diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs index 20bf580a716..8e7a99e46a5 100644 --- a/compiler/rustc_codegen_llvm/src/builder.rs +++ b/compiler/rustc_codegen_llvm/src/builder.rs @@ -737,6 +737,8 @@ fn store_with_flags( // a hint, and use regular stores everywhere else. // (In the future, we could alternatively ensure that an sfence gets emitted after a sequence of movnt // before any kind of synchronizing operation. But it's not clear how to do that with LLVM.) + // For more context, see and + // . const WELL_BEHAVED_NONTEMPORAL_ARCHS: &[&str] = &["aarch64", "arm", "riscv32", "riscv64"]; diff --git a/tests/codegen/intrinsics/nontemporal.rs b/tests/codegen/intrinsics/nontemporal.rs index 828cb7e8287..ff2d6296066 100644 --- a/tests/codegen/intrinsics/nontemporal.rs +++ b/tests/codegen/intrinsics/nontemporal.rs @@ -1,6 +1,14 @@ //@ compile-flags: -O -//@ compile-flags: --target aarch64-unknown-linux-gnu -//@ needs-llvm-components: aarch64 +//@revisions: with_nontemporal without_nontemporal +//@[with_nontemporal] compile-flags: --target aarch64-unknown-linux-gnu +//@[with_nontemporal] needs-llvm-components: aarch64 +//@[without_nontemporal] compile-flags: --target x86_64-unknown-linux-gnu +//@[without_nontemporal] needs-llvm-components: x86 + +// Ensure that we *do* emit the `!nontemporal` flag on architectures where it +// is well-behaved, but do *not* emit it on architectures where it is ill-behaved. +// For more context, see and +// . #![feature(no_core, lang_items, intrinsics)] #![no_core] @@ -21,7 +29,8 @@ impl Copy for *mut T {} #[no_mangle] pub fn a(a: &mut u32, b: u32) { // CHECK-LABEL: define{{.*}}void @a - // CHECK: store i32 %b, ptr %a, align 4, !nontemporal + // with_nontemporal: store i32 %b, ptr %a, align 4, !nontemporal + // without_nontemporal-NOT: nontemporal unsafe { nontemporal_store(a, b); }