Make codegen coverage_context optional, and check

Addresses Issue #78286

Libraries compiled with coverage and linked with out enabling coverage
would fail when attempting to add the library's coverage statements to
the codegen coverage context (None).

Now, if coverage statements are encountered while compiling / linking
with `-Z instrument-coverage` disabled, codegen will *not* attempt to
add code regions to a coverage map, and it will not inject the LLVM
instrprof_increment intrinsic calls.

1 files changed, 12 insertions, 12 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/coverageinfo.rs b/compiler/rustc_codegen_ssa/src/mir/coverageinfo.rs
index a2ad27b925c..4811adea9ec 100644
--- a/compiler/rustc_codegen_ssa/src/mir/coverageinfo.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/coverageinfo.rs
@@ -10,19 +10,19 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         let Coverage { kind, code_region } = coverage;
         match kind {
             CoverageKind::Counter { function_source_hash, id } => {
-                bx.add_counter_region(self.instance, function_source_hash, id, code_region);
+                if bx.add_counter_region(self.instance, function_source_hash, id, code_region) {
+                    let coverageinfo = bx.tcx().coverageinfo(self.instance.def_id());
 
-                let coverageinfo = bx.tcx().coverageinfo(self.instance.def_id());
-
-                let fn_name = bx.create_pgo_func_name_var(self.instance);
-                let hash = bx.const_u64(function_source_hash);
-                let num_counters = bx.const_u32(coverageinfo.num_counters);
-                let id = bx.const_u32(u32::from(id));
-                debug!(
-                    "codegen intrinsic instrprof.increment(fn_name={:?}, hash={:?}, num_counters={:?}, index={:?})",
-                    fn_name, hash, num_counters, id,
-                );
-                bx.instrprof_increment(fn_name, hash, num_counters, id);
+                    let fn_name = bx.create_pgo_func_name_var(self.instance);
+                    let hash = bx.const_u64(function_source_hash);
+                    let num_counters = bx.const_u32(coverageinfo.num_counters);
+                    let id = bx.const_u32(u32::from(id));
+                    debug!(
+                        "codegen intrinsic instrprof.increment(fn_name={:?}, hash={:?}, num_counters={:?}, index={:?})",
+                        fn_name, hash, num_counters, id,
+                    );
+                    bx.instrprof_increment(fn_name, hash, num_counters, id);
+                }
             }
             CoverageKind::Expression { id, lhs, op, rhs } => {
                 bx.add_counter_expression_region(self.instance, id, lhs, op, rhs, code_region);