[clang] [RFC] Add clang atomic control options and pragmas (PR #102569)

[Matt Arsenault via cfe-commits]

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@@ -5881,6 +5881,32 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   RenderFloatingPointOptions(TC, D, OFastEnabled, Args, CmdArgs, JA);
 
+  if (Arg *AtomicArg = Args.getLastArg(options::OPT_fatomic_EQ)) {
+    if (!AtomicArg->getNumValues()) {
+      D.Diag(clang::diag::warn_drv_empty_joined_argument)
+          << AtomicArg->getAsString(Args);
+    } else {
+      bool Valid = true;
+      std::set<StringRef> Keys;
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arsenm wrote:

Don't use std::set 

https://github.com/llvm/llvm-project/pull/102569