[frontend] Added support for the -use-malloc flag.

Added a new static ParseLangArgs, which fills in a LangOptions object.
Also moved the handling of -debug-constraints out of the loop in CompilerInvocation::parseArgs() and into ParseLangArgs, now that it has a proper home.

Swift SVN r11172

lib/Frontend/CompilerInvocation.cpp

@@ -63,6 +63,21 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   return false;
 }
 
+static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
+                          DiagnosticEngine &Diags) {
+  using namespace options;
+
+  if (Args.hasArg(OPT_use_malloc)) {
+    Opts.UseMalloc = true;
+  }
+
+  if (Args.hasArg(OPT_debug_constraints)) {
+    Opts.DebugConstraintSolver = true;
+  }
+
+  return false;
+}
+
 bool CompilerInvocation::parseArgs(ArrayRef<const char *> Args,
                                    DiagnosticEngine &Diags) {
   using namespace driver::options;
@@ -97,6 +112,10 @@ bool CompilerInvocation::parseArgs(ArrayRef<const char *> Args,
     return true;
   }
 
+  if (ParseLangArgs(LangOpts, *ParsedArgs, Diags)) {
+    return true;
+  }
+
   for (auto InputArg : *ParsedArgs) {
     switch (InputArg->getOption().getID()) {
     case OPT_target:
@@ -131,10 +150,6 @@ bool CompilerInvocation::parseArgs(ArrayRef<const char *> Args,
       ExtraClangArgs.push_back(InputArg->getValue());
       break;
 
-    case OPT_debug_constraints:
-      LangOpts.DebugConstraintSolver = true;
-      break;
-
     case OPT_l:
       addLinkLibrary(InputArg->getValue(), LibraryKind::Library);
       break;