Rename ThreadPool::getThreadCount() to getMaxConcurrency() (NFC) (#82296)

This is addressing a long-time TODO to rename this misleading API. The
old one is preserved for now but marked deprecated.

bolt/tools/merge-fdata/merge-fdata.cpp

@@ -317,7 +317,8 @@ void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
   ThreadPoolStrategy S = optimal_concurrency(
       std::max(Filenames.size() / 4, static_cast<size_t>(1)));
   ThreadPool Pool(S);
-  DenseMap<llvm::thread::id, ProfileTy> ParsedProfiles(Pool.getThreadCount());
+  DenseMap<llvm::thread::id, ProfileTy> ParsedProfiles(
+      Pool.getMaxConcurrency());
   for (const auto &Filename : Filenames)
     Pool.async(ParseProfile, std::cref(Filename), std::ref(ParsedProfiles));
   Pool.wait();

clang/tools/clang-scan-deps/ClangScanDeps.cpp

@@ -870,7 +870,7 @@ int clang_scan_deps_main(int argc, char **argv, const llvm::ToolContext &) {
                                     EagerLoadModules);
   llvm::ThreadPool Pool(llvm::hardware_concurrency(NumThreads));
   std::vector<std::unique_ptr<DependencyScanningTool>> WorkerTools;
-  for (unsigned I = 0; I < Pool.getThreadCount(); ++I)
+  for (unsigned I = 0; I < Pool.getMaxConcurrency(); ++I)
     WorkerTools.push_back(std::make_unique<DependencyScanningTool>(Service));
 
   std::vector<tooling::CompileCommand> Inputs =
@@ -894,13 +894,13 @@ int clang_scan_deps_main(int argc, char **argv, const llvm::ToolContext &) {
 
   if (Verbose) {
     llvm::outs() << "Running clang-scan-deps on " << Inputs.size()
-                 << " files using " << Pool.getThreadCount() << " workers\n";
+                 << " files using " << Pool.getMaxConcurrency() << " workers\n";
   }
 
   llvm::Timer T;
   T.startTimer();
 
-  for (unsigned I = 0; I < Pool.getThreadCount(); ++I) {
+  for (unsigned I = 0; I < Pool.getMaxConcurrency(); ++I) {
     Pool.async([&, I]() {
       llvm::DenseSet<ModuleID> AlreadySeenModules;
       while (auto MaybeInputIndex = GetNextInputIndex()) {

llvm/include/llvm/Support/ThreadPool.h

@@ -104,9 +104,12 @@ public:
   /// not to waste the thread.
   void wait(ThreadPoolTaskGroup &Group);
 
-  // TODO: misleading legacy name warning!
   // Returns the maximum number of worker threads in the pool, not the current
   // number of threads!
+  unsigned getMaxConcurrency() const { return MaxThreadCount; }
+
+  // TODO: misleading legacy name warning!
+  LLVM_DEPRECATED("Use getMaxConcurrency instead", "getMaxConcurrency")
   unsigned getThreadCount() const { return MaxThreadCount; }
 
   /// Returns true if the current thread is a worker thread of this thread pool.

llvm/lib/Debuginfod/Debuginfod.cpp

@@ -414,7 +414,7 @@ Error DebuginfodCollection::findBinaries(StringRef Path) {
   sys::fs::recursive_directory_iterator I(Twine(Path), EC), E;
   std::mutex IteratorMutex;
   ThreadPoolTaskGroup IteratorGroup(Pool);
-  for (unsigned WorkerIndex = 0; WorkerIndex < Pool.getThreadCount();
+  for (unsigned WorkerIndex = 0; WorkerIndex < Pool.getMaxConcurrency();
        WorkerIndex++) {
     IteratorGroup.async([&, this]() -> void {
       std::string FilePath;

llvm/lib/LTO/LTO.cpp

@@ -1537,7 +1537,7 @@ public:
   }
 
   unsigned getThreadCount() override {
-    return BackendThreadPool.getThreadCount();
+    return BackendThreadPool.getMaxConcurrency();
   }
 };
 } // end anonymous namespace

mlir/include/mlir/IR/Threading.h

@@ -68,7 +68,7 @@ LogicalResult failableParallelForEach(MLIRContext *context, IteratorT begin,
   // Otherwise, process the elements in parallel.
   llvm::ThreadPool &threadPool = context->getThreadPool();
   llvm::ThreadPoolTaskGroup tasksGroup(threadPool);
-  size_t numActions = std::min(numElements, threadPool.getThreadCount());
+  size_t numActions = std::min(numElements, threadPool.getMaxConcurrency());
   for (unsigned i = 0; i < numActions; ++i)
     tasksGroup.async(processFn);
   // If the current thread is a worker thread from the pool, then waiting for

mlir/lib/ExecutionEngine/AsyncRuntime.cpp

@@ -437,7 +437,7 @@ extern "C" void mlirAsyncRuntimeAwaitAllInGroupAndExecute(AsyncGroup *group,
 }
 
 extern "C" int64_t mlirAsyncRuntimGetNumWorkerThreads() {
-  return getDefaultAsyncRuntime()->getThreadPool().getThreadCount();
+  return getDefaultAsyncRuntime()->getThreadPool().getMaxConcurrency();
 }
 
 //===----------------------------------------------------------------------===//

mlir/lib/IR/MLIRContext.cpp

@@ -638,7 +638,7 @@ unsigned MLIRContext::getNumThreads() {
   if (isMultithreadingEnabled()) {
     assert(impl->threadPool &&
            "multi-threading is enabled but threadpool not set");
-    return impl->threadPool->getThreadCount();
+    return impl->threadPool->getMaxConcurrency();
   }
   // No multithreading or active thread pool. Return 1 thread.
   return 1;

mlir/lib/Pass/Pass.cpp

@@ -748,7 +748,7 @@ void OpToOpPassAdaptor::runOnOperationAsyncImpl(bool verifyPasses) {
   // Create the async executors if they haven't been created, or if the main
   // pipeline has changed.
   if (asyncExecutors.empty() || hasSizeMismatch(asyncExecutors.front(), mgrs))
-    asyncExecutors.assign(context->getThreadPool().getThreadCount(), mgrs);
+    asyncExecutors.assign(context->getThreadPool().getMaxConcurrency(), mgrs);
 
   // This struct represents the information for a single operation to be
   // scheduled on a pass manager.