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Fix PR8441, a race condition in the static attributes list. While the reference counting was itself threadsafe,

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the implicit removal of each object from the global list was not.  Make this operation atomic.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118461 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2010-11-09 00:27:03 +00:00
parent 4b97c55648
commit 3afb024907
1 changed files with 12 additions and 5 deletions
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17
lib/VMCore/Attributes.cpp
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@ -106,7 +106,10 @@ Attributes Attribute::typeIncompatible(const Type *Ty) {
// AttributeListImpl Definition
//===----------------------------------------------------------------------===//
namespace llvm {
static ManagedStatic<sys::SmartMutex<true> > ALMutex;
class AttributeListImpl : public FoldingSetNode {
sys::cas_flag RefCount;
@ -122,10 +125,15 @@ public:
RefCount = 0;
}
void AddRef() { sys::AtomicIncrement(&RefCount); }
void AddRef() {
sys::SmartScopedLock<true> Lock(*ALMutex);
++RefCount;
}
void DropRef() {
sys::cas_flag old = sys::AtomicDecrement(&RefCount);
if (old == 0) delete this;
sys::SmartScopedLock<true> Lock(*ALMutex);
sys::cas_flag old = RefCount++;
if (old == 0)
delete this;
}
void Profile(FoldingSetNodeID &ID) const {
@ -139,11 +147,10 @@ public:
};
}
static ManagedStatic<sys::SmartMutex<true> > ALMutex;
static ManagedStatic<FoldingSet<AttributeListImpl> > AttributesLists;
AttributeListImpl::~AttributeListImpl() {
sys::SmartScopedLock<true> Lock(*ALMutex);
// NOTE: Lock must be acquired by caller.
AttributesLists->RemoveNode(this);
}