Rollup merge of #138659 - Zalathar:no-body-span, r=oli-obk

coverage: Don't store a body span in `FunctionCoverageInfo`

We aren't using this body span for anything truly essential, and having it around will be awkward when we eventually start to support expansion regions, since they aren't necessarily within the main body.

11 files changed, 23 insertions, 45 deletions

diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
index 80e54bf045e..5b487bc1a8b 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
+++ b/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);
@@ -118,9 +123,8 @@ fn fill_region_tables<'tcx>(
     let ffi::Regions { code_regions, branch_regions, mcdc_branch_regions, mcdc_decision_regions } =
         &mut covfun.regions;
 
-    let make_cov_span = |span: Span| {
-        spans::make_coverage_span(local_file_id, source_map, fn_cov_info, &source_file, span)
-    };
+    let make_cov_span =
+        |span: Span| spans::make_coverage_span(local_file_id, source_map, &source_file, span);
     let discard_all = tcx.sess.coverage_discard_all_spans_in_codegen();
 
     // For each counter/region pair in this function+file, convert it to a
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs
index 6d1d91340c2..3193be31ada 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs
@@ -1,4 +1,3 @@
-use rustc_middle::mir::coverage::FunctionCoverageInfo;
 use rustc_span::source_map::SourceMap;
 use rustc_span::{BytePos, Pos, SourceFile, Span};
 use tracing::debug;
@@ -19,11 +18,10 @@ use crate::coverageinfo::mapgen::LocalFileId;
 pub(crate) fn make_coverage_span(
     file_id: LocalFileId,
     source_map: &SourceMap,
-    fn_cov_info: &FunctionCoverageInfo,
     file: &SourceFile,
     span: Span,
 ) -> Option<ffi::CoverageSpan> {
-    let span = ensure_non_empty_span(source_map, fn_cov_info, span)?;
+    let span = ensure_non_empty_span(source_map, span)?;
 
     let lo = span.lo();
     let hi = span.hi();
@@ -55,36 +53,22 @@ pub(crate) fn make_coverage_span(
     })
 }
 
-fn ensure_non_empty_span(
-    source_map: &SourceMap,
-    fn_cov_info: &FunctionCoverageInfo,
-    span: Span,
-) -> Option<Span> {
+fn ensure_non_empty_span(source_map: &SourceMap, span: Span) -> Option<Span> {
     if !span.is_empty() {
         return Some(span);
     }
 
-    let lo = span.lo();
-    let hi = span.hi();
-
-    // The span is empty, so try to expand it to cover an adjacent '{' or '}',
-    // but only within the bounds of the body span.
-    let try_next = hi < fn_cov_info.body_span.hi();
-    let try_prev = fn_cov_info.body_span.lo() < lo;
-    if !(try_next || try_prev) {
-        return None;
-    }
-
+    // The span is empty, so try to enlarge it to cover an adjacent '{' or '}'.
     source_map
         .span_to_source(span, |src, start, end| try {
             // Adjusting span endpoints by `BytePos(1)` is normally a bug,
             // but in this case we have specifically checked that the character
             // we're skipping over is one of two specific ASCII characters, so
             // adjusting by exactly 1 byte is correct.
-            if try_next && src.as_bytes()[end] == b'{' {
-                Some(span.with_hi(hi + BytePos(1)))
-            } else if try_prev && src.as_bytes()[start - 1] == b'}' {
-                Some(span.with_lo(lo - BytePos(1)))
+            if src.as_bytes().get(end).copied() == Some(b'{') {
+                Some(span.with_hi(span.hi() + BytePos(1)))
+            } else if start > 0 && src.as_bytes()[start - 1] == b'}' {
+                Some(span.with_lo(span.lo() - BytePos(1)))
             } else {
                 None
             }
diff --git a/compiler/rustc_middle/src/mir/coverage.rs b/compiler/rustc_middle/src/mir/coverage.rs
index 8c6b11a681e..e26575b552e 100644
--- a/compiler/rustc_middle/src/mir/coverage.rs
+++ b/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.
diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index 573f7895da2..5a038b27337 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/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:?};")?;
     }
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 1ccae0fd7fe..572dbae8fd2 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/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,
diff --git a/tests/mir-opt/coverage/branch_match_arms.main.InstrumentCoverage.diff b/tests/mir-opt/coverage/branch_match_arms.main.InstrumentCoverage.diff
index e9f48a85f9c..8e1cdb7182b 100644
--- a/tests/mir-opt/coverage/branch_match_arms.main.InstrumentCoverage.diff
+++ b/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);
diff --git a/tests/mir-opt/coverage/instrument_coverage.bar.InstrumentCoverage.diff b/tests/mir-opt/coverage/instrument_coverage.bar.InstrumentCoverage.diff
index cbef6de917d..06e5f011c76 100644
--- a/tests/mir-opt/coverage/instrument_coverage.bar.InstrumentCoverage.diff
+++ b/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);
diff --git a/tests/mir-opt/coverage/instrument_coverage.main.InstrumentCoverage.diff b/tests/mir-opt/coverage/instrument_coverage.main.InstrumentCoverage.diff
index b166d79a412..1a71cb8dea7 100644
--- a/tests/mir-opt/coverage/instrument_coverage.main.InstrumentCoverage.diff
+++ b/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);
diff --git a/tests/mir-opt/coverage/instrument_coverage.rs b/tests/mir-opt/coverage/instrument_coverage.rs
index 48647402d0f..d4ed4b67375 100644
--- a/tests/mir-opt/coverage/instrument_coverage.rs
+++ b/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
diff --git a/tests/mir-opt/coverage/instrument_coverage_cleanup.main.CleanupPostBorrowck.diff b/tests/mir-opt/coverage/instrument_coverage_cleanup.main.CleanupPostBorrowck.diff
index 855f806aae1..1a22adeba6f 100644
--- a/tests/mir-opt/coverage/instrument_coverage_cleanup.main.CleanupPostBorrowck.diff
+++ b/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);
diff --git a/tests/mir-opt/coverage/instrument_coverage_cleanup.main.InstrumentCoverage.diff b/tests/mir-opt/coverage/instrument_coverage_cleanup.main.InstrumentCoverage.diff
index df1f1e8bc50..b77969a3e16 100644
--- a/tests/mir-opt/coverage/instrument_coverage_cleanup.main.InstrumentCoverage.diff
+++ b/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);