Add test/embedded/linkage-mergeable-dead-strip.swift test

Author: kubamracek

test/embedded/linkage-mergeable-dead-strip.swift

@@ -0,0 +1,26 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -enable-experimental-feature Embedded -enable-experimental-feature SymbolLinkageMarkers -module-name main -mergeable-symbols -O %s -emit-ir | %FileCheck %s --check-prefix=CHECK-IR
+// RUN: %target-swift-frontend -enable-experimental-feature Embedded -enable-experimental-feature SymbolLinkageMarkers -module-name main -mergeable-symbols -O %s -c -o %t/a.o
+// RUN: %target-clang %t/a.o -o %t/a.out -dead_strip
+// RUN: %llvm-nm --defined-only --format=just-symbols --demangle %t/a.out | sort | %FileCheck %s --check-prefix=CHECK-NM
+// RUN: %target-run %t/a.out | %FileCheck %s
+
+// REQUIRES: swift_in_compiler
+// REQUIRES: executable_test
+// REQUIRES: OS=macosx
+// REQUIRES: swift_feature_Embedded
+
+public func a_this_is_unused() { }
+
+@_used
+public func b_this_is_unused_but_explicitly_retained() { }
+
+// CHECK-IR: define weak_odr {{.*}}@"$e4main16a_this_is_unusedyyF"()
+// CHECK-IR: define weak_odr {{.*}}@"$e4main40b_this_is_unused_but_explicitly_retainedyyF"()
+
+// CHECK-NM-NOT: $e4main14this_is_unusedyyF
+// CHECK-NM: $e4main40b_this_is_unused_but_explicitly_retainedyyF
+
+print("Hello")
+// CHECK: Hello