[clang] [llvm] [win][x64] Unwind v2 3/n: Add support for emitting unwind v2 information (equivalent to MSVC /d2epilogunwind) (PR #129142)

[Eli Friedman via cfe-commits]

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@@ -500,7 +500,8 @@ MCSymbol *MCStreamer::emitLineTableLabel() {
 MCSymbol *MCStreamer::emitCFILabel() {
   // Return a dummy non-null value so that label fields appear filled in when
   // generating textual assembly.
-  return (MCSymbol *)1;
+  static size_t DummyLabelValue = 0;
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efriedma-quic wrote:

(Also, non-const static variables are basically banned in LLVM code: in contexts like LTO, we run multiple instances of the compiler in parallel, and a static variable will explode if you do that.)

https://github.com/llvm/llvm-project/pull/129142