[clang] [CIR] Add scoped atomic load operation (PR #171134)

[Andy Kaylor via cfe-commits]

================
@@ -749,6 +743,21 @@ static void emitAtomicExprWithDynamicMemOrder(
       });
 }
 
+// Map clang sync scope to CIR sync scope.
+static cir::SyncScopeKind convertSyncScopeToCIR(clang::SyncScope scope) {
+  switch (scope) {
+  default: {
+    assert(!cir::MissingFeatures::atomicSyncScopeID());
----------------
andykaylor wrote:

This seems like it should have an `errorNYI` diagnostic. There are a lot of cases covered by this default.

https://github.com/llvm/llvm-project/pull/171134