[llvm] [BOLT][DWARF][NFC] Add option to specify DW_AT_comp_dir (PR #79395)

[Maksim Panchenko via llvm-commits]

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@@ -1574,12 +1575,21 @@ void BinaryContext::preprocessDWODebugInfo() {
   for (const std::unique_ptr<DWARFUnit> &CU : DwCtx->compile_units()) {
     DWARFUnit *const DwarfUnit = CU.get();
     if (std::optional<uint64_t> DWOId = DwarfUnit->getDWOId()) {
-      DWARFUnit *DWOCU = DwarfUnit->getNonSkeletonUnitDIE(false).getDwarfUnit();
+      DWARFUnit *DWOCU = nullptr;
+      std::string DWOName = dwarf::toString(
+          DwarfUnit->getUnitDIE().find(
+              {dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}),
+          "");
+      if (opts::CompDirOverride.empty()) {
+        DWOCU = DwarfUnit->getNonSkeletonUnitDIE(false).getDwarfUnit();
+      } else {
+        SmallString<16> AbsolutePath;
+        sys::path::append(AbsolutePath, opts::CompDirOverride);
+        sys::path::append(AbsolutePath, DWOName);
+        DWOCU = DwarfUnit->getNonSkeletonUnitDIE(false, AbsolutePath)
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maksfb wrote:

Can you keep just one call to `getNonSkeletonUnitDIE()`, but set `AbsolutePath` only when `CompDirOverride` is set?

https://github.com/llvm/llvm-project/pull/79395