8 files changed, 62 insertions, 35 deletions
diff --git a/compiler/rustc_codegen_llvm/src/callee.rs b/compiler/rustc_codegen_llvm/src/callee.rs
index d5778757caa..0c9f7f19551 100644
--- a/compiler/rustc_codegen_llvm/src/callee.rs
+++ b/compiler/rustc_codegen_llvm/src/callee.rs
@@ -59,7 +59,7 @@ pub fn get_fn<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'tcx>) ->
             // To avoid this, we set the Storage Class to "DllImport" so that
             // LLVM will prefix the name with `__imp_`. Ideally, we'd like the
             // existing logic below to set the Storage Class, but it has an
-            // exemption for MinGW for backwards compatability.
+            // exemption for MinGW for backwards compatibility.
             let llfn = cx.declare_fn(
                 &common::i686_decorated_name(
                     &dllimport,
diff --git a/compiler/rustc_codegen_llvm/src/common.rs b/compiler/rustc_codegen_llvm/src/common.rs
index 0b0816c27b6..d1b643f4967 100644
--- a/compiler/rustc_codegen_llvm/src/common.rs
+++ b/compiler/rustc_codegen_llvm/src/common.rs
@@ -203,6 +203,7 @@ impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
                 unsafe {
                     llvm::LLVMSetInitializer(g, sc);
                     llvm::LLVMSetGlobalConstant(g, True);
+                    llvm::LLVMSetUnnamedAddress(g, llvm::UnnamedAddr::Global);
                     llvm::LLVMRustSetLinkage(g, llvm::Linkage::InternalLinkage);
                 }
                 (s.to_owned(), g)
diff --git a/compiler/rustc_codegen_llvm/src/consts.rs b/compiler/rustc_codegen_llvm/src/consts.rs
index 73821b1685d..307c1264dc1 100644
--- a/compiler/rustc_codegen_llvm/src/consts.rs
+++ b/compiler/rustc_codegen_llvm/src/consts.rs
@@ -374,15 +374,7 @@ impl<'ll> StaticMethods for CodegenCx<'ll, '_> {
 
             let g = self.get_static(def_id);
 
-            // boolean SSA values are i1, but they have to be stored in i8 slots,
-            // otherwise some LLVM optimization passes don't work as expected
-            let mut val_llty = self.val_ty(v);
-            let v = if val_llty == self.type_i1() {
-                val_llty = self.type_i8();
-                llvm::LLVMConstZExt(v, val_llty)
-            } else {
-                v
-            };
+            let val_llty = self.val_ty(v);
 
             let instance = Instance::mono(self.tcx, def_id);
             let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all());
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index b4b2ab1e1f8..242c6aed906 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -26,8 +26,8 @@ use rustc_middle::{bug, span_bug};
 use rustc_session::config::{BranchProtection, CFGuard, CFProtection};
 use rustc_session::config::{CrateType, DebugInfo, PAuthKey, PacRet};
 use rustc_session::Session;
-use rustc_span::source_map::Span;
 use rustc_span::source_map::Spanned;
+use rustc_span::Span;
 use rustc_target::abi::{
     call::FnAbi, HasDataLayout, PointeeInfo, Size, TargetDataLayout, VariantIdx,
 };
@@ -368,6 +368,24 @@ pub unsafe fn create_module<'ll>(
         llvm::LLVMMDNodeInContext(llcx, &name_metadata, 1),
     );
 
+    // Add module flags specified via -Z llvm_module_flag
+    for (key, value, behavior) in &sess.opts.unstable_opts.llvm_module_flag {
+        let key = format!("{key}\0");
+        let behavior = match behavior.as_str() {
+            "error" => llvm::LLVMModFlagBehavior::Error,
+            "warning" => llvm::LLVMModFlagBehavior::Warning,
+            "require" => llvm::LLVMModFlagBehavior::Require,
+            "override" => llvm::LLVMModFlagBehavior::Override,
+            "append" => llvm::LLVMModFlagBehavior::Append,
+            "appendunique" => llvm::LLVMModFlagBehavior::AppendUnique,
+            "max" => llvm::LLVMModFlagBehavior::Max,
+            "min" => llvm::LLVMModFlagBehavior::Min,
+            // We already checked this during option parsing
+            _ => unreachable!(),
+        };
+        llvm::LLVMRustAddModuleFlag(llmod, behavior, key.as_ptr().cast(), *value)
+    }
+
     llmod
 }
 
diff --git a/compiler/rustc_codegen_llvm/src/errors.rs b/compiler/rustc_codegen_llvm/src/errors.rs
index 665d195790c..10ca5ad802a 100644
--- a/compiler/rustc_codegen_llvm/src/errors.rs
+++ b/compiler/rustc_codegen_llvm/src/errors.rs
@@ -26,6 +26,13 @@ pub(crate) struct UnknownCTargetFeature<'a> {
     pub rust_feature: PossibleFeature<'a>,
 }
 
+#[derive(Diagnostic)]
+#[diag(codegen_llvm_unstable_ctarget_feature)]
+#[note]
+pub(crate) struct UnstableCTargetFeature<'a> {
+    pub feature: &'a str,
+}
+
 #[derive(Subdiagnostic)]
 pub(crate) enum PossibleFeature<'a> {
     #[help(codegen_llvm_possible_feature)]
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index 8a6a5f79b3b..3242e78ab7e 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -4,9 +4,9 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![cfg_attr(not(bootstrap), allow(internal_features))]
-#![cfg_attr(not(bootstrap), feature(rustdoc_internals))]
-#![cfg_attr(not(bootstrap), doc(rust_logo))]
+#![allow(internal_features)]
+#![feature(rustdoc_internals)]
+#![doc(rust_logo)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(exact_size_is_empty)]
 #![feature(extern_types)]
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index a038b3af03d..7fc02a95be0 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -969,7 +969,6 @@ extern "C" {
         ConstantIndices: *const &'a Value,
         NumIndices: c_uint,
     ) -> &'a Value;
-    pub fn LLVMConstZExt<'a>(ConstantVal: &'a Value, ToType: &'a Type) -> &'a Value;
     pub fn LLVMConstPtrToInt<'a>(ConstantVal: &'a Value, ToType: &'a Type) -> &'a Value;
     pub fn LLVMConstIntToPtr<'a>(ConstantVal: &'a Value, ToType: &'a Type) -> &'a Value;
     pub fn LLVMConstBitCast<'a>(ConstantVal: &'a Value, ToType: &'a Type) -> &'a Value;
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 7c8ef67ffd1..c86bf81fc13 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -1,7 +1,7 @@
 use crate::back::write::create_informational_target_machine;
 use crate::errors::{
     PossibleFeature, TargetFeatureDisableOrEnable, UnknownCTargetFeature,
-    UnknownCTargetFeaturePrefix,
+    UnknownCTargetFeaturePrefix, UnstableCTargetFeature,
 };
 use crate::llvm;
 use libc::c_int;
@@ -293,7 +293,7 @@ pub fn target_features(sess: &Session, allow_unstable: bool) -> Vec<Symbol> {
     supported_target_features(sess)
         .iter()
         .filter_map(|&(feature, gate)| {
-            if sess.is_nightly_build() || allow_unstable || gate.is_none() {
+            if sess.is_nightly_build() || allow_unstable || gate.is_stable() {
                 Some(feature)
             } else {
                 None
@@ -531,25 +531,35 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<Str
             };
 
             let feature = backend_feature_name(s)?;
-            // Warn against use of LLVM specific feature names on the CLI.
-            if diagnostics && !supported_features.iter().any(|&(v, _)| v == feature) {
-                let rust_feature = supported_features.iter().find_map(|&(rust_feature, _)| {
-                    let llvm_features = to_llvm_features(sess, rust_feature);
-                    if llvm_features.contains(&feature) && !llvm_features.contains(&rust_feature) {
-                        Some(rust_feature)
+            // Warn against use of LLVM specific feature names and unstable features on the CLI.
+            if diagnostics {
+                let feature_state = supported_features.iter().find(|&&(v, _)| v == feature);
+                if feature_state.is_none() {
+                    let rust_feature = supported_features.iter().find_map(|&(rust_feature, _)| {
+                        let llvm_features = to_llvm_features(sess, rust_feature);
+                        if llvm_features.contains(&feature)
+                            && !llvm_features.contains(&rust_feature)
+                        {
+                            Some(rust_feature)
+                        } else {
+                            None
+                        }
+                    });
+                    let unknown_feature = if let Some(rust_feature) = rust_feature {
+                        UnknownCTargetFeature {
+                            feature,
+                            rust_feature: PossibleFeature::Some { rust_feature },
+                        }
                     } else {
-                        None
-                    }
-                });
-                let unknown_feature = if let Some(rust_feature) = rust_feature {
-                    UnknownCTargetFeature {
-                        feature,
-                        rust_feature: PossibleFeature::Some { rust_feature },
-                    }
-                } else {
-                    UnknownCTargetFeature { feature, rust_feature: PossibleFeature::None }
-                };
-                sess.emit_warning(unknown_feature);
+                        UnknownCTargetFeature { feature, rust_feature: PossibleFeature::None }
+                    };
+                    sess.emit_warning(unknown_feature);
+                } else if feature_state
+                    .is_some_and(|(_name, feature_gate)| !feature_gate.is_stable())
+                {
+                    // An unstable feature. Warn about using it.
+                    sess.emit_warning(UnstableCTargetFeature { feature });
+                }
             }
 
             if diagnostics {