Replace linear search with logrithmic one.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20580 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/DataStructure/DataStructure.cpp b/lib/Analysis/DataStructure/DataStructure.cpp
index 7679eeb..58a0aa5 100644
--- a/lib/Analysis/DataStructure/DataStructure.cpp
+++ b/lib/Analysis/DataStructure/DataStructure.cpp
@@ -443,10 +443,7 @@
     case Type::StructTyID: {
       const StructType *STy = cast<StructType>(SubType);
       const StructLayout &SL = *TD.getStructLayout(STy);
-
-      unsigned i = 0, e = SL.MemberOffsets.size();
-      for (; i+1 < e && SL.MemberOffsets[i+1] <= Offset-O; ++i)
-        /* empty */;
+      unsigned i = SL.getElementContainingOffset(Offset-O);
 
       // The offset we are looking for must be in the i'th element...
       SubType = STy->getElementType(i);