Auto merge of #3901 - RalfJung:rustup, r=RalfJung

Rustup

This has a larger large "fmt" diff, probably there was a bug rustfmt update. For some reason the automatic `./miri fmt` on CI failed so this PR had to be created by hand -- it is unclear to me why this occurred.

1 files changed, 10 insertions, 30 deletions

diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 29afe6f6bfc..fd8db4ad1d5 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -217,10 +217,10 @@ impl<'a> IntoIterator for LLVMFeature<'a> {
 // where `{ARCH}` is the architecture name. Look for instances of `SubtargetFeature`.
 //
 // Check the current rustc fork of LLVM in the repo at https://github.com/rust-lang/llvm-project/.
-// The commit in use can be found via the `llvm-project` submodule in https://github.com/rust-lang/rust/tree/master/src
-// Though note that Rust can also be build with an external precompiled version of LLVM
-// which might lead to failures if the oldest tested / supported LLVM version
-// doesn't yet support the relevant intrinsics
+// The commit in use can be found via the `llvm-project` submodule in
+// https://github.com/rust-lang/rust/tree/master/src Though note that Rust can also be build with
+// an external precompiled version of LLVM which might lead to failures if the oldest tested /
+// supported LLVM version doesn't yet support the relevant intrinsics.
 pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFeature<'a>> {
     let arch = if sess.target.arch == "x86_64" {
         "x86"
@@ -258,28 +258,14 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         ("aarch64", "fhm") => Some(LLVMFeature::new("fp16fml")),
         ("aarch64", "fp16") => Some(LLVMFeature::new("fullfp16")),
         // Filter out features that are not supported by the current LLVM version
-        ("aarch64", "faminmax") if get_version().0 < 18 => None,
-        ("aarch64", "fp8") if get_version().0 < 18 => None,
-        ("aarch64", "fp8dot2") if get_version().0 < 18 => None,
-        ("aarch64", "fp8dot4") if get_version().0 < 18 => None,
-        ("aarch64", "fp8fma") if get_version().0 < 18 => None,
         ("aarch64", "fpmr") if get_version().0 != 18 => None,
-        ("aarch64", "lut") if get_version().0 < 18 => None,
-        ("aarch64", "sme-f8f16") if get_version().0 < 18 => None,
-        ("aarch64", "sme-f8f32") if get_version().0 < 18 => None,
-        ("aarch64", "sme-fa64") if get_version().0 < 18 => None,
-        ("aarch64", "sme-lutv2") if get_version().0 < 18 => None,
-        ("aarch64", "ssve-fp8dot2") if get_version().0 < 18 => None,
-        ("aarch64", "ssve-fp8dot4") if get_version().0 < 18 => None,
-        ("aarch64", "ssve-fp8fma") if get_version().0 < 18 => None,
-        ("aarch64", "v9.5a") if get_version().0 < 18 => None,
-        // In LLVM 18, `unaligned-scalar-mem` was merged with `unaligned-vector-mem` into a single feature called
-        // `fast-unaligned-access`. In LLVM 19, it was split back out.
+        // In LLVM 18, `unaligned-scalar-mem` was merged with `unaligned-vector-mem` into a single
+        // feature called `fast-unaligned-access`. In LLVM 19, it was split back out.
         ("riscv32" | "riscv64", "unaligned-scalar-mem") if get_version().0 == 18 => {
             Some(LLVMFeature::new("fast-unaligned-access"))
         }
-        // For LLVM 18, enable the evex512 target feature if a avx512 target feature is enabled.
-        ("x86", s) if get_version().0 >= 18 && s.starts_with("avx512") => {
+        // Enable the evex512 target feature if an avx512 target feature is enabled.
+        ("x86", s) if s.starts_with("avx512") => {
             Some(LLVMFeature::with_dependency(s, TargetFeatureFoldStrength::EnableOnly("evex512")))
         }
         (_, s) => Some(LLVMFeature::new(s)),
@@ -420,7 +406,8 @@ fn print_target_features(out: &mut String, sess: &Session, tm: &llvm::TargetMach
         .supported_target_features()
         .iter()
         .filter_map(|(feature, _gate, _implied)| {
-            // LLVM asserts that these are sorted. LLVM and Rust both use byte comparison for these strings.
+            // LLVM asserts that these are sorted. LLVM and Rust both use byte comparison for these
+            // strings.
             let llvm_feature = to_llvm_features(sess, *feature)?.llvm_feature_name;
             let desc =
                 match llvm_target_features.binary_search_by_key(&llvm_feature, |(f, _d)| f).ok() {
@@ -587,7 +574,6 @@ pub(crate) fn global_llvm_features(
     // -Ctarget-features
     if !only_base_features {
         let supported_features = sess.target.supported_target_features();
-        let (llvm_major, _, _) = get_version();
         let mut featsmap = FxHashMap::default();
 
         // insert implied features
@@ -664,12 +650,6 @@ pub(crate) fn global_llvm_features(
                     return None;
                 }
 
-                // if the target-feature is "backchain" and LLVM version is greater than 18
-                // then we also need to add "+backchain" to the target-features attribute.
-                // otherwise, we will only add the naked `backchain` attribute to the attribute-group.
-                if feature == "backchain" && llvm_major < 18 {
-                    return None;
-                }
                 // ... otherwise though we run through `to_llvm_features` when
                 // passing requests down to LLVM. This means that all in-language
                 // features also work on the command line instead of having two