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-rw-r--r--compiler/rustc_codegen_llvm/src/abi.rs17
-rw-r--r--compiler/rustc_codegen_llvm/src/attributes.rs50
-rw-r--r--compiler/rustc_codegen_llvm/src/back/write.rs7
-rw-r--r--compiler/rustc_codegen_llvm/src/builder.rs30
-rw-r--r--compiler/rustc_codegen_llvm/src/builder/autodiff.rs24
-rw-r--r--compiler/rustc_codegen_llvm/src/context.rs39
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs299
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs42
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/unused.rs170
-rw-r--r--compiler/rustc_codegen_llvm/src/errors.rs4
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm_util.rs17
11 files changed, 353 insertions, 346 deletions
diff --git a/compiler/rustc_codegen_llvm/src/abi.rs b/compiler/rustc_codegen_llvm/src/abi.rs
index 71059338151..8294e29d07d 100644
--- a/compiler/rustc_codegen_llvm/src/abi.rs
+++ b/compiler/rustc_codegen_llvm/src/abi.rs
@@ -17,14 +17,13 @@ use rustc_target::callconv::{
 use rustc_target::spec::SanitizerSet;
 use smallvec::SmallVec;
 
-use crate::attributes::llfn_attrs_from_instance;
+use crate::attributes::{self, llfn_attrs_from_instance};
 use crate::builder::Builder;
 use crate::context::CodegenCx;
 use crate::llvm::{self, Attribute, AttributePlace};
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
-use crate::{attributes, llvm_util};
 
 trait ArgAttributesExt {
     fn apply_attrs_to_llfn(&self, idx: AttributePlace, cx: &CodegenCx<'_, '_>, llfn: &Value);
@@ -437,7 +436,6 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
 
         let apply_range_attr = |idx: AttributePlace, scalar: rustc_abi::Scalar| {
             if cx.sess().opts.optimize != config::OptLevel::No
-                && llvm_util::get_version() >= (19, 0, 0)
                 && matches!(scalar.primitive(), Primitive::Int(..))
                 // If the value is a boolean, the range is 0..2 and that ultimately
                 // become 0..0 when the type becomes i1, which would be rejected
@@ -571,19 +569,6 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
             }
             _ => {}
         }
-        if bx.cx.sess().opts.optimize != config::OptLevel::No
-                && llvm_util::get_version() < (19, 0, 0)
-                && let BackendRepr::Scalar(scalar) = self.ret.layout.backend_repr
-                && matches!(scalar.primitive(), Primitive::Int(..))
-                // If the value is a boolean, the range is 0..2 and that ultimately
-                // become 0..0 when the type becomes i1, which would be rejected
-                // by the LLVM verifier.
-                && !scalar.is_bool()
-                // LLVM also rejects full range.
-                && !scalar.is_always_valid(bx)
-        {
-            bx.range_metadata(callsite, scalar.valid_range(bx));
-        }
         for arg in self.args.iter() {
             match &arg.mode {
                 PassMode::Ignore => {}
diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index 3d7afa17bdf..e8c42d16733 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -407,30 +407,28 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
         // Do not set sanitizer attributes for naked functions.
         to_add.extend(sanitize_attrs(cx, codegen_fn_attrs.no_sanitize));
 
-        if llvm_util::get_version() >= (19, 0, 0) {
-            // For non-naked functions, set branch protection attributes on aarch64.
-            if let Some(BranchProtection { bti, pac_ret }) =
-                cx.sess().opts.unstable_opts.branch_protection
-            {
-                assert!(cx.sess().target.arch == "aarch64");
-                if bti {
-                    to_add.push(llvm::CreateAttrString(cx.llcx, "branch-target-enforcement"));
-                }
-                if let Some(PacRet { leaf, pc, key }) = pac_ret {
-                    if pc {
-                        to_add.push(llvm::CreateAttrString(cx.llcx, "branch-protection-pauth-lr"));
-                    }
-                    to_add.push(llvm::CreateAttrStringValue(
-                        cx.llcx,
-                        "sign-return-address",
-                        if leaf { "all" } else { "non-leaf" },
-                    ));
-                    to_add.push(llvm::CreateAttrStringValue(
-                        cx.llcx,
-                        "sign-return-address-key",
-                        if key == PAuthKey::A { "a_key" } else { "b_key" },
-                    ));
+        // For non-naked functions, set branch protection attributes on aarch64.
+        if let Some(BranchProtection { bti, pac_ret }) =
+            cx.sess().opts.unstable_opts.branch_protection
+        {
+            assert!(cx.sess().target.arch == "aarch64");
+            if bti {
+                to_add.push(llvm::CreateAttrString(cx.llcx, "branch-target-enforcement"));
+            }
+            if let Some(PacRet { leaf, pc, key }) = pac_ret {
+                if pc {
+                    to_add.push(llvm::CreateAttrString(cx.llcx, "branch-protection-pauth-lr"));
                 }
+                to_add.push(llvm::CreateAttrStringValue(
+                    cx.llcx,
+                    "sign-return-address",
+                    if leaf { "all" } else { "non-leaf" },
+                ));
+                to_add.push(llvm::CreateAttrStringValue(
+                    cx.llcx,
+                    "sign-return-address-key",
+                    if key == PAuthKey::A { "a_key" } else { "b_key" },
+                ));
             }
         }
     }
@@ -510,12 +508,6 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
             InstructionSetAttr::ArmA32 => "-thumb-mode".to_string(),
             InstructionSetAttr::ArmT32 => "+thumb-mode".to_string(),
         }))
-        // HACK: LLVM versions 19+ do not have the FPMR feature and treat it as always enabled
-        // It only exists as a feature in LLVM 18, cannot be passed down for any other version
-        .chain(match &*cx.tcx.sess.target.arch {
-            "aarch64" if llvm_util::get_version().0 == 18 => vec!["+fpmr".to_string()],
-            _ => vec![],
-        })
         .collect::<Vec<String>>();
 
     if cx.tcx.sess.target.is_like_wasm {
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index bf6138142b6..76d431a4975 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -439,12 +439,9 @@ fn report_inline_asm(
     let span = if cookie == 0 || matches!(cgcx.lto, Lto::Fat | Lto::Thin) {
         SpanData::default()
     } else {
-        let lo = BytePos::from_u32(cookie as u32);
-        let hi = BytePos::from_u32((cookie >> 32) as u32);
         SpanData {
-            lo,
-            // LLVM version < 19 silently truncates the cookie to 32 bits in some situations.
-            hi: if hi.to_u32() != 0 { hi } else { lo },
+            lo: BytePos::from_u32(cookie as u32),
+            hi: BytePos::from_u32((cookie >> 32) as u32),
             ctxt: SyntaxContext::root(),
             parent: None,
         }
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 297f104d124..35134e9f5a0 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -30,6 +30,7 @@ use smallvec::SmallVec;
 use tracing::{debug, instrument};
 
 use crate::abi::FnAbiLlvmExt;
+use crate::attributes;
 use crate::common::Funclet;
 use crate::context::{CodegenCx, FullCx, GenericCx, SCx};
 use crate::llvm::{
@@ -38,7 +39,6 @@ use crate::llvm::{
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
-use crate::{attributes, llvm_util};
 
 #[must_use]
 pub(crate) struct GenericBuilder<'a, 'll, CX: Borrow<SCx<'ll>>> {
@@ -927,11 +927,9 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         debug_assert_ne!(self.val_ty(val), dest_ty);
 
         let trunc = self.trunc(val, dest_ty);
-        if llvm_util::get_version() >= (19, 0, 0) {
-            unsafe {
-                if llvm::LLVMIsAInstruction(trunc).is_some() {
-                    llvm::LLVMSetNUW(trunc, True);
-                }
+        unsafe {
+            if llvm::LLVMIsAInstruction(trunc).is_some() {
+                llvm::LLVMSetNUW(trunc, True);
             }
         }
         trunc
@@ -941,11 +939,9 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         debug_assert_ne!(self.val_ty(val), dest_ty);
 
         let trunc = self.trunc(val, dest_ty);
-        if llvm_util::get_version() >= (19, 0, 0) {
-            unsafe {
-                if llvm::LLVMIsAInstruction(trunc).is_some() {
-                    llvm::LLVMSetNSW(trunc, True);
-                }
+        unsafe {
+            if llvm::LLVMIsAInstruction(trunc).is_some() {
+                llvm::LLVMSetNSW(trunc, True);
             }
         }
         trunc
@@ -1899,10 +1895,6 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
         hash: &'ll Value,
         bitmap_bits: &'ll Value,
     ) {
-        assert!(
-            crate::llvm_util::get_version() >= (19, 0, 0),
-            "MCDC intrinsics require LLVM 19 or later"
-        );
         self.call_intrinsic("llvm.instrprof.mcdc.parameters", &[fn_name, hash, bitmap_bits]);
     }
 
@@ -1914,10 +1906,6 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
         bitmap_index: &'ll Value,
         mcdc_temp: &'ll Value,
     ) {
-        assert!(
-            crate::llvm_util::get_version() >= (19, 0, 0),
-            "MCDC intrinsics require LLVM 19 or later"
-        );
         let args = &[fn_name, hash, bitmap_index, mcdc_temp];
         self.call_intrinsic("llvm.instrprof.mcdc.tvbitmap.update", args);
     }
@@ -1929,10 +1917,6 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
 
     #[instrument(level = "debug", skip(self))]
     pub(crate) fn mcdc_condbitmap_update(&mut self, cond_index: &'ll Value, mcdc_temp: &'ll Value) {
-        assert!(
-            crate::llvm_util::get_version() >= (19, 0, 0),
-            "MCDC intrinsics require LLVM 19 or later"
-        );
         let align = self.tcx.data_layout.i32_align.abi;
         let current_tv_index = self.load(self.cx.type_i32(), mcdc_temp, align);
         let new_tv_index = self.add(current_tv_index, cond_index);
diff --git a/compiler/rustc_codegen_llvm/src/builder/autodiff.rs b/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
index 7d264ba4d00..5e7ef27143b 100644
--- a/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
+++ b/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
@@ -201,7 +201,23 @@ fn compute_enzyme_fn_ty<'ll>(
         }
 
         if attrs.width == 1 {
-            todo!("Handle sret for scalar ad");
+            // Enzyme returns a struct of style:
+            // `{ original_ret(if requested), float, float, ... }`
+            let mut struct_elements = vec![];
+            if attrs.has_primal_ret() {
+                struct_elements.push(inner_ret_ty);
+            }
+            // Next, we push the list of active floats, since they will be lowered to `enzyme_out`,
+            // and therefore part of the return struct.
+            let param_tys = cx.func_params_types(fn_ty);
+            for (act, param_ty) in attrs.input_activity.iter().zip(param_tys) {
+                if matches!(act, DiffActivity::Active) {
+                    // Now find the float type at position i based on the fn_ty,
+                    // to know what (f16/f32/f64/...) to add to the struct.
+                    struct_elements.push(param_ty);
+                }
+            }
+            ret_ty = cx.type_struct(&struct_elements, false);
         } else {
             // First we check if we also have to deal with the primal return.
             match attrs.mode {
@@ -388,7 +404,11 @@ fn generate_enzyme_call<'ll>(
                 // now store the result of the enzyme call into the sret pointer.
                 let sret_ptr = outer_args[0];
                 let call_ty = cx.val_ty(call);
-                assert_eq!(cx.type_kind(call_ty), TypeKind::Array);
+                if attrs.width == 1 {
+                    assert_eq!(cx.type_kind(call_ty), TypeKind::Struct);
+                } else {
+                    assert_eq!(cx.type_kind(call_ty), TypeKind::Array);
+                }
                 llvm::LLVMBuildStore(&builder.llbuilder, call, sret_ptr);
             }
             builder.ret_void();
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index 3be8cd5f6ac..4ec69995518 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -164,23 +164,6 @@ pub(crate) unsafe fn create_module<'ll>(
     let mut target_data_layout = sess.target.data_layout.to_string();
     let llvm_version = llvm_util::get_version();
 
-    if llvm_version < (19, 0, 0) {
-        if sess.target.arch == "aarch64" || sess.target.arch.starts_with("arm64") {
-            // LLVM 19 sets -Fn32 in its data layout string for 64-bit ARM
-            // Earlier LLVMs leave this default, so remove it.
-            // See https://github.com/llvm/llvm-project/pull/90702
-            target_data_layout = target_data_layout.replace("-Fn32", "");
-        }
-    }
-
-    if llvm_version < (19, 0, 0) {
-        if sess.target.arch == "loongarch64" {
-            // LLVM 19 updates the LoongArch64 data layout.
-            // See https://github.com/llvm/llvm-project/pull/93814
-            target_data_layout = target_data_layout.replace("-n32:64", "-n64");
-        }
-    }
-
     if llvm_version < (20, 0, 0) {
         if sess.target.arch == "aarch64" || sess.target.arch.starts_with("arm64") {
             // LLVM 20 defines three additional address spaces for alternate
@@ -328,6 +311,22 @@ pub(crate) unsafe fn create_module<'ll>(
                 pfe.prefix().into(),
             );
         }
+
+        // Add "kcfi-arity" module flag if KCFI arity indicator is enabled. (See
+        // https://github.com/llvm/llvm-project/pull/117121.)
+        if sess.is_sanitizer_kcfi_arity_enabled() {
+            // KCFI arity indicator requires LLVM 21.0.0 or later.
+            if llvm_version < (21, 0, 0) {
+                tcx.dcx().emit_err(crate::errors::SanitizerKcfiArityRequiresLLVM2100);
+            }
+
+            llvm::add_module_flag_u32(
+                llmod,
+                llvm::ModuleFlagMergeBehavior::Override,
+                "kcfi-arity",
+                1,
+            );
+        }
     }
 
     // Control Flow Guard is currently only supported by MSVC and LLVM on Windows.
@@ -1202,10 +1201,8 @@ impl<'ll> CodegenCx<'ll, '_> {
 
         if self.sess().instrument_coverage() {
             ifn!("llvm.instrprof.increment", fn(ptr, t_i64, t_i32, t_i32) -> void);
-            if crate::llvm_util::get_version() >= (19, 0, 0) {
-                ifn!("llvm.instrprof.mcdc.parameters", fn(ptr, t_i64, t_i32) -> void);
-                ifn!("llvm.instrprof.mcdc.tvbitmap.update", fn(ptr, t_i64, t_i32, ptr) -> void);
-            }
+            ifn!("llvm.instrprof.mcdc.parameters", fn(ptr, t_i64, t_i32) -> void);
+            ifn!("llvm.instrprof.mcdc.tvbitmap.update", fn(ptr, t_i64, t_i32, ptr) -> void);
         }
 
         ifn!("llvm.type.test", fn(ptr, t_metadata) -> i1);
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
index 9a2473d6cf2..55b1e728b70 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
@@ -5,15 +5,11 @@ use rustc_abi::Align;
 use rustc_codegen_ssa::traits::{
     BaseTypeCodegenMethods, ConstCodegenMethods, StaticCodegenMethods,
 };
-use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
-use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_index::IndexVec;
-use rustc_middle::mir;
-use rustc_middle::mir::mono::MonoItemPartitions;
-use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::ty::TyCtxt;
 use rustc_session::RemapFileNameExt;
 use rustc_session::config::RemapPathScopeComponents;
-use rustc_span::def_id::DefIdSet;
 use rustc_span::{SourceFile, StableSourceFileId};
 use tracing::debug;
 
@@ -24,6 +20,7 @@ use crate::llvm;
 
 mod covfun;
 mod spans;
+mod unused;
 
 /// Generates and exports the coverage map, which is embedded in special
 /// linker sections in the final binary.
@@ -56,13 +53,6 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
         None => return,
     };
 
-    // The order of entries in this global file table needs to be deterministic,
-    // and ideally should also be independent of the details of stable-hashing,
-    // because coverage tests snapshots (`.cov-map`) can observe the order and
-    // would need to be re-blessed if it changes. As long as those requirements
-    // are satisfied, the order can be arbitrary.
-    let mut global_file_table = GlobalFileTable::new();
-
     let mut covfun_records = instances_used
         .iter()
         .copied()
@@ -70,18 +60,13 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
         // order that doesn't depend on the stable-hash-based order in which
         // instances were visited during codegen.
         .sorted_by_cached_key(|&instance| tcx.symbol_name(instance).name)
-        .filter_map(|instance| prepare_covfun_record(tcx, &mut global_file_table, instance, true))
+        .filter_map(|instance| prepare_covfun_record(tcx, instance, true))
         .collect::<Vec<_>>();
 
     // In a single designated CGU, also prepare covfun records for functions
     // in this crate that were instrumented for coverage, but are unused.
     if cx.codegen_unit.is_code_coverage_dead_code_cgu() {
-        let mut unused_instances = gather_unused_function_instances(cx);
-        // Sort the unused instances by symbol name, for the same reason as the used ones.
-        unused_instances.sort_by_cached_key(|&instance| tcx.symbol_name(instance).name);
-        covfun_records.extend(unused_instances.into_iter().filter_map(|instance| {
-            prepare_covfun_record(tcx, &mut global_file_table, instance, false)
-        }));
+        unused::prepare_covfun_records_for_unused_functions(cx, &mut covfun_records);
     }
 
     // If there are no covfun records for this CGU, don't generate a covmap record.
@@ -93,91 +78,88 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
         return;
     }
 
-    // Encode all filenames referenced by coverage mappings in this CGU.
-    let filenames_buffer = global_file_table.make_filenames_buffer(tcx);
-    // The `llvm-cov` tool uses this hash to associate each covfun record with
-    // its corresponding filenames table, since the final binary will typically
-    // contain multiple covmap records from different compilation units.
-    let filenames_hash = llvm_cov::hash_bytes(&filenames_buffer);
-
-    let mut unused_function_names = vec![];
+    // Prepare the global file table for this CGU, containing all paths needed
+    // by one or more covfun records.
+    let global_file_table =
+        GlobalFileTable::build(tcx, covfun_records.iter().flat_map(|c| c.all_source_files()));
 
     for covfun in &covfun_records {
-        unused_function_names.extend(covfun.mangled_function_name_if_unused());
-
-        covfun::generate_covfun_record(cx, filenames_hash, covfun)
-    }
-
-    // For unused functions, we need to take their mangled names and store them
-    // in a specially-named global array. LLVM's `InstrProfiling` pass will
-    // detect this global and include those names in its `__llvm_prf_names`
-    // section. (See `llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp`.)
-    if !unused_function_names.is_empty() {
-        assert!(cx.codegen_unit.is_code_coverage_dead_code_cgu());
-
-        let name_globals = unused_function_names
-            .into_iter()
-            .map(|mangled_function_name| cx.const_str(mangled_function_name).0)
-            .collect::<Vec<_>>();
-        let initializer = cx.const_array(cx.type_ptr(), &name_globals);
-
-        let array = llvm::add_global(cx.llmod, cx.val_ty(initializer), c"__llvm_coverage_names");
-        llvm::set_global_constant(array, true);
-        llvm::set_linkage(array, llvm::Linkage::InternalLinkage);
-        llvm::set_initializer(array, initializer);
+        covfun::generate_covfun_record(cx, &global_file_table, covfun)
     }
 
     // Generate the coverage map header, which contains the filenames used by
     // this CGU's coverage mappings, and store it in a well-known global.
     // (This is skipped if we returned early due to having no covfun records.)
-    generate_covmap_record(cx, covmap_version, &filenames_buffer);
+    generate_covmap_record(cx, covmap_version, &global_file_table.filenames_buffer);
 }
 
-/// Maps "global" (per-CGU) file ID numbers to their underlying source files.
+/// Maps "global" (per-CGU) file ID numbers to their underlying source file paths.
+#[derive(Debug)]
 struct GlobalFileTable {
     /// This "raw" table doesn't include the working dir, so a file's
     /// global ID is its index in this set **plus one**.
-    raw_file_table: FxIndexMap<StableSourceFileId, Arc<SourceFile>>,
+    raw_file_table: FxIndexMap<StableSourceFileId, String>,
+
+    /// The file table in encoded form (possibly compressed), which can be
+    /// included directly in this CGU's `__llvm_covmap` record.
+    filenames_buffer: Vec<u8>,
+
+    /// Truncated hash of the bytes in `filenames_buffer`.
+    ///
+    /// The `llvm-cov` tool uses this hash to associate each covfun record with
+    /// its corresponding filenames table, since the final binary will typically
+    /// contain multiple covmap records from different compilation units.
+    filenames_hash: u64,
 }
 
 impl GlobalFileTable {
-    fn new() -> Self {
-        Self { raw_file_table: FxIndexMap::default() }
-    }
+    /// Builds a "global file table" for this CGU, mapping numeric IDs to
+    /// path strings.
+    fn build<'a>(tcx: TyCtxt<'_>, all_files: impl Iterator<Item = &'a SourceFile>) -> Self {
+        let mut raw_file_table = FxIndexMap::default();
+
+        for file in all_files {
+            raw_file_table.entry(file.stable_id).or_insert_with(|| {
+                file.name
+                    .for_scope(tcx.sess, RemapPathScopeComponents::MACRO)
+                    .to_string_lossy()
+                    .into_owned()
+            });
+        }
 
-    fn global_file_id_for_file(&mut self, file: &Arc<SourceFile>) -> GlobalFileId {
-        // Ensure the given file has a table entry, and get its index.
-        let entry = self.raw_file_table.entry(file.stable_id);
-        let raw_id = entry.index();
-        entry.or_insert_with(|| Arc::clone(file));
+        // FIXME(Zalathar): Consider sorting the file table here, but maybe
+        // only after adding filename support to coverage-dump, so that the
+        // table order isn't directly visible in `.coverage-map` snapshots.
 
-        // The raw file table doesn't include an entry for the working dir
-        // (which has ID 0), so add 1 to get the correct ID.
-        GlobalFileId::from_usize(raw_id + 1)
-    }
+        let mut table = Vec::with_capacity(raw_file_table.len() + 1);
 
-    fn make_filenames_buffer(&self, tcx: TyCtxt<'_>) -> Vec<u8> {
-        let mut table = Vec::with_capacity(self.raw_file_table.len() + 1);
-
-        // LLVM Coverage Mapping Format version 6 (zero-based encoded as 5)
-        // requires setting the first filename to the compilation directory.
-        // Since rustc generates coverage maps with relative paths, the
-        // compilation directory can be combined with the relative paths
-        // to get absolute paths, if needed.
-        table.push(
-            tcx.sess
-                .opts
-                .working_dir
-                .for_scope(tcx.sess, RemapPathScopeComponents::MACRO)
-                .to_string_lossy(),
-        );
+        // Since version 6 of the LLVM coverage mapping format, the first entry
+        // in the global file table is treated as a base directory, used to
+        // resolve any other entries that are stored as relative paths.
+        let base_dir = tcx
+            .sess
+            .opts
+            .working_dir
+            .for_scope(tcx.sess, RemapPathScopeComponents::MACRO)
+            .to_string_lossy();
+        table.push(base_dir.as_ref());
 
         // Add the regular entries after the base directory.
-        table.extend(self.raw_file_table.values().map(|file| {
-            file.name.for_scope(tcx.sess, RemapPathScopeComponents::MACRO).to_string_lossy()
-        }));
+        table.extend(raw_file_table.values().map(|name| name.as_str()));
 
-        llvm_cov::write_filenames_to_buffer(&table)
+        // Encode the file table into a buffer, and get the hash of its encoded
+        // bytes, so that we can embed that hash in `__llvm_covfun` records.
+        let filenames_buffer = llvm_cov::write_filenames_to_buffer(&table);
+        let filenames_hash = llvm_cov::hash_bytes(&filenames_buffer);
+
+        Self { raw_file_table, filenames_buffer, filenames_hash }
+    }
+
+    fn get_existing_id(&self, file: &SourceFile) -> Option<GlobalFileId> {
+        let raw_id = self.raw_file_table.get_index_of(&file.stable_id)?;
+        // The raw file table doesn't include an entry for the base dir
+        // (which has ID 0), so add 1 to get the correct ID.
+        Some(GlobalFileId::from_usize(raw_id + 1))
     }
 }
 
@@ -193,26 +175,31 @@ rustc_index::newtype_index! {
     struct LocalFileId {}
 }
 
-/// Holds a mapping from "local" (per-function) file IDs to "global" (per-CGU)
-/// file IDs.
+/// Holds a mapping from "local" (per-function) file IDs to their corresponding
+/// source files.
 #[derive(Debug, Default)]
 struct VirtualFileMapping {
-    local_to_global: IndexVec<LocalFileId, GlobalFileId>,
-    global_to_local: FxIndexMap<GlobalFileId, LocalFileId>,
+    local_file_table: IndexVec<LocalFileId, Arc<SourceFile>>,
 }
 
 impl VirtualFileMapping {
-    fn local_id_for_global(&mut self, global_file_id: GlobalFileId) -> LocalFileId {
-        *self
-            .global_to_local
-            .entry(global_file_id)
-            .or_insert_with(|| self.local_to_global.push(global_file_id))
+    fn push_file(&mut self, source_file: &Arc<SourceFile>) -> LocalFileId {
+        self.local_file_table.push(Arc::clone(source_file))
     }
 
-    fn to_vec(&self) -> Vec<u32> {
-        // This clone could be avoided by transmuting `&[GlobalFileId]` to `&[u32]`,
-        // but it isn't hot or expensive enough to justify the extra unsafety.
-        self.local_to_global.iter().map(|&global| GlobalFileId::as_u32(global)).collect()
+    /// Resolves all of the filenames in this local file mapping to a list of
+    /// global file IDs in its CGU, for inclusion in this function's
+    /// `__llvm_covfun` record.
+    ///
+    /// The global file IDs are returned as `u32` to make FFI easier.
+    fn resolve_all(&self, global_file_table: &GlobalFileTable) -> Option<Vec<u32>> {
+        self.local_file_table
+            .iter()
+            .map(|file| try {
+                let id = global_file_table.get_existing_id(file)?;
+                GlobalFileId::as_u32(id)
+            })
+            .collect::<Option<Vec<_>>>()
     }
 }
 
@@ -249,121 +236,3 @@ fn generate_covmap_record<'ll>(cx: &CodegenCx<'ll, '_>, version: u32, filenames_
 
     cx.add_used_global(covmap_global);
 }
-
-/// Each CGU will normally only emit coverage metadata for the functions that it actually generates.
-/// But since we don't want unused functions to disappear from coverage reports, we also scan for
-/// functions that were instrumented but are not participating in codegen.
-///
-/// These unused functions don't need to be codegenned, but we do need to add them to the function
-/// coverage map (in a single designated CGU) so that we still emit coverage mappings for them.
-/// We also end up adding their symbol names to a special global array that LLVM will include in
-/// its embedded coverage data.
-fn gather_unused_function_instances<'tcx>(cx: &CodegenCx<'_, 'tcx>) -> Vec<ty::Instance<'tcx>> {
-    assert!(cx.codegen_unit.is_code_coverage_dead_code_cgu());
-
-    let tcx = cx.tcx;
-    let usage = prepare_usage_sets(tcx);
-
-    let is_unused_fn = |def_id: LocalDefId| -> bool {
-        // Usage sets expect `DefId`, so convert from `LocalDefId`.
-        let d: DefId = LocalDefId::to_def_id(def_id);
-        // To be potentially eligible for "unused function" mappings, a definition must:
-        // - Be eligible for coverage instrumentation
-        // - Not participate directly in codegen (or have lost all its coverage statements)
-        // - Not have any coverage statements inlined into codegenned functions
-        tcx.is_eligible_for_coverage(def_id)
-            && (!usage.all_mono_items.contains(&d) || usage.missing_own_coverage.contains(&d))
-            && !usage.used_via_inlining.contains(&d)
-    };
-
-    // FIXME(#79651): Consider trying to filter out dummy instantiations of
-    // unused generic functions from library crates, because they can produce
-    // "unused instantiation" in coverage reports even when they are actually
-    // used by some downstream crate in the same binary.
-
-    tcx.mir_keys(())
-        .iter()
-        .copied()
-        .filter(|&def_id| is_unused_fn(def_id))
-        .map(|def_id| make_dummy_instance(tcx, def_id))
-        .collect::<Vec<_>>()
-}
-
-struct UsageSets<'tcx> {
-    all_mono_items: &'tcx DefIdSet,
-    used_via_inlining: FxHashSet<DefId>,
-    missing_own_coverage: FxHashSet<DefId>,
-}
-
-/// Prepare sets of definitions that are relevant to deciding whether something
-/// is an "unused function" for coverage purposes.
-fn prepare_usage_sets<'tcx>(tcx: TyCtxt<'tcx>) -> UsageSets<'tcx> {
-    let MonoItemPartitions { all_mono_items, codegen_units, .. } =
-        tcx.collect_and_partition_mono_items(());
-
-    // Obtain a MIR body for each function participating in codegen, via an
-    // arbitrary instance.
-    let mut def_ids_seen = FxHashSet::default();
-    let def_and_mir_for_all_mono_fns = codegen_units
-        .iter()
-        .flat_map(|cgu| cgu.items().keys())
-        .filter_map(|item| match item {
-            mir::mono::MonoItem::Fn(instance) => Some(instance),
-            mir::mono::MonoItem::Static(_) | mir::mono::MonoItem::GlobalAsm(_) => None,
-        })
-        // We only need one arbitrary instance per definition.
-        .filter(move |instance| def_ids_seen.insert(instance.def_id()))
-        .map(|instance| {
-            // We don't care about the instance, just its underlying MIR.
-            let body = tcx.instance_mir(instance.def);
-            (instance.def_id(), body)
-        });
-
-    // Functions whose coverage statements were found inlined into other functions.
-    let mut used_via_inlining = FxHashSet::default();
-    // Functions that were instrumented, but had all of their coverage statements
-    // removed by later MIR transforms (e.g. UnreachablePropagation).
-    let mut missing_own_coverage = FxHashSet::default();
-
-    for (def_id, body) in def_and_mir_for_all_mono_fns {
-        let mut saw_own_coverage = false;
-
-        // Inspect every coverage statement in the function's MIR.
-        for stmt in body
-            .basic_blocks
-            .iter()
-            .flat_map(|block| &block.statements)
-            .filter(|stmt| matches!(stmt.kind, mir::StatementKind::Coverage(_)))
-        {
-            if let Some(inlined) = stmt.source_info.scope.inlined_instance(&body.source_scopes) {
-                // This coverage statement was inlined from another function.
-                used_via_inlining.insert(inlined.def_id());
-            } else {
-                // Non-inlined coverage statements belong to the enclosing function.
-                saw_own_coverage = true;
-            }
-        }
-
-        if !saw_own_coverage && body.function_coverage_info.is_some() {
-            missing_own_coverage.insert(def_id);
-        }
-    }
-
-    UsageSets { all_mono_items, used_via_inlining, missing_own_coverage }
-}
-
-fn make_dummy_instance<'tcx>(tcx: TyCtxt<'tcx>, local_def_id: LocalDefId) -> ty::Instance<'tcx> {
-    let def_id = local_def_id.to_def_id();
-
-    // Make a dummy instance that fills in all generics with placeholders.
-    ty::Instance::new(
-        def_id,
-        ty::GenericArgs::for_item(tcx, def_id, |param, _| {
-            if let ty::GenericParamDefKind::Lifetime = param.kind {
-                tcx.lifetimes.re_erased.into()
-            } else {
-                tcx.mk_param_from_def(param)
-            }
-        }),
-    )
-}
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
index 048e1988c32..7bdbc685952 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
@@ -5,6 +5,7 @@
 //! [^win]: On Windows the section name is `.lcovfun`.
 
 use std::ffi::CString;
+use std::sync::Arc;
 
 use rustc_abi::Align;
 use rustc_codegen_ssa::traits::{
@@ -15,7 +16,7 @@ use rustc_middle::mir::coverage::{
     MappingKind, Op,
 };
 use rustc_middle::ty::{Instance, TyCtxt};
-use rustc_span::Span;
+use rustc_span::{SourceFile, Span};
 use rustc_target::spec::HasTargetSpec;
 use tracing::debug;
 
@@ -38,16 +39,15 @@ pub(crate) struct CovfunRecord<'tcx> {
 }
 
 impl<'tcx> CovfunRecord<'tcx> {
-    /// FIXME(Zalathar): Make this the responsibility of the code that determines
-    /// which functions are unused.
-    pub(crate) fn mangled_function_name_if_unused(&self) -> Option<&'tcx str> {
-        (!self.is_used).then_some(self.mangled_function_name)
+    /// Iterator that yields all source files referred to by this function's
+    /// coverage mappings. Used to build the global file table for the CGU.
+    pub(crate) fn all_source_files(&self) -> impl Iterator<Item = &SourceFile> {
+        self.virtual_file_mapping.local_file_table.iter().map(Arc::as_ref)
     }
 }
 
 pub(crate) fn prepare_covfun_record<'tcx>(
     tcx: TyCtxt<'tcx>,
-    global_file_table: &mut GlobalFileTable,
     instance: Instance<'tcx>,
     is_used: bool,
 ) -> Option<CovfunRecord<'tcx>> {
@@ -65,7 +65,7 @@ pub(crate) fn prepare_covfun_record<'tcx>(
         regions: ffi::Regions::default(),
     };
 
-    fill_region_tables(tcx, global_file_table, fn_cov_info, ids_info, &mut covfun);
+    fill_region_tables(tcx, fn_cov_info, ids_info, &mut covfun);
 
     if covfun.regions.has_no_regions() {
         debug!(?covfun, "function has no mappings to embed; skipping");
@@ -100,7 +100,6 @@ fn prepare_expressions(ids_info: &CoverageIdsInfo) -> Vec<ffi::CounterExpression
 /// Populates the mapping region tables in the current function's covfun record.
 fn fill_region_tables<'tcx>(
     tcx: TyCtxt<'tcx>,
-    global_file_table: &mut GlobalFileTable,
     fn_cov_info: &'tcx FunctionCoverageInfo,
     ids_info: &'tcx CoverageIdsInfo,
     covfun: &mut CovfunRecord<'tcx>,
@@ -114,11 +113,7 @@ fn fill_region_tables<'tcx>(
     };
     let source_file = source_map.lookup_source_file(first_span.lo());
 
-    // Look up the global file ID for that file.
-    let global_file_id = global_file_table.global_file_id_for_file(&source_file);
-
-    // Associate that global file ID with a local file ID for this function.
-    let local_file_id = covfun.virtual_file_mapping.local_id_for_global(global_file_id);
+    let local_file_id = covfun.virtual_file_mapping.push_file(&source_file);
 
     // In rare cases, _all_ of a function's spans are discarded, and coverage
     // codegen needs to handle that gracefully to avoid #133606.
@@ -187,7 +182,7 @@ fn fill_region_tables<'tcx>(
 /// as a global variable in the `__llvm_covfun` section.
 pub(crate) fn generate_covfun_record<'tcx>(
     cx: &CodegenCx<'_, 'tcx>,
-    filenames_hash: u64,
+    global_file_table: &GlobalFileTable,
     covfun: &CovfunRecord<'tcx>,
 ) {
     let &CovfunRecord {
@@ -199,12 +194,19 @@ pub(crate) fn generate_covfun_record<'tcx>(
         ref regions,
     } = covfun;
 
+    let Some(local_file_table) = virtual_file_mapping.resolve_all(global_file_table) else {
+        debug_assert!(
+            false,
+            "all local files should be present in the global file table: \
+                global_file_table = {global_file_table:?}, \
+                virtual_file_mapping = {virtual_file_mapping:?}"
+        );
+        return;
+    };
+
     // Encode the function's coverage mappings into a buffer.
-    let coverage_mapping_buffer = llvm_cov::write_function_mappings_to_buffer(
-        &virtual_file_mapping.to_vec(),
-        expressions,
-        regions,
-    );
+    let coverage_mapping_buffer =
+        llvm_cov::write_function_mappings_to_buffer(&local_file_table, expressions, regions);
 
     // A covfun record consists of four target-endian integers, followed by the
     // encoded mapping data in bytes. Note that the length field is 32 bits.
@@ -217,7 +219,7 @@ pub(crate) fn generate_covfun_record<'tcx>(
             cx.const_u64(func_name_hash),
             cx.const_u32(coverage_mapping_buffer.len() as u32),
             cx.const_u64(source_hash),
-            cx.const_u64(filenames_hash),
+            cx.const_u64(global_file_table.filenames_hash),
             cx.const_bytes(&coverage_mapping_buffer),
         ],
         // This struct needs to be packed, so that the 32-bit length field
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/unused.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/unused.rs
new file mode 100644
index 00000000000..68f60f169b5
--- /dev/null
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/unused.rs
@@ -0,0 +1,170 @@
+use rustc_codegen_ssa::traits::{BaseTypeCodegenMethods, ConstCodegenMethods};
+use rustc_data_structures::fx::FxHashSet;
+use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_middle::mir;
+use rustc_middle::mir::mono::MonoItemPartitions;
+use rustc_middle::ty::{self, TyCtxt};
+use rustc_span::def_id::DefIdSet;
+
+use crate::common::CodegenCx;
+use crate::coverageinfo::mapgen::covfun::{CovfunRecord, prepare_covfun_record};
+use crate::llvm;
+
+/// Each CGU will normally only emit coverage metadata for the functions that it actually generates.
+/// But since we don't want unused functions to disappear from coverage reports, we also scan for
+/// functions that were instrumented but are not participating in codegen.
+///
+/// These unused functions don't need to be codegenned, but we do need to add them to the function
+/// coverage map (in a single designated CGU) so that we still emit coverage mappings for them.
+/// We also end up adding their symbol names to a special global array that LLVM will include in
+/// its embedded coverage data.
+pub(crate) fn prepare_covfun_records_for_unused_functions<'tcx>(
+    cx: &CodegenCx<'_, 'tcx>,
+    covfun_records: &mut Vec<CovfunRecord<'tcx>>,
+) {
+    assert!(cx.codegen_unit.is_code_coverage_dead_code_cgu());
+
+    let mut unused_instances = gather_unused_function_instances(cx);
+    // Sort the unused instances by symbol name, so that their order isn't hash-sensitive.
+    unused_instances.sort_by_key(|instance| instance.symbol_name);
+
+    // Try to create a covfun record for each unused function.
+    let mut name_globals = Vec::with_capacity(unused_instances.len());
+    covfun_records.extend(unused_instances.into_iter().filter_map(|unused| try {
+        let record = prepare_covfun_record(cx.tcx, unused.instance, false)?;
+        // If successful, also store its symbol name in a global constant.
+        name_globals.push(cx.const_str(unused.symbol_name.name).0);
+        record
+    }));
+
+    // Store the names of unused functions in a specially-named global array.
+    // LLVM's `InstrProfilling` pass will detect this array, and include the
+    // referenced names in its `__llvm_prf_names` section.
+    // (See `llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp`.)
+    if !name_globals.is_empty() {
+        let initializer = cx.const_array(cx.type_ptr(), &name_globals);
+
+        let array = llvm::add_global(cx.llmod, cx.val_ty(initializer), c"__llvm_coverage_names");
+        llvm::set_global_constant(array, true);
+        llvm::set_linkage(array, llvm::Linkage::InternalLinkage);
+        llvm::set_initializer(array, initializer);
+    }
+}
+
+/// Holds a dummy function instance along with its symbol name, to avoid having
+/// to repeatedly query for the name.
+struct UnusedInstance<'tcx> {
+    instance: ty::Instance<'tcx>,
+    symbol_name: ty::SymbolName<'tcx>,
+}
+
+fn gather_unused_function_instances<'tcx>(cx: &CodegenCx<'_, 'tcx>) -> Vec<UnusedInstance<'tcx>> {
+    assert!(cx.codegen_unit.is_code_coverage_dead_code_cgu());
+
+    let tcx = cx.tcx;
+    let usage = prepare_usage_sets(tcx);
+
+    let is_unused_fn = |def_id: LocalDefId| -> bool {
+        // Usage sets expect `DefId`, so convert from `LocalDefId`.
+        let d: DefId = LocalDefId::to_def_id(def_id);
+        // To be potentially eligible for "unused function" mappings, a definition must:
+        // - Be eligible for coverage instrumentation
+        // - Not participate directly in codegen (or have lost all its coverage statements)
+        // - Not have any coverage statements inlined into codegenned functions
+        tcx.is_eligible_for_coverage(def_id)
+            && (!usage.all_mono_items.contains(&d) || usage.missing_own_coverage.contains(&d))
+            && !usage.used_via_inlining.contains(&d)
+    };
+
+    // FIXME(#79651): Consider trying to filter out dummy instantiations of
+    // unused generic functions from library crates, because they can produce
+    // "unused instantiation" in coverage reports even when they are actually
+    // used by some downstream crate in the same binary.
+
+    tcx.mir_keys(())
+        .iter()
+        .copied()
+        .filter(|&def_id| is_unused_fn(def_id))
+        .map(|def_id| make_dummy_instance(tcx, def_id))
+        .map(|instance| UnusedInstance { instance, symbol_name: tcx.symbol_name(instance) })
+        .collect::<Vec<_>>()
+}
+
+struct UsageSets<'tcx> {
+    all_mono_items: &'tcx DefIdSet,
+    used_via_inlining: FxHashSet<DefId>,
+    missing_own_coverage: FxHashSet<DefId>,
+}
+
+/// Prepare sets of definitions that are relevant to deciding whether something
+/// is an "unused function" for coverage purposes.
+fn prepare_usage_sets<'tcx>(tcx: TyCtxt<'tcx>) -> UsageSets<'tcx> {
+    let MonoItemPartitions { all_mono_items, codegen_units, .. } =
+        tcx.collect_and_partition_mono_items(());
+
+    // Obtain a MIR body for each function participating in codegen, via an
+    // arbitrary instance.
+    let mut def_ids_seen = FxHashSet::default();
+    let def_and_mir_for_all_mono_fns = codegen_units
+        .iter()
+        .flat_map(|cgu| cgu.items().keys())
+        .filter_map(|item| match item {
+            mir::mono::MonoItem::Fn(instance) => Some(instance),
+            mir::mono::MonoItem::Static(_) | mir::mono::MonoItem::GlobalAsm(_) => None,
+        })
+        // We only need one arbitrary instance per definition.
+        .filter(move |instance| def_ids_seen.insert(instance.def_id()))
+        .map(|instance| {
+            // We don't care about the instance, just its underlying MIR.
+            let body = tcx.instance_mir(instance.def);
+            (instance.def_id(), body)
+        });
+
+    // Functions whose coverage statements were found inlined into other functions.
+    let mut used_via_inlining = FxHashSet::default();
+    // Functions that were instrumented, but had all of their coverage statements
+    // removed by later MIR transforms (e.g. UnreachablePropagation).
+    let mut missing_own_coverage = FxHashSet::default();
+
+    for (def_id, body) in def_and_mir_for_all_mono_fns {
+        let mut saw_own_coverage = false;
+
+        // Inspect every coverage statement in the function's MIR.
+        for stmt in body
+            .basic_blocks
+            .iter()
+            .flat_map(|block| &block.statements)
+            .filter(|stmt| matches!(stmt.kind, mir::StatementKind::Coverage(_)))
+        {
+            if let Some(inlined) = stmt.source_info.scope.inlined_instance(&body.source_scopes) {
+                // This coverage statement was inlined from another function.
+                used_via_inlining.insert(inlined.def_id());
+            } else {
+                // Non-inlined coverage statements belong to the enclosing function.
+                saw_own_coverage = true;
+            }
+        }
+
+        if !saw_own_coverage && body.function_coverage_info.is_some() {
+            missing_own_coverage.insert(def_id);
+        }
+    }
+
+    UsageSets { all_mono_items, used_via_inlining, missing_own_coverage }
+}
+
+fn make_dummy_instance<'tcx>(tcx: TyCtxt<'tcx>, local_def_id: LocalDefId) -> ty::Instance<'tcx> {
+    let def_id = local_def_id.to_def_id();
+
+    // Make a dummy instance that fills in all generics with placeholders.
+    ty::Instance::new(
+        def_id,
+        ty::GenericArgs::for_item(tcx, def_id, |param, _| {
+            if let ty::GenericParamDefKind::Lifetime = param.kind {
+                tcx.lifetimes.re_erased.into()
+            } else {
+                tcx.mk_param_from_def(param)
+            }
+        }),
+    )
+}
diff --git a/compiler/rustc_codegen_llvm/src/errors.rs b/compiler/rustc_codegen_llvm/src/errors.rs
index 4c5a78ca74f..ecf108f988f 100644
--- a/compiler/rustc_codegen_llvm/src/errors.rs
+++ b/compiler/rustc_codegen_llvm/src/errors.rs
@@ -217,3 +217,7 @@ pub(crate) struct MismatchedDataLayout<'a> {
 pub(crate) struct FixedX18InvalidArch<'a> {
     pub arch: &'a str,
 }
+
+#[derive(Diagnostic)]
+#[diag(codegen_llvm_sanitizer_kcfi_arity_requires_llvm_21_0_0)]
+pub(crate) struct SanitizerKcfiArityRequiresLLVM2100;
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 4e85286ed55..36e35f81392 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -256,7 +256,6 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         ("aarch64", "pmuv3") => Some(LLVMFeature::new("perfmon")),
         ("aarch64", "paca") => Some(LLVMFeature::new("pauth")),
         ("aarch64", "pacg") => Some(LLVMFeature::new("pauth")),
-        ("aarch64", "pauth-lr") if get_version().0 < 19 => None,
         // Before LLVM 20 those two features were packaged together as b16b16
         ("aarch64", "sve-b16b16") if get_version().0 < 20 => Some(LLVMFeature::new("b16b16")),
         ("aarch64", "sme-b16b16") if get_version().0 < 20 => Some(LLVMFeature::new("b16b16")),
@@ -270,20 +269,9 @@ 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", "fpmr") if get_version().0 != 18 => None,
+        ("aarch64", "fpmr") => None, // only existed in 18
         ("arm", "fp16") => Some(LLVMFeature::new("fullfp16")),
-        // 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" | "unaligned-vector-mem")
-            if get_version().0 == 18 =>
-        {
-            Some(LLVMFeature::new("fast-unaligned-access"))
-        }
         // Filter out features that are not supported by the current LLVM version
-        ("riscv32" | "riscv64", "zaamo") if get_version().0 < 19 => None,
-        ("riscv32" | "riscv64", "zabha") if get_version().0 < 19 => None,
-        ("riscv32" | "riscv64", "zalrsc") if get_version().0 < 19 => None,
-        ("riscv32" | "riscv64", "zama16b") if get_version().0 < 19 => None,
         ("riscv32" | "riscv64", "zacas") if get_version().0 < 20 => None,
         // Enable the evex512 target feature if an avx512 target feature is enabled.
         ("x86", s) if s.starts_with("avx512") => {
@@ -295,10 +283,9 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         ("sparc", "leoncasa") => Some(LLVMFeature::new("hasleoncasa")),
         // In LLVM 19, there is no `v8plus` feature and `v9` means "SPARC-V9 instruction available and SPARC-V8+ ABI used".
         // https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp#L27-L28
-        // Before LLVM 19, there is no `v8plus` feature and `v9` means "SPARC-V9 instruction available".
+        // Before LLVM 19, there was no `v8plus` feature and `v9` means "SPARC-V9 instruction available".
         // https://github.com/llvm/llvm-project/blob/llvmorg-18.1.0/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp#L26
         ("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")