From 2cd5155c0e8f2448dbdbc9c9cd468e589f9745e9 Mon Sep 17 00:00:00 2001
From: Torok Edwin <edwintorok@gmail.com>
Date: Mon, 31 Aug 2009 16:14:59 +0000
Subject: [PATCH] Free the constants that have no uses in ~LLVMContext. This
 fixes leaks from LLVMContext in multithreaded apps. Since constants are only
 deleted if they have no uses, it is safe to not delete a Module on shutdown,
 as many single-threaded tools do. Multithreaded apps should however delete
 the Module before destroying the Context to ensure that there are no leaks
 (assuming they use a different context for each thread).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80590 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/VMCore/ConstantsContext.h |  8 ++++++++
 lib/VMCore/LLVMContextImpl.h  | 23 ++++++++++++++++++++++-
 lib/VMCore/Type.cpp           |  2 +-
 lib/VMCore/TypesContext.h     |  2 --
 4 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/lib/VMCore/ConstantsContext.h b/lib/VMCore/ConstantsContext.h
index 22aba7e1d35..f4a2cde5d0f 100644
--- a/lib/VMCore/ConstantsContext.h
+++ b/lib/VMCore/ConstantsContext.h
@@ -575,6 +575,14 @@ public:
   // to enforce proper synchronization.
   typename MapTy::iterator map_begin() { return Map.begin(); }
   typename MapTy::iterator map_end() { return Map.end(); }
+
+  void freeConstants() {
+    for (typename MapTy::iterator I=Map.begin(), E=Map.end();
+         I != E; ++I) {
+      if (I->second->use_empty())
+        delete I->second;
+    }
+  }
     
   /// InsertOrGetItem - Return an iterator for the specified element.
   /// If the element exists in the map, the returned iterator points to the
diff --git a/lib/VMCore/LLVMContextImpl.h b/lib/VMCore/LLVMContextImpl.h
index 4016c0aa05a..2faf6ac6e38 100644
--- a/lib/VMCore/LLVMContextImpl.h
+++ b/lib/VMCore/LLVMContextImpl.h
@@ -96,7 +96,6 @@ struct DenseMapAPFloatKeyInfo {
 class LLVMContextImpl {
 public:
   sys::SmartRWMutex<true> ConstantsLock;
-  
   typedef DenseMap<DenseMapAPIntKeyInfo::KeyTy, ConstantInt*, 
                          DenseMapAPIntKeyInfo> IntMapTy;
   IntMapTy IntConstants;
@@ -196,6 +195,28 @@ public:
     Int16Ty(C, 16),
     Int32Ty(C, 32),
     Int64Ty(C, 64) { }
+
+  ~LLVMContextImpl()
+  {
+    ExprConstants.freeConstants();
+    ArrayConstants.freeConstants();
+    StructConstants.freeConstants();
+    VectorConstants.freeConstants();
+
+    AggZeroConstants.freeConstants();
+    NullPtrConstants.freeConstants();
+    UndefValueConstants.freeConstants();
+    for (IntMapTy::iterator I=IntConstants.begin(), E=IntConstants.end(); 
+         I != E; ++I) {
+      if (I->second->use_empty())
+        delete I->second;
+    }
+    for (FPMapTy::iterator I=FPConstants.begin(), E=FPConstants.end(); 
+         I != E; ++I) {
+      if (I->second->use_empty())
+        delete I->second;
+    }
+  }
 };
 
 }
diff --git a/lib/VMCore/Type.cpp b/lib/VMCore/Type.cpp
index 696ac96ae6a..ba190d92301 100644
--- a/lib/VMCore/Type.cpp
+++ b/lib/VMCore/Type.cpp
@@ -500,7 +500,7 @@ void DerivedType::dropAllTypeUses() {
       
         llvm_release_global_lock();
       }
-    } else {
+    } else if (!AlwaysOpaqueTy) {
       AlwaysOpaqueTy = OpaqueType::get(getContext());
       Holder = new PATypeHolder(AlwaysOpaqueTy);
     } 
diff --git a/lib/VMCore/TypesContext.h b/lib/VMCore/TypesContext.h
index 2a287fe5df6..e7950bd211f 100644
--- a/lib/VMCore/TypesContext.h
+++ b/lib/VMCore/TypesContext.h
@@ -221,7 +221,6 @@ public:
     // PATypeHolder won't destroy non-abstract types.
     // We can't destroy them by simply iterating, because
     // they may contain references to each-other.
-#if 0
     for (std::multimap<unsigned, PATypeHolder>::iterator I
          = TypesByHash.begin(), E = TypesByHash.end(); I != E; ++I) {
       Type *Ty = const_cast<Type*>(I->second.Ty);
@@ -235,7 +234,6 @@ public:
         operator delete(Ty);
       }
     }
-#endif
   }
 
   void RemoveFromTypesByHash(unsigned Hash, const Type *Ty) {
-- 
2.34.1