Add an accessor method to get the slot's index. This will limit the use of AttributeWithIndex.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173495 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/IR/Attributes.cpp b/lib/IR/Attributes.cpp
index cbbf484..b09d55d 100644
--- a/lib/IR/Attributes.cpp
+++ b/lib/IR/Attributes.cpp
@@ -682,6 +682,12 @@
   return AttrList ? AttrList->getNumAttributes() : 0;
 }
 
+unsigned AttributeSet::getSlotIndex(unsigned Slot) const {
+  assert(AttrList && Slot < AttrList->getNumAttributes() &&
+         "Slot # out of range!");
+  return AttrList->getSlotIndex(Slot);
+}
+
 /// getSlot - Return the AttributeWithIndex at the specified slot.  This
 /// holds a number plus a set of attributes.
 const AttributeWithIndex &AttributeSet::getSlot(unsigned Slot) const {