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Get rid of this horrible "benign race" by exploiting ManagedStatic to initialize 

the array on its first access.

llvm-svn: 80040
This commit is contained in:
Owen Anderson 2009-08-25 22:27:22 +00:00
parent 23d2c76f31
commit 3b1665eca5
1 changed files with 14 additions and 7 deletions
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21
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -5014,8 +5014,20 @@ void SDNode::Profile(FoldingSetNodeID &ID) const {
AddNodeIDNode(ID, this);
}
namespace {
struct EVTArray {
std::vector<EVT> VTs;
EVTArray() {
VTs.reserve(MVT::LAST_VALUETYPE);
for (unsigned i = 0; i < MVT::LAST_VALUETYPE; ++i)
VTs.push_back(MVT((MVT::SimpleValueType)i));
}
};
}
static ManagedStatic<std::set<EVT, EVT::compareRawBits> > EVTs;
static EVT VTs[MVT::LAST_VALUETYPE];
static ManagedStatic<EVTArray> SimpleVTArray;
static ManagedStatic<sys::SmartMutex<true> > VTMutex;
/// getValueTypeList - Return a pointer to the specified value type.
@ -5025,12 +5037,7 @@ const EVT *SDNode::getValueTypeList(EVT VT) {
sys::SmartScopedLock<true> Lock(*VTMutex);
return &(*EVTs->insert(VT).first);
} else {
// All writes to this location will have the same value, so it's ok
// to race on it. We only need to ensure that at least one write has
// succeeded before we return the pointer into the array.
VTs[VT.getSimpleVT().SimpleTy] = VT;
sys::MemoryFence();
return VTs + VT.getSimpleVT().SimpleTy;
return &SimpleVTArray->VTs[VT.getSimpleVT().SimpleTy];
}
}