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-rw-r--r--compiler/rustc_codegen_llvm/Cargo.toml2
-rw-r--r--compiler/rustc_codegen_llvm/src/attributes.rs2
-rw-r--r--compiler/rustc_codegen_llvm/src/back/write.rs3
-rw-r--r--compiler/rustc_codegen_llvm/src/base.rs2
-rw-r--r--compiler/rustc_codegen_llvm/src/callee.rs2
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs36
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/llvm_cov.rs5
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs84
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs204
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs123
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs126
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs19
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs2
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs3
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs25
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/mod.rs2
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs4
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/mod.rs3
-rw-r--r--compiler/rustc_codegen_llvm/src/lib.rs3
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm/ffi.rs28
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm_util.rs8
-rw-r--r--compiler/rustc_codegen_llvm/src/type_of.rs2
22 files changed, 351 insertions, 337 deletions
diff --git a/compiler/rustc_codegen_llvm/Cargo.toml b/compiler/rustc_codegen_llvm/Cargo.toml
index 03a871297c4..689986d642d 100644
--- a/compiler/rustc_codegen_llvm/Cargo.toml
+++ b/compiler/rustc_codegen_llvm/Cargo.toml
@@ -16,7 +16,7 @@ object = { version = "0.36.3", default-features = false, features = ["std", "rea
 rustc-demangle = "0.1.21"
 rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
-rustc_attr = { path = "../rustc_attr" }
+rustc_attr_parsing = { path = "../rustc_attr_parsing" }
 rustc_codegen_ssa = { path = "../rustc_codegen_ssa" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index 5552a241060..f8454fd9960 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -1,6 +1,6 @@
 //! Set and unset common attributes on LLVM values.
 
-use rustc_attr::{InlineAttr, InstructionSetAttr, OptimizeAttr};
+use rustc_attr_parsing::{InlineAttr, InstructionSetAttr, OptimizeAttr};
 use rustc_codegen_ssa::traits::*;
 use rustc_hir::def_id::DefId;
 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, PatchableFunctionEntry};
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 66ca4e2b473..45294ea35b1 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -25,8 +25,7 @@ use rustc_session::Session;
 use rustc_session::config::{
     self, Lto, OutputType, Passes, RemapPathScopeComponents, SplitDwarfKind, SwitchWithOptPath,
 };
-use rustc_span::symbol::sym;
-use rustc_span::{BytePos, InnerSpan, Pos, SpanData, SyntaxContext};
+use rustc_span::{BytePos, InnerSpan, Pos, SpanData, SyntaxContext, sym};
 use rustc_target::spec::{CodeModel, RelocModel, SanitizerSet, SplitDebuginfo, TlsModel};
 use tracing::debug;
 
diff --git a/compiler/rustc_codegen_llvm/src/base.rs b/compiler/rustc_codegen_llvm/src/base.rs
index f62310bd948..d05faf5577b 100644
--- a/compiler/rustc_codegen_llvm/src/base.rs
+++ b/compiler/rustc_codegen_llvm/src/base.rs
@@ -23,7 +23,7 @@ use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
 use rustc_middle::mir::mono::{Linkage, Visibility};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::DebugInfo;
-use rustc_span::symbol::Symbol;
+use rustc_span::Symbol;
 use rustc_target::spec::SanitizerSet;
 
 use super::ModuleLlvm;
diff --git a/compiler/rustc_codegen_llvm/src/callee.rs b/compiler/rustc_codegen_llvm/src/callee.rs
index ec77f32caf4..aa9a0f34f55 100644
--- a/compiler/rustc_codegen_llvm/src/callee.rs
+++ b/compiler/rustc_codegen_llvm/src/callee.rs
@@ -106,7 +106,7 @@ pub(crate) fn get_fn<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'t
                 // This is a monomorphization of a generic function.
                 if !(cx.tcx.sess.opts.share_generics()
                     || tcx.codegen_fn_attrs(instance_def_id).inline
-                        == rustc_attr::InlineAttr::Never)
+                        == rustc_attr_parsing::InlineAttr::Never)
                 {
                     // When not sharing generics, all instances are in the same
                     // crate and have hidden visibility.
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs
index 1f133141c18..b617f4d37f5 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs
@@ -1,6 +1,4 @@
-use rustc_middle::mir::coverage::{CounterId, CovTerm, ExpressionId, SourceRegion};
-
-use crate::coverageinfo::mapgen::LocalFileId;
+use rustc_middle::mir::coverage::{CounterId, CovTerm, ExpressionId};
 
 /// Must match the layout of `LLVMRustCounterKind`.
 #[derive(Copy, Clone, Debug)]
@@ -126,30 +124,16 @@ pub(crate) struct CoverageSpan {
     /// Local index into the function's local-to-global file ID table.
     /// The value at that index is itself an index into the coverage filename
     /// table in the CGU's `__llvm_covmap` section.
-    file_id: u32,
+    pub(crate) file_id: u32,
 
     /// 1-based starting line of the source code span.
-    start_line: u32,
+    pub(crate) start_line: u32,
     /// 1-based starting column of the source code span.
-    start_col: u32,
+    pub(crate) start_col: u32,
     /// 1-based ending line of the source code span.
-    end_line: u32,
+    pub(crate) end_line: u32,
     /// 1-based ending column of the source code span. High bit must be unset.
-    end_col: u32,
-}
-
-impl CoverageSpan {
-    pub(crate) fn from_source_region(
-        local_file_id: LocalFileId,
-        code_region: &SourceRegion,
-    ) -> Self {
-        let file_id = local_file_id.as_u32();
-        let &SourceRegion { start_line, start_col, end_line, end_col } = code_region;
-        // Internally, LLVM uses the high bit of `end_col` to distinguish between
-        // code regions and gap regions, so it can't be used by the column number.
-        assert!(end_col & (1u32 << 31) == 0, "high bit of `end_col` must be unset: {end_col:#X}");
-        Self { file_id, start_line, start_col, end_line, end_col }
-    }
+    pub(crate) end_col: u32,
 }
 
 /// Holds tables of the various region types in one struct.
@@ -184,7 +168,7 @@ impl Regions {
 #[derive(Clone, Debug)]
 #[repr(C)]
 pub(crate) struct CodeRegion {
-    pub(crate) span: CoverageSpan,
+    pub(crate) cov_span: CoverageSpan,
     pub(crate) counter: Counter,
 }
 
@@ -192,7 +176,7 @@ pub(crate) struct CodeRegion {
 #[derive(Clone, Debug)]
 #[repr(C)]
 pub(crate) struct BranchRegion {
-    pub(crate) span: CoverageSpan,
+    pub(crate) cov_span: CoverageSpan,
     pub(crate) true_counter: Counter,
     pub(crate) false_counter: Counter,
 }
@@ -201,7 +185,7 @@ pub(crate) struct BranchRegion {
 #[derive(Clone, Debug)]
 #[repr(C)]
 pub(crate) struct MCDCBranchRegion {
-    pub(crate) span: CoverageSpan,
+    pub(crate) cov_span: CoverageSpan,
     pub(crate) true_counter: Counter,
     pub(crate) false_counter: Counter,
     pub(crate) mcdc_branch_params: mcdc::BranchParameters,
@@ -211,6 +195,6 @@ pub(crate) struct MCDCBranchRegion {
 #[derive(Clone, Debug)]
 #[repr(C)]
 pub(crate) struct MCDCDecisionRegion {
-    pub(crate) span: CoverageSpan,
+    pub(crate) cov_span: CoverageSpan,
     pub(crate) mcdc_decision_params: mcdc::DecisionParameters,
 }
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/llvm_cov.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/llvm_cov.rs
index 086cf1f44a0..2cd7fa3225a 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/llvm_cov.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/llvm_cov.rs
@@ -40,11 +40,10 @@ pub(crate) fn create_pgo_func_name_var<'ll>(
     }
 }
 
-pub(crate) fn write_filenames_to_buffer<'a>(
-    filenames: impl IntoIterator<Item = &'a str>,
-) -> Vec<u8> {
+pub(crate) fn write_filenames_to_buffer(filenames: &[impl AsRef<str>]) -> Vec<u8> {
     let (pointers, lengths) = filenames
         .into_iter()
+        .map(AsRef::as_ref)
         .map(|s: &str| (s.as_c_char_ptr(), s.len()))
         .unzip::<_, _, Vec<_>, Vec<_>>();
 
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs
deleted file mode 100644
index c5d1ebdfe7c..00000000000
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs
+++ /dev/null
@@ -1,84 +0,0 @@
-use rustc_data_structures::captures::Captures;
-use rustc_middle::mir::coverage::{
-    CovTerm, CoverageIdsInfo, Expression, FunctionCoverageInfo, Mapping, MappingKind, Op,
-    SourceRegion,
-};
-
-use crate::coverageinfo::ffi::{Counter, CounterExpression, ExprKind};
-
-pub(crate) struct FunctionCoverage<'tcx> {
-    pub(crate) function_coverage_info: &'tcx FunctionCoverageInfo,
-    /// If `None`, the corresponding function is unused.
-    ids_info: Option<&'tcx CoverageIdsInfo>,
-}
-
-impl<'tcx> FunctionCoverage<'tcx> {
-    pub(crate) fn new_used(
-        function_coverage_info: &'tcx FunctionCoverageInfo,
-        ids_info: &'tcx CoverageIdsInfo,
-    ) -> Self {
-        Self { function_coverage_info, ids_info: Some(ids_info) }
-    }
-
-    pub(crate) fn new_unused(function_coverage_info: &'tcx FunctionCoverageInfo) -> Self {
-        Self { function_coverage_info, ids_info: None }
-    }
-
-    /// Returns true for a used (called) function, and false for an unused function.
-    pub(crate) fn is_used(&self) -> bool {
-        self.ids_info.is_some()
-    }
-
-    /// Return the source hash, generated from the HIR node structure, and used to indicate whether
-    /// or not the source code structure changed between different compilations.
-    pub(crate) fn source_hash(&self) -> u64 {
-        if self.is_used() { self.function_coverage_info.function_source_hash } else { 0 }
-    }
-
-    /// Convert this function's coverage expression data into a form that can be
-    /// passed through FFI to LLVM.
-    pub(crate) fn counter_expressions(
-        &self,
-    ) -> impl Iterator<Item = CounterExpression> + ExactSizeIterator + Captures<'_> {
-        // We know that LLVM will optimize out any unused expressions before
-        // producing the final coverage map, so there's no need to do the same
-        // thing on the Rust side unless we're confident we can do much better.
-        // (See `CounterExpressionsMinimizer` in `CoverageMappingWriter.cpp`.)
-
-        self.function_coverage_info.expressions.iter().map(move |&Expression { lhs, op, rhs }| {
-            CounterExpression {
-                lhs: self.counter_for_term(lhs),
-                kind: match op {
-                    Op::Add => ExprKind::Add,
-                    Op::Subtract => ExprKind::Subtract,
-                },
-                rhs: self.counter_for_term(rhs),
-            }
-        })
-    }
-
-    /// Converts this function's coverage mappings into an intermediate form
-    /// that will be used by `mapgen` when preparing for FFI.
-    pub(crate) fn counter_regions(
-        &self,
-    ) -> impl Iterator<Item = (MappingKind, &SourceRegion)> + ExactSizeIterator {
-        self.function_coverage_info.mappings.iter().map(move |mapping| {
-            let Mapping { kind, source_region } = mapping;
-            let kind =
-                kind.map_terms(|term| if self.is_zero_term(term) { CovTerm::Zero } else { term });
-            (kind, source_region)
-        })
-    }
-
-    fn counter_for_term(&self, term: CovTerm) -> Counter {
-        if self.is_zero_term(term) { Counter::ZERO } else { Counter::from_term(term) }
-    }
-
-    fn is_zero_term(&self, term: CovTerm) -> bool {
-        match self.ids_info {
-            Some(ids_info) => ids_info.is_zero_term(term),
-            // This function is unused, so all coverage counters/expressions are zero.
-            None => true,
-        }
-    }
-}
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
index 4f2af732527..b3ad2a0e409 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
@@ -1,28 +1,28 @@
-use std::iter;
+use std::sync::Arc;
 
-use itertools::Itertools as _;
+use itertools::Itertools;
 use rustc_abi::Align;
 use rustc_codegen_ssa::traits::{
     BaseTypeCodegenMethods, ConstCodegenMethods, StaticCodegenMethods,
 };
-use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
+use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_index::IndexVec;
+use rustc_middle::mir;
 use rustc_middle::ty::{self, TyCtxt};
-use rustc_middle::{bug, mir};
 use rustc_session::RemapFileNameExt;
 use rustc_session::config::RemapPathScopeComponents;
 use rustc_span::def_id::DefIdSet;
-use rustc_span::{Span, Symbol};
+use rustc_span::{SourceFile, StableSourceFileId};
 use tracing::debug;
 
 use crate::common::CodegenCx;
 use crate::coverageinfo::llvm_cov;
-use crate::coverageinfo::map_data::FunctionCoverage;
 use crate::coverageinfo::mapgen::covfun::prepare_covfun_record;
 use crate::llvm;
 
 mod covfun;
+mod spans;
 
 /// Generates and exports the coverage map, which is embedded in special
 /// linker sections in the final binary.
@@ -49,46 +49,40 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
 
     debug!("Generating coverage map for CodegenUnit: `{}`", cx.codegen_unit.name());
 
-    // In order to show that unused functions have coverage counts of zero (0), LLVM requires the
-    // functions exist. Generate synthetic functions with a (required) single counter, and add the
-    // MIR `Coverage` code regions to the `function_coverage_map`, before calling
-    // `ctx.take_function_coverage_map()`.
-    if cx.codegen_unit.is_code_coverage_dead_code_cgu() {
-        add_unused_functions(cx);
-    }
-
     // FIXME(#132395): Can this be none even when coverage is enabled?
-    let function_coverage_map = match cx.coverage_cx {
-        Some(ref cx) => cx.take_function_coverage_map(),
+    let instances_used = match cx.coverage_cx {
+        Some(ref cx) => cx.instances_used.borrow(),
         None => return,
     };
-    if function_coverage_map.is_empty() {
-        // This CGU has no functions with coverage instrumentation.
-        return;
-    }
-
-    let all_file_names = function_coverage_map
-        .iter()
-        .map(|(_, fn_cov)| fn_cov.function_coverage_info.body_span)
-        .map(|span| span_file_name(tcx, span));
-    let global_file_table = GlobalFileTable::new(all_file_names);
-
-    // 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::new();
+    // 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 covfun_records = function_coverage_map
-        .into_iter()
-        .filter_map(|(instance, function_coverage)| {
-            prepare_covfun_record(tcx, &global_file_table, instance, &function_coverage)
-        })
+    let mut covfun_records = instances_used
+        .iter()
+        .copied()
+        // Sort by symbol name, so that the global file table is built in an
+        // 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))
         .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)
+        }));
+    }
+
     // If there are no covfun records for this CGU, don't generate a covmap record.
     // Emitting a covmap record without any covfun records causes `llvm-cov` to
     // fail when generating coverage reports, and if there are no covfun records
@@ -98,6 +92,15 @@ 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![];
+
     for covfun in &covfun_records {
         unused_function_names.extend(covfun.mangled_function_name_if_unused());
 
@@ -129,54 +132,51 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
     generate_covmap_record(cx, covmap_version, &filenames_buffer);
 }
 
-/// Maps "global" (per-CGU) file ID numbers to their underlying filenames.
+/// Maps "global" (per-CGU) file ID numbers to their underlying source files.
 struct GlobalFileTable {
-    /// This "raw" table doesn't include the working dir, so a filename's
+    /// 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: FxIndexSet<Symbol>,
+    raw_file_table: FxIndexMap<StableSourceFileId, Arc<SourceFile>>,
 }
 
 impl GlobalFileTable {
-    fn new(all_file_names: impl IntoIterator<Item = Symbol>) -> Self {
-        // Collect all of the filenames into a set. Filenames usually come in
-        // contiguous runs, so we can dedup adjacent ones to save work.
-        let mut raw_file_table = all_file_names.into_iter().dedup().collect::<FxIndexSet<Symbol>>();
-
-        // Sort the file table by its actual string values, not the arbitrary
-        // ordering of its symbols.
-        raw_file_table.sort_unstable_by(|a, b| a.as_str().cmp(b.as_str()));
-
-        Self { raw_file_table }
+    fn new() -> Self {
+        Self { raw_file_table: FxIndexMap::default() }
     }
 
-    fn global_file_id_for_file_name(&self, file_name: Symbol) -> GlobalFileId {
-        let raw_id = self.raw_file_table.get_index_of(&file_name).unwrap_or_else(|| {
-            bug!("file name not found in prepared global file table: {file_name}");
-        });
+    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));
+
         // 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)
     }
 
     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.
-        use rustc_session::RemapFileNameExt;
-        use rustc_session::config::RemapPathScopeComponents;
-        let working_dir: &str = &tcx
-            .sess
-            .opts
-            .working_dir
-            .for_scope(tcx.sess, RemapPathScopeComponents::MACRO)
-            .to_string_lossy();
-
-        // Insert the working dir at index 0, before the other filenames.
-        let filenames =
-            iter::once(working_dir).chain(self.raw_file_table.iter().map(Symbol::as_str));
-        llvm_cov::write_filenames_to_buffer(filenames)
+        table.push(
+            tcx.sess
+                .opts
+                .working_dir
+                .for_scope(tcx.sess, RemapPathScopeComponents::MACRO)
+                .to_string_lossy(),
+        );
+
+        // 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()
+        }));
+
+        llvm_cov::write_filenames_to_buffer(&table)
     }
 }
 
@@ -189,7 +189,7 @@ rustc_index::newtype_index! {
     /// An index into a function's list of global file IDs. That underlying list
     /// of local-to-global mappings will be embedded in the function's record in
     /// the `__llvm_covfun` linker section.
-    pub(crate) struct LocalFileId {}
+    struct LocalFileId {}
 }
 
 /// Holds a mapping from "local" (per-function) file IDs to "global" (per-CGU)
@@ -215,13 +215,6 @@ impl VirtualFileMapping {
     }
 }
 
-fn span_file_name(tcx: TyCtxt<'_>, span: Span) -> Symbol {
-    let source_file = tcx.sess.source_map().lookup_source_file(span.lo());
-    let name =
-        source_file.name.for_scope(tcx.sess, RemapPathScopeComponents::MACRO).to_string_lossy();
-    Symbol::intern(&name)
-}
-
 /// Generates the contents of the covmap record for this CGU, which mostly
 /// consists of a header and a list of filenames. The record is then stored
 /// as a global variable in the `__llvm_covmap` section.
@@ -264,39 +257,35 @@ fn generate_covmap_record<'ll>(cx: &CodegenCx<'ll, '_>, version: u32, filenames_
 /// 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 add_unused_functions(cx: &CodegenCx<'_, '_>) {
+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 {
-        let def_id = def_id.to_def_id();
-
-        // To be eligible for "unused function" mappings, a definition must:
-        // - Be function-like
+        // 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.def_kind(def_id).is_fn_like()
-            && (!usage.all_mono_items.contains(&def_id)
-                || usage.missing_own_coverage.contains(&def_id))
-            && !usage.used_via_inlining.contains(&def_id)
+        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)
     };
 
-    // Scan for unused functions that were instrumented for coverage.
-    for def_id in tcx.mir_keys(()).iter().copied().filter(|&def_id| is_unused_fn(def_id)) {
-        // Get the coverage info from MIR, skipping functions that were never instrumented.
-        let body = tcx.optimized_mir(def_id);
-        let Some(function_coverage_info) = body.function_coverage_info.as_deref() else { continue };
-
-        // 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.
+    // 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.
 
-        debug!("generating unused fn: {def_id:?}");
-        add_unused_function_coverage(cx, def_id, function_coverage_info);
-    }
+    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> {
@@ -361,16 +350,11 @@ fn prepare_usage_sets<'tcx>(tcx: TyCtxt<'tcx>) -> UsageSets<'tcx> {
     UsageSets { all_mono_items, used_via_inlining, missing_own_coverage }
 }
 
-fn add_unused_function_coverage<'tcx>(
-    cx: &CodegenCx<'_, 'tcx>,
-    def_id: LocalDefId,
-    function_coverage_info: &'tcx mir::coverage::FunctionCoverageInfo,
-) {
-    let tcx = cx.tcx;
-    let def_id = def_id.to_def_id();
+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.
-    let instance = ty::Instance::new(
+    ty::Instance::new(
         def_id,
         ty::GenericArgs::for_item(tcx, def_id, |param, _| {
             if let ty::GenericParamDefKind::Lifetime = param.kind {
@@ -379,9 +363,5 @@ fn add_unused_function_coverage<'tcx>(
                 tcx.mk_param_from_def(param)
             }
         }),
-    );
-
-    // An unused function's mappings will all be rewritten to map to zero.
-    let function_coverage = FunctionCoverage::new_unused(function_coverage_info);
-    cx.coverage_cx().function_coverage_map.borrow_mut().insert(instance, function_coverage);
+    )
 }
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
index 33e7a0f2f20..5428d776f41 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
@@ -10,15 +10,16 @@ use rustc_abi::Align;
 use rustc_codegen_ssa::traits::{
     BaseTypeCodegenMethods, ConstCodegenMethods, StaticCodegenMethods,
 };
-use rustc_middle::bug;
-use rustc_middle::mir::coverage::MappingKind;
+use rustc_middle::mir::coverage::{
+    CovTerm, CoverageIdsInfo, Expression, FunctionCoverageInfo, Mapping, MappingKind, Op,
+};
 use rustc_middle::ty::{Instance, TyCtxt};
+use rustc_span::Span;
 use rustc_target::spec::HasTargetSpec;
 use tracing::debug;
 
 use crate::common::CodegenCx;
-use crate::coverageinfo::map_data::FunctionCoverage;
-use crate::coverageinfo::mapgen::{GlobalFileTable, VirtualFileMapping, span_file_name};
+use crate::coverageinfo::mapgen::{GlobalFileTable, VirtualFileMapping, spans};
 use crate::coverageinfo::{ffi, llvm_cov};
 use crate::llvm;
 
@@ -45,77 +46,129 @@ impl<'tcx> CovfunRecord<'tcx> {
 
 pub(crate) fn prepare_covfun_record<'tcx>(
     tcx: TyCtxt<'tcx>,
-    global_file_table: &GlobalFileTable,
+    global_file_table: &mut GlobalFileTable,
     instance: Instance<'tcx>,
-    function_coverage: &FunctionCoverage<'tcx>,
+    is_used: bool,
 ) -> Option<CovfunRecord<'tcx>> {
+    let fn_cov_info = tcx.instance_mir(instance.def).function_coverage_info.as_deref()?;
+    let ids_info = tcx.coverage_ids_info(instance.def);
+
+    let expressions = prepare_expressions(fn_cov_info, ids_info, is_used);
+
     let mut covfun = CovfunRecord {
         mangled_function_name: tcx.symbol_name(instance).name,
-        source_hash: function_coverage.source_hash(),
-        is_used: function_coverage.is_used(),
+        source_hash: if is_used { fn_cov_info.function_source_hash } else { 0 },
+        is_used,
         virtual_file_mapping: VirtualFileMapping::default(),
-        expressions: function_coverage.counter_expressions().collect::<Vec<_>>(),
+        expressions,
         regions: ffi::Regions::default(),
     };
 
-    fill_region_tables(tcx, global_file_table, function_coverage, &mut covfun);
+    fill_region_tables(tcx, global_file_table, fn_cov_info, ids_info, &mut covfun);
 
     if covfun.regions.has_no_regions() {
-        if covfun.is_used {
-            bug!("a used function should have had coverage mapping data but did not: {covfun:?}");
-        } else {
-            debug!(?covfun, "unused function had no coverage mapping data");
-            return None;
-        }
+        debug!(?covfun, "function has no mappings to embed; skipping");
+        return None;
     }
 
     Some(covfun)
 }
 
+/// Convert the function's coverage-counter expressions into a form suitable for FFI.
+fn prepare_expressions(
+    fn_cov_info: &FunctionCoverageInfo,
+    ids_info: &CoverageIdsInfo,
+    is_used: bool,
+) -> Vec<ffi::CounterExpression> {
+    // If any counters or expressions were removed by MIR opts, replace their
+    // terms with zero.
+    let counter_for_term = |term| {
+        if !is_used || ids_info.is_zero_term(term) {
+            ffi::Counter::ZERO
+        } else {
+            ffi::Counter::from_term(term)
+        }
+    };
+
+    // We know that LLVM will optimize out any unused expressions before
+    // producing the final coverage map, so there's no need to do the same
+    // thing on the Rust side unless we're confident we can do much better.
+    // (See `CounterExpressionsMinimizer` in `CoverageMappingWriter.cpp`.)
+    fn_cov_info
+        .expressions
+        .iter()
+        .map(move |&Expression { lhs, op, rhs }| ffi::CounterExpression {
+            lhs: counter_for_term(lhs),
+            kind: match op {
+                Op::Add => ffi::ExprKind::Add,
+                Op::Subtract => ffi::ExprKind::Subtract,
+            },
+            rhs: counter_for_term(rhs),
+        })
+        .collect::<Vec<_>>()
+}
+
 /// Populates the mapping region tables in the current function's covfun record.
 fn fill_region_tables<'tcx>(
     tcx: TyCtxt<'tcx>,
-    global_file_table: &GlobalFileTable,
-    function_coverage: &FunctionCoverage<'tcx>,
+    global_file_table: &mut GlobalFileTable,
+    fn_cov_info: &'tcx FunctionCoverageInfo,
+    ids_info: &'tcx CoverageIdsInfo,
     covfun: &mut CovfunRecord<'tcx>,
 ) {
-    let counter_regions = function_coverage.counter_regions();
-    if counter_regions.is_empty() {
-        return;
-    }
-
     // Currently a function's mappings must all be in the same file as its body span.
-    let file_name = span_file_name(tcx, function_coverage.function_coverage_info.body_span);
+    let source_map = tcx.sess.source_map();
+    let source_file = source_map.lookup_source_file(fn_cov_info.body_span.lo());
 
-    // Look up the global file ID for that filename.
-    let global_file_id = global_file_table.global_file_id_for_file_name(file_name);
+    // 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);
-    debug!("  file id: {local_file_id:?} => {global_file_id:?} = '{file_name:?}'");
 
     let ffi::Regions { code_regions, branch_regions, mcdc_branch_regions, mcdc_decision_regions } =
         &mut covfun.regions;
 
+    let make_cov_span = |span: Span| {
+        spans::make_coverage_span(local_file_id, source_map, fn_cov_info, &source_file, span)
+    };
+    let discard_all = tcx.sess.coverage_discard_all_spans_in_codegen();
+
     // For each counter/region pair in this function+file, convert it to a
     // form suitable for FFI.
-    for (mapping_kind, region) in counter_regions {
-        debug!("Adding counter {mapping_kind:?} to map for {region:?}");
-        let span = ffi::CoverageSpan::from_source_region(local_file_id, region);
-        match mapping_kind {
+    let is_zero_term = |term| !covfun.is_used || ids_info.is_zero_term(term);
+    for &Mapping { ref kind, span } in &fn_cov_info.mappings {
+        // If the mapping refers to counters/expressions that were removed by
+        // MIR opts, replace those occurrences with zero.
+        let kind = kind.map_terms(|term| if is_zero_term(term) { CovTerm::Zero } else { term });
+
+        // Convert the `Span` into coordinates that we can pass to LLVM, or
+        // discard the span if conversion fails. In rare, cases _all_ of a
+        // function's spans are discarded, and the rest of coverage codegen
+        // needs to handle that gracefully to avoid a repeat of #133606.
+        // We don't have a good test case for triggering that organically, so
+        // instead we set `-Zcoverage-options=discard-all-spans-in-codegen`
+        // to force it to occur.
+        let Some(cov_span) = make_cov_span(span) else { continue };
+        if discard_all {
+            continue;
+        }
+
+        match kind {
             MappingKind::Code(term) => {
-                code_regions.push(ffi::CodeRegion { span, counter: ffi::Counter::from_term(term) });
+                code_regions
+                    .push(ffi::CodeRegion { cov_span, counter: ffi::Counter::from_term(term) });
             }
             MappingKind::Branch { true_term, false_term } => {
                 branch_regions.push(ffi::BranchRegion {
-                    span,
+                    cov_span,
                     true_counter: ffi::Counter::from_term(true_term),
                     false_counter: ffi::Counter::from_term(false_term),
                 });
             }
             MappingKind::MCDCBranch { true_term, false_term, mcdc_params } => {
                 mcdc_branch_regions.push(ffi::MCDCBranchRegion {
-                    span,
+                    cov_span,
                     true_counter: ffi::Counter::from_term(true_term),
                     false_counter: ffi::Counter::from_term(false_term),
                     mcdc_branch_params: ffi::mcdc::BranchParameters::from(mcdc_params),
@@ -123,7 +176,7 @@ fn fill_region_tables<'tcx>(
             }
             MappingKind::MCDCDecision(mcdc_decision_params) => {
                 mcdc_decision_regions.push(ffi::MCDCDecisionRegion {
-                    span,
+                    cov_span,
                     mcdc_decision_params: ffi::mcdc::DecisionParameters::from(mcdc_decision_params),
                 });
             }
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs
new file mode 100644
index 00000000000..6d1d91340c2
--- /dev/null
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs
@@ -0,0 +1,126 @@
+use rustc_middle::mir::coverage::FunctionCoverageInfo;
+use rustc_span::source_map::SourceMap;
+use rustc_span::{BytePos, Pos, SourceFile, Span};
+use tracing::debug;
+
+use crate::coverageinfo::ffi;
+use crate::coverageinfo::mapgen::LocalFileId;
+
+/// Converts the span into its start line and column, and end line and column.
+///
+/// Line numbers and column numbers are 1-based. Unlike most column numbers emitted by
+/// the compiler, these column numbers are denoted in **bytes**, because that's what
+/// LLVM's `llvm-cov` tool expects to see in coverage maps.
+///
+/// Returns `None` if the conversion failed for some reason. This shouldn't happen,
+/// but it's hard to rule out entirely (especially in the presence of complex macros
+/// or other expansions), and if it does happen then skipping a span or function is
+/// better than an ICE or `llvm-cov` failure that the user might have no way to avoid.
+pub(crate) fn make_coverage_span(
+    file_id: LocalFileId,
+    source_map: &SourceMap,
+    fn_cov_info: &FunctionCoverageInfo,
+    file: &SourceFile,
+    span: Span,
+) -> Option<ffi::CoverageSpan> {
+    let span = ensure_non_empty_span(source_map, fn_cov_info, span)?;
+
+    let lo = span.lo();
+    let hi = span.hi();
+
+    // Column numbers need to be in bytes, so we can't use the more convenient
+    // `SourceMap` methods for looking up file coordinates.
+    let line_and_byte_column = |pos: BytePos| -> Option<(usize, usize)> {
+        let rpos = file.relative_position(pos);
+        let line_index = file.lookup_line(rpos)?;
+        let line_start = file.lines()[line_index];
+        // Line numbers and column numbers are 1-based, so add 1 to each.
+        Some((line_index + 1, (rpos - line_start).to_usize() + 1))
+    };
+
+    let (mut start_line, start_col) = line_and_byte_column(lo)?;
+    let (mut end_line, end_col) = line_and_byte_column(hi)?;
+
+    // Apply an offset so that code in doctests has correct line numbers.
+    // FIXME(#79417): Currently we have no way to offset doctest _columns_.
+    start_line = source_map.doctest_offset_line(&file.name, start_line);
+    end_line = source_map.doctest_offset_line(&file.name, end_line);
+
+    check_coverage_span(ffi::CoverageSpan {
+        file_id: file_id.as_u32(),
+        start_line: start_line as u32,
+        start_col: start_col as u32,
+        end_line: end_line as u32,
+        end_col: end_col as u32,
+    })
+}
+
+fn ensure_non_empty_span(
+    source_map: &SourceMap,
+    fn_cov_info: &FunctionCoverageInfo,
+    span: Span,
+) -> Option<Span> {
+    if !span.is_empty() {
+        return Some(span);
+    }
+
+    let lo = span.lo();
+    let hi = span.hi();
+
+    // The span is empty, so try to expand it to cover an adjacent '{' or '}',
+    // but only within the bounds of the body span.
+    let try_next = hi < fn_cov_info.body_span.hi();
+    let try_prev = fn_cov_info.body_span.lo() < lo;
+    if !(try_next || try_prev) {
+        return None;
+    }
+
+    source_map
+        .span_to_source(span, |src, start, end| try {
+            // Adjusting span endpoints by `BytePos(1)` is normally a bug,
+            // but in this case we have specifically checked that the character
+            // we're skipping over is one of two specific ASCII characters, so
+            // adjusting by exactly 1 byte is correct.
+            if try_next && src.as_bytes()[end] == b'{' {
+                Some(span.with_hi(hi + BytePos(1)))
+            } else if try_prev && src.as_bytes()[start - 1] == b'}' {
+                Some(span.with_lo(lo - BytePos(1)))
+            } else {
+                None
+            }
+        })
+        .ok()?
+}
+
+/// If `llvm-cov` sees a source region that is improperly ordered (end < start),
+/// it will immediately exit with a fatal error. To prevent that from happening,
+/// discard regions that are improperly ordered, or might be interpreted in a
+/// way that makes them improperly ordered.
+fn check_coverage_span(cov_span: ffi::CoverageSpan) -> Option<ffi::CoverageSpan> {
+    let ffi::CoverageSpan { file_id: _, start_line, start_col, end_line, end_col } = cov_span;
+
+    // Line/column coordinates are supposed to be 1-based. If we ever emit
+    // coordinates of 0, `llvm-cov` might misinterpret them.
+    let all_nonzero = [start_line, start_col, end_line, end_col].into_iter().all(|x| x != 0);
+    // Coverage mappings use the high bit of `end_col` to indicate that a
+    // region is actually a "gap" region, so make sure it's unset.
+    let end_col_has_high_bit_unset = (end_col & (1 << 31)) == 0;
+    // If a region is improperly ordered (end < start), `llvm-cov` will exit
+    // with a fatal error, which is inconvenient for users and hard to debug.
+    let is_ordered = (start_line, start_col) <= (end_line, end_col);
+
+    if all_nonzero && end_col_has_high_bit_unset && is_ordered {
+        Some(cov_span)
+    } else {
+        debug!(
+            ?cov_span,
+            ?all_nonzero,
+            ?end_col_has_high_bit_unset,
+            ?is_ordered,
+            "Skipping source region that would be misinterpreted or rejected by LLVM"
+        );
+        // If this happens in a debug build, ICE to make it easier to notice.
+        debug_assert!(false, "Improper source region: {cov_span:?}");
+        None
+    }
+}
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
index 82b6677e203..7311cd9d230 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
@@ -5,7 +5,7 @@ use rustc_abi::Size;
 use rustc_codegen_ssa::traits::{
     BuilderMethods, ConstCodegenMethods, CoverageInfoBuilderMethods, MiscCodegenMethods,
 };
-use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
+use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_middle::mir::coverage::CoverageKind;
 use rustc_middle::ty::Instance;
 use rustc_middle::ty::layout::HasTyCtxt;
@@ -13,18 +13,16 @@ use tracing::{debug, instrument};
 
 use crate::builder::Builder;
 use crate::common::CodegenCx;
-use crate::coverageinfo::map_data::FunctionCoverage;
 use crate::llvm;
 
 pub(crate) mod ffi;
 mod llvm_cov;
-pub(crate) mod map_data;
 mod mapgen;
 
 /// Extra per-CGU context/state needed for coverage instrumentation.
 pub(crate) struct CguCoverageContext<'ll, 'tcx> {
     /// Coverage data for each instrumented function identified by DefId.
-    pub(crate) function_coverage_map: RefCell<FxIndexMap<Instance<'tcx>, FunctionCoverage<'tcx>>>,
+    pub(crate) instances_used: RefCell<FxIndexSet<Instance<'tcx>>>,
     pub(crate) pgo_func_name_var_map: RefCell<FxHashMap<Instance<'tcx>, &'ll llvm::Value>>,
     pub(crate) mcdc_condition_bitmap_map: RefCell<FxHashMap<Instance<'tcx>, Vec<&'ll llvm::Value>>>,
 
@@ -34,17 +32,13 @@ pub(crate) struct CguCoverageContext<'ll, 'tcx> {
 impl<'ll, 'tcx> CguCoverageContext<'ll, 'tcx> {
     pub(crate) fn new() -> Self {
         Self {
-            function_coverage_map: Default::default(),
+            instances_used: RefCell::<FxIndexSet<_>>::default(),
             pgo_func_name_var_map: Default::default(),
             mcdc_condition_bitmap_map: Default::default(),
             covfun_section_name: Default::default(),
         }
     }
 
-    fn take_function_coverage_map(&self) -> FxIndexMap<Instance<'tcx>, FunctionCoverage<'tcx>> {
-        self.function_coverage_map.replace(FxIndexMap::default())
-    }
-
     /// LLVM use a temp value to record evaluated mcdc test vector of each decision, which is
     /// called condition bitmap. In order to handle nested decisions, several condition bitmaps can
     /// be allocated for a function body. These values are named `mcdc.addr.{i}` and are a 32-bit
@@ -157,12 +151,7 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
         // Mark the instance as used in this CGU, for coverage purposes.
         // This includes functions that were not partitioned into this CGU,
         // but were MIR-inlined into one of this CGU's functions.
-        coverage_cx.function_coverage_map.borrow_mut().entry(instance).or_insert_with(|| {
-            FunctionCoverage::new_used(
-                function_coverage_info,
-                bx.tcx.coverage_ids_info(instance.def),
-            )
-        });
+        coverage_cx.instances_used.borrow_mut().insert(instance);
 
         match *kind {
             CoverageKind::SpanMarker | CoverageKind::BlockMarker { .. } => unreachable!(
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs b/compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs
index aef8642f199..2c9f1cda13a 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs
@@ -7,7 +7,7 @@ use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_middle::bug;
 use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerType;
 use rustc_session::config::{CrateType, DebugInfo};
-use rustc_span::symbol::sym;
+use rustc_span::sym;
 
 use crate::builder::Builder;
 use crate::common::CodegenCx;
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
index 59275254022..40248a9009a 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
@@ -16,8 +16,7 @@ use rustc_middle::ty::{
     self, AdtKind, CoroutineArgsExt, Instance, PolyExistentialTraitRef, Ty, TyCtxt, Visibility,
 };
 use rustc_session::config::{self, DebugInfo, Lto};
-use rustc_span::symbol::Symbol;
-use rustc_span::{DUMMY_SP, FileName, FileNameDisplayPreference, SourceFile, hygiene};
+use rustc_span::{DUMMY_SP, FileName, FileNameDisplayPreference, SourceFile, Symbol, hygiene};
 use rustc_symbol_mangling::typeid_for_trait_ref;
 use rustc_target::spec::DebuginfoKind;
 use smallvec::smallvec;
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs
index d374767f187..23e11748e52 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs
@@ -212,21 +212,17 @@ pub(super) fn build_enum_type_di_node<'ll, 'tcx>(
         ),
         |cx, enum_type_di_node| {
             match enum_type_and_layout.variants {
-                Variants::Single { index: variant_index } => {
-                    if enum_adt_def.variants().is_empty() {
-                        // Uninhabited enums have Variants::Single. We don't generate
-                        // any members for them.
-                        return smallvec![];
-                    }
-
-                    build_single_variant_union_fields(
-                        cx,
-                        enum_adt_def,
-                        enum_type_and_layout,
-                        enum_type_di_node,
-                        variant_index,
-                    )
+                Variants::Empty => {
+                    // We don't generate any members for uninhabited types.
+                    return smallvec![];
                 }
+                Variants::Single { index: variant_index } => build_single_variant_union_fields(
+                    cx,
+                    enum_adt_def,
+                    enum_type_and_layout,
+                    enum_type_di_node,
+                    variant_index,
+                ),
                 Variants::Multiple {
                     tag_encoding: TagEncoding::Direct,
                     ref variants,
@@ -303,6 +299,7 @@ pub(super) fn build_coroutine_di_node<'ll, 'tcx>(
                 )
             }
             Variants::Single { .. }
+            | Variants::Empty
             | Variants::Multiple { tag_encoding: TagEncoding::Niche { .. }, .. } => {
                 bug!(
                     "Encountered coroutine with non-direct-tag layout: {:?}",
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/mod.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/mod.rs
index 65ab22ad89e..9f6a5cc89e0 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/mod.rs
@@ -392,7 +392,7 @@ fn compute_discriminant_value<'ll, 'tcx>(
     variant_index: VariantIdx,
 ) -> DiscrResult {
     match enum_type_and_layout.layout.variants() {
-        &Variants::Single { .. } => DiscrResult::NoDiscriminant,
+        &Variants::Single { .. } | &Variants::Empty => DiscrResult::NoDiscriminant,
         &Variants::Multiple { tag_encoding: TagEncoding::Direct, .. } => DiscrResult::Value(
             enum_type_and_layout.ty.discriminant_for_variant(cx.tcx, variant_index).unwrap().val,
         ),
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs
index 241bf167a81..11824398f24 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs
@@ -358,8 +358,8 @@ fn build_discr_member_di_node<'ll, 'tcx>(
     let containing_scope = enum_or_coroutine_type_di_node;
 
     match enum_or_coroutine_type_and_layout.layout.variants() {
-        // A single-variant enum has no discriminant.
-        &Variants::Single { .. } => None,
+        // A single-variant or no-variant enum has no discriminant.
+        &Variants::Single { .. } | &Variants::Empty => None,
 
         &Variants::Multiple { tag_field, .. } => {
             let tag_base_type = tag_base_type(cx.tcx, enum_or_coroutine_type_and_layout);
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
index a8fdfbed592..fae698bea2a 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
@@ -19,9 +19,8 @@ use rustc_middle::ty::layout::{HasTypingEnv, LayoutOf};
 use rustc_middle::ty::{self, GenericArgsRef, Instance, Ty, TypeVisitableExt};
 use rustc_session::Session;
 use rustc_session::config::{self, DebugInfo};
-use rustc_span::symbol::Symbol;
 use rustc_span::{
-    BytePos, Pos, SourceFile, SourceFileAndLine, SourceFileHash, Span, StableSourceFileId,
+    BytePos, Pos, SourceFile, SourceFileAndLine, SourceFileHash, Span, StableSourceFileId, Symbol,
 };
 use smallvec::SmallVec;
 use tracing::debug;
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index af8562db054..0de0c6a7a89 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -17,6 +17,7 @@
 #![feature(iter_intersperse)]
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
+#![feature(try_blocks)]
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
@@ -43,7 +44,7 @@ use rustc_middle::ty::TyCtxt;
 use rustc_middle::util::Providers;
 use rustc_session::Session;
 use rustc_session::config::{OptLevel, OutputFilenames, PrintKind, PrintRequest};
-use rustc_span::symbol::Symbol;
+use rustc_span::Symbol;
 
 mod back {
     pub(crate) mod archive;
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index d62632d1431..9a2bfd95562 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -56,25 +56,6 @@ pub enum LLVMRustResult {
     Failure,
 }
 
-// Rust version of the C struct with the same name in rustc_llvm/llvm-wrapper/RustWrapper.cpp.
-#[repr(C)]
-pub struct LLVMRustCOFFShortExport {
-    pub name: *const c_char,
-    pub ordinal_present: bool,
-    /// value of `ordinal` only important when `ordinal_present` is true
-    pub ordinal: u16,
-}
-
-impl LLVMRustCOFFShortExport {
-    pub fn new(name: *const c_char, ordinal: Option<u16>) -> LLVMRustCOFFShortExport {
-        LLVMRustCOFFShortExport {
-            name,
-            ordinal_present: ordinal.is_some(),
-            ordinal: ordinal.unwrap_or(0),
-        }
-    }
-}
-
 /// Translation of LLVM's MachineTypes enum, defined in llvm\include\llvm\BinaryFormat\COFF.h.
 ///
 /// We include only architectures supported on Windows.
@@ -2347,15 +2328,6 @@ unsafe extern "C" {
     ) -> &'a mut RustArchiveMember<'a>;
     pub fn LLVMRustArchiveMemberFree<'a>(Member: &'a mut RustArchiveMember<'a>);
 
-    pub fn LLVMRustWriteImportLibrary(
-        ImportName: *const c_char,
-        Path: *const c_char,
-        Exports: *const LLVMRustCOFFShortExport,
-        NumExports: usize,
-        Machine: u16,
-        MinGW: bool,
-    ) -> LLVMRustResult;
-
     pub fn LLVMRustSetDataLayoutFromTargetMachine<'a>(M: &'a Module, TM: &'a TargetMachine);
 
     pub fn LLVMRustPositionBuilderAtStart<'a>(B: &Builder<'a>, BB: &'a BasicBlock);
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index bfec7d708cf..628c0b1c29c 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -15,7 +15,7 @@ use rustc_fs_util::path_to_c_string;
 use rustc_middle::bug;
 use rustc_session::Session;
 use rustc_session::config::{PrintKind, PrintRequest};
-use rustc_span::symbol::Symbol;
+use rustc_span::Symbol;
 use rustc_target::spec::{MergeFunctions, PanicStrategy, SmallDataThresholdSupport};
 use rustc_target::target_features::{RUSTC_SPECIAL_FEATURES, RUSTC_SPECIFIC_FEATURES};
 
@@ -373,9 +373,9 @@ pub fn target_features_cfg(sess: &Session, allow_unstable: bool) -> Vec<Symbol>
         .rust_target_features()
         .iter()
         .filter(|(_, gate, _)| gate.in_cfg())
-        .filter_map(|&(feature, gate, _)| {
+        .filter_map(|(feature, gate, _)| {
             if sess.is_nightly_build() || allow_unstable || gate.requires_nightly().is_none() {
-                Some(feature)
+                Some(*feature)
             } else {
                 None
             }
@@ -718,7 +718,7 @@ pub(crate) fn global_llvm_features(
                         }
                         Some((_, stability, _)) => {
                             if let Err(reason) =
-                                stability.compute_toggleability(&sess.target).allow_toggle()
+                                stability.toggle_allowed(&sess.target, enable_disable == '+')
                             {
                                 sess.dcx().emit_warn(ForbiddenCTargetFeature { feature, reason });
                             } else if stability.requires_nightly().is_some() {
diff --git a/compiler/rustc_codegen_llvm/src/type_of.rs b/compiler/rustc_codegen_llvm/src/type_of.rs
index 2b05e24a7ba..b0b6da869da 100644
--- a/compiler/rustc_codegen_llvm/src/type_of.rs
+++ b/compiler/rustc_codegen_llvm/src/type_of.rs
@@ -38,7 +38,7 @@ fn uncached_llvm_type<'a, 'tcx>(
             if let (&ty::Adt(def, _), &Variants::Single { index }) =
                 (layout.ty.kind(), &layout.variants)
             {
-                if def.is_enum() && !def.variants().is_empty() {
+                if def.is_enum() {
                     write!(&mut name, "::{}", def.variant(index).name).unwrap();
                 }
             }