Auto merge of #117071 - matthiaskrgr:rollup-1tcxdgj, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #105666 (rustdoc: align stability badge to baseline instead of bottom)
 - #117042 (coverage: Emit the filenames section before encoding per-function mappings)
 - #117044 (Miri subtree update)
 - #117049 (add a `csky-unknown-linux-gnuabiv2hf` target )
 - #117051 (fix broken link: update incremental compilation url)
 - #117069 (x.ps1: remove the check for Python from Windows Store)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 100 insertions, 62 deletions

diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
index 2f825b801ac..274e0aeaaba 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
@@ -1,11 +1,12 @@
 use crate::common::CodegenCx;
 use crate::coverageinfo;
 use crate::coverageinfo::ffi::CounterMappingRegion;
-use crate::coverageinfo::map_data::FunctionCoverage;
+use crate::coverageinfo::map_data::{FunctionCoverage, FunctionCoverageCollector};
 use crate::llvm;
 
+use itertools::Itertools as _;
 use rustc_codegen_ssa::traits::{BaseTypeMethods, ConstMethods};
-use rustc_data_structures::fx::FxIndexSet;
+use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
 use rustc_index::IndexVec;
@@ -57,11 +58,32 @@ pub fn finalize(cx: &CodegenCx<'_, '_>) {
         return;
     }
 
-    let mut global_file_table = GlobalFileTable::new(tcx);
+    let function_coverage_entries = function_coverage_map
+        .into_iter()
+        .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 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);
+
+    let filenames_size = filenames_buffer.len();
+    let filenames_val = cx.const_bytes(&filenames_buffer);
+    let filenames_ref = coverageinfo::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.
+    let cov_data_val = generate_coverage_map(cx, version, filenames_size, filenames_val);
+    coverageinfo::save_cov_data_to_mod(cx, cov_data_val);
+
+    let mut unused_function_names = Vec::new();
+    let covfun_section_name = coverageinfo::covfun_section_name(cx);
 
     // Encode coverage mappings and generate function records
-    let mut function_data = Vec::new();
-    for (instance, function_coverage) in function_coverage_map {
+    for (instance, function_coverage) in function_coverage_entries {
         debug!("Generate function coverage for {}, {:?}", cx.codegen_unit.name(), instance);
 
         let mangled_function_name = tcx.symbol_name(instance).name;
@@ -69,7 +91,7 @@ pub fn finalize(cx: &CodegenCx<'_, '_>) {
         let is_used = function_coverage.is_used();
 
         let coverage_mapping_buffer =
-            encode_mappings_for_function(&mut global_file_table, &function_coverage);
+            encode_mappings_for_function(&global_file_table, &function_coverage);
 
         if coverage_mapping_buffer.is_empty() {
             if function_coverage.is_used() {
@@ -83,23 +105,6 @@ pub fn finalize(cx: &CodegenCx<'_, '_>) {
             }
         }
 
-        function_data.push((mangled_function_name, source_hash, is_used, coverage_mapping_buffer));
-    }
-
-    // Encode all filenames referenced by counters/expressions in this module
-    let filenames_buffer = global_file_table.into_filenames_buffer();
-
-    let filenames_size = filenames_buffer.len();
-    let filenames_val = cx.const_bytes(&filenames_buffer);
-    let filenames_ref = coverageinfo::hash_bytes(&filenames_buffer);
-
-    // Generate the LLVM IR representation of the coverage map and store it in a well-known global
-    let cov_data_val = generate_coverage_map(cx, version, filenames_size, filenames_val);
-
-    let mut unused_function_names = Vec::new();
-
-    let covfun_section_name = coverageinfo::covfun_section_name(cx);
-    for (mangled_function_name, source_hash, is_used, coverage_mapping_buffer) in function_data {
         if !is_used {
             unused_function_names.push(mangled_function_name);
         }
@@ -133,92 +138,125 @@ pub fn finalize(cx: &CodegenCx<'_, '_>) {
         llvm::set_linkage(array, llvm::Linkage::InternalLinkage);
         llvm::set_initializer(array, initializer);
     }
-
-    // Save the coverage data value to LLVM IR
-    coverageinfo::save_cov_data_to_mod(cx, cov_data_val);
 }
 
+/// Maps "global" (per-CGU) file ID numbers to their underlying filenames.
 struct GlobalFileTable {
-    global_file_table: FxIndexSet<Symbol>,
+    /// This "raw" table doesn't include the working dir, so a filename's
+    /// global ID is its index in this set **plus one**.
+    raw_file_table: FxIndexSet<Symbol>,
 }
 
 impl GlobalFileTable {
-    fn new(tcx: TyCtxt<'_>) -> Self {
-        let mut global_file_table = FxIndexSet::default();
+    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 global_file_id_for_file_name(&self, file_name: Symbol) -> u32 {
+        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
+    }
+
+    fn make_filenames_buffer(&self, tcx: TyCtxt<'_>) -> Vec<u8> {
         // 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;
-        let working_dir =
-            Symbol::intern(&tcx.sess.opts.working_dir.for_codegen(&tcx.sess).to_string_lossy());
-        global_file_table.insert(working_dir);
-        Self { global_file_table }
-    }
-
-    fn global_file_id_for_file_name(&mut self, file_name: Symbol) -> u32 {
-        let (global_file_id, _) = self.global_file_table.insert_full(file_name);
-        global_file_id as u32
-    }
-
-    fn into_filenames_buffer(self) -> Vec<u8> {
-        // This method takes `self` so that the caller can't accidentally
-        // modify the original file table after encoding it into a buffer.
+        let working_dir: &str = &tcx.sess.opts.working_dir.for_codegen(&tcx.sess).to_string_lossy();
 
         llvm::build_byte_buffer(|buffer| {
             coverageinfo::write_filenames_section_to_buffer(
-                self.global_file_table.iter().map(Symbol::as_str),
+                // 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,
             );
         })
     }
 }
 
+rustc_index::newtype_index! {
+    // Tell the newtype macro to not generate `Encode`/`Decode` impls.
+    #[custom_encodable]
+    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>,
+}
+
+impl VirtualFileMapping {
+    fn local_id_for_global(&mut self, global_file_id: u32) -> LocalFileId {
+        *self
+            .global_to_local
+            .entry(global_file_id)
+            .or_insert_with(|| self.local_to_global.push(global_file_id))
+    }
+
+    fn into_vec(self) -> Vec<u32> {
+        self.local_to_global.raw
+    }
+}
+
 /// 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(
-    global_file_table: &mut GlobalFileTable,
+    global_file_table: &GlobalFileTable,
     function_coverage: &FunctionCoverage<'_>,
 ) -> Vec<u8> {
-    let (expressions, counter_regions) = function_coverage.get_expressions_and_counter_regions();
-
-    let mut counter_regions = counter_regions.collect::<Vec<_>>();
+    let counter_regions = function_coverage.counter_regions();
     if counter_regions.is_empty() {
         return Vec::new();
     }
 
-    let mut virtual_file_mapping = IndexVec::<u32, u32>::new();
+    let expressions = function_coverage.counter_expressions().collect::<Vec<_>>();
+
+    let mut virtual_file_mapping = VirtualFileMapping::default();
     let mut mapping_regions = Vec::with_capacity(counter_regions.len());
 
-    // Sort and group the list of (counter, region) mapping pairs by filename.
-    // (Preserve any further ordering imposed by `FunctionCoverage`.)
+    // 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.
-    counter_regions.sort_by_key(|(_counter, region)| region.file_name);
-    for counter_regions_for_file in
-        counter_regions.group_by(|(_, a), (_, b)| a.file_name == b.file_name)
+    for (file_name, counter_regions_for_file) in
+        &counter_regions.group_by(|(_counter, region)| region.file_name)
     {
-        // Look up (or allocate) the global file ID for this filename.
-        let file_name = counter_regions_for_file[0].1.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: u32 = virtual_file_mapping.push(global_file_id);
-        debug!("  file id: local {local_file_id} => global {global_file_id} = '{file_name:?}'");
+        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 &(counter, region) in counter_regions_for_file {
+        for (counter, region) in counter_regions_for_file {
             let CodeRegion { file_name: _, start_line, start_col, end_line, end_col } = *region;
 
             debug!("Adding counter {counter:?} to map for {region:?}");
             mapping_regions.push(CounterMappingRegion::code_region(
                 counter,
-                local_file_id,
+                local_file_id.as_u32(),
                 start_line,
                 start_col,
                 end_line,
@@ -230,7 +268,7 @@ fn encode_mappings_for_function(
     // Encode the function's coverage mappings into a buffer.
     llvm::build_byte_buffer(|buffer| {
         coverageinfo::write_mapping_to_buffer(
-            virtual_file_mapping.raw,
+            virtual_file_mapping.into_vec(),
             expressions,
             mapping_regions,
             buffer,
@@ -419,7 +457,7 @@ fn add_unused_function_coverage<'tcx>(
 ) {
     // An unused function's mappings will automatically be rewritten to map to
     // zero, because none of its counters/expressions are marked as seen.
-    let function_coverage = FunctionCoverage::unused(instance, function_coverage_info);
+    let function_coverage = FunctionCoverageCollector::unused(instance, function_coverage_info);
 
     if let Some(coverage_context) = cx.coverage_context() {
         coverage_context.function_coverage_map.borrow_mut().insert(instance, function_coverage);