[clang] Add clang atomic control options and attribute (PR #114841)

[Yaxun Liu via cfe-commits]

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@@ -625,6 +625,43 @@ static Attr *handleHLSLControlFlowHint(Sema &S, Stmt *St, const ParsedAttr &A,
   return ::new (S.Context) HLSLControlFlowHintAttr(S.Context, A);
 }
 
+static Attr *handleAtomicAttr(Sema &S, Stmt *St, const ParsedAttr &A,
+                              SourceRange Range) {
+  if (!isa<CompoundStmt>(St)) {
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yxsamliu wrote:

Yes we still need this. The infrastructure from Attr.td parses the attribute and creates ParsedAttr. The AtomicAttr in AST still needs to be created in Sema by this handler. However, we could avoid the specific parsing function for AtomicAttr in ParseDecl.cpp

https://github.com/llvm/llvm-project/pull/114841