about summary refs log tree commit diff
path: root/compiler/rustc_codegen_llvm
diff options
context:
space:
mode:
Diffstat (limited to 'compiler/rustc_codegen_llvm')
-rw-r--r--compiler/rustc_codegen_llvm/src/builder.rs7
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs10
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/llvm_cov.rs100
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs8
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs187
-rw-r--r--compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs99
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs60
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/mod.rs4
-rw-r--r--compiler/rustc_codegen_llvm/src/lib.rs29
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm/ffi.rs54
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm/mod.rs9
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm_util.rs25
12 files changed, 330 insertions, 262 deletions
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 751b2235dc8..ac76b781218 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -1574,6 +1574,7 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
                 cfi::typeid_for_fnabi(self.tcx, fn_abi, options)
             };
             let typeid_metadata = self.cx.typeid_metadata(typeid).unwrap();
+            let dbg_loc = self.get_dbg_loc();
 
             // Test whether the function pointer is associated with the type identifier.
             let cond = self.type_test(llfn, typeid_metadata);
@@ -1582,10 +1583,16 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
             self.cond_br(cond, bb_pass, bb_fail);
 
             self.switch_to_block(bb_fail);
+            if let Some(dbg_loc) = dbg_loc {
+                self.set_dbg_loc(dbg_loc);
+            }
             self.abort();
             self.unreachable();
 
             self.switch_to_block(bb_pass);
+            if let Some(dbg_loc) = dbg_loc {
+                self.set_dbg_loc(dbg_loc);
+            }
         }
     }
 
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs
index feac97f3e2b..a6e07ea2a60 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs
@@ -1,5 +1,7 @@
 use rustc_middle::mir::coverage::{CounterId, CovTerm, ExpressionId, SourceRegion};
 
+use crate::coverageinfo::mapgen::LocalFileId;
+
 /// Must match the layout of `LLVMRustCounterKind`.
 #[derive(Copy, Clone, Debug)]
 #[repr(C)]
@@ -137,8 +139,12 @@ pub(crate) struct CoverageSpan {
 }
 
 impl CoverageSpan {
-    pub(crate) fn from_source_region(file_id: u32, code_region: &SourceRegion) -> Self {
-        let &SourceRegion { file_name: _, start_line, start_col, end_line, end_col } = code_region;
+    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}");
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/llvm_cov.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/llvm_cov.rs
new file mode 100644
index 00000000000..99c2d12b261
--- /dev/null
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/llvm_cov.rs
@@ -0,0 +1,100 @@
+//! Safe wrappers for coverage-specific FFI functions.
+
+use std::ffi::CString;
+
+use crate::common::AsCCharPtr;
+use crate::coverageinfo::ffi;
+use crate::llvm;
+
+pub(crate) fn covmap_var_name() -> CString {
+    CString::new(llvm::build_byte_buffer(|s| unsafe {
+        llvm::LLVMRustCoverageWriteCovmapVarNameToString(s);
+    }))
+    .expect("covmap variable name should not contain NUL")
+}
+
+pub(crate) fn covmap_section_name(llmod: &llvm::Module) -> CString {
+    CString::new(llvm::build_byte_buffer(|s| unsafe {
+        llvm::LLVMRustCoverageWriteCovmapSectionNameToString(llmod, s);
+    }))
+    .expect("covmap section name should not contain NUL")
+}
+
+pub(crate) fn covfun_section_name(llmod: &llvm::Module) -> CString {
+    CString::new(llvm::build_byte_buffer(|s| unsafe {
+        llvm::LLVMRustCoverageWriteCovfunSectionNameToString(llmod, s);
+    }))
+    .expect("covfun section name should not contain NUL")
+}
+
+pub(crate) fn create_pgo_func_name_var<'ll>(
+    llfn: &'ll llvm::Value,
+    mangled_fn_name: &str,
+) -> &'ll llvm::Value {
+    unsafe {
+        llvm::LLVMRustCoverageCreatePGOFuncNameVar(
+            llfn,
+            mangled_fn_name.as_c_char_ptr(),
+            mangled_fn_name.len(),
+        )
+    }
+}
+
+pub(crate) fn write_filenames_to_buffer<'a>(
+    filenames: impl IntoIterator<Item = &'a str>,
+) -> Vec<u8> {
+    let (pointers, lengths) = filenames
+        .into_iter()
+        .map(|s: &str| (s.as_c_char_ptr(), s.len()))
+        .unzip::<_, _, Vec<_>, Vec<_>>();
+
+    llvm::build_byte_buffer(|buffer| unsafe {
+        llvm::LLVMRustCoverageWriteFilenamesToBuffer(
+            pointers.as_ptr(),
+            pointers.len(),
+            lengths.as_ptr(),
+            lengths.len(),
+            buffer,
+        );
+    })
+}
+
+pub(crate) fn write_function_mappings_to_buffer(
+    virtual_file_mapping: &[u32],
+    expressions: &[ffi::CounterExpression],
+    code_regions: &[ffi::CodeRegion],
+    branch_regions: &[ffi::BranchRegion],
+    mcdc_branch_regions: &[ffi::MCDCBranchRegion],
+    mcdc_decision_regions: &[ffi::MCDCDecisionRegion],
+) -> Vec<u8> {
+    llvm::build_byte_buffer(|buffer| unsafe {
+        llvm::LLVMRustCoverageWriteFunctionMappingsToBuffer(
+            virtual_file_mapping.as_ptr(),
+            virtual_file_mapping.len(),
+            expressions.as_ptr(),
+            expressions.len(),
+            code_regions.as_ptr(),
+            code_regions.len(),
+            branch_regions.as_ptr(),
+            branch_regions.len(),
+            mcdc_branch_regions.as_ptr(),
+            mcdc_branch_regions.len(),
+            mcdc_decision_regions.as_ptr(),
+            mcdc_decision_regions.len(),
+            buffer,
+        )
+    })
+}
+
+/// Hashes some bytes into a 64-bit hash, via LLVM's `IndexedInstrProf::ComputeHash`,
+/// as required for parts of the LLVM coverage mapping format.
+pub(crate) fn hash_bytes(bytes: &[u8]) -> u64 {
+    unsafe { llvm::LLVMRustCoverageHashBytes(bytes.as_c_char_ptr(), bytes.len()) }
+}
+
+/// Returns LLVM's `coverage::CovMapVersion::CurrentVersion` (CoverageMapping.h)
+/// as a raw numeric value. For historical reasons, the numeric value is 1 less
+/// than the number in the version's name, so `Version7` is actually `6u32`.
+pub(crate) fn mapping_version() -> u32 {
+    unsafe { llvm::LLVMRustCoverageMappingVersion() }
+}
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs
index 5ed640b840e..e3c0df27883 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs
@@ -6,7 +6,6 @@ use rustc_middle::mir::coverage::{
     SourceRegion,
 };
 use rustc_middle::ty::Instance;
-use rustc_span::Symbol;
 use tracing::{debug, instrument};
 
 use crate::coverageinfo::ffi::{Counter, CounterExpression, ExprKind};
@@ -180,7 +179,7 @@ impl<'tcx> FunctionCoverageCollector<'tcx> {
 }
 
 pub(crate) struct FunctionCoverage<'tcx> {
-    function_coverage_info: &'tcx FunctionCoverageInfo,
+    pub(crate) function_coverage_info: &'tcx FunctionCoverageInfo,
     is_used: bool,
 
     counters_seen: BitSet<CounterId>,
@@ -199,11 +198,6 @@ impl<'tcx> FunctionCoverage<'tcx> {
         if self.is_used { self.function_coverage_info.function_source_hash } else { 0 }
     }
 
-    /// Returns an iterator over all filenames used by this function's mappings.
-    pub(crate) fn all_file_names(&self) -> impl Iterator<Item = Symbol> + Captures<'_> {
-        self.function_coverage_info.mappings.iter().map(|mapping| mapping.source_region.file_name)
-    }
-
     /// Convert this function's coverage expression data into a form that can be
     /// passed through FFI to LLVM.
     pub(crate) fn counter_expressions(
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
index f6378199fe2..b582dd967a7 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
@@ -1,4 +1,5 @@
 use std::ffi::CString;
+use std::iter;
 
 use itertools::Itertools as _;
 use rustc_abi::Align;
@@ -11,15 +12,17 @@ use rustc_index::IndexVec;
 use rustc_middle::mir::coverage::MappingKind;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_middle::{bug, mir};
-use rustc_span::Symbol;
+use rustc_session::RemapFileNameExt;
+use rustc_session::config::RemapPathScopeComponents;
 use rustc_span::def_id::DefIdSet;
+use rustc_span::{Span, Symbol};
 use rustc_target::spec::HasTargetSpec;
 use tracing::debug;
 
 use crate::common::CodegenCx;
-use crate::coverageinfo::ffi;
 use crate::coverageinfo::map_data::{FunctionCoverage, FunctionCoverageCollector};
-use crate::{coverageinfo, llvm};
+use crate::coverageinfo::{ffi, llvm_cov};
+use crate::llvm;
 
 /// Generates and exports the coverage map, which is embedded in special
 /// linker sections in the final binary.
@@ -33,7 +36,7 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
     // agrees with our Rust-side code. Expected versions (encoded as n-1) are:
     // - `CovMapVersion::Version7` (6) used by LLVM 18-19
     let covmap_version = {
-        let llvm_covmap_version = coverageinfo::mapping_version();
+        let llvm_covmap_version = llvm_cov::mapping_version();
         let expected_versions = 6..=6;
         assert!(
             expected_versions.contains(&llvm_covmap_version),
@@ -69,8 +72,10 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
         .map(|(instance, function_coverage)| (instance, function_coverage.into_finished()))
         .collect::<Vec<_>>();
 
-    let all_file_names =
-        function_coverage_entries.iter().flat_map(|(_, fn_cov)| fn_cov.all_file_names());
+    let all_file_names = function_coverage_entries
+        .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.
@@ -78,7 +83,7 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
 
     let filenames_size = filenames_buffer.len();
     let filenames_val = cx.const_bytes(&filenames_buffer);
-    let filenames_ref = coverageinfo::hash_bytes(&filenames_buffer);
+    let filenames_ref = llvm_cov::hash_bytes(&filenames_buffer);
 
     // Generate the coverage map header, which contains the filenames used by
     // this CGU's coverage mappings, and store it in a well-known global.
@@ -95,7 +100,7 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
         let is_used = function_coverage.is_used();
 
         let coverage_mapping_buffer =
-            encode_mappings_for_function(&global_file_table, &function_coverage);
+            encode_mappings_for_function(tcx, &global_file_table, &function_coverage);
 
         if coverage_mapping_buffer.is_empty() {
             if function_coverage.is_used() {
@@ -163,13 +168,13 @@ impl GlobalFileTable {
         Self { raw_file_table }
     }
 
-    fn global_file_id_for_file_name(&self, file_name: Symbol) -> u32 {
+    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}");
         });
         // 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.
-        (raw_id + 1) as u32
+        GlobalFileId::from_usize(raw_id + 1)
     }
 
     fn make_filenames_buffer(&self, tcx: TyCtxt<'_>) -> Vec<u8> {
@@ -187,30 +192,35 @@ impl GlobalFileTable {
             .for_scope(tcx.sess, RemapPathScopeComponents::MACRO)
             .to_string_lossy();
 
-        llvm::build_byte_buffer(|buffer| {
-            coverageinfo::write_filenames_section_to_buffer(
-                // Insert the working dir at index 0, before the other filenames.
-                std::iter::once(working_dir).chain(self.raw_file_table.iter().map(Symbol::as_str)),
-                buffer,
-            );
-        })
+        // 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)
     }
 }
 
 rustc_index::newtype_index! {
-    struct LocalFileId {}
+    /// An index into the CGU's overall list of file paths. The underlying paths
+    /// will be embedded in the `__llvm_covmap` linker section.
+    struct GlobalFileId {}
+}
+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 {}
 }
 
 /// Holds a mapping from "local" (per-function) file IDs to "global" (per-CGU)
 /// file IDs.
 #[derive(Default)]
 struct VirtualFileMapping {
-    local_to_global: IndexVec<LocalFileId, u32>,
-    global_to_local: FxIndexMap<u32, LocalFileId>,
+    local_to_global: IndexVec<LocalFileId, GlobalFileId>,
+    global_to_local: FxIndexMap<GlobalFileId, LocalFileId>,
 }
 
 impl VirtualFileMapping {
-    fn local_id_for_global(&mut self, global_file_id: u32) -> LocalFileId {
+    fn local_id_for_global(&mut self, global_file_id: GlobalFileId) -> LocalFileId {
         *self
             .global_to_local
             .entry(global_file_id)
@@ -218,16 +228,26 @@ impl VirtualFileMapping {
     }
 
     fn into_vec(self) -> Vec<u32> {
-        self.local_to_global.raw
+        // This conversion should be optimized away to ~zero overhead.
+        // In any case, it's probably not hot enough to worry about.
+        self.local_to_global.into_iter().map(|global| global.as_u32()).collect()
     }
 }
 
+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)
+}
+
 /// Using the expressions and counter regions collected for a single function,
 /// generate the variable-sized payload of its corresponding `__llvm_covfun`
 /// entry. The payload is returned as a vector of bytes.
 ///
 /// Newly-encountered filenames will be added to the global file table.
 fn encode_mappings_for_function(
+    tcx: TyCtxt<'_>,
     global_file_table: &GlobalFileTable,
     function_coverage: &FunctionCoverage<'_>,
 ) -> Vec<u8> {
@@ -244,69 +264,58 @@ fn encode_mappings_for_function(
     let mut mcdc_branch_regions = vec![];
     let mut mcdc_decision_regions = vec![];
 
-    // Group mappings into runs with the same filename, preserving the order
-    // yielded by `FunctionCoverage`.
-    // Prepare file IDs for each filename, and prepare the mapping data so that
-    // we can pass it through FFI to LLVM.
-    for (file_name, counter_regions_for_file) in
-        &counter_regions.group_by(|(_, region)| region.file_name)
-    {
-        // Look up the global file ID for this filename.
-        let global_file_id = global_file_table.global_file_id_for_file_name(file_name);
-
-        // Associate that global file ID with a local file ID for this function.
-        let local_file_id = virtual_file_mapping.local_id_for_global(global_file_id);
-        debug!("  file id: {local_file_id:?} => global {global_file_id} = '{file_name:?}'");
-
-        // For each counter/region pair in this function+file, convert it to a
-        // form suitable for FFI.
-        for (mapping_kind, region) in counter_regions_for_file {
-            debug!("Adding counter {mapping_kind:?} to map for {region:?}");
-            let span = ffi::CoverageSpan::from_source_region(local_file_id.as_u32(), region);
-            match mapping_kind {
-                MappingKind::Code(term) => {
-                    code_regions
-                        .push(ffi::CodeRegion { span, counter: ffi::Counter::from_term(term) });
-                }
-                MappingKind::Branch { true_term, false_term } => {
-                    branch_regions.push(ffi::BranchRegion {
-                        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,
-                        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),
-                    });
-                }
-                MappingKind::MCDCDecision(mcdc_decision_params) => {
-                    mcdc_decision_regions.push(ffi::MCDCDecisionRegion {
-                        span,
-                        mcdc_decision_params: ffi::mcdc::DecisionParameters::from(
-                            mcdc_decision_params,
-                        ),
-                    });
-                }
+    // 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);
+
+    // Look up the global file ID for that filename.
+    let global_file_id = global_file_table.global_file_id_for_file_name(file_name);
+
+    // Associate that global file ID with a local file ID for this function.
+    let local_file_id = virtual_file_mapping.local_id_for_global(global_file_id);
+    debug!("  file id: {local_file_id:?} => {global_file_id:?} = '{file_name:?}'");
+
+    // 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 {
+            MappingKind::Code(term) => {
+                code_regions.push(ffi::CodeRegion { span, counter: ffi::Counter::from_term(term) });
+            }
+            MappingKind::Branch { true_term, false_term } => {
+                branch_regions.push(ffi::BranchRegion {
+                    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,
+                    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),
+                });
+            }
+            MappingKind::MCDCDecision(mcdc_decision_params) => {
+                mcdc_decision_regions.push(ffi::MCDCDecisionRegion {
+                    span,
+                    mcdc_decision_params: ffi::mcdc::DecisionParameters::from(mcdc_decision_params),
+                });
             }
         }
     }
 
     // Encode the function's coverage mappings into a buffer.
-    llvm::build_byte_buffer(|buffer| {
-        coverageinfo::write_mapping_to_buffer(
-            virtual_file_mapping.into_vec(),
-            expressions,
-            &code_regions,
-            &branch_regions,
-            &mcdc_branch_regions,
-            &mcdc_decision_regions,
-            buffer,
-        );
-    })
+    llvm_cov::write_function_mappings_to_buffer(
+        &virtual_file_mapping.into_vec(),
+        &expressions,
+        &code_regions,
+        &branch_regions,
+        &mcdc_branch_regions,
+        &mcdc_decision_regions,
+    )
 }
 
 /// Generates the contents of the covmap record for this CGU, which mostly
@@ -335,23 +344,11 @@ fn generate_covmap_record<'ll>(
     let covmap_data =
         cx.const_struct(&[cov_data_header_val, filenames_val], /*packed=*/ false);
 
-    let covmap_var_name = CString::new(llvm::build_byte_buffer(|s| unsafe {
-        llvm::LLVMRustCoverageWriteMappingVarNameToString(s);
-    }))
-    .unwrap();
-    debug!("covmap var name: {:?}", covmap_var_name);
-
-    let covmap_section_name = CString::new(llvm::build_byte_buffer(|s| unsafe {
-        llvm::LLVMRustCoverageWriteMapSectionNameToString(cx.llmod, s);
-    }))
-    .expect("covmap section name should not contain NUL");
-    debug!("covmap section name: {:?}", covmap_section_name);
-
-    let llglobal = llvm::add_global(cx.llmod, cx.val_ty(covmap_data), &covmap_var_name);
+    let llglobal = llvm::add_global(cx.llmod, cx.val_ty(covmap_data), &llvm_cov::covmap_var_name());
     llvm::set_initializer(llglobal, covmap_data);
     llvm::set_global_constant(llglobal, true);
     llvm::set_linkage(llglobal, llvm::Linkage::PrivateLinkage);
-    llvm::set_section(llglobal, &covmap_section_name);
+    llvm::set_section(llglobal, &llvm_cov::covmap_section_name(cx.llmod));
     // LLVM's coverage mapping format specifies 8-byte alignment for items in this section.
     // <https://llvm.org/docs/CoverageMappingFormat.html>
     llvm::set_alignment(llglobal, Align::EIGHT);
@@ -373,7 +370,7 @@ fn generate_covfun_record(
     let coverage_mapping_size = coverage_mapping_buffer.len();
     let coverage_mapping_val = cx.const_bytes(&coverage_mapping_buffer);
 
-    let func_name_hash = coverageinfo::hash_bytes(mangled_function_name.as_bytes());
+    let func_name_hash = llvm_cov::hash_bytes(mangled_function_name.as_bytes());
     let func_name_hash_val = cx.const_u64(func_name_hash);
     let coverage_mapping_size_val = cx.const_u32(coverage_mapping_size as u32);
     let source_hash_val = cx.const_u64(source_hash);
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
index aaba0684c12..bf773cd2667 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
@@ -1,24 +1,23 @@
 use std::cell::{OnceCell, RefCell};
 use std::ffi::{CStr, CString};
 
-use libc::c_uint;
 use rustc_abi::Size;
 use rustc_codegen_ssa::traits::{
     BuilderMethods, ConstCodegenMethods, CoverageInfoBuilderMethods, MiscCodegenMethods,
 };
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
-use rustc_llvm::RustString;
 use rustc_middle::mir::coverage::CoverageKind;
 use rustc_middle::ty::Instance;
 use rustc_middle::ty::layout::HasTyCtxt;
 use tracing::{debug, instrument};
 
 use crate::builder::Builder;
-use crate::common::{AsCCharPtr, CodegenCx};
+use crate::common::CodegenCx;
 use crate::coverageinfo::map_data::FunctionCoverageCollector;
 use crate::llvm;
 
 pub(crate) mod ffi;
+mod llvm_cov;
 pub(crate) mod map_data;
 mod mapgen;
 
@@ -80,12 +79,9 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
     /// - `__LLVM_COV,__llvm_covfun` on macOS (includes `__LLVM_COV,` segment prefix)
     /// - `.lcovfun$M` on Windows (includes `$M` sorting suffix)
     fn covfun_section_name(&self) -> &CStr {
-        self.coverage_cx().covfun_section_name.get_or_init(|| {
-            CString::new(llvm::build_byte_buffer(|s| unsafe {
-                llvm::LLVMRustCoverageWriteFuncSectionNameToString(self.llmod, s);
-            }))
-            .expect("covfun section name should not contain NUL")
-        })
+        self.coverage_cx()
+            .covfun_section_name
+            .get_or_init(|| llvm_cov::covfun_section_name(self.llmod))
     }
 
     /// For LLVM codegen, returns a function-specific `Value` for a global
@@ -95,9 +91,11 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
     fn get_pgo_func_name_var(&self, instance: Instance<'tcx>) -> &'ll llvm::Value {
         debug!("getting pgo_func_name_var for instance={:?}", instance);
         let mut pgo_func_name_var_map = self.coverage_cx().pgo_func_name_var_map.borrow_mut();
-        pgo_func_name_var_map
-            .entry(instance)
-            .or_insert_with(|| create_pgo_func_name_var(self, instance))
+        pgo_func_name_var_map.entry(instance).or_insert_with(|| {
+            let llfn = self.get_fn(instance);
+            let mangled_fn_name: &str = self.tcx.symbol_name(instance).name;
+            llvm_cov::create_pgo_func_name_var(llfn, mangled_fn_name)
+        })
     }
 }
 
@@ -225,80 +223,3 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
         }
     }
 }
-
-/// Calls llvm::createPGOFuncNameVar() with the given function instance's
-/// mangled function name. The LLVM API returns an llvm::GlobalVariable
-/// containing the function name, with the specific variable name and linkage
-/// required by LLVM InstrProf source-based coverage instrumentation. Use
-/// `bx.get_pgo_func_name_var()` to ensure the variable is only created once per
-/// `Instance`.
-fn create_pgo_func_name_var<'ll, 'tcx>(
-    cx: &CodegenCx<'ll, 'tcx>,
-    instance: Instance<'tcx>,
-) -> &'ll llvm::Value {
-    let mangled_fn_name: &str = cx.tcx.symbol_name(instance).name;
-    let llfn = cx.get_fn(instance);
-    unsafe {
-        llvm::LLVMRustCoverageCreatePGOFuncNameVar(
-            llfn,
-            mangled_fn_name.as_c_char_ptr(),
-            mangled_fn_name.len(),
-        )
-    }
-}
-
-pub(crate) fn write_filenames_section_to_buffer<'a>(
-    filenames: impl IntoIterator<Item = &'a str>,
-    buffer: &RustString,
-) {
-    let (pointers, lengths) = filenames
-        .into_iter()
-        .map(|s: &str| (s.as_c_char_ptr(), s.len()))
-        .unzip::<_, _, Vec<_>, Vec<_>>();
-
-    unsafe {
-        llvm::LLVMRustCoverageWriteFilenamesSectionToBuffer(
-            pointers.as_ptr(),
-            pointers.len(),
-            lengths.as_ptr(),
-            lengths.len(),
-            buffer,
-        );
-    }
-}
-
-pub(crate) fn write_mapping_to_buffer(
-    virtual_file_mapping: Vec<u32>,
-    expressions: Vec<ffi::CounterExpression>,
-    code_regions: &[ffi::CodeRegion],
-    branch_regions: &[ffi::BranchRegion],
-    mcdc_branch_regions: &[ffi::MCDCBranchRegion],
-    mcdc_decision_regions: &[ffi::MCDCDecisionRegion],
-    buffer: &RustString,
-) {
-    unsafe {
-        llvm::LLVMRustCoverageWriteMappingToBuffer(
-            virtual_file_mapping.as_ptr(),
-            virtual_file_mapping.len() as c_uint,
-            expressions.as_ptr(),
-            expressions.len() as c_uint,
-            code_regions.as_ptr(),
-            code_regions.len() as c_uint,
-            branch_regions.as_ptr(),
-            branch_regions.len() as c_uint,
-            mcdc_branch_regions.as_ptr(),
-            mcdc_branch_regions.len() as c_uint,
-            mcdc_decision_regions.as_ptr(),
-            mcdc_decision_regions.len() as c_uint,
-            buffer,
-        );
-    }
-}
-
-pub(crate) fn hash_bytes(bytes: &[u8]) -> u64 {
-    unsafe { llvm::LLVMRustCoverageHashByteArray(bytes.as_c_char_ptr(), bytes.len()) }
-}
-
-pub(crate) fn mapping_version() -> u32 {
-    unsafe { llvm::LLVMRustCoverageMappingVersion() }
-}
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
index ac6c2fb1b83..0f1909486ec 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
@@ -1,11 +1,15 @@
+use std::collections::hash_map::Entry;
+
 use rustc_codegen_ssa::mir::debuginfo::{DebugScope, FunctionDebugContext};
 use rustc_codegen_ssa::traits::*;
+use rustc_data_structures::fx::FxHashMap;
 use rustc_index::Idx;
 use rustc_index::bit_set::BitSet;
 use rustc_middle::mir::{Body, SourceScope};
 use rustc_middle::ty::layout::FnAbiOf;
 use rustc_middle::ty::{self, Instance};
 use rustc_session::config::DebugInfo;
+use rustc_span::BytePos;
 
 use super::metadata::file_metadata;
 use super::utils::DIB;
@@ -37,10 +41,20 @@ pub(crate) fn compute_mir_scopes<'ll, 'tcx>(
         None
     };
     let mut instantiated = BitSet::new_empty(mir.source_scopes.len());
+    let mut discriminators = FxHashMap::default();
     // Instantiate all scopes.
     for idx in 0..mir.source_scopes.len() {
         let scope = SourceScope::new(idx);
-        make_mir_scope(cx, instance, mir, &variables, debug_context, &mut instantiated, scope);
+        make_mir_scope(
+            cx,
+            instance,
+            mir,
+            &variables,
+            debug_context,
+            &mut instantiated,
+            &mut discriminators,
+            scope,
+        );
     }
     assert!(instantiated.count() == mir.source_scopes.len());
 }
@@ -52,6 +66,7 @@ fn make_mir_scope<'ll, 'tcx>(
     variables: &Option<BitSet<SourceScope>>,
     debug_context: &mut FunctionDebugContext<'tcx, &'ll DIScope, &'ll DILocation>,
     instantiated: &mut BitSet<SourceScope>,
+    discriminators: &mut FxHashMap<BytePos, u32>,
     scope: SourceScope,
 ) {
     if instantiated.contains(scope) {
@@ -60,7 +75,16 @@ fn make_mir_scope<'ll, 'tcx>(
 
     let scope_data = &mir.source_scopes[scope];
     let parent_scope = if let Some(parent) = scope_data.parent_scope {
-        make_mir_scope(cx, instance, mir, variables, debug_context, instantiated, parent);
+        make_mir_scope(
+            cx,
+            instance,
+            mir,
+            variables,
+            debug_context,
+            instantiated,
+            discriminators,
+            parent,
+        );
         debug_context.scopes[parent]
     } else {
         // The root is the function itself.
@@ -117,7 +141,37 @@ fn make_mir_scope<'ll, 'tcx>(
         // FIXME(eddyb) this doesn't account for the macro-related
         // `Span` fixups that `rustc_codegen_ssa::mir::debuginfo` does.
         let callsite_scope = parent_scope.adjust_dbg_scope_for_span(cx, callsite_span);
-        cx.dbg_loc(callsite_scope, parent_scope.inlined_at, callsite_span)
+        let loc = cx.dbg_loc(callsite_scope, parent_scope.inlined_at, callsite_span);
+
+        // NB: In order to produce proper debug info for variables (particularly
+        // arguments) in multiply-inline functions, LLVM expects to see a single
+        // DILocalVariable with multiple different DILocations in the IR. While
+        // the source information for each DILocation would be identical, their
+        // inlinedAt attributes will be unique to the particular callsite.
+        //
+        // We generate DILocations here based on the callsite's location in the
+        // source code. A single location in the source code usually can't
+        // produce multiple distinct calls so this mostly works, until
+        // proc-macros get involved. A proc-macro can generate multiple calls
+        // at the same span, which breaks the assumption that we're going to
+        // produce a unique DILocation for every scope we process here. We
+        // have to explicitly add discriminators if we see inlines into the
+        // same source code location.
+        //
+        // Note further that we can't key this hashtable on the span itself,
+        // because these spans could have distinct SyntaxContexts. We have
+        // to key on exactly what we're giving to LLVM.
+        match discriminators.entry(callsite_span.lo()) {
+            Entry::Occupied(mut o) => {
+                *o.get_mut() += 1;
+                unsafe { llvm::LLVMRustDILocationCloneWithBaseDiscriminator(loc, *o.get()) }
+                    .expect("Failed to encode discriminator in DILocation")
+            }
+            Entry::Vacant(v) => {
+                v.insert(0);
+                loc
+            }
+        }
     });
 
     debug_context.scopes[scope] = DebugScope {
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
index 9e1e5127e80..89492e4b9fe 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
@@ -206,6 +206,10 @@ impl<'ll> DebugInfoBuilderMethods for Builder<'_, 'll, '_> {
         }
     }
 
+    fn get_dbg_loc(&self) -> Option<&'ll DILocation> {
+        unsafe { llvm::LLVMGetCurrentDebugLocation2(self.llbuilder) }
+    }
+
     fn insert_reference_to_gdb_debug_scripts_section_global(&mut self) {
         gdb::insert_reference_to_gdb_debug_scripts_section_global(self)
     }
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index b85d28a2f1f..3dfb86d422d 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -22,7 +22,6 @@
 
 use std::any::Any;
 use std::ffi::CStr;
-use std::io::Write;
 use std::mem::ManuallyDrop;
 
 use back::owned_target_machine::OwnedTargetMachine;
@@ -165,30 +164,12 @@ impl WriteBackendMethods for LlvmCodegenBackend {
     type ThinData = back::lto::ThinData;
     type ThinBuffer = back::lto::ThinBuffer;
     fn print_pass_timings(&self) {
-        unsafe {
-            let mut size = 0;
-            let cstr = llvm::LLVMRustPrintPassTimings(&raw mut size);
-            if cstr.is_null() {
-                println!("failed to get pass timings");
-            } else {
-                let timings = std::slice::from_raw_parts(cstr as *const u8, size);
-                std::io::stdout().write_all(timings).unwrap();
-                libc::free(cstr as *mut _);
-            }
-        }
+        let timings = llvm::build_string(|s| unsafe { llvm::LLVMRustPrintPassTimings(s) }).unwrap();
+        print!("{timings}");
     }
     fn print_statistics(&self) {
-        unsafe {
-            let mut size = 0;
-            let cstr = llvm::LLVMRustPrintStatistics(&raw mut size);
-            if cstr.is_null() {
-                println!("failed to get pass stats");
-            } else {
-                let stats = std::slice::from_raw_parts(cstr as *const u8, size);
-                std::io::stdout().write_all(stats).unwrap();
-                libc::free(cstr as *mut _);
-            }
-        }
+        let stats = llvm::build_string(|s| unsafe { llvm::LLVMRustPrintStatistics(s) }).unwrap();
+        print!("{stats}");
     }
     fn run_link(
         cgcx: &CodegenContext<Self>,
@@ -401,7 +382,7 @@ impl CodegenBackend for LlvmCodegenBackend {
 
         // Run the linker on any artifacts that resulted from the LLVM run.
         // This should produce either a finished executable or library.
-        link_binary(sess, &LlvmArchiveBuilderBuilder, &codegen_results, outputs)
+        link_binary(sess, &LlvmArchiveBuilderBuilder, codegen_results, outputs)
     }
 }
 
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index d84ae8d8836..7f59264824e 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -204,7 +204,7 @@ pub enum DLLStorageClass {
     DllExport = 2, // Function to be accessible from DLL.
 }
 
-/// Matches LLVMRustAttribute in LLVMWrapper.h
+/// Must match the layout of `LLVMRustAttributeKind`.
 /// Semantically a subset of the C++ enum llvm::Attribute::AttrKind,
 /// though it is not ABI compatible (since it's a C++ enum)
 #[repr(C)]
@@ -1063,6 +1063,7 @@ unsafe extern "C" {
 
     // Metadata
     pub fn LLVMSetCurrentDebugLocation2<'a>(Builder: &Builder<'a>, Loc: *const Metadata);
+    pub fn LLVMGetCurrentDebugLocation2<'a>(Builder: &Builder<'a>) -> Option<&'a Metadata>;
 
     // Terminators
     pub fn LLVMBuildRetVoid<'a>(B: &Builder<'a>) -> &'a Value;
@@ -1765,11 +1766,11 @@ unsafe extern "C" {
     /// Returns a string describing the last error caused by an LLVMRust* call.
     pub fn LLVMRustGetLastError() -> *const c_char;
 
-    /// Print the pass timings since static dtors aren't picking them up.
-    pub fn LLVMRustPrintPassTimings(size: *const size_t) -> *const c_char;
+    /// Prints the timing information collected by `-Ztime-llvm-passes`.
+    pub(crate) fn LLVMRustPrintPassTimings(OutStr: &RustString);
 
-    /// Print the statistics since static dtors aren't picking them up.
-    pub fn LLVMRustPrintStatistics(size: *const size_t) -> *const c_char;
+    /// Prints the statistics collected by `-Zprint-codegen-stats`.
+    pub(crate) fn LLVMRustPrintStatistics(OutStr: &RustString);
 
     /// Prepares inline assembly.
     pub fn LLVMRustInlineAsm(
@@ -1789,8 +1790,7 @@ unsafe extern "C" {
         ConstraintsLen: size_t,
     ) -> bool;
 
-    #[allow(improper_ctypes)]
-    pub(crate) fn LLVMRustCoverageWriteFilenamesSectionToBuffer(
+    pub(crate) fn LLVMRustCoverageWriteFilenamesToBuffer(
         Filenames: *const *const c_char,
         FilenamesLen: size_t,
         Lengths: *const size_t,
@@ -1798,20 +1798,19 @@ unsafe extern "C" {
         BufferOut: &RustString,
     );
 
-    #[allow(improper_ctypes)]
-    pub(crate) fn LLVMRustCoverageWriteMappingToBuffer(
+    pub(crate) fn LLVMRustCoverageWriteFunctionMappingsToBuffer(
         VirtualFileMappingIDs: *const c_uint,
-        NumVirtualFileMappingIDs: c_uint,
+        NumVirtualFileMappingIDs: size_t,
         Expressions: *const crate::coverageinfo::ffi::CounterExpression,
-        NumExpressions: c_uint,
+        NumExpressions: size_t,
         CodeRegions: *const crate::coverageinfo::ffi::CodeRegion,
-        NumCodeRegions: c_uint,
+        NumCodeRegions: size_t,
         BranchRegions: *const crate::coverageinfo::ffi::BranchRegion,
-        NumBranchRegions: c_uint,
+        NumBranchRegions: size_t,
         MCDCBranchRegions: *const crate::coverageinfo::ffi::MCDCBranchRegion,
-        NumMCDCBranchRegions: c_uint,
+        NumMCDCBranchRegions: size_t,
         MCDCDecisionRegions: *const crate::coverageinfo::ffi::MCDCDecisionRegion,
-        NumMCDCDecisionRegions: c_uint,
+        NumMCDCDecisionRegions: size_t,
         BufferOut: &RustString,
     );
 
@@ -1820,16 +1819,13 @@ unsafe extern "C" {
         FuncName: *const c_char,
         FuncNameLen: size_t,
     ) -> &Value;
-    pub(crate) fn LLVMRustCoverageHashByteArray(Bytes: *const c_char, NumBytes: size_t) -> u64;
+    pub(crate) fn LLVMRustCoverageHashBytes(Bytes: *const c_char, NumBytes: size_t) -> u64;
 
-    #[allow(improper_ctypes)]
-    pub(crate) fn LLVMRustCoverageWriteMapSectionNameToString(M: &Module, Str: &RustString);
+    pub(crate) fn LLVMRustCoverageWriteCovmapSectionNameToString(M: &Module, OutStr: &RustString);
 
-    #[allow(improper_ctypes)]
-    pub(crate) fn LLVMRustCoverageWriteFuncSectionNameToString(M: &Module, Str: &RustString);
+    pub(crate) fn LLVMRustCoverageWriteCovfunSectionNameToString(M: &Module, OutStr: &RustString);
 
-    #[allow(improper_ctypes)]
-    pub(crate) fn LLVMRustCoverageWriteMappingVarNameToString(Str: &RustString);
+    pub(crate) fn LLVMRustCoverageWriteCovmapVarNameToString(OutStr: &RustString);
 
     pub(crate) fn LLVMRustCoverageMappingVersion() -> u32;
     pub fn LLVMRustDebugMetadataVersion() -> u32;
@@ -2179,18 +2175,19 @@ unsafe extern "C" {
         Scope: &'a DIScope,
         InlinedAt: Option<&'a DILocation>,
     ) -> &'a DILocation;
+    pub fn LLVMRustDILocationCloneWithBaseDiscriminator<'a>(
+        Location: &'a DILocation,
+        BD: c_uint,
+    ) -> Option<&'a DILocation>;
     pub fn LLVMRustDIBuilderCreateOpDeref() -> u64;
     pub fn LLVMRustDIBuilderCreateOpPlusUconst() -> u64;
     pub fn LLVMRustDIBuilderCreateOpLLVMFragment() -> u64;
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustWriteTypeToString(Type: &Type, s: &RustString);
-    #[allow(improper_ctypes)]
     pub fn LLVMRustWriteValueToString(value_ref: &Value, s: &RustString);
 
     pub fn LLVMRustHasFeature(T: &TargetMachine, s: *const c_char) -> bool;
 
-    #[allow(improper_ctypes)]
     pub(crate) fn LLVMRustPrintTargetCPUs(TM: &TargetMachine, OutStr: &RustString);
     pub fn LLVMRustGetTargetFeaturesCount(T: &TargetMachine) -> size_t;
     pub fn LLVMRustGetTargetFeature(
@@ -2295,10 +2292,8 @@ unsafe extern "C" {
     pub fn LLVMRustArchiveIteratorFree<'a>(AIR: &'a mut ArchiveIterator<'a>);
     pub fn LLVMRustDestroyArchive(AR: &'static mut Archive);
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustWriteTwineToString(T: &Twine, s: &RustString);
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustUnpackOptimizationDiagnostic<'a>(
         DI: &'a DiagnosticInfo,
         pass_name_out: &RustString,
@@ -2316,7 +2311,6 @@ unsafe extern "C" {
         message_out: &mut Option<&'a Twine>,
     );
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustWriteDiagnosticInfoToString(DI: &DiagnosticInfo, s: &RustString);
     pub fn LLVMRustGetDiagInfoKind(DI: &DiagnosticInfo) -> DiagnosticKind;
 
@@ -2325,7 +2319,6 @@ unsafe extern "C" {
         cookie_out: &mut c_uint,
     ) -> &'a SMDiagnostic;
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustUnpackSMDiagnostic(
         d: &SMDiagnostic,
         message_out: &RustString,
@@ -2372,7 +2365,6 @@ unsafe extern "C" {
     pub fn LLVMRustModuleBufferLen(p: &ModuleBuffer) -> usize;
     pub fn LLVMRustModuleBufferFree(p: &'static mut ModuleBuffer);
     pub fn LLVMRustModuleCost(M: &Module) -> u64;
-    #[allow(improper_ctypes)]
     pub fn LLVMRustModuleInstructionStats(M: &Module, Str: &RustString);
 
     pub fn LLVMRustThinLTOBufferCreate(
@@ -2425,7 +2417,6 @@ unsafe extern "C" {
         bytecode_len: usize,
     ) -> bool;
     pub fn LLVMRustLinkerFree<'a>(linker: &'a mut Linker<'a>);
-    #[allow(improper_ctypes)]
     pub fn LLVMRustComputeLTOCacheKey(
         key_out: &RustString,
         mod_id: *const c_char,
@@ -2448,7 +2439,6 @@ unsafe extern "C" {
         pgo_available: bool,
     );
 
-    #[allow(improper_ctypes)]
     pub fn LLVMRustGetMangledName(V: &Value, out: &RustString);
 
     pub fn LLVMRustGetElementTypeArgIndex(CallSite: &Value) -> i32;
diff --git a/compiler/rustc_codegen_llvm/src/llvm/mod.rs b/compiler/rustc_codegen_llvm/src/llvm/mod.rs
index 3b0bf47366e..909afe35a17 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/mod.rs
@@ -1,6 +1,5 @@
 #![allow(non_snake_case)]
 
-use std::cell::RefCell;
 use std::ffi::{CStr, CString};
 use std::ops::Deref;
 use std::ptr;
@@ -301,15 +300,11 @@ pub fn set_value_name(value: &Value, name: &[u8]) {
 }
 
 pub fn build_string(f: impl FnOnce(&RustString)) -> Result<String, FromUtf8Error> {
-    let sr = RustString { bytes: RefCell::new(Vec::new()) };
-    f(&sr);
-    String::from_utf8(sr.bytes.into_inner())
+    String::from_utf8(RustString::build_byte_buffer(f))
 }
 
 pub fn build_byte_buffer(f: impl FnOnce(&RustString)) -> Vec<u8> {
-    let sr = RustString { bytes: RefCell::new(Vec::new()) };
-    f(&sr);
-    sr.bytes.into_inner()
+    RustString::build_byte_buffer(f)
 }
 
 pub fn twine_to_string(tr: &Twine) -> String {
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 6f2d86cc601..db2b03d9aed 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -228,6 +228,8 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         "x86"
     } else if sess.target.arch == "arm64ec" {
         "aarch64"
+    } else if sess.target.arch == "sparc64" {
+        "sparc"
     } else {
         &*sess.target.arch
     };
@@ -280,6 +282,13 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         // Support for `wide-arithmetic` will first land in LLVM 20 as part of
         // llvm/llvm-project#111598
         ("wasm32" | "wasm64", "wide-arithmetic") if get_version() < (20, 0, 0) => None,
+        ("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".
+        // 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,
         (_, s) => Some(LLVMFeature::new(s)),
     }
 }
@@ -335,15 +344,23 @@ pub fn target_features(sess: &Session, allow_unstable: bool) -> Vec<Symbol> {
         })
     {
         if enabled {
+            // Also add all transitively implied features.
             features.extend(sess.target.implied_target_features(std::iter::once(feature)));
         } else {
+            // Remove transitively reverse-implied features.
+
             // We don't care about the order in `features` since the only thing we use it for is the
             // `features.contains` below.
             #[allow(rustc::potential_query_instability)]
             features.retain(|f| {
-                // Keep a feature if it does not imply `feature`. Or, equivalently,
-                // remove the reverse-dependencies of `feature`.
-                !sess.target.implied_target_features(std::iter::once(*f)).contains(&feature)
+                if sess.target.implied_target_features(std::iter::once(*f)).contains(&feature) {
+                    // If `f` if implies `feature`, then `!feature` implies `!f`, so we have to
+                    // remove `f`. (This is the standard logical contraposition principle.)
+                    false
+                } else {
+                    // We can keep `f`.
+                    true
+                }
             });
         }
     }
@@ -619,6 +636,8 @@ pub(crate) fn global_llvm_features(
             .features
             .split(',')
             .filter(|v| !v.is_empty() && backend_feature_name(sess, v).is_some())
+            // Drop +v8plus feature introduced in LLVM 20.
+            .filter(|v| *v != "+v8plus" || get_version() >= (20, 0, 0))
             .map(String::from),
     );