use e.g. vx for what they call vector.

There are a number of implied target features between the vector facilities (based on the Facility Indications table):

The remaining facilities do not have any implied target features (that we provide):

The added target features are those that have ISA implications, can be queried at runtime, and have LLVM support. LLVM defines more target features, but I'm not sure those are useful. They can always be added later, and can already be set globally using -Ctarget-feature.

I'll also update the is_s390x_feature_supported macro (added in rust-lang/stdarch#1699, not yet on nightly, that needs an stdarch sync) to include these target features.

@Amanieu you had some reservations about the "vector" target feature name. It does appear to be the most "official" name we have. On the one hand the name is very generic, and some of the other names are rather long. For the neural-network-processing-assist even LLVM thought that was a bit much and shortened it to nnp-assist. Also for vector-packed-decimal-enhancement facility 1 the llvm naming is inconsistent. On the other hand, the cpuinfo names are very cryptic, and aren't found in the IBM documentation.

r? @Amanieu

cc @uweigand @taiki-e

bors added a commit to rust-lang-ci/rust that referenced this pull request

Feb 20, 2025

@bors

Rollup of 12 pull requests

Successful merges:

r? @ghost @rustbot modify labels: rollup

try-job: test-various try-job: x86_64-msvc-1 try-job: x86_64-msvc-2 try-job: i686-msvc-1 try-job: i686-msvc-2 try-job: i686-mingw-1 try-job: i686-mingw-2 try-job: i686-mingw-3 try-job: x86_64-gnu-nopt

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@folkertdev

The target feature names are, right now, based on the llvm target feature names. These mostly line up well with the names of Facility Inidications names. The linux kernel uses shorter, more cryptic names. (e.g. "vector" is vx). We can deviate from the llvm names, but the CPU vendor (IBM) does not appear to use e.g. vx for what they call vector.

There are a number of implied target features between the vector facilities (based on the Facility Inidications table):

And then there are a number of facilities without any implied target features

The added target features are those that have ISA implications, can be queried at runtime, and have LLVM support. LLVM defines more target features, but I'm not sure those are useful. They can always be added later, and can already be set globally using -Ctarget-feature.

@folkertdev

not sure what happened there, maybe some formatting config got updated while this was open? Anyway, fixed now

@rustbot ready

@workingjubilee

We released an edition, yeah.

@workingjubilee

@bors

📌 Commit 69c7e1d has been approved by Amanieu

It is now in the queue for this repository.

workingjubilee added a commit to workingjubilee/rustc that referenced this pull request

Feb 20, 2025

@workingjubilee

…r=Amanieu

add more s390x target features

Closes rust-lang#88937

tracking issue: rust-lang#130869

The target feature names are, right now, just the llvm target feature names. These mostly line up well with the names of Facility Indications names. The linux kernel (and /proc/cpuinfo) uses shorter, more cryptic names. (e.g. "vector" is vx). We can deviate from the llvm names, but the CPU vendor (IBM) does not appear to use e.g. vx for what they call vector.

There are a number of implied target features between the vector facilities (based on the Facility Indications table):

The remaining facilities do not have any implied target features (that we provide):

The added target features are those that have ISA implications, can be queried at runtime, and have LLVM support. LLVM defines more target features, but I'm not sure those are useful. They can always be added later, and can already be set globally using -Ctarget-feature.

I'll also update the is_s390x_feature_supported macro (added in rust-lang/stdarch#1699, not yet on nightly, that needs an stdarch sync) to include these target features.

@Amanieu you had some reservations about the "vector" target feature name. It does appear to be the most "official" name we have. On the one hand the name is very generic, and some of the other names are rather long. For the neural-network-processing-assist even LLVM thought that was a bit much and shortened it to nnp-assist. Also for vector-packed-decimal-enhancement facility 1 the llvm naming is inconsistent. On the other hand, the cpuinfo names are very cryptic, and aren't found in the IBM documentation.

r? @Amanieu

cc @uweigand @taiki-e

bors added a commit to rust-lang-ci/rust that referenced this pull request

Feb 21, 2025

@bors

Rollup of 10 pull requests

Successful merges:

r? @ghost @rustbot modify labels: rollup

try-job: aarch64-gnu try-job: armhf-gnu try-job: i686-mingw-1 try-job: i686-mingw-2 try-job: i686-mingw-3 try-job: test-various try-job: x86_64-gnu-nopt try-job: x86_64-msvc-1 try-job: x86_64-msvc-2

bors added a commit to rust-lang-ci/rust that referenced this pull request

Feb 21, 2025

@bors

bors added a commit to rust-lang-ci/rust that referenced this pull request

Feb 21, 2025

@bors

rust-timer added a commit to rust-lang-ci/rust that referenced this pull request

Feb 21, 2025

@rust-timer

Rollup merge of rust-lang#135630 - folkertdev:s390x-target-features, r=Amanieu

add more s390x target features

Closes rust-lang#88937

tracking issue: rust-lang#130869

The target feature names are, right now, just the llvm target feature names. These mostly line up well with the names of Facility Indications names. The linux kernel (and /proc/cpuinfo) uses shorter, more cryptic names. (e.g. "vector" is vx). We can deviate from the llvm names, but the CPU vendor (IBM) does not appear to use e.g. vx for what they call vector.

There are a number of implied target features between the vector facilities (based on the Facility Indications table):

The remaining facilities do not have any implied target features (that we provide):

The added target features are those that have ISA implications, can be queried at runtime, and have LLVM support. LLVM defines more target features, but I'm not sure those are useful. They can always be added later, and can already be set globally using -Ctarget-feature.

I'll also update the is_s390x_feature_supported macro (added in rust-lang/stdarch#1699, not yet on nightly, that needs an stdarch sync) to include these target features.

@Amanieu you had some reservations about the "vector" target feature name. It does appear to be the most "official" name we have. On the one hand the name is very generic, and some of the other names are rather long. For the neural-network-processing-assist even LLVM thought that was a bit much and shortened it to nnp-assist. Also for vector-packed-decimal-enhancement facility 1 the llvm naming is inconsistent. On the other hand, the cpuinfo names are very cryptic, and aren't found in the IBM documentation.

r? @Amanieu

cc @uweigand @taiki-e

github-actions bot pushed a commit to tautschnig/verify-rust-std that referenced this pull request

Mar 11, 2025

@bors

github-actions bot pushed a commit to tautschnig/verify-rust-std that referenced this pull request

Mar 11, 2025

@bors

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