[llvm] [llvm-ml] Add MASM unwind v3 support for x64 exception handling and improve MSVC compat (PR #202809)

[Mikołaj Piróg via llvm-commits]

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@@ -81,6 +83,9 @@ def safeseh : MLFlag<"safeseh">,
                        "exception handlers or containing exception handlers "
                        "that are all declared with .SAFESEH. Only available in "
                        "32-bit.">;
+def unwindv3 : MLFlag<"unwindv3">,
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mikolaj-pirog wrote:

What will happen when assembly with pp2 will be used and this flag is not used?

https://github.com/llvm/llvm-project/pull/202809