[clang] [MS] Add /Zc:tlsGuards option to control tls guard emission (PR #113830)

[Eli Friedman via cfe-commits]

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@@ -4063,6 +4063,11 @@ defm threadsafe_statics : BoolFOption<"threadsafe-statics",
   NegFlag<SetFalse, [], [ClangOption, CC1Option],
           "Do not emit code to make initialization of local statics thread safe">,
   PosFlag<SetTrue>>;
+defm tls_guards : BoolFOption<"tls-guards",
+  LangOpts<"TlsGuards">, DefaultTrue,
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efriedma-quic wrote:

My understanding is that if a tls variable is defined inside a function, we don't call __dyn_tls_on_demand_init anyway.  But I don't care that much about the name.

https://github.com/llvm/llvm-project/pull/113830