[llvm] Reduce llvm-gsymutil memory usage (PR #91023)

[Alexander Yermolovich via llvm-commits]

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@@ -658,6 +673,8 @@ void DWARFUnit::clearDIEs(bool KeepCUDie) {
   // It depends on the implementation whether the request is fulfilled.
   // Create a new vector with a small capacity and assign it to the DieArray to
   // have previous contents freed.
+  llvm::sys::ScopedWriter CULock(CUDieArrayMutex);
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ayermolo wrote:

Not clear to me, why do we need two different locks?

https://github.com/llvm/llvm-project/pull/91023