[CodeGen] Port AtomicExpand to new Pass Manager (#71220)

Port the `atomicexpand` pass to the new Pass Manager. 
Fixes #64559

Author: Ris-Bali

llvm/include/llvm/CodeGen/AtomicExpand.h

@@ -0,0 +1,30 @@
+//===-- AtomicExpand.h - Expand Atomic Instructions -------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_ATOMICEXPAND_H
+#define LLVM_CODEGEN_ATOMICEXPAND_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class Function;
+class TargetMachine;
+
+class AtomicExpandPass : public PassInfoMixin<AtomicExpandPass> {
+private:
+  const TargetMachine *TM;
+
+public:
+  AtomicExpandPass(const TargetMachine *TM) : TM(TM) {}
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_CODEGEN_ATOMICEXPAND_H

llvm/include/llvm/CodeGen/Passes.h

@@ -44,7 +44,7 @@ namespace llvm {
   /// AtomicExpandPass - At IR level this pass replace atomic instructions with
   /// __atomic_* library calls, or target specific instruction which implement the
   /// same semantics in a way which better fits the target backend.
-  FunctionPass *createAtomicExpandPass();
+  FunctionPass *createAtomicExpandLegacyPass();
 
   /// createUnreachableBlockEliminationPass - The LLVM code generator does not
   /// work well with unreachable basic blocks (what live ranges make sense for a

llvm/include/llvm/InitializePasses.h

@@ -52,7 +52,7 @@ void initializeAAResultsWrapperPassPass(PassRegistry&);
 void initializeAlwaysInlinerLegacyPassPass(PassRegistry&);
 void initializeAssignmentTrackingAnalysisPass(PassRegistry &);
 void initializeAssumptionCacheTrackerPass(PassRegistry&);
-void initializeAtomicExpandPass(PassRegistry&);
+void initializeAtomicExpandLegacyPass(PassRegistry &);
 void initializeBasicBlockPathCloningPass(PassRegistry &);
 void initializeBasicBlockSectionsProfileReaderWrapperPassPass(PassRegistry &);
 void initializeBasicBlockSectionsPass(PassRegistry &);

llvm/include/llvm/LinkAllPasses.h

@@ -60,6 +60,7 @@ namespace {
       if (std::getenv("bar") != (char*) -1)
         return;
 
+      (void)llvm::createAtomicExpandLegacyPass();
       (void) llvm::createBasicAAWrapperPass();
       (void) llvm::createSCEVAAWrapperPass();
       (void) llvm::createTypeBasedAAWrapperPass();