From: Owen Anderson <resistor@mac.com>
Date: Wed, 8 Sep 2010 18:03:32 +0000 (+0000)
Subject: Clarify the ownership model of LLVMContext and Module. Namely, contexts own
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=30268be89df6444f5ffb585439b3fbfec9055197;p=oota-llvm.git

Clarify the ownership model of LLVMContext and Module. Namely, contexts own
modules are instantiated in them.  If the context is deleted, all of its owned
modules are also deleted.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113374 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/LLVMContext.h b/include/llvm/LLVMContext.h
index 7cb6579aef6..76492b7102e 100644
--- a/include/llvm/LLVMContext.h
+++ b/include/llvm/LLVMContext.h
@@ -20,6 +20,7 @@ namespace llvm {
 class LLVMContextImpl;
 class StringRef;
 class Instruction;
+class Module;
 template <typename T> class SmallVectorImpl;
 
 /// This is an important class for using LLVM in a threaded context.  It
@@ -37,6 +38,13 @@ public:
   LLVMContext();
   ~LLVMContext();
   
+  /// addModule - Register a module as being instantiated in this context.  If
+  /// the context is deleted, the module will be deleted as well.
+  void addModule(Module*);
+  
+  /// removeModule - Unregister a module from this context.
+  void removeModule(Module*);
+  
   // Pinned metadata names, which always have the same value.  This is a
   // compile-time performance optimization, not a correctness optimization.
   enum {
diff --git a/lib/VMCore/LLVMContext.cpp b/lib/VMCore/LLVMContext.cpp
index 563c651315a..60fb830e9b5 100644
--- a/lib/VMCore/LLVMContext.cpp
+++ b/lib/VMCore/LLVMContext.cpp
@@ -34,6 +34,14 @@ LLVMContext::LLVMContext() : pImpl(new LLVMContextImpl(*this)) {
 }
 LLVMContext::~LLVMContext() { delete pImpl; }
 
+void LLVMContext::addModule(Module *M) {
+  pImpl->OwnedModules.insert(M);
+}
+
+void LLVMContext::removeModule(Module *M) {
+  pImpl->OwnedModules.erase(M);
+}
+
 //===----------------------------------------------------------------------===//
 // Recoverable Backend Errors
 //===----------------------------------------------------------------------===//
diff --git a/lib/VMCore/LLVMContextImpl.cpp b/lib/VMCore/LLVMContextImpl.cpp
index 93a075f0fcc..610c5027c34 100644
--- a/lib/VMCore/LLVMContextImpl.cpp
+++ b/lib/VMCore/LLVMContextImpl.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "LLVMContextImpl.h"
+#include "llvm/Module.h"
 #include <algorithm>
 using namespace llvm;
 
@@ -51,6 +52,15 @@ struct DropReferences {
 }
 
 LLVMContextImpl::~LLVMContextImpl() {
+  // NOTE: We need to delete the contents of OwnedModules, but we have to
+  // duplicate it into a temporary vector, because the destructor of Module
+  // will try to remove itself from OwnedModules set.  This would cause
+  // iterator invalidation if we iterated on the set directly.
+  std::vector<Module*> Modules(OwnedModules.begin(), OwnedModules.end());
+  for (std::vector<Module*>::iterator I = Modules.begin(), E = Modules.end();
+       I != E; ++I)
+    delete *I;
+  
   std::for_each(ExprConstants.map_begin(), ExprConstants.map_end(),
                 DropReferences());
   std::for_each(ArrayConstants.map_begin(), ArrayConstants.map_end(),
diff --git a/lib/VMCore/LLVMContextImpl.h b/lib/VMCore/LLVMContextImpl.h
index 51b2992898c..6df804ab084 100644
--- a/lib/VMCore/LLVMContextImpl.h
+++ b/lib/VMCore/LLVMContextImpl.h
@@ -115,6 +115,10 @@ public:
   
 class LLVMContextImpl {
 public:
+  /// OwnedModules - The set of modules instantiated in this context, and which
+  /// will be automatically deleted if this context is deleted.
+  SmallPtrSet<Module*, 4> OwnedModules;
+  
   void *InlineAsmDiagHandler, *InlineAsmDiagContext;
   
   typedef DenseMap<DenseMapAPIntKeyInfo::KeyTy, ConstantInt*, 
diff --git a/lib/VMCore/Module.cpp b/lib/VMCore/Module.cpp
index d7ddf96cb07..341e527acb5 100644
--- a/lib/VMCore/Module.cpp
+++ b/lib/VMCore/Module.cpp
@@ -62,9 +62,11 @@ Module::Module(StringRef MID, LLVMContext& C)
   ValSymTab = new ValueSymbolTable();
   TypeSymTab = new TypeSymbolTable();
   NamedMDSymTab = new StringMap<NamedMDNode *>();
+  Context.addModule(this);
 }
 
 Module::~Module() {
+  Context.removeModule(this);
   dropAllReferences();
   GlobalList.clear();
   FunctionList.clear();