Add BitVector::anyCommon().

The existing operation (A & B).any() is very slow.

llvm-svn: 156760

llvm/include/llvm/ADT/BitVector.h

@@ -272,6 +272,16 @@ public:
     return (*this)[Idx];
   }
 
+  /// Test if any common bits are set.
+  bool anyCommon(const BitVector &RHS) const {
+    unsigned ThisWords = NumBitWords(size());
+    unsigned RHSWords  = NumBitWords(RHS.size());
+    for (unsigned i = 0, e = std::min(ThisWords, RHSWords); i != e; ++i)
+      if (Bits[i] & RHS.Bits[i])
+        return true;
+    return false;
+  }
+
   // Comparison operators.
   bool operator==(const BitVector &RHS) const {
     unsigned ThisWords = NumBitWords(size());

llvm/unittests/ADT/BitVectorTest.cpp

@@ -242,6 +242,34 @@ TEST(BitVectorTest, PortableBitMask) {
   A.clearBitsNotInMask(Mask1, 1);
   EXPECT_EQ(64-4u, A.count());
 }
-}
 
+TEST(BitVectorTest, BinOps) {
+  BitVector A;
+  BitVector B;
+
+  A.resize(65);
+  EXPECT_FALSE(A.anyCommon(B));
+  EXPECT_FALSE(B.anyCommon(B));
+
+  B.resize(64);
+  A.set(64);
+  EXPECT_FALSE(A.anyCommon(B));
+  EXPECT_FALSE(B.anyCommon(A));
+
+  B.set(63);
+  EXPECT_FALSE(A.anyCommon(B));
+  EXPECT_FALSE(B.anyCommon(A));
+
+  A.set(63);
+  EXPECT_TRUE(A.anyCommon(B));
+  EXPECT_TRUE(B.anyCommon(A));
+
+  B.resize(70);
+  B.set(64);
+  B.reset(63);
+  A.resize(64);
+  EXPECT_FALSE(A.anyCommon(B));
+  EXPECT_FALSE(B.anyCommon(A));
+}
+}
 #endif