Add codegen test that makes sure PGO instrumentation is emitted as expected.

Author: michaelwoerister

src/test/codegen/pgo-instrumentation.rs

@@ -0,0 +1,20 @@
+// Test that `-Zpgo-gen` creates expected instrumentation artifacts in LLVM IR.
+
+// needs-profiler-support
+// compile-flags: -Z pgo-gen -Ccodegen-units=1
+
+// CHECK: @__llvm_profile_raw_version =
+// CHECK: @__profc_{{.*}}pgo_instrumentation{{.*}}some_function{{.*}} = private global
+// CHECK: @__profd_{{.*}}pgo_instrumentation{{.*}}some_function{{.*}} = private global
+// CHECK: @__profc_{{.*}}pgo_instrumentation{{.*}}main{{.*}} = private global
+// CHECK: @__profd_{{.*}}pgo_instrumentation{{.*}}main{{.*}} = private global
+// CHECK: @__llvm_profile_filename = {{.*}}"default_%m.profraw\00"{{.*}}
+
+#[inline(never)]
+fn some_function() {
+
+}
+
+fn main() {
+    some_function();
+}