From 5b137847773bea965ada5d8c37fa9afa56e1b08a Mon Sep 17 00:00:00 2001
From: Chandler Carruth <chandlerc@gmail.com>
Date: Sun, 17 Jun 2012 11:28:13 +0000
Subject: [PATCH] Add a unit test for 'swap', and fix a pile of bugs in
 SmallDenseMap::swap.

First, make it parse cleanly. Yay for uninstantiated methods.

Second, make the inline-buckets case work correctly. This is way
trickier than it should be due to the uninitialized values in empty and
tombstone buckets.

Finally fix a few typos that caused construction/destruction mismatches
in the counting unittest.

llvm-svn: 158641
---
 include/llvm/ADT/DenseMap.h    | 41 ++++++++++++++++++++++++++++------
 unittests/ADT/DenseMapTest.cpp | 36 +++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 7 deletions(-)

diff --git a/include/llvm/ADT/DenseMap.h b/include/llvm/ADT/DenseMap.h
index dcae0de19d4..045b5c6a442 100644
--- a/include/llvm/ADT/DenseMap.h
+++ b/include/llvm/ADT/DenseMap.h
@@ -716,11 +716,40 @@ public:
   }
 
   void swap(SmallDenseMap& RHS) {
-    std::swap(NumEntries, RHS.NumEntries);
+    unsigned TmpNumEntries = RHS.NumEntries;
+    RHS.NumEntries = NumEntries;
+    NumEntries = TmpNumEntries;
     std::swap(NumTombstones, RHS.NumTombstones);
+
+    const KeyT EmptyKey = this->getEmptyKey();
+    const KeyT TombstoneKey = this->getTombstoneKey();
     if (Small && RHS.Small) {
-      for (unsigned i = 0, e = InlineBuckets; i != e; ++i)
-        std::swap(getInlineBuckets()[i], RHS.getInlineBuckes()[i]);
+      // If we're swapping inline bucket arrays, we have to cope with some of
+      // the tricky bits of DenseMap's storage system: the buckets are not
+      // fully initialized. Thus we swap every key, but we may have
+      // a one-directional move of the value.
+      for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
+        BucketT *LHSB = &getInlineBuckets()[i],
+                *RHSB = &RHS.getInlineBuckets()[i];
+        bool hasLHSValue = (!KeyInfoT::isEqual(LHSB->first, EmptyKey) &&
+                            !KeyInfoT::isEqual(LHSB->first, TombstoneKey));
+        bool hasRHSValue = (!KeyInfoT::isEqual(RHSB->first, EmptyKey) &&
+                            !KeyInfoT::isEqual(RHSB->first, TombstoneKey));
+        if (hasLHSValue && hasRHSValue) {
+          // Swap together if we can...
+          std::swap(*LHSB, *RHSB);
+          continue;
+        }
+        // Swap separately and handle any assymetry.
+        std::swap(LHSB->first, RHSB->first);
+        if (hasLHSValue) {
+          new (&RHSB->second) ValueT(llvm_move(LHSB->second));
+          LHSB->second.~ValueT();
+        } else if (hasRHSValue) {
+          new (&LHSB->second) ValueT(llvm_move(RHSB->second));
+          RHSB->second.~ValueT();
+        }
+      }
       return;
     }
     if (!Small && !RHS.Small) {
@@ -737,16 +766,14 @@ public:
     LargeSide.getLargeRep()->~LargeRep();
     LargeSide.Small = true;
     // This is similar to the standard move-from-old-buckets, but the bucket
-    // count hasn't actually rotate in this case. So we have to carefully
+    // count hasn't actually rotated in this case. So we have to carefully
     // move construct the keys and values into their new locations, but there
     // is no need to re-hash things.
-    const KeyT EmptyKey = this->getEmptyKey();
-    const KeyT TombstoneKey = this->getTombstoneKey();
     for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
       BucketT *NewB = &LargeSide.getInlineBuckets()[i],
               *OldB = &SmallSide.getInlineBuckets()[i];
       new (&NewB->first) KeyT(llvm_move(OldB->first));
-      NewB->first.~KeyT();
+      OldB->first.~KeyT();
       if (!KeyInfoT::isEqual(NewB->first, EmptyKey) &&
           !KeyInfoT::isEqual(NewB->first, TombstoneKey)) {
         new (&NewB->second) ValueT(llvm_move(OldB->second));
diff --git a/unittests/ADT/DenseMapTest.cpp b/unittests/ADT/DenseMapTest.cpp
index bd9a3f24ec3..75e7006434a 100644
--- a/unittests/ADT/DenseMapTest.cpp
+++ b/unittests/ADT/DenseMapTest.cpp
@@ -218,6 +218,42 @@ TYPED_TEST(DenseMapTest, AssignmentTest) {
   EXPECT_EQ(this->getValue(), copyMap[this->getKey()]);
 }
 
+// Test swap method
+TYPED_TEST(DenseMapTest, SwapTest) {
+  this->Map[this->getKey()] = this->getValue();
+  TypeParam otherMap;
+
+  this->Map.swap(otherMap);
+  EXPECT_EQ(0u, this->Map.size());
+  EXPECT_TRUE(this->Map.empty());
+  EXPECT_EQ(1u, otherMap.size());
+  EXPECT_EQ(this->getValue(), otherMap[this->getKey()]);
+
+  this->Map.swap(otherMap);
+  EXPECT_EQ(0u, otherMap.size());
+  EXPECT_TRUE(otherMap.empty());
+  EXPECT_EQ(1u, this->Map.size());
+  EXPECT_EQ(this->getValue(), this->Map[this->getKey()]);
+
+  // Make this more interesting by inserting 100 numbers into the map.
+  for (int i = 0; i < 100; ++i)
+    this->Map[this->getKey(i)] = this->getValue(i);
+
+  this->Map.swap(otherMap);
+  EXPECT_EQ(0u, this->Map.size());
+  EXPECT_TRUE(this->Map.empty());
+  EXPECT_EQ(100u, otherMap.size());
+  for (int i = 0; i < 100; ++i)
+    EXPECT_EQ(this->getValue(i), otherMap[this->getKey(i)]);
+
+  this->Map.swap(otherMap);
+  EXPECT_EQ(0u, otherMap.size());
+  EXPECT_TRUE(otherMap.empty());
+  EXPECT_EQ(100u, this->Map.size());
+  for (int i = 0; i < 100; ++i)
+    EXPECT_EQ(this->getValue(i), this->Map[this->getKey(i)]);
+}
+
 // A more complex iteration test
 TYPED_TEST(DenseMapTest, IterationTest) {
   bool visited[100];