Auto merge of rust-lang#141243 - Zalathar:rollup-x5xt80l, r=Zalathar

Rollup of 5 pull requests

Successful merges:

 - rust-lang#140847 (coverage: Detect unused local file IDs to avoid an LLVM assertion)
 - rust-lang#141117 (opt-dist: fix deprecated BOLT -icf=1 option)
 - rust-lang#141225 (more ice tests)
 - rust-lang#141239 (dladdr cannot leave dli_fname to be null)
 - rust-lang#141242 (in `tests/ui/asm/aarch64/parse-error.rs`, only test cases specific to that target)

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

Author: bors

compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs

@@ -155,6 +155,20 @@ pub(crate) struct Regions {
 impl Regions {
     /// Returns true if none of this structure's tables contain any regions.
     pub(crate) fn has_no_regions(&self) -> bool {
+        // Every region has a span, so if there are no spans then there are no regions.
+        self.all_cov_spans().next().is_none()
+    }
+
+    pub(crate) fn all_cov_spans(&self) -> impl Iterator<Item = &CoverageSpan> {
+        macro_rules! iter_cov_spans {
+            ( $( $regions:expr ),* $(,)? ) => {
+                std::iter::empty()
+                $(
+                    .chain( $regions.iter().map(|region| &region.cov_span) )
+                )*
+            }
+        }
+
         let Self {
             code_regions,
             expansion_regions,
@@ -163,11 +177,13 @@ impl Regions {
             mcdc_decision_regions,
         } = self;
 
-        code_regions.is_empty()
-            && expansion_regions.is_empty()
-            && branch_regions.is_empty()
-            && mcdc_branch_regions.is_empty()
-            && mcdc_decision_regions.is_empty()
+        iter_cov_spans!(
+            code_regions,
+            expansion_regions,
+            branch_regions,
+            mcdc_branch_regions,
+            mcdc_decision_regions,
+        )
     }
 }
 

compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs

@@ -11,6 +11,7 @@ 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,
@@ -104,6 +105,16 @@ 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();
@@ -115,6 +126,12 @@ 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
@@ -135,16 +152,6 @@ 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);
 
@@ -177,6 +184,19 @@ 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.
@@ -185,6 +205,10 @@ 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,