Revert obsolete llvm-link -preserve-modules option/test

This testing mode is now obsolete with the change to linkInModule
to take a std::unique_ptr to Module.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258399 91177308-0d34-0410-b5e6-96231b3b80d8

test/Linker/only-needed-named-metadata.ll

@@ -23,11 +23,6 @@
 ; ONLYNEEDED-NOT:@analias
 ; ONLYNEEDED-NOT:@globalfunc2()
 
-; Test -only-needed link with the modules preserved instead of freeing to
-; catch any cross-module references to metadata, which the bitcode writer
-; will assert on.
-; RUN: llvm-link -preserve-modules -o %t3.bc -only-needed %S/Inputs/only-needed-named-metadata.ll %S/only-needed-named-metadata.ll
-
 @X = global i32 5
 @U = global i32 6
 @U_linkonce = linkonce_odr hidden global i32 6

tools/llvm-link/llvm-link.cpp

@@ -89,10 +89,6 @@ static cl::opt<bool>
 SuppressWarnings("suppress-warnings", cl::desc("Suppress all linking warnings"),
                  cl::init(false));
 
-static cl::opt<bool>
-    PreserveModules("preserve-modules",
-                    cl::desc("Preserve linked modules for testing"));
-
 static cl::opt<bool> PreserveBitcodeUseListOrder(
     "preserve-bc-uselistorder",
     cl::desc("Preserve use-list order when writing LLVM bitcode."),
@@ -284,15 +280,6 @@ static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L,
       return false;
     // All linker flags apply to linking of subsequent files.
     ApplicableFlags = Flags;
-
-    // If requested for testing, preserve modules by releasing them from
-    // the unique_ptr before the are freed. This can help catch any
-    // cross-module references from e.g. unneeded metadata references
-    // that aren't properly set to null but instead mapped to the source
-    // module version. The bitcode writer will assert if it finds any such
-    // cross-module references.
-    if (PreserveModules)
-      M.release();
   }
 
   return true;