coverage: Revert "unused local file IDs" due to empty function names

This reverts commit 3b22c21dd8c30f499051fe7a758ca0e5d81eb638, reversing
changes made to 5f292eea6d63abbd26f1e6e00a0b8cf21d828d7d.

1 files changed, 10 insertions, 34 deletions

diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
index d3a815fabe7..7bdbc685952 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
@@ -11,7 +11,6 @@ use rustc_abi::Align;
 use rustc_codegen_ssa::traits::{
     BaseTypeCodegenMethods as _, ConstCodegenMethods, StaticCodegenMethods,
 };
-use rustc_index::IndexVec;
 use rustc_middle::mir::coverage::{
     BasicCoverageBlock, CovTerm, CoverageIdsInfo, Expression, FunctionCoverageInfo, Mapping,
     MappingKind, Op,
@@ -105,16 +104,6 @@ fn fill_region_tables<'tcx>(
     ids_info: &'tcx CoverageIdsInfo,
     covfun: &mut CovfunRecord<'tcx>,
 ) {
-    // If this function is unused, replace all counters with zero.
-    let counter_for_bcb = |bcb: BasicCoverageBlock| -> ffi::Counter {
-        let term = if covfun.is_used {
-            ids_info.term_for_bcb[bcb].expect("every BCB in a mapping was given a term")
-        } else {
-            CovTerm::Zero
-        };
-        ffi::Counter::from_term(term)
-    };
-
     // Currently a function's mappings must all be in the same file, so use the
     // first mapping's span to determine the file.
     let source_map = tcx.sess.source_map();
@@ -126,12 +115,6 @@ fn fill_region_tables<'tcx>(
 
     let local_file_id = covfun.virtual_file_mapping.push_file(&source_file);
 
-    // If this testing flag is set, add an extra unused entry to the local
-    // file table, to help test the code for detecting unused file IDs.
-    if tcx.sess.coverage_inject_unused_local_file() {
-        covfun.virtual_file_mapping.push_file(&source_file);
-    }
-
     // In rare cases, _all_ of a function's spans are discarded, and coverage
     // codegen needs to handle that gracefully to avoid #133606.
     // It's hard for tests to trigger this organically, so instead we set
@@ -152,6 +135,16 @@ fn fill_region_tables<'tcx>(
     // For each counter/region pair in this function+file, convert it to a
     // form suitable for FFI.
     for &Mapping { ref kind, span } in &fn_cov_info.mappings {
+        // If this function is unused, replace all counters with zero.
+        let counter_for_bcb = |bcb: BasicCoverageBlock| -> ffi::Counter {
+            let term = if covfun.is_used {
+                ids_info.term_for_bcb[bcb].expect("every BCB in a mapping was given a term")
+            } else {
+                CovTerm::Zero
+            };
+            ffi::Counter::from_term(term)
+        };
+
         let Some(coords) = make_coords(span) else { continue };
         let cov_span = coords.make_coverage_span(local_file_id);
 
@@ -184,19 +177,6 @@ fn fill_region_tables<'tcx>(
     }
 }
 
-/// LLVM requires all local file IDs to have at least one mapping region.
-/// If that's not the case, skip this function, to avoid an assertion failure
-/// (or worse) in LLVM.
-fn check_local_file_table(covfun: &CovfunRecord<'_>) -> bool {
-    let mut local_file_id_seen =
-        IndexVec::<u32, _>::from_elem_n(false, covfun.virtual_file_mapping.local_file_table.len());
-    for cov_span in covfun.regions.all_cov_spans() {
-        local_file_id_seen[cov_span.file_id] = true;
-    }
-
-    local_file_id_seen.into_iter().all(|seen| seen)
-}
-
 /// Generates the contents of the covfun record for this function, which
 /// contains the function's coverage mapping data. The record is then stored
 /// as a global variable in the `__llvm_covfun` section.
@@ -205,10 +185,6 @@ pub(crate) fn generate_covfun_record<'tcx>(
     global_file_table: &GlobalFileTable,
     covfun: &CovfunRecord<'tcx>,
 ) {
-    if !check_local_file_table(covfun) {
-        return;
-    }
-
     let &CovfunRecord {
         mangled_function_name,
         source_hash,