[NVPTX] Support __scoped_atomic_* operations in NVPTX (#184737)

Summary:
All the infrastructure for this is here, it's just no one's turned it
on.

clang/lib/CodeGen/Targets/NVPTX.cpp

@@ -8,6 +8,7 @@
 
 #include "ABIInfoImpl.h"
 #include "TargetInfo.h"
+#include "clang/Basic/SyncScope.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/IR/CallingConv.h"
@@ -50,6 +51,9 @@ public:
                            CodeGen::CodeGenModule &M) const override;
   bool shouldEmitStaticExternCAliases() const override;
 
+  StringRef getLLVMSyncScopeStr(const LangOptions &LangOpts, SyncScope Scope,
+                                llvm::AtomicOrdering Ordering) const override;
+
   llvm::Constant *getNullPointer(const CodeGen::CodeGenModule &CGM,
                                  llvm::PointerType *T,
                                  QualType QT) const override;
@@ -299,6 +303,35 @@ bool NVPTXTargetCodeGenInfo::shouldEmitStaticExternCAliases() const {
   return false;
 }
 
+StringRef NVPTXTargetCodeGenInfo::getLLVMSyncScopeStr(
+    const LangOptions &LangOpts, SyncScope Scope,
+    llvm::AtomicOrdering Ordering) const {
+  switch (Scope) {
+  case SyncScope::HIPSingleThread:
+  case SyncScope::SingleScope:
+    return "singlethread";
+  case SyncScope::HIPWavefront:
+  case SyncScope::OpenCLSubGroup:
+  case SyncScope::WavefrontScope:
+  case SyncScope::HIPWorkgroup:
+  case SyncScope::OpenCLWorkGroup:
+  case SyncScope::WorkgroupScope:
+    return "block";
+  case SyncScope::HIPCluster:
+  case SyncScope::ClusterScope:
+    return "cluster";
+  case SyncScope::HIPAgent:
+  case SyncScope::OpenCLDevice:
+  case SyncScope::DeviceScope:
+    return "device";
+  case SyncScope::SystemScope:
+  case SyncScope::HIPSystem:
+  case SyncScope::OpenCLAllSVMDevices:
+    return "";
+  }
+  llvm_unreachable("Unknown SyncScope enum");
+}
+
 llvm::Constant *
 NVPTXTargetCodeGenInfo::getNullPointer(const CodeGen::CodeGenModule &CGM,
                                        llvm::PointerType *PT,