[llvm] fix llvm-gsymutil verification (PR #141751)

[Greg Clayton via llvm-commits]

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@@ -713,6 +713,10 @@ llvm::Error DwarfTransformer::verify(StringRef GsymPath,
                                      OutputAggregator &Out) {
   Out << "Verifying GSYM file \"" << GsymPath << "\":\n";
 
+  for (const auto &CU : DICtx.compile_units()) {
+    CU->clear();
+  }
+
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clayborg wrote:

So if there is some state that wasn't cleared in the DWARFUnit objects (or DWARFCompileUnit objects) then we should be doing one of two things:
- Instead of calling `void DWARFUnit::clearDIEs(bool KeepCUDie, bool KeepDWODies = false);`, we call `DWARFUnit::clear()`. This should reset all of the state correctly and avoid the assertion
- in `void clearDIEs(bool KeepCUDie, bool KeepDWODies = false);` we should clear any state related to the DIEs that needs to be cleared.

https://github.com/llvm/llvm-project/pull/141751