Add the attributes that are passed in instead of the ones we're merging into.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173108 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/IR/Attributes.cpp b/lib/IR/Attributes.cpp
index 5c95d4a..fe6366d 100644
--- a/lib/IR/Attributes.cpp
+++ b/lib/IR/Attributes.cpp
@@ -693,12 +693,12 @@
 
 AttributeSet AttributeSet::addRetAttributes(LLVMContext &C,
                                             AttributeSet Attrs) const {
-  return addAttr(C, ReturnIndex, getAttributes(ReturnIndex));
+  return addAttr(C, ReturnIndex, Attrs.getAttributes(ReturnIndex));
 }
 
 AttributeSet AttributeSet::addFnAttributes(LLVMContext &C,
                                            AttributeSet Attrs) const {
-  return addAttr(C, FunctionIndex, getAttributes(FunctionIndex));
+  return addAttr(C, FunctionIndex, Attrs.getAttributes(FunctionIndex));
 }
 
 AttributeSet AttributeSet::addAttr(LLVMContext &C, unsigned Idx,