LowerConstantIntrinsics: Fix missing test for byval behavior

llvm/test/Transforms/LowerConstantIntrinsics/objectsize_basic.ll

@@ -81,3 +81,11 @@ entry:
                                                i1 false, i1 false)
   ret i64 %0
 }
+
+; CHECK-LABEL: @test_objectsize_byval_arg(
+; CHECK: ret i64 42
+define i64 @test_objectsize_byval_arg([42 x i8]* byval([42 x i8]) %ptr) {
+  %cast = bitcast [42 x i8]* %ptr to i8*
+  %size = tail call i64 @llvm.objectsize.i64(i8* %cast, i1 true, i1 false, i1 false)
+  ret i64 %size
+}