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Reduce contention on the Attributes lock by using atomic operations for reference counting rather than locking.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79560 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2009-08-20 19:03:20 +00:00
parent d9b207122e
commit 72689b4094
1 changed files with 7 additions and 7 deletions
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14
lib/VMCore/Attributes.cpp
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@ -15,6 +15,7 @@
#include "llvm/Type.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/System/Atomic.h"
#include "llvm/System/Mutex.h"
#include "llvm/Support/Streams.h"
#include "llvm/Support/ManagedStatic.h"
@ -97,7 +98,7 @@ Attributes Attribute::typeIncompatible(const Type *Ty) {
namespace llvm {
class AttributeListImpl : public FoldingSetNode {
unsigned RefCount;
sys::cas_flag RefCount;
// AttributesList is uniqued, these should not be publicly available.
void operator=(const AttributeListImpl &); // Do not implement
@ -111,8 +112,11 @@ public:
RefCount = 0;
}
void AddRef() { ++RefCount; }
void DropRef() { if (--RefCount == 0) delete this; }
void AddRef() { sys::AtomicIncrement(&RefCount); }
void DropRef() {
sys::cas_flag old = sys::AtomicDecrement(&RefCount);
if (old == 0) delete this;
}
void Profile(FoldingSetNodeID &ID) const {
Profile(ID, Attrs.data(), Attrs.size());
@ -175,17 +179,14 @@ AttrListPtr AttrListPtr::get(const AttributeWithIndex *Attrs, unsigned NumAttrs)
//===----------------------------------------------------------------------===//
AttrListPtr::AttrListPtr(AttributeListImpl *LI) : AttrList(LI) {
sys::SmartScopedLock<true> Lock(*ALMutex);
if (LI) LI->AddRef();
}
AttrListPtr::AttrListPtr(const AttrListPtr &P) : AttrList(P.AttrList) {
sys::SmartScopedLock<true> Lock(*ALMutex);
if (AttrList) AttrList->AddRef();
}
const AttrListPtr &AttrListPtr::operator=(const AttrListPtr &RHS) {
sys::SmartScopedLock<true> Lock(*ALMutex);
if (AttrList == RHS.AttrList) return *this;
if (AttrList) AttrList->DropRef();
AttrList = RHS.AttrList;
@ -194,7 +195,6 @@ const AttrListPtr &AttrListPtr::operator=(const AttrListPtr &RHS) {
}
AttrListPtr::~AttrListPtr() {
sys::SmartScopedLock<true> Lock(*ALMutex);
if (AttrList) AttrList->DropRef();
}