Add the clflushopt x86 target feature#157098
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This was referenced May 29, 2026
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`CLFLUSHOPT` is a standalone x86 CPUID feature (Intel Skylake+ / AMD Excavator+, ~2015) not part of any psABI microarchitecture level, so it needs its own unstable target feature, gated behind `clflushopt_target_feature`. This is the compiler half of exposing the `_mm_clflushopt` intrinsic; the stdarch half is blocked on this landing. Also bless two UI test references (check-cfg/target_feature and target-feature/invalid-attribute) that enumerate the full set of valid target features, since `clflushopt` is now part of that list.
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Could you also add the feature to the is_x86_feature_detected! macro defined at
https://github.com/rust-lang/rust/blob/main/library/std_detect/src/detect/arch/x86.rs
and add a test for it in library/std_detect/tests/x86-specific.rs?
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Wire up runtime detection for the `clflushopt` feature: add it to the `is_x86_feature_detected!` feature list (gated on `clflushopt_target_feature`), enable it from CPUID leaf 7 EBX bit 23, and add it to the std_detect x86-specific dump test.
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Some changes occurred in cc @Amanieu, @folkertdev, @sayantn |
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Thanks for the feedback, I've tried to address it. |
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Adds the unstable
clflushoptx86 target feature, gated behind#![feature(clflushopt_target_feature)].CLFLUSHOPTis a standalone x86 CPUID feature (Intel Skylake+ / AMDExcavator+, ~2015) that is not part of any psABI microarchitecture level, so it
needs its own feature flag.
This is the compiler half of a two-PR feature and is a hard dependency for the
stdarch side. The
_mm_clflushoptintrinsic (rust-lang/stdarch#1456) cannotcompile until this target feature exists, so the stdarch PR is blocked on this
one merging and syncing into stdarch's pinned toolchain.
clflushopt_target_feature#157096_mm_clflushoptstdarch#1456This mirrors the existing unstable x86 target features (e.g.
movrs,apxf).clflushoptis a standard LLVM x86 feature name, so it maps 1:1 throughto_llvm_featureswith no remap entry needed.r? compiler