Reapply r79708 with the appropriate fix for the case that still requires locking.
llvm-svn: 79731
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 72f2112..6ce30f6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5022,12 +5022,16 @@
/// getValueTypeList - Return a pointer to the specified value type.
///
const EVT *SDNode::getValueTypeList(EVT VT) {
- sys::SmartScopedLock<true> Lock(*VTMutex);
if (VT.isExtended()) {
+ 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;
- return &VTs[VT.getSimpleVT().SimpleTy];
+ sys::MemoryFence();
+ return VTs + VT.getSimpleVT().SimpleTy;
}
}