[clang] [memprof] Export __memprof_default_options_str on Darwin (PR #128920)

[Teresa Johnson via cfe-commits]

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@@ -1617,6 +1617,10 @@ void DarwinClang::AddLinkRuntimeLibArgs(const ArgList &Args,
     }
   }
 
+  if (Sanitize.needsMemProfRt())
+    if (hasExportSymbolDirective(Args))
+      addExportedSymbol(CmdArgs, "___memprof_default_options_str");
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teresajohnson wrote:

Looks like this file already includes a header from llvm/ProfileData, so maybe put it into MemProf.h in that directory?

I just noticed that the symbol name here has an extra leading underscore (noticed because I couldn't find it searching the code). Which would be avoided by using a common variable. But also makes me wonder how this is working?

https://github.com/llvm/llvm-project/pull/128920