[llvm] [OFFLOAD] Add support for indexed per-thread containers (PR #164263)

[Kevin Sala Penades via llvm-commits]

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@@ -14,101 +14,256 @@
 #define OFFLOAD_PERTHREADTABLE_H
 
 #include <list>
+#include <llvm/ADT/SmallVector.h>
+#include <llvm/Support/Error.h>
 #include <memory>
 #include <mutex>
+#include <type_traits>
+
+template <typename ObjectType> class PerThread {
+  std::mutex Mutex;
+  llvm::SmallVector<std::shared_ptr<ObjectType>> ThreadDataList;
+
+  ObjectType &getThreadData() {
+    static thread_local std::shared_ptr<ObjectType> ThreadData = nullptr;
+    if (!ThreadData) {
+      ThreadData = std::make_shared<ObjectType>();
+      std::lock_guard<std::mutex> Lock(Mutex);
+      ThreadDataList.push_back(ThreadData);
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kevinsala wrote:

Are you referring to creating the object (and the smart pointer) in the emplace back statement? If so, that would move the allocation of the object within the mutex-protected region.

https://github.com/llvm/llvm-project/pull/164263