coverage: Rename basic_coverage_blocks to just graph

Zalathar · Zalathar · commit 544809e48a3d · 2024-12-20T17:48:59.000+11:00
During coverage instrumentation, this variable always holds the coverage graph,
which is a simplified view of the MIR control-flow graph. The new name is
clearer in context, and also shorter.
diff --git a/compiler/rustc_mir_transform/src/coverage/mappings.rs b/compiler/rustc_mir_transform/src/coverage/mappings.rs
@@ -80,7 +80,7 @@ pub(super) fn extract_all_mapping_info_from_mir<'tcx>(
     tcx: TyCtxt<'tcx>,
     mir_body: &mir::Body<'tcx>,
     hir_info: &ExtractedHirInfo,
-    basic_coverage_blocks: &CoverageGraph,
+    graph: &CoverageGraph,
 ) -> ExtractedMappings {
     let mut code_mappings = vec![];
     let mut branch_pairs = vec![];
@@ -102,23 +102,23 @@ pub(super) fn extract_all_mapping_info_from_mir<'tcx>(
         }
     } else {
         // Extract coverage spans from MIR statements/terminators as normal.
-        extract_refined_covspans(mir_body, hir_info, basic_coverage_blocks, &mut code_mappings);
+        extract_refined_covspans(mir_body, hir_info, graph, &mut code_mappings);
     }
 
-    branch_pairs.extend(extract_branch_pairs(mir_body, hir_info, basic_coverage_blocks));
+    branch_pairs.extend(extract_branch_pairs(mir_body, hir_info, graph));
 
     extract_mcdc_mappings(
         mir_body,
         tcx,
         hir_info.body_span,
-        basic_coverage_blocks,
+        graph,
         &mut mcdc_bitmap_bits,
         &mut mcdc_degraded_branches,
         &mut mcdc_mappings,
     );
 
     ExtractedMappings {
-        num_bcbs: basic_coverage_blocks.num_nodes(),
+        num_bcbs: graph.num_nodes(),
         code_mappings,
         branch_pairs,
         mcdc_bitmap_bits,
@@ -211,7 +211,7 @@ fn resolve_block_markers(
 pub(super) fn extract_branch_pairs(
     mir_body: &mir::Body<'_>,
     hir_info: &ExtractedHirInfo,
-    basic_coverage_blocks: &CoverageGraph,
+    graph: &CoverageGraph,
 ) -> Vec<BranchPair> {
     let Some(coverage_info_hi) = mir_body.coverage_info_hi.as_deref() else { return vec![] };
 
@@ -228,8 +228,7 @@ pub(super) fn extract_branch_pairs(
             }
             let span = unexpand_into_body_span(raw_span, hir_info.body_span)?;
 
-            let bcb_from_marker =
-                |marker: BlockMarkerId| basic_coverage_blocks.bcb_from_bb(block_markers[marker]?);
+            let bcb_from_marker = |marker: BlockMarkerId| graph.bcb_from_bb(block_markers[marker]?);
 
             let true_bcb = bcb_from_marker(true_marker)?;
             let false_bcb = bcb_from_marker(false_marker)?;
@@ -243,7 +242,7 @@ pub(super) fn extract_mcdc_mappings(
     mir_body: &mir::Body<'_>,
     tcx: TyCtxt<'_>,
     body_span: Span,
-    basic_coverage_blocks: &CoverageGraph,
+    graph: &CoverageGraph,
     mcdc_bitmap_bits: &mut usize,
     mcdc_degraded_branches: &mut impl Extend<MCDCBranch>,
     mcdc_mappings: &mut impl Extend<(MCDCDecision, Vec<MCDCBranch>)>,
@@ -252,8 +251,7 @@ pub(super) fn extract_mcdc_mappings(
 
     let block_markers = resolve_block_markers(coverage_info_hi, mir_body);
 
-    let bcb_from_marker =
-        |marker: BlockMarkerId| basic_coverage_blocks.bcb_from_bb(block_markers[marker]?);
+    let bcb_from_marker = |marker: BlockMarkerId| graph.bcb_from_bb(block_markers[marker]?);
 
     let check_branch_bcb =
         |raw_span: Span, true_marker: BlockMarkerId, false_marker: BlockMarkerId| {
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -71,16 +71,15 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
     let _span = debug_span!("instrument_function_for_coverage", ?def_id).entered();
 
     let hir_info = extract_hir_info(tcx, def_id.expect_local());
-    let basic_coverage_blocks = CoverageGraph::from_mir(mir_body);
+
+    // Build the coverage graph, which is a simplified view of the MIR control-flow
+    // graph that ignores some details not relevant to coverage instrumentation.
+    let graph = CoverageGraph::from_mir(mir_body);
 
     ////////////////////////////////////////////////////
     // Extract coverage spans and other mapping info from MIR.
-    let extracted_mappings = mappings::extract_all_mapping_info_from_mir(
-        tcx,
-        mir_body,
-        &hir_info,
-        &basic_coverage_blocks,
-    );
+    let extracted_mappings =
+        mappings::extract_all_mapping_info_from_mir(tcx, mir_body, &hir_info, &graph);
 
     ////////////////////////////////////////////////////
     // Create an optimized mix of `Counter`s and `Expression`s for the `CoverageGraph`. Ensure
@@ -94,7 +93,7 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
     }
 
     let coverage_counters =
-        CoverageCounters::make_bcb_counters(&basic_coverage_blocks, &bcbs_with_counter_mappings);
+        CoverageCounters::make_bcb_counters(&graph, &bcbs_with_counter_mappings);
 
     let mappings = create_mappings(&extracted_mappings, &coverage_counters);
     if mappings.is_empty() {
@@ -103,14 +102,9 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
         return;
     }
 
-    inject_coverage_statements(
-        mir_body,
-        &basic_coverage_blocks,
-        &extracted_mappings,
-        &coverage_counters,
-    );
+    inject_coverage_statements(mir_body, &graph, &extracted_mappings, &coverage_counters);
 
-    inject_mcdc_statements(mir_body, &basic_coverage_blocks, &extracted_mappings);
+    inject_mcdc_statements(mir_body, &graph, &extracted_mappings);
 
     let mcdc_num_condition_bitmaps = extracted_mappings
         .mcdc_mappings
@@ -243,7 +237,7 @@ fn create_mappings(
 /// inject any necessary coverage statements into MIR.
 fn inject_coverage_statements<'tcx>(
     mir_body: &mut mir::Body<'tcx>,
-    basic_coverage_blocks: &CoverageGraph,
+    graph: &CoverageGraph,
     extracted_mappings: &ExtractedMappings,
     coverage_counters: &CoverageCounters,
 ) {
@@ -253,12 +247,12 @@ fn inject_coverage_statements<'tcx>(
         // For BCB nodes this is just their first block, but for edges we need
         // to create a new block between the two BCBs, and inject into that.
         let target_bb = match site {
-            Site::Node { bcb } => basic_coverage_blocks[bcb].leader_bb(),
+            Site::Node { bcb } => graph[bcb].leader_bb(),
             Site::Edge { from_bcb, to_bcb } => {
                 // Create a new block between the last block of `from_bcb` and
                 // the first block of `to_bcb`.
-                let from_bb = basic_coverage_blocks[from_bcb].last_bb();
-                let to_bb = basic_coverage_blocks[to_bcb].leader_bb();
+                let from_bb = graph[from_bcb].last_bb();
+                let to_bb = graph[to_bcb].leader_bb();
 
                 let new_bb = inject_edge_counter_basic_block(mir_body, from_bb, to_bb);
                 debug!(
@@ -291,7 +285,7 @@ fn inject_coverage_statements<'tcx>(
         inject_statement(
             mir_body,
             CoverageKind::ExpressionUsed { id: expression_id },
-            basic_coverage_blocks[bcb].leader_bb(),
+            graph[bcb].leader_bb(),
         );
     }
 }
@@ -300,13 +294,13 @@ fn inject_coverage_statements<'tcx>(
 /// For each decision inject statements to update test vector bitmap after it has been evaluated.
 fn inject_mcdc_statements<'tcx>(
     mir_body: &mut mir::Body<'tcx>,
-    basic_coverage_blocks: &CoverageGraph,
+    graph: &CoverageGraph,
     extracted_mappings: &ExtractedMappings,
 ) {
     for (decision, conditions) in &extracted_mappings.mcdc_mappings {
         // Inject test vector update first because `inject_statement` always insert new statement at head.
         for &end in &decision.end_bcbs {
-            let end_bb = basic_coverage_blocks[end].leader_bb();
+            let end_bb = graph[end].leader_bb();
             inject_statement(
                 mir_body,
                 CoverageKind::TestVectorBitmapUpdate {
@@ -327,7 +321,7 @@ fn inject_mcdc_statements<'tcx>(
         } in conditions
         {
             for (index, bcb) in [(false_index, false_bcb), (true_index, true_bcb)] {
-                let bb = basic_coverage_blocks[bcb].leader_bb();
+                let bb = graph[bcb].leader_bb();
                 inject_statement(
                     mir_body,
                     CoverageKind::CondBitmapUpdate {
diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs
@@ -17,14 +17,13 @@ mod from_mir;
 pub(super) fn extract_refined_covspans(
     mir_body: &mir::Body<'_>,
     hir_info: &ExtractedHirInfo,
-    basic_coverage_blocks: &CoverageGraph,
+    graph: &CoverageGraph,
     code_mappings: &mut impl Extend<mappings::CodeMapping>,
 ) {
-    let ExtractedCovspans { mut covspans } =
-        extract_covspans_from_mir(mir_body, hir_info, basic_coverage_blocks);
+    let ExtractedCovspans { mut covspans } = extract_covspans_from_mir(mir_body, hir_info, graph);
 
     // First, perform the passes that need macro information.
-    covspans.sort_by(|a, b| basic_coverage_blocks.cmp_in_dominator_order(a.bcb, b.bcb));
+    covspans.sort_by(|a, b| graph.cmp_in_dominator_order(a.bcb, b.bcb));
     remove_unwanted_expansion_spans(&mut covspans);
     split_visible_macro_spans(&mut covspans);
 
@@ -34,7 +33,7 @@ pub(super) fn extract_refined_covspans(
     let compare_covspans = |a: &Covspan, b: &Covspan| {
         compare_spans(a.span, b.span)
             // After deduplication, we want to keep only the most-dominated BCB.
-            .then_with(|| basic_coverage_blocks.cmp_in_dominator_order(a.bcb, b.bcb).reverse())
+            .then_with(|| graph.cmp_in_dominator_order(a.bcb, b.bcb).reverse())
     };
     covspans.sort_by(compare_covspans);
 
diff --git a/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs b/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
@@ -22,13 +22,13 @@ pub(crate) struct ExtractedCovspans {
 pub(crate) fn extract_covspans_from_mir(
     mir_body: &mir::Body<'_>,
     hir_info: &ExtractedHirInfo,
-    basic_coverage_blocks: &CoverageGraph,
+    graph: &CoverageGraph,
 ) -> ExtractedCovspans {
     let &ExtractedHirInfo { body_span, .. } = hir_info;
 
     let mut covspans = vec![];
 
-    for (bcb, bcb_data) in basic_coverage_blocks.iter_enumerated() {
+    for (bcb, bcb_data) in graph.iter_enumerated() {
         bcb_to_initial_coverage_spans(mir_body, body_span, bcb, bcb_data, &mut covspans);
     }
 
diff --git a/compiler/rustc_mir_transform/src/coverage/tests.rs b/compiler/rustc_mir_transform/src/coverage/tests.rs
@@ -223,24 +223,20 @@ fn print_mir_graphviz(name: &str, mir_body: &Body<'_>) {
     }
 }
 
-fn print_coverage_graphviz(
-    name: &str,
-    mir_body: &Body<'_>,
-    basic_coverage_blocks: &graph::CoverageGraph,
-) {
+fn print_coverage_graphviz(name: &str, mir_body: &Body<'_>, graph: &graph::CoverageGraph) {
     if PRINT_GRAPHS {
         println!(
             "digraph {} {{\n{}\n}}",
             name,
-            basic_coverage_blocks
+            graph
                 .iter_enumerated()
                 .map(|(bcb, bcb_data)| {
                     format!(
                         "    {:?} [label=\"{:?}: {}\"];\n{}",
                         bcb,
                         bcb,
                         mir_body[bcb_data.last_bb()].terminator().kind.name(),
-                        basic_coverage_blocks
+                        graph
                             .successors(bcb)
                             .map(|successor| { format!("    {:?} -> {:?};", bcb, successor) })
                             .join("\n")
@@ -300,11 +296,11 @@ fn goto_switchint<'a>() -> Body<'a> {
 
 #[track_caller]
 fn assert_successors(
-    basic_coverage_blocks: &graph::CoverageGraph,
+    graph: &graph::CoverageGraph,
     bcb: BasicCoverageBlock,
     expected_successors: &[BasicCoverageBlock],
 ) {
-    let mut successors = basic_coverage_blocks.successors[bcb].clone();
+    let mut successors = graph.successors[bcb].clone();
     successors.sort_unstable();
     assert_eq!(successors, expected_successors);
 }
@@ -315,8 +311,8 @@ fn test_covgraph_goto_switchint() {
     if false {
         eprintln!("basic_blocks = {}", debug_basic_blocks(&mir_body));
     }
-    let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
-    print_coverage_graphviz("covgraph_goto_switchint ", &mir_body, &basic_coverage_blocks);
+    let graph = graph::CoverageGraph::from_mir(&mir_body);
+    print_coverage_graphviz("covgraph_goto_switchint ", &mir_body, &graph);
     /*
     ┌──────────────┐     ┌─────────────────┐
     │ bcb2: Return │ ◀── │ bcb0: SwitchInt │
@@ -328,16 +324,11 @@ fn test_covgraph_goto_switchint() {
                          │  bcb1: Return   │
                          └─────────────────┘
     */
-    assert_eq!(
-        basic_coverage_blocks.num_nodes(),
-        3,
-        "basic_coverage_blocks: {:?}",
-        basic_coverage_blocks.iter_enumerated().collect::<Vec<_>>()
-    );
+    assert_eq!(graph.num_nodes(), 3, "graph: {:?}", graph.iter_enumerated().collect::<Vec<_>>());
 
-    assert_successors(&basic_coverage_blocks, bcb(0), &[bcb(1), bcb(2)]);
-    assert_successors(&basic_coverage_blocks, bcb(1), &[]);
-    assert_successors(&basic_coverage_blocks, bcb(2), &[]);
+    assert_successors(&graph, bcb(0), &[bcb(1), bcb(2)]);
+    assert_successors(&graph, bcb(1), &[]);
+    assert_successors(&graph, bcb(2), &[]);
 }
 
 /// Create a mock `Body` with a loop.
@@ -383,12 +374,8 @@ fn switchint_then_loop_else_return<'a>() -> Body<'a> {
 #[test]
 fn test_covgraph_switchint_then_loop_else_return() {
     let mir_body = switchint_then_loop_else_return();
-    let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
-    print_coverage_graphviz(
-        "covgraph_switchint_then_loop_else_return",
-        &mir_body,
-        &basic_coverage_blocks,
-    );
+    let graph = graph::CoverageGraph::from_mir(&mir_body);
+    print_coverage_graphviz("covgraph_switchint_then_loop_else_return", &mir_body, &graph);
     /*
                        ┌─────────────────┐
                        │   bcb0: Call    │
@@ -408,17 +395,12 @@ fn test_covgraph_switchint_then_loop_else_return() {
       │                                     │
       └─────────────────────────────────────┘
     */
-    assert_eq!(
-        basic_coverage_blocks.num_nodes(),
-        4,
-        "basic_coverage_blocks: {:?}",
-        basic_coverage_blocks.iter_enumerated().collect::<Vec<_>>()
-    );
+    assert_eq!(graph.num_nodes(), 4, "graph: {:?}", graph.iter_enumerated().collect::<Vec<_>>());
 
-    assert_successors(&basic_coverage_blocks, bcb(0), &[bcb(1)]);
-    assert_successors(&basic_coverage_blocks, bcb(1), &[bcb(2), bcb(3)]);
-    assert_successors(&basic_coverage_blocks, bcb(2), &[]);
-    assert_successors(&basic_coverage_blocks, bcb(3), &[bcb(1)]);
+    assert_successors(&graph, bcb(0), &[bcb(1)]);
+    assert_successors(&graph, bcb(1), &[bcb(2), bcb(3)]);
+    assert_successors(&graph, bcb(2), &[]);
+    assert_successors(&graph, bcb(3), &[bcb(1)]);
 }
 
 /// Create a mock `Body` with nested loops.
@@ -494,11 +476,11 @@ fn switchint_loop_then_inner_loop_else_break<'a>() -> Body<'a> {
 #[test]
 fn test_covgraph_switchint_loop_then_inner_loop_else_break() {
     let mir_body = switchint_loop_then_inner_loop_else_break();
-    let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
+    let graph = graph::CoverageGraph::from_mir(&mir_body);
     print_coverage_graphviz(
         "covgraph_switchint_loop_then_inner_loop_else_break",
         &mir_body,
-        &basic_coverage_blocks,
+        &graph,
     );
     /*
                          ┌─────────────────┐
@@ -531,18 +513,13 @@ fn test_covgraph_switchint_loop_then_inner_loop_else_break() {
       │                                            │
       └────────────────────────────────────────────┘
     */
-    assert_eq!(
-        basic_coverage_blocks.num_nodes(),
-        7,
-        "basic_coverage_blocks: {:?}",
-        basic_coverage_blocks.iter_enumerated().collect::<Vec<_>>()
-    );
-
-    assert_successors(&basic_coverage_blocks, bcb(0), &[bcb(1)]);
-    assert_successors(&basic_coverage_blocks, bcb(1), &[bcb(2), bcb(3)]);
-    assert_successors(&basic_coverage_blocks, bcb(2), &[]);
-    assert_successors(&basic_coverage_blocks, bcb(3), &[bcb(4)]);
-    assert_successors(&basic_coverage_blocks, bcb(4), &[bcb(5), bcb(6)]);
-    assert_successors(&basic_coverage_blocks, bcb(5), &[bcb(1)]);
-    assert_successors(&basic_coverage_blocks, bcb(6), &[bcb(4)]);
+    assert_eq!(graph.num_nodes(), 7, "graph: {:?}", graph.iter_enumerated().collect::<Vec<_>>());
+
+    assert_successors(&graph, bcb(0), &[bcb(1)]);
+    assert_successors(&graph, bcb(1), &[bcb(2), bcb(3)]);
+    assert_successors(&graph, bcb(2), &[]);
+    assert_successors(&graph, bcb(3), &[bcb(4)]);
+    assert_successors(&graph, bcb(4), &[bcb(5), bcb(6)]);
+    assert_successors(&graph, bcb(5), &[bcb(1)]);
+    assert_successors(&graph, bcb(6), &[bcb(4)]);
 }
