coverage: Don't store a body span in FunctionCoverageInfo

Author: Zalathar

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

@@ -105,9 +105,14 @@ fn fill_region_tables<'tcx>(
     ids_info: &'tcx CoverageIdsInfo,
     covfun: &mut CovfunRecord<'tcx>,
 ) {
-    // Currently a function's mappings must all be in the same file as its body span.
+    // 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();
-    let source_file = source_map.lookup_source_file(fn_cov_info.body_span.lo());
+    let Some(first_span) = (try { fn_cov_info.mappings.first()?.span }) else {
+        debug_assert!(false, "function has no mappings: {:?}", covfun.mangled_function_name);
+        return;
+    };
+    let source_file = source_map.lookup_source_file(first_span.lo());
 
     // Look up the global file ID for that file.
     let global_file_id = global_file_table.global_file_id_for_file(&source_file);

compiler/rustc_middle/src/mir/coverage.rs

@@ -194,7 +194,6 @@ pub struct Mapping {
 #[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct FunctionCoverageInfo {
     pub function_source_hash: u64,
-    pub body_span: Span,
 
     /// Used in conjunction with `priority_list` to create physical counters
     /// and counter expressions, after MIR optimizations.

compiler/rustc_middle/src/mir/pretty.rs

@@ -620,9 +620,8 @@ fn write_function_coverage_info(
     function_coverage_info: &coverage::FunctionCoverageInfo,
     w: &mut dyn io::Write,
 ) -> io::Result<()> {
-    let coverage::FunctionCoverageInfo { body_span, mappings, .. } = function_coverage_info;
+    let coverage::FunctionCoverageInfo { mappings, .. } = function_coverage_info;
 
-    writeln!(w, "{INDENT}coverage body span: {body_span:?}")?;
     for coverage::Mapping { kind, span } in mappings {
         writeln!(w, "{INDENT}coverage {kind:?} => {span:?};")?;
     }

compiler/rustc_mir_transform/src/coverage/mod.rs

@@ -107,7 +107,6 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
 
     mir_body.function_coverage_info = Some(Box::new(FunctionCoverageInfo {
         function_source_hash: hir_info.function_source_hash,
-        body_span: hir_info.body_span,
 
         node_flow_data,
         priority_list,

tests/mir-opt/coverage/branch_match_arms.main.InstrumentCoverage.diff

@@ -26,7 +26,6 @@
           debug a => _9;
       }
 
-+     coverage body span: $DIR/branch_match_arms.rs:14:11: 21:2 (#0)
 +     coverage Code { bcb: bcb0 } => $DIR/branch_match_arms.rs:14:1: 15:21 (#0);
 +     coverage Code { bcb: bcb1 } => $DIR/branch_match_arms.rs:16:17: 16:33 (#0);
 +     coverage Code { bcb: bcb3 } => $DIR/branch_match_arms.rs:17:17: 17:33 (#0);

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

@@ -4,8 +4,7 @@
   fn bar() -> bool {
       let mut _0: bool;
 
-+     coverage body span: $DIR/instrument_coverage.rs:29:18: 31:2 (#0)
-+     coverage Code { bcb: bcb0 } => $DIR/instrument_coverage.rs:29:1: 31:2 (#0);
++     coverage Code { bcb: bcb0 } => $DIR/instrument_coverage.rs:27:1: 29:2 (#0);
 + 
       bb0: {
 +         Coverage::VirtualCounter(bcb0);

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

@@ -7,12 +7,11 @@
       let mut _2: bool;
       let mut _3: !;
 
-+     coverage body span: $DIR/instrument_coverage.rs:14:11: 20:2 (#0)
-+     coverage Code { bcb: bcb0 } => $DIR/instrument_coverage.rs:14:1: 14:11 (#0);
-+     coverage Code { bcb: bcb1 } => $DIR/instrument_coverage.rs:16:12: 16:17 (#0);
-+     coverage Code { bcb: bcb2 } => $DIR/instrument_coverage.rs:17:13: 17:18 (#0);
-+     coverage Code { bcb: bcb3 } => $DIR/instrument_coverage.rs:18:10: 18:10 (#0);
-+     coverage Code { bcb: bcb2 } => $DIR/instrument_coverage.rs:20:2: 20:2 (#0);
++     coverage Code { bcb: bcb0 } => $DIR/instrument_coverage.rs:13:1: 13:11 (#0);
++     coverage Code { bcb: bcb1 } => $DIR/instrument_coverage.rs:15:12: 15:17 (#0);
++     coverage Code { bcb: bcb2 } => $DIR/instrument_coverage.rs:16:13: 16:18 (#0);
++     coverage Code { bcb: bcb3 } => $DIR/instrument_coverage.rs:17:10: 17:10 (#0);
++     coverage Code { bcb: bcb2 } => $DIR/instrument_coverage.rs:19:2: 19:2 (#0);
 + 
       bb0: {
 +         Coverage::VirtualCounter(bcb0);

tests/mir-opt/coverage/instrument_coverage.rs

@@ -7,7 +7,6 @@
 
 // EMIT_MIR instrument_coverage.main.InstrumentCoverage.diff
 // CHECK-LABEL: fn main()
-// CHECK: coverage body span:
 // CHECK: coverage Code { bcb: bcb{{[0-9]+}} } =>
 // CHECK: bb0:
 // CHECK: Coverage::VirtualCounter
@@ -21,7 +20,6 @@ fn main() {
 
 // EMIT_MIR instrument_coverage.bar.InstrumentCoverage.diff
 // CHECK-LABEL: fn bar()
-// CHECK: coverage body span:
 // CHECK: coverage Code { bcb: bcb{{[0-9]+}} } =>
 // CHECK: bb0:
 // CHECK: Coverage::VirtualCounter

tests/mir-opt/coverage/instrument_coverage_cleanup.main.CleanupPostBorrowck.diff

@@ -7,7 +7,6 @@
 
       coverage branch { true: BlockMarkerId(0), false: BlockMarkerId(1) } => $DIR/instrument_coverage_cleanup.rs:14:8: 14:36 (#0)
 
-      coverage body span: $DIR/instrument_coverage_cleanup.rs:13:11: 15:2 (#0)
       coverage Code { bcb: bcb0 } => $DIR/instrument_coverage_cleanup.rs:13:1: 14:36 (#0);
       coverage Code { bcb: bcb3 } => $DIR/instrument_coverage_cleanup.rs:14:37: 14:39 (#0);
       coverage Code { bcb: bcb1 } => $DIR/instrument_coverage_cleanup.rs:14:39: 14:39 (#0);

tests/mir-opt/coverage/instrument_coverage_cleanup.main.InstrumentCoverage.diff

@@ -7,7 +7,6 @@
 
       coverage branch { true: BlockMarkerId(0), false: BlockMarkerId(1) } => $DIR/instrument_coverage_cleanup.rs:14:8: 14:36 (#0)
 
-+     coverage body span: $DIR/instrument_coverage_cleanup.rs:13:11: 15:2 (#0)
 +     coverage Code { bcb: bcb0 } => $DIR/instrument_coverage_cleanup.rs:13:1: 14:36 (#0);
 +     coverage Code { bcb: bcb3 } => $DIR/instrument_coverage_cleanup.rs:14:37: 14:39 (#0);
 +     coverage Code { bcb: bcb1 } => $DIR/instrument_coverage_cleanup.rs:14:39: 14:39 (#0);