[llvm] [BOLT][DWARF][NFC] Add parallelization for processing of DWO debug information (PR #100282)

[Sayhaan Siddiqui via llvm-commits]

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@@ -757,9 +768,12 @@ void DWARFRewriter::updateDebugInfo() {
               : std::optional<std::string>(opts::DwarfOutputPath.c_str());
       std::string DWOName = DIEBlder.updateDWONameCompDir(
           *StrOffstsWriter, *StrWriter, *CU, DwarfOutputPath, std::nullopt);
-      processSplitCU(*CU, **SplitCU, DIEBlder, *TempRangesSectionWriter,
-                     AddressWriter, DWOName, DwarfOutputPath);
+      ThreadPool.async([&, DwarfOutputPath, DWOName] {
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sayhaan wrote:

Yes, ran into a similar issue for DwarfOutputPath where it was nullopt and the output path was empty as a result so the folder was missing dwo files.

https://github.com/llvm/llvm-project/pull/100282