[LLD][MinGW] Add support for --functionpadmin option

This introduces the MinGW counterpart of lld-link's -functionpadmin.

Author: cjacek

lld/MinGW/Driver.cpp

@@ -329,6 +329,14 @@ bool link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
       add("-build-id");
   }
 
+  if (auto *a = args.getLastArg(OPT_functionpadmin)) {
+    StringRef v = a->getValue();
+    if (v.empty())
+      add("-functionpadmin");
+    else
+      add("-functionpadmin:" + v);
+  }
+
   if (args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false))
     add("-WX");
   else

lld/MinGW/Options.td

@@ -215,6 +215,9 @@ defm error_limit:
 def build_id: J<"build-id=">, HelpText<"Generate build ID note (pass none to disable)">, 
   MetaVarName<"<arg>">;
 def : F<"build-id">, Alias<build_id>, HelpText<"Alias for --build-id=">;
+def functionpadmin: J<"functionpadmin=">, HelpText<"Prepares an image for hotpatching">,
+  MetaVarName<"<arg>">;
+def : F<"functionpadmin">, Alias<functionpadmin>, HelpText<"Alias for --functionpadmin=">;
 
 // Alias
 def alias_Bdynamic_call_shared: Flag<["-"], "call_shared">, Alias<Bdynamic>;

lld/test/MinGW/driver.test

@@ -445,6 +445,13 @@ RUN: ld.lld -### foo.o -m i386pep --build-id=fast 2>&1 | FileCheck -check-prefix
 BUILD_ID_WARN: unsupported build id hashing: fast, using default hashing.
 BUILD_ID_WARN: -build-id{{ }}
 
+RUN: ld.lld -### foo.o -m i386pep --functionpadmin= 2>&1 | FileCheck -check-prefix=FUNCTIONPADMIN %s
+RUN: ld.lld -### foo.o -m i386pep --functionpadmin 2>&1 | FileCheck -check-prefix=FUNCTIONPADMIN %s
+FUNCTIONPADMIN: -functionpadmin{{ }}
+
+RUN: ld.lld -### foo.o -m i386pep --functionpadmin=2 2>&1 | FileCheck -check-prefix=FUNCTIONPADMIN2 %s
+FUNCTIONPADMIN2: -functionpadmin:2{{ }}
+
 RUN: ld.lld -### foo.o -m i386pep --build-id=none 2>&1 | FileCheck -check-prefix=NO_BUILD_ID %s
 RUN: ld.lld -### foo.o -m i386pep -s 2>&1 | FileCheck -check-prefix=NO_BUILD_ID %s
 RUN: ld.lld -### foo.o -m i386pep -S 2>&1 | FileCheck -check-prefix=NO_BUILD_ID %s