Rollup merge of #138003 - sayantn:new-amx, r=Amanieu

Add the new `amx` target features and the `movrs` target feature

Adds 5 new `amx` target features included in LLVM20. These are guarded under `x86_amx_intrinsics` (#126622)

 - `amx-avx512`
 - `amx-fp8`
 - `amx-movrs`
 - `amx-tf32`
 - `amx-transpose`

Adds the `movrs` target feature (from #137976).

`@rustbot` label O-x86_64 O-x86_32 T-compiler A-target-feature
r? `@Amanieu`

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -300,6 +300,13 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         ("sparc", "v8plus") if get_version().0 == 19 => Some(LLVMFeature::new("v9")),
         ("sparc", "v8plus") if get_version().0 < 19 => None,
         ("powerpc", "power8-crypto") => Some(LLVMFeature::new("crypto")),
+        // These new `amx` variants and `movrs` were introduced in LLVM20
+        ("x86", "amx-avx512" | "amx-fp8" | "amx-movrs" | "amx-tf32" | "amx-transpose")
+            if get_version().0 < 20 =>
+        {
+            None
+        }
+        ("x86", "movrs") if get_version().0 < 20 => None,
         (_, s) => Some(LLVMFeature::new(s)),
     }
 }

compiler/rustc_feature/src/unstable.rs

@@ -324,6 +324,7 @@ declare_features! (
     (unstable, loongarch_target_feature, "1.73.0", Some(44839)),
     (unstable, m68k_target_feature, "1.85.0", Some(134328)),
     (unstable, mips_target_feature, "1.27.0", Some(44839)),
+    (unstable, movrs_target_feature, "CURRENT_RUSTC_VERSION", Some(137976)),
     (unstable, powerpc_target_feature, "1.27.0", Some(44839)),
     (unstable, prfchw_target_feature, "1.78.0", Some(44839)),
     (unstable, riscv_target_feature, "1.45.0", Some(44839)),

compiler/rustc_span/src/symbol.rs

@@ -1378,6 +1378,7 @@ symbols! {
         movbe_target_feature,
         move_ref_pattern,
         move_size_limit,
+        movrs_target_feature,
         mul,
         mul_assign,
         mul_with_overflow,

compiler/rustc_target/src/target_features.rs

@@ -380,11 +380,16 @@ static X86_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     // tidy-alphabetical-start
     ("adx", Stable, &[]),
     ("aes", Stable, &["sse2"]),
+    ("amx-avx512", Unstable(sym::x86_amx_intrinsics), &["amx-tile"]),
     ("amx-bf16", Unstable(sym::x86_amx_intrinsics), &["amx-tile"]),
     ("amx-complex", Unstable(sym::x86_amx_intrinsics), &["amx-tile"]),
     ("amx-fp16", Unstable(sym::x86_amx_intrinsics), &["amx-tile"]),
+    ("amx-fp8", Unstable(sym::x86_amx_intrinsics), &["amx-tile"]),
     ("amx-int8", Unstable(sym::x86_amx_intrinsics), &["amx-tile"]),
+    ("amx-movrs", Unstable(sym::x86_amx_intrinsics), &["amx-tile"]),
+    ("amx-tf32", Unstable(sym::x86_amx_intrinsics), &["amx-tile"]),
     ("amx-tile", Unstable(sym::x86_amx_intrinsics), &[]),
+    ("amx-transpose", Unstable(sym::x86_amx_intrinsics), &["amx-tile"]),
     ("avx", Stable, &["sse4.2"]),
     ("avx2", Stable, &["avx"]),
     ("avx512bf16", Unstable(sym::avx512_target_feature), &["avx512bw"]),
@@ -418,6 +423,7 @@ static X86_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("lahfsahf", Unstable(sym::lahfsahf_target_feature), &[]),
     ("lzcnt", Stable, &[]),
     ("movbe", Stable, &[]),
+    ("movrs", Unstable(sym::movrs_target_feature), &[]),
     ("pclmulqdq", Stable, &["sse2"]),
     ("popcnt", Stable, &[]),
     ("prfchw", Unstable(sym::prfchw_target_feature), &[]),

tests/ui/check-cfg/target_feature.stderr

@@ -17,11 +17,16 @@ LL |     cfg!(target_feature = "_UNEXPECTED_VALUE");
 `aes`
 `altivec`
 `alu32`
+`amx-avx512`
 `amx-bf16`
 `amx-complex`
 `amx-fp16`
+`amx-fp8`
 `amx-int8`
+`amx-movrs`
+`amx-tf32`
 `amx-tile`
+`amx-transpose`
 `atomics`
 `avx`
 `avx2`
@@ -152,6 +157,7 @@ LL |     cfg!(target_feature = "_UNEXPECTED_VALUE");
 `mclass`
 `mops`
 `movbe`
+`movrs`
 `mp`
 `mp1e2`
 `msa`

tests/ui/feature-gates/feature-gate-movrs_target_feature.rs

@@ -0,0 +1,6 @@
+//@ only-x86_64
+#[target_feature(enable = "movrs")]
+//~^ ERROR: currently unstable
+unsafe fn foo() {}
+
+fn main() {}

tests/ui/feature-gates/feature-gate-movrs_target_feature.stderr

@@ -0,0 +1,13 @@
+error[E0658]: the target feature `movrs` is currently unstable
+  --> $DIR/feature-gate-movrs_target_feature.rs:2:18
+   |
+LL | #[target_feature(enable = "movrs")]
+   |                  ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #137976 <https://github.com/rust-lang/rust/issues/137976> for more information
+   = help: add `#![feature(movrs_target_feature)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0658`.