Fix and add tests

Author: royitaqi

llvm/docs/CommandGuide/dsymutil.rst

@@ -70,6 +70,14 @@ OPTIONS
 
  Print this help output.
 
+.. option:: --include-swiftmodules-from-interface
+
+ Whether or not to copy binary swiftmodules built from textual .swiftinterface
+ files into the dSYM bundle. These typically come only from the SDK (since
+ textual interfaces require library evolution) and thus are a waste of space to
+ copy into the bundle. Turn this on if the swiftmodules are different from
+ those in the SDK.
+
 .. option:: --keep-function-for-static
 
  Make a static variable keep the enclosing function even if it would have been

llvm/test/tools/dsymutil/ARM/swiftmodule-include-from-interface.test

@@ -0,0 +1,33 @@
+# RUN: dsymutil -include-swiftmodules-from-interface -verbose -oso-prepend-path=%p -y -o %t.dSYM  %s | FileCheck %s
+#
+# RUN: dsymutil -include-swiftmodules-from-interface --linker parallel -verbose -oso-prepend-path=%p -y %s -o %t-parallel.dSYM | FileCheck %s
+#
+# To regenerate:
+# echo ''>I.swift
+# echo ''>B.swift
+# echo 'import I'>main.swift
+# xcrun swiftc -emit-module-interface-path I.swiftinterface -enable-library-evolution I.swift
+# xcrun swiftc -emit-module-path B.swiftmodule B.swift -Xfrontend -no-serialize-debugging-options
+# xcrun swiftc -explicit-module-build main.swift -I. -module-cache-path cache -g -Xfrontend  -no-serialize-debugging-options
+# output is "B.swiftmodule" and "cache/I*.swiftmodule"
+#
+# CHECK-NOT: Skipping compiled textual Swift interface: {{.*}}/Inputs/Binary.swiftmodule
+# CHECK-NOT: Skipping compiled textual Swift interface: {{.*}}/Inputs/FromInterface.swiftmodule
+
+#
+---
+triple:          'arm64-apple-darwin'
+objects:
+  - filename:        '../Inputs/Binary.swiftmodule'
+    timestamp:       0
+    type:            50
+    symbols:         []
+  - filename:        '../Inputs/FromInterface.swiftmodule'
+    timestamp:       0
+    type:            50
+    symbols:         []
+  - filename:        '../Inputs/FromInterface.swiftmodule'
+    timestamp:       0
+    type:            50
+    symbols:         []
+...