Auto merge of #18183 - lnicola:sync-from-rust, r=lnicola

internal: Sync from downstream

1 files changed, 27 insertions, 37 deletions

diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 618602ed70f..71fd7afb148 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -1,4 +1,4 @@
-use std::ffi::{c_char, c_void, CStr, CString};
+use std::ffi::{CStr, CString, c_char, c_void};
 use std::fmt::Write;
 use std::path::Path;
 use std::sync::Once;
@@ -11,10 +11,10 @@ use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_data_structures::unord::UnordSet;
 use rustc_fs_util::path_to_c_string;
 use rustc_middle::bug;
-use rustc_session::config::{PrintKind, PrintRequest};
 use rustc_session::Session;
+use rustc_session::config::{PrintKind, PrintRequest};
 use rustc_span::symbol::Symbol;
-use rustc_target::spec::{MergeFunctions, PanicStrategy};
+use rustc_target::spec::{MergeFunctions, PanicStrategy, SmallDataThresholdSupport};
 use rustc_target::target_features::{RUSTC_SPECIAL_FEATURES, RUSTC_SPECIFIC_FEATURES};
 
 use crate::back::write::create_informational_target_machine;
@@ -125,6 +125,18 @@ unsafe fn configure_llvm(sess: &Session) {
         for arg in sess_args {
             add(&(*arg), true);
         }
+
+        match (
+            sess.opts.unstable_opts.small_data_threshold,
+            sess.target.small_data_threshold_support(),
+        ) {
+            // Set up the small-data optimization limit for architectures that use
+            // an LLVM argument to control this.
+            (Some(threshold), SmallDataThresholdSupport::LlvmArg(arg)) => {
+                add(&format!("--{arg}={threshold}"), false)
+            }
+            _ => (),
+        };
     }
 
     if sess.opts.unstable_opts.llvm_time_trace {
@@ -205,10 +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"
@@ -246,28 +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)),
@@ -290,7 +288,7 @@ pub(crate) fn check_tied_features(
             }
         }
     }
-    return None;
+    None
 }
 
 /// Used to generate cfg variables and apply features
@@ -353,9 +351,7 @@ pub fn target_features(sess: &Session, allow_unstable: bool) -> Vec<Symbol> {
                 None
             }
         })
-        .filter(|feature| {
-            RUSTC_SPECIAL_FEATURES.contains(feature) || features.contains(&Symbol::intern(feature))
-        })
+        .filter(|feature| features.contains(&Symbol::intern(feature)))
         .map(|feature| Symbol::intern(feature))
         .collect()
 }
@@ -410,7 +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() {
@@ -577,7 +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
@@ -654,12 +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