add ConstantRange::difference (to perform set difference/relative complement)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159352 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/ConstantRange.cpp b/lib/Support/ConstantRange.cpp
index 61d333f..91d086b 100644
--- a/lib/Support/ConstantRange.cpp
+++ b/lib/Support/ConstantRange.cpp
@@ -248,6 +248,12 @@
return ConstantRange(Lower - Val, Upper - Val);
}
+/// \brief Subtract the specified range from this range (aka relative complement
+/// of the sets).
+ConstantRange ConstantRange::difference(const ConstantRange &CR) const {
+ return intersectWith(CR.inverse());
+}
+
/// intersectWith - Return the range that results from the intersection of this
/// range with another range. The resultant range is guaranteed to include all
/// elements contained in both input ranges, and to have the smallest possible