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| author | Nikita Popov <npopov@redhat.com> | 2022-07-27 14:26:00 +0200 |
|---|---|---|
| committer | Nikita Popov <npopov@redhat.com> | 2022-08-09 12:39:59 +0200 |
| commit | 89582e8193e0da64a54c4ffae7f9fa64ed9fe2af (patch) | |
| tree | 9bdc713a34c12cf2d5ea2f68573cdb06ea14421b | |
| parent | 9d97606193458be2eadd0d708c082bd9a79dd612 (diff) | |
| download | rust-89582e8193e0da64a54c4ffae7f9fa64ed9fe2af.tar.gz rust-89582e8193e0da64a54c4ffae7f9fa64ed9fe2af.zip | |
Pass +atomics-32 feature for thumbv6m target
https://reviews.llvm.org/D120026 changed atomics on thumbv6m to use libatomic, to ensure that atomic load/store are compatible with atomic RMW/CAS. However, Rust wants to expose only load/store without libcalls. https://reviews.llvm.org/D130480 added support for this behind the +atomics-32 target feature, so enable that feature.
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/llvm_util.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_target/src/spec/thumbv6m_none_eabi.rs | 4 |
2 files changed, 5 insertions, 1 deletions
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs index a0a640473eb..96d238eda59 100644 --- a/compiler/rustc_codegen_llvm/src/llvm_util.rs +++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs @@ -440,6 +440,8 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<Str .features .split(',') .filter(|v| !v.is_empty() && backend_feature_name(v).is_some()) + // Drop +atomics-32 feature introduced in LLVM 15. + .filter(|v| *v != "+atomics-32" || get_version() >= (15, 0, 0)) .map(String::from), ); diff --git a/compiler/rustc_target/src/spec/thumbv6m_none_eabi.rs b/compiler/rustc_target/src/spec/thumbv6m_none_eabi.rs index 2546ab9b7e6..c9bb0112f0e 100644 --- a/compiler/rustc_target/src/spec/thumbv6m_none_eabi.rs +++ b/compiler/rustc_target/src/spec/thumbv6m_none_eabi.rs @@ -13,7 +13,9 @@ pub fn target() -> Target { abi: "eabi".into(), // The ARMv6-M architecture doesn't support unaligned loads/stores so we disable them // with +strict-align. - features: "+strict-align".into(), + // Also force-enable 32-bit atomics, which allows the use of atomic load/store only. + // The resulting atomics are ABI incompatible with atomics backed by libatomic. + features: "+strict-align,+atomics-32".into(), // There are no atomic CAS instructions available in the instruction set of the ARMv6-M // architecture atomic_cas: false, |