[NVPTX] Simplify error output when SyncScope ID not found

Author: gonzalobg

llvm/lib/Target/NVPTX/NVPTXISelDAGToDAG.cpp

@@ -4176,7 +4176,7 @@ bool NVPTXDAGToDAGISel::tryFence(SDNode *N) {
   return true;
 }
 
-NVPTXScopes::NVPTXScopes(LLVMContext &C) : CTX(&C) {
+NVPTXScopes::NVPTXScopes(LLVMContext &C) {
   Scopes[C.getOrInsertSyncScopeID("singlethread")] = NVPTX::Scope::Thread;
   Scopes[C.getOrInsertSyncScopeID("")] = NVPTX::Scope::System;
   Scopes[C.getOrInsertSyncScopeID("block")] = NVPTX::Scope::Block;
@@ -4191,13 +4191,11 @@ NVPTX::Scope NVPTXScopes::operator[](SyncScope::ID ID) const {
 
   auto S = Scopes.find(ID);
   if (S == Scopes.end()) {
-    SmallVector<StringRef, 8> ScopeNames;
-    assert(CTX != nullptr && "CTX is nullptr");
-    CTX->getSyncScopeNames(ScopeNames);
-    StringRef Unknown{"unknown"};
-    auto Name = ID < ScopeNames.size() ? ScopeNames[ID] : Unknown;
-    report_fatal_error(
-        formatv("Could not find scope ID={} with name \"{}\".", int(ID), Name));
+    // TODO:
+    // - Add API to LLVMContext to get the name of a single scope.
+    // - Use that API here to print an error containing the name
+    //   of this Unknown ID.
+    report_fatal_error(formatv("Could not find scope ID={}.", int(ID)));
   }
   return S->second;
 }

llvm/lib/Target/NVPTX/NVPTXISelDAGToDAG.h

@@ -35,7 +35,6 @@ struct NVPTXScopes {
 
 private:
   SmallMapVector<SyncScope::ID, NVPTX::Scope, 8> Scopes{};
-  LLVMContext *CTX = nullptr;
 };
 
 class LLVM_LIBRARY_VISIBILITY NVPTXDAGToDAGISel : public SelectionDAGISel {