Added two SubtargetFeatures::AddFeatures methods, which accept a comma-separated string or already parsed command line parameters as input, and some code re-factoring to use these new methods.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89516 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/lto/LTOCodeGenerator.cpp b/tools/lto/LTOCodeGenerator.cpp
index 0b9cb29..f079c2e 100644
--- a/tools/lto/LTOCodeGenerator.cpp
+++ b/tools/lto/LTOCodeGenerator.cpp
@@ -304,10 +304,17 @@
             break;
         }
 
+        // Prepare subtarget feature set for the given command line options.
+        SubtargetFeatures features;
+
+        // Set the rest of features by default.
+        // Note: Please keep this after all explict feature settings to make sure
+        // defaults will not override explicitly set options.
+        features.AddFeatures(
+            SubtargetFeatures::getDefaultSubtargetFeatures(llvm::Triple(Triple)));
+
         // construct LTModule, hand over ownership of module and target
-        const std::string FeatureStr = 
-            SubtargetFeatures::getDefaultSubtargetFeatures(llvm::Triple(Triple));
-        _target = march->createTargetMachine(Triple, FeatureStr);
+        _target = march->createTargetMachine(Triple, features.getString());
     }
     return false;
 }