Rollup merge of #122542 - Zalathar:cleanup, r=oli-obk

coverage: Clean up marker statements that aren't needed later

Some of the marker statements used by coverage are added during MIR building for use by the InstrumentCoverage pass (during analysis), and are not needed afterwards.

```@rustbot``` label +A-code-coverage

1 files changed, 1 insertions, 9 deletions

diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
index 133084b7c12..54f4bc06340 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
@@ -85,14 +85,6 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
 
         let bx = self;
 
-        match coverage.kind {
-            // Marker statements have no effect during codegen,
-            // so return early and don't create `func_coverage`.
-            CoverageKind::SpanMarker | CoverageKind::BlockMarker { .. } => return,
-            // Match exhaustively to ensure that newly-added kinds are classified correctly.
-            CoverageKind::CounterIncrement { .. } | CoverageKind::ExpressionUsed { .. } => {}
-        }
-
         let Some(function_coverage_info) =
             bx.tcx.instance_mir(instance.def).function_coverage_info.as_deref()
         else {
@@ -109,7 +101,7 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
         let Coverage { kind } = coverage;
         match *kind {
             CoverageKind::SpanMarker | CoverageKind::BlockMarker { .. } => unreachable!(
-                "unexpected marker statement {kind:?} should have caused an early return"
+                "marker statement {kind:?} should have been removed by CleanupPostBorrowck"
             ),
             CoverageKind::CounterIncrement { id } => {
                 func_coverage.mark_counter_id_seen(id);