[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:

Capturing DwarfOutputPath and DWOName by reference in the async call resulted in errors where they were invalid values, likely because the ThreadPool executed it asynchronously so they were out of scope.

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