[PATCH] D77038: Fix bug in BitVector and SmallBitVector DenseMap hashing

[Brad Moody via Phabricator via llvm-commits]

bmoody updated this revision to Diff 258466.
bmoody added a comment.

Make suggested changes to SmallBitVector, un-deleting SmallBitVector::getData.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D77038/new/

https://reviews.llvm.org/D77038

Files:
  llvm/include/llvm/ADT/BitVector.h
  llvm/include/llvm/ADT/SmallBitVector.h
  llvm/unittests/ADT/BitVectorTest.cpp


Index: llvm/unittests/ADT/BitVectorTest.cpp
===================================================================
--- llvm/unittests/ADT/BitVectorTest.cpp
+++ llvm/unittests/ADT/BitVectorTest.cpp
@@ -1229,4 +1229,34 @@
   EXPECT_EQ(true, Set.erase(A));
   EXPECT_EQ(0U, Set.size());
 }
+
+/// Test that capacity doesn't affect hashing.
+TYPED_TEST(BitVectorTest, DenseMapHashing) {
+  using DMI = DenseMapInfo<TypeParam>;
+  {
+    TypeParam A;
+    A.resize(200);
+    A.set(100);
+
+    TypeParam B;
+    B.resize(200);
+    B.set(100);
+    B.reserve(1000);
+
+    EXPECT_EQ(DMI::getHashValue(A), DMI::getHashValue(B));
+  }
+  {
+    TypeParam A;
+    A.resize(20);
+    A.set(10);
+
+    TypeParam B;
+    B.resize(20);
+    B.set(10);
+    B.reserve(1000);
+
+    EXPECT_EQ(DMI::getHashValue(A), DMI::getHashValue(B));
+  }
+}
+
 } // namespace
Index: llvm/include/llvm/ADT/SmallBitVector.h
===================================================================
--- llvm/include/llvm/ADT/SmallBitVector.h
+++ llvm/include/llvm/ADT/SmallBitVector.h
@@ -668,8 +668,11 @@
   }
   bool isInvalid() const { return X == (uintptr_t)-1; }
 
-  ArrayRef<uintptr_t> getData() const {
-    return isSmall() ? makeArrayRef(X) : getPointer()->getData();
+  ArrayRef<uintptr_t> getData(uintptr_t &Store) const {
+    if (!isSmall())
+      return getPointer()->getData();
+    Store = getSmallBits();
+    return makeArrayRef(Store);
   }
 
 private:
@@ -717,8 +720,9 @@
     return V;
   }
   static unsigned getHashValue(const SmallBitVector &V) {
+    uintptr_t Store;
     return DenseMapInfo<std::pair<unsigned, ArrayRef<uintptr_t>>>::getHashValue(
-        std::make_pair(V.size(), V.getData()));
+        std::make_pair(V.size(), V.getData(Store)));
   }
   static bool isEqual(const SmallBitVector &LHS, const SmallBitVector &RHS) {
     if (LHS.isInvalid() || RHS.isInvalid())
Index: llvm/include/llvm/ADT/BitVector.h
===================================================================
--- llvm/include/llvm/ADT/BitVector.h
+++ llvm/include/llvm/ADT/BitVector.h
@@ -759,7 +759,9 @@
   }
   bool isInvalid() const { return Size == (unsigned)-1; }
 
-  ArrayRef<BitWord> getData() const { return Bits; }
+  ArrayRef<BitWord> getData() const {
+    return Bits.take_front(NumBitWords(size()));
+  }
 
   //===--------------------------------------------------------------------===//
   // Portable bit mask operations.


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