[llvm] [win][arm64ec] Handle empty function names (PR #151609)

[Daniel Paoliello via llvm-commits]

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@@ -46,7 +47,7 @@ class DSOLocalEquivalent;
 
 class LLVM_ABI TargetLoweringObjectFile : public MCObjectFileInfo {
   /// Name-mangler for global names.
-  Mangler *Mang = nullptr;
+  std::unique_ptr<Mangler> Mang = std::make_unique<Mangler>();
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dpaoliello wrote:

> It won't produce exactly the same names the mangler would, but I don't think that matters.

That was my worry, that we'd end up with the Arm64EC name and ordinary name being completely different. I suppose that doesn't really matter since the function is unnamed so there's no guarantee about naming in a different compilation so the anti-dependencies are moot?

https://github.com/llvm/llvm-project/pull/151609