Merge pull request #68486 from kubamracek/embedded-internalize

[embedded] Avoid marking all public symbols as 'do not dead strip' in embedded Swift

Author: kubamracek

lib/Frontend/CompilerInvocation.cpp

@@ -3096,6 +3096,9 @@ bool CompilerInvocation::parseArgs(
   // Now that we've parsed everything, setup some inter-option-dependent state.
   setIRGenOutputOptsFromFrontendOptions(IRGenOpts, FrontendOpts);
   setBridgingHeaderFromFrontendOptions(ClangImporterOpts, FrontendOpts);
+  if (LangOpts.hasFeature(Feature::Embedded)) {
+    IRGenOpts.InternalizeAtLink = true;
+  }
 
   return false;
 }

test/embedded/internalize-no-stdlib.swift

@@ -0,0 +1,37 @@
+// This test checks that embedded Swift doesn't mark public functions/symbols as llvm.used / llvm.compiler.used
+
+// RUN: %target-swift-emit-ir %s -parse-stdlib -enable-experimental-feature Embedded -target arm64e-apple-none-elf | %FileCheck %s --check-prefix CHECK-ELF
+// RUN: %target-swift-emit-ir %s -parse-stdlib -enable-experimental-feature Embedded -target arm64e-apple-none-macho | %FileCheck %s --check-prefix CHECK-MACHO
+
+// REQUIRES: swift_in_compiler
+
+struct Bool {}
+
+protocol Player {
+  func play()
+  var canPlay: Bool { get }
+}
+
+struct Concrete : Player {
+  func play() { }
+  var canPlay: Bool { Bool() }
+}
+
+func start(p: some Player) {
+  p.play()
+}
+
+public func main() {
+  start(p: Concrete())
+}
+
+// CHECK-ELF: @"\01l_entry_point" =
+// CHECK-ELF: @__swift_reflection_version =
+// CHECK-ELF: @_swift1_autolink_entries =
+// CHECK-ELF: @llvm.compiler.used = appending global [3 x ptr] [ptr @"\01l_entry_point", ptr @__swift_reflection_version, ptr @_swift1_autolink_entries], section "llvm.metadata"
+// CHECK-ELF-NOT: @llvm.used
+
+// CHECK-MACHO: @"\01l_entry_point" =
+// CHECK-MACHO: @__swift_reflection_version =
+// CHECK-MACHO-NOT: @llvm.compiler.used
+// CHECK-MACHO: @llvm.used = appending global [2 x ptr] [ptr @"\01l_entry_point", ptr @__swift_reflection_version], section "llvm.metadata"