coverage: Eagerly do start-of-function codegen for coverage

1 files changed, 4 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index 0064c16f5d9..cf6e2e8d14c 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -259,6 +259,10 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     // Apply debuginfo to the newly allocated locals.
     fx.debug_introduce_locals(&mut start_bx);
 
+    // If the backend supports coverage, and coverage is enabled for this function,
+    // do any necessary start-of-function codegen (e.g. locals for MC/DC bitmaps).
+    start_bx.init_coverage(instance);
+
     // The builders will be created separately for each basic block at `codegen_block`.
     // So drop the builder of `start_llbb` to avoid having two at the same time.
     drop(start_bx);