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

[Kevin Frei via llvm-commits]

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@@ -658,6 +711,9 @@ 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 FreeLock(CUDieFreeMutex);
+  llvm::sys::ScopedWriter CULock(CUDieArrayMutex);
+  llvm::sys::ScopedWriter AllLock(AllDieArrayMutex);
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kevinfrei wrote:

@dwblaikie what are you thoughts here? I've updated the diff to use the 3 locks as efficiently as I can come up with. If you'd like to chat in real time, I'm happy to hop on a VC in whatever host system you're comfortable with (and my calendar is fully blocked off all day Friday) I really do need this diff landed.

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