Require fma and f16c for avx512f in std_detect
#1781
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
sayantn
force-pushed
the
fix-avx512f
branch
2 times, most recently
from
1585181 to
67de384
Compare
This was referenced Apr 24, 2025
VlaDexa
added a commit
to VlaDexa/rust
that referenced
this pull request
May 2, 2025
Remove `avx512dq` and `avx512vl` implication for `avx512fp16` According to Intel, `avx512fp16` requires only `avx512bw`, but LLVM also enables `avx512vl` and `avx512dq` when `avx512fp16` is active. This is relic code, and will be fixed in LLVM soon. We should remove this from Rust too asap, especially before the stabilization of AVX512 Related: - llvm/llvm-project#136209 - rust-lang#138940 - rust-lang/stdarch#1781 - rust-lang#111137 `@rustbot` label O-x86_64 O-x86_32 A-SIMD A-target-feature T-compiler -T-libs r? `@Amanieu` **Update: the LLVM fix has been merged** cc `@rust-lang/wg-llvm` will it be possible to update the rustc llvm version to something after llvm/llvm-project#137450
Zalathar
added a commit
to Zalathar/rust
that referenced
this pull request
May 2, 2025
Remove `avx512dq` and `avx512vl` implication for `avx512fp16` According to Intel, `avx512fp16` requires only `avx512bw`, but LLVM also enables `avx512vl` and `avx512dq` when `avx512fp16` is active. This is relic code, and will be fixed in LLVM soon. We should remove this from Rust too asap, especially before the stabilization of AVX512 Related: - llvm/llvm-project#136209 - rust-lang#138940 - rust-lang/stdarch#1781 - rust-lang#111137 ``@rustbot`` label O-x86_64 O-x86_32 A-SIMD A-target-feature T-compiler -T-libs r? ``@Amanieu`` **Update: the LLVM fix has been merged** cc ``@rust-lang/wg-llvm`` will it be possible to update the rustc llvm version to something after llvm/llvm-project#137450
rust-timer
added a commit
to rust-lang-ci/rust
that referenced
this pull request
May 2, 2025
Rollup merge of rust-lang#140389 - sayantn:avx512fp16, r=Amanieu Remove `avx512dq` and `avx512vl` implication for `avx512fp16` According to Intel, `avx512fp16` requires only `avx512bw`, but LLVM also enables `avx512vl` and `avx512dq` when `avx512fp16` is active. This is relic code, and will be fixed in LLVM soon. We should remove this from Rust too asap, especially before the stabilization of AVX512 Related: - llvm/llvm-project#136209 - rust-lang#138940 - rust-lang/stdarch#1781 - rust-lang#111137 ``@rustbot`` label O-x86_64 O-x86_32 A-SIMD A-target-feature T-compiler -T-libs r? ``@Amanieu`` **Update: the LLVM fix has been merged** cc ``@rust-lang/wg-llvm`` will it be possible to update the rustc llvm version to something after llvm/llvm-project#137450
github-actions bot
pushed a commit
to model-checking/verify-rust-std
that referenced
this pull request
May 9, 2025
Remove `avx512dq` and `avx512vl` implication for `avx512fp16` According to Intel, `avx512fp16` requires only `avx512bw`, but LLVM also enables `avx512vl` and `avx512dq` when `avx512fp16` is active. This is relic code, and will be fixed in LLVM soon. We should remove this from Rust too asap, especially before the stabilization of AVX512 Related: - llvm/llvm-project#136209 - rust-lang#138940 - rust-lang/stdarch#1781 - rust-lang#111137 ``@rustbot`` label O-x86_64 O-x86_32 A-SIMD A-target-feature T-compiler -T-libs r? ``@Amanieu`` **Update: the LLVM fix has been merged** cc ``@rust-lang/wg-llvm`` will it be possible to update the rustc llvm version to something after llvm/llvm-project#137450
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The target feature
avx512fimpliesavx2,fmaandf16cin rustc, but Intel only guarantees thatavx2will be there whenavx512fis present, nothing aboutfmaorf16c. This is correct behavior by rustc, and is based on how the assembler decides what encoding to use, VEX vs EVEX. So this PR simply requires thatfmaandf16cbe present when enabling any AVX512 target features, to match exactly with rustc behavior.Related:
avx512dqandavx512vlimplication foravx512fp16rust#140389