add rbitsets_have_common function

[r26325]

include/libfirm/adt/raw_bitset.h

@@ -348,6 +348,26 @@ static inline int rbitset_equal(const unsigned *bitset1,
 	return memcmp(bitset1, bitset2, BITSET_SIZE_BYTES(size)) == 0;
 }
 
+/**
+ * Tests wether 2 bitsets wether at least 1 bit is set in both.
+ *
+ * @param bitset1  the first bitset
+ * @param bitset2  the second bitset
+ * @param size     size of both bitsets
+ */
+static inline int rbitsets_have_common(const unsigned *bitset1,
+                                       const unsigned *bitset2, size_t size)
+{
+	unsigned i;
+	unsigned n = BITSET_SIZE_ELEMS(size);
+
+	for (i = 0; i < n; ++i) {
+		if ((bitset1[i] & bitset2[i]) != 0)
+			return 1;
+	}
+	return 0;
+}
+
 /**
  * Copy a raw bitset into another.
  *