[llvm] r214790 - Fix SmallDenseMap assignment operator.

[Andrew Trick]

Author: atrick
Date: Mon Aug  4 17:18:25 2014
New Revision: 214790

URL: http://llvm.org/viewvc/llvm-project?rev=214790&view=rev
Log:
Fix SmallDenseMap assignment operator.

Self assignment would lead to buckets of garbage, causing quadratic probing to hang.

Modified:
    llvm/trunk/include/llvm/ADT/DenseMap.h
    llvm/trunk/unittests/ADT/DenseMapTest.cpp

Modified: llvm/trunk/include/llvm/ADT/DenseMap.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/DenseMap.h?rev=214790&r1=214789&r2=214790&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/DenseMap.h (original)
+++ llvm/trunk/include/llvm/ADT/DenseMap.h Mon Aug  4 17:18:25 2014
@@ -305,6 +305,7 @@ protected:
 
   template <typename OtherBaseT>
   void copyFrom(const DenseMapBase<OtherBaseT, KeyT, ValueT, KeyInfoT>& other) {
+    assert(&other != this);
     assert(getNumBuckets() == other.getNumBuckets());
 
     setNumEntries(other.getNumEntries());
@@ -574,7 +575,8 @@ public:
   }
 
   DenseMap& operator=(const DenseMap& other) {
-    copyFrom(other);
+    if (&other != this)
+      copyFrom(other);
     return *this;
   }
 
@@ -799,7 +801,8 @@ public:
   }
 
   SmallDenseMap& operator=(const SmallDenseMap& other) {
-    copyFrom(other);
+    if (&other != this)
+      copyFrom(other);
     return *this;
   }
 

Modified: llvm/trunk/unittests/ADT/DenseMapTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ADT/DenseMapTest.cpp?rev=214790&r1=214789&r2=214790&view=diff
==============================================================================
--- llvm/trunk/unittests/ADT/DenseMapTest.cpp (original)
+++ llvm/trunk/unittests/ADT/DenseMapTest.cpp Mon Aug  4 17:18:25 2014
@@ -244,6 +244,11 @@ TYPED_TEST(DenseMapTest, AssignmentTest)
 
   EXPECT_EQ(1u, copyMap.size());
   EXPECT_EQ(this->getValue(), copyMap[this->getKey()]);
+
+  // test self-assignment.
+  copyMap = copyMap;
+  EXPECT_EQ(1u, copyMap.size());
+  EXPECT_EQ(this->getValue(), copyMap[this->getKey()]);
 }
 
 // Test swap method