[embedded] Mark all functions as 'nounwind' in embedded Swift, add dependency tests

lib/IRGen/IRGenModule.cpp

@@ -1444,6 +1444,12 @@ void IRGenModule::constructInitialFnAttributes(
     Attrs.addAttribute(llvm::Attribute::StackProtectReq);
     Attrs.addAttribute("stack-protector-buffer-size", llvm::utostr(8));
   }
+
+  // Mark as 'nounwind' to avoid referencing exception personality symbols, this
+  // is okay even with C++ interop on because the landinpads are trapping.
+  if (Context.LangOpts.hasFeature(Feature::Embedded)) {
+    Attrs.addAttribute(llvm::Attribute::NoUnwind);
+  }
 }
 
 llvm::AttributeList IRGenModule::constructInitialAttributes() {

lib/IRGen/IRGenSIL.cpp

@@ -1846,6 +1846,12 @@ IRGenSILFunction::IRGenSILFunction(IRGenModule &IGM, SILFunction *f)
     CurFn->addFnAttr(llvm::Attribute::NoInline);
   }
 
+  // Mark as 'nounwind' to avoid referencing exception personality symbols, this
+  // is okay even with C++ interop on because the landinpads are trapping.
+  if (IGM.Context.LangOpts.hasFeature(Feature::Embedded)) {
+    CurFn->addFnAttr(llvm::Attribute::NoUnwind);
+  }
+
   auto optMode = f->getOptimizationMode();
   if (optMode != OptimizationMode::NotSet &&
       optMode != f->getModule().getOptions().OptMode) {

test/embedded/dependencies.swift

@@ -0,0 +1,68 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend -parse-as-library -enable-experimental-feature Embedded %s -c -o %t/a.o
+
+// RUN: grep DEP\: %s | sed 's#// DEP\: ##' | sort > %t/allowed-dependencies.txt
+
+// Linux/ELF doesn't use the "_" prefix in symbol mangling.
+// RUN: if [ %target-os == "linux-gnu" ]; then sed -E -i -e 's/^_(.*)$/\1/' %t/allowed-dependencies.txt; fi
+
+// RUN: %llvm-nm --undefined-only --format=just-symbols %t/a.o | sort | tee %t/actual-dependencies.txt
+
+// Fail if there is any entry in actual-dependencies.txt that's not in allowed-dependencies.txt
+// RUN: test -z "`comm -13 %t/allowed-dependencies.txt %t/actual-dependencies.txt`"
+
+// DEP: ___stack_chk_fail
+// DEP: ___stack_chk_guard
+// DEP: _free
+// DEP: _memset
+// DEP: _putchar
+// DEP: _posix_memalign
+
+// RUN: %target-clang -x c -c %S/Inputs/print.c -o %t/print.o
+// RUN: %target-clang %t/a.o %t/print.o -o %t/a.out
+// RUN: %target-run %t/a.out | %FileCheck %s
+
+// REQUIRES: swift_in_compiler
+// REQUIRES: executable_test
+// REQUIRES: optimized_stdlib
+// REQUIRES: OS=macosx || OS=linux-gnu
+
+@_silgen_name("putchar")
+func putchar(_: UInt8)
+
+public func print(_ s: StaticString, terminator: StaticString = "\n") {
+  var p = s.utf8Start
+  while p.pointee != 0 {
+    putchar(p.pointee)
+    p += 1
+  }
+  p = terminator.utf8Start
+  while p.pointee != 0 {
+    putchar(p.pointee)
+    p += 1
+  }
+}
+
+class MyClass {
+  func foo() { print("MyClass.foo") }
+}
+
+class MySubClass: MyClass {
+  override func foo() { print("MySubClass.foo") }
+}
+
+@main
+struct Main {
+  static var objects: [MyClass] = []
+  static func main() {
+    print("Hello Embedded Swift!")
+    // CHECK: Hello Embedded Swift!
+    objects.append(MyClass())
+    objects.append(MySubClass())
+    for o in objects {
+      o.foo()
+    }
+    // CHECK: MyClass.foo
+    // CHECK: MySubClass.foo
+  }
+}