!! (WIP) Per-function coverage table

Author: Zalathar

compiler/rustc_codegen_llvm/src/coverageinfo/map_data.rs

@@ -3,6 +3,7 @@ use crate::coverageinfo::ffi::{Counter, CounterExpression, ExprKind};
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_index::bit_set::BitSet;
 use rustc_index::IndexVec;
+use rustc_middle::mir;
 use rustc_middle::mir::coverage::{CodeRegion, CounterId, CovTerm, ExpressionId, Op};
 use rustc_middle::ty::Instance;
 use rustc_middle::ty::TyCtxt;
@@ -129,7 +130,7 @@ impl<'tcx> FunctionCoverage<'tcx> {
         self.add_mappings(CovTerm::Zero, std::slice::from_ref(code_region));
     }
 
-    pub(crate) fn add_mappings(&mut self, kind: CovTerm, code_regions: &[CodeRegion]) {
+    fn add_mappings(&mut self, kind: CovTerm, code_regions: &[CodeRegion]) {
         // There's no need to sort the regions by filename before grouping here,
         // because the result is the same either way.
         for regions_for_file in code_regions.group_by(|a, b| a.file_name == b.file_name) {
@@ -140,7 +141,11 @@ impl<'tcx> FunctionCoverage<'tcx> {
         }
     }
 
-    pub(crate) fn finalize(&mut self) {
+    pub(crate) fn finalize(&mut self, coverage_info: &mir::coverage::FunctionCoverageInfo) {
+        for &(mapping_kind, ref code_region) in &coverage_info.mappings {
+            self.add_mappings(mapping_kind, std::slice::from_ref(code_region));
+        }
+
         let zero_expressions = self.simplify_expressions_and_get_zero_expressions();
 
         let mapping_kind_sort_key = |mapping_kind: &CovTerm| match mapping_kind {

compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs

@@ -61,7 +61,10 @@ pub fn finalize(cx: &CodegenCx<'_, '_>) {
     let mut function_data = Vec::new();
     for (instance, mut function_coverage) in function_coverage_map {
         debug!("Generate function coverage for {}, {:?}", cx.codegen_unit.name(), instance);
-        function_coverage.finalize();
+        let Some(coverage_info) = tcx.instance_mir(instance.def).coverage_info.as_ref() else {
+            continue;
+        };
+        function_coverage.finalize(coverage_info);
         let function_coverage = function_coverage;
 
         let mangled_function_name = tcx.symbol_name(instance).name;

compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs

@@ -137,9 +137,6 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
             CoverageKind::Expression { id, lhs, op, rhs } => {
                 func_coverage.add_expression_data(id, lhs, op, rhs);
             }
-            CoverageKind::Mappings { kind, ref code_regions } => {
-                func_coverage.add_mappings(kind, code_regions);
-            }
         }
     }
 }

compiler/rustc_middle/src/mir/coverage.rs

@@ -75,10 +75,6 @@ pub enum CoverageKind {
         op: Op,
         rhs: CovTerm,
     },
-    Mappings {
-        kind: CovTerm,
-        code_regions: Vec<CodeRegion>,
-    },
 }
 
 impl Debug for CoverageKind {
@@ -97,11 +93,6 @@ impl Debug for CoverageKind {
                 },
                 rhs,
             ),
-            Mappings { kind, code_regions } => fmt
-                .debug_struct("Mappings")
-                .field("kind", kind)
-                .field("code_regions", code_regions)
-                .finish(),
         }
     }
 }
@@ -144,4 +135,6 @@ impl Op {
 }
 
 #[derive(Clone, Debug, TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
-pub struct FunctionCoverageInfo {}
+pub struct FunctionCoverageInfo {
+    pub mappings: Vec<(CovTerm, CodeRegion)>,
+}

compiler/rustc_mir_transform/src/coverage/mod.rs

@@ -107,6 +107,7 @@ struct Instrumentor<'a, 'tcx> {
     function_source_hash: u64,
     basic_coverage_blocks: CoverageGraph,
     coverage_counters: CoverageCounters,
+    mappings: Vec<(CovTerm, CodeRegion)>,
 }
 
 impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
@@ -148,6 +149,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
             function_source_hash,
             basic_coverage_blocks,
             coverage_counters,
+            mappings: Vec::new(),
         }
     }
 
@@ -276,6 +278,9 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
                 self.make_mir_coverage_kind(intermediate_expression),
             );
         }
+
+        self.mir_body.coverage_info =
+            Some(Box::new(FunctionCoverageInfo { mappings: std::mem::take(&mut self.mappings) }));
     }
 
     /// Injects a single [`StatementKind::Coverage`] for each BCB that has one
@@ -305,20 +310,14 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
             debug_used_expressions.add_expression_operands(&counter_kind);
             graphviz_data.add_bcb_coverage_spans_with_counter(bcb, bcb_spans, &counter_kind);
 
-            // Convert the coverage spans into a vector of code regions to be
-            // associated with this BCB's coverage statement.
-            let code_regions = bcb_spans
-                .iter()
-                .map(|coverage_span| {
-                    make_code_region(source_map, file_name, coverage_span.span, body_span)
-                })
-                .collect::<Vec<_>>();
+            let mapping_kind = counter_kind.as_term();
+            self.mappings.extend(bcb_spans.iter().map(|coverage_span| {
+                (
+                    mapping_kind,
+                    make_code_region(source_map, file_name, coverage_span.span, body_span),
+                )
+            }));
 
-            inject_statement(
-                self.mir_body,
-                CoverageKind::Mappings { kind: counter_kind.as_term(), code_regions },
-                mir::START_BLOCK,
-            );
             inject_statement(
                 self.mir_body,
                 self.make_mir_coverage_kind(&counter_kind),

compiler/rustc_mir_transform/src/coverage/query.rs

@@ -58,6 +58,12 @@ impl CoverageVisitor {
         for coverage in all_coverage_in_mir_body(body) {
             self.visit_coverage(coverage);
         }
+
+        for (mapping_kind, _code_region) in
+            body.coverage_info.iter().flat_map(|coverage_info| &coverage_info.mappings)
+        {
+            self.update_from_term(*mapping_kind);
+        }
     }
 
     fn visit_coverage(&mut self, coverage: &Coverage) {
@@ -68,7 +74,6 @@ impl CoverageVisitor {
                 self.update_from_term(lhs);
                 self.update_from_term(rhs);
             }
-            CoverageKind::Mappings { kind, .. } => self.update_from_term(kind),
         }
     }
 }
@@ -92,12 +97,10 @@ fn coverageinfo<'tcx>(tcx: TyCtxt<'tcx>, instance_def: ty::InstanceDef<'tcx>) ->
 
 fn covered_code_regions(tcx: TyCtxt<'_>, def_id: DefId) -> Vec<&CodeRegion> {
     let body = mir_body(tcx, def_id);
-    all_coverage_in_mir_body(body)
-        // Only `Mappings` statements have a list of code regions.
-        .flat_map(|coverage| match coverage.kind {
-            CoverageKind::Mappings { ref code_regions, .. } => code_regions.as_slice(),
-            _ => &[],
-        })
+    body.coverage_info
+        .iter()
+        .flat_map(|coverage_info| &coverage_info.mappings)
+        .map(|(_mapping_kind, code_region)| code_region)
         .collect()
 }
 

tests/mir-opt/instrument_coverage.bar.InstrumentCoverage.diff

@@ -6,7 +6,6 @@
 
       bb0: {
 +         Coverage::Counter(0);
-+         Coverage::Mappings { kind: Counter(0), code_regions: [/the/src/instrument_coverage.rs:20:1 - 22:2] };
           _0 = const true;
           return;
       }

tests/mir-opt/instrument_coverage.main.InstrumentCoverage.diff

@@ -8,11 +8,7 @@
       let mut _3: !;
 
       bb0: {
-+         Coverage::Mappings { kind: Counter(1), code_regions: [/the/src/instrument_coverage.rs:15:10 - 15:11] };
-+         Coverage::Mappings { kind: Expression(1), code_regions: [/the/src/instrument_coverage.rs:14:13 - 14:18, /the/src/instrument_coverage.rs:17:1 - 17:2] };
-+         Coverage::Mappings { kind: Expression(0), code_regions: [/the/src/instrument_coverage.rs:12:5 - 13:17] };
 +         Coverage::Counter(0);
-+         Coverage::Mappings { kind: Counter(0), code_regions: [/the/src/instrument_coverage.rs:11:1 - 11:11] };
           goto -> bb1;
       }