[BOLT][DWARF][NFC] Move initialization of DWOName outside of lambda

[sayhaan]

Followup to the splitting of processUnitDIE, moves code that accesses common resource to be outside of the function that will be parallelized.

Followup to #99957

[llvmbot]

@llvm/pr-subscribers-bolt

Author: Sayhaan Siddiqui (sayhaan)

Changes

Followup to the splitting of processUnitDIE, moves code that accesses common resource to be outside of the function that will be parallelized.

---

Full diff: https://github.com/llvm/llvm-project/pull/99728.diff

1 Files Affected:

• (modified) bolt/lib/Rewrite/DWARFRewriter.cpp (+12-12)

diff --git a/bolt/lib/Rewrite/DWARFRewriter.cpp b/bolt/lib/Rewrite/DWARFRewriter.cpp
index f0dd7baf82879..66520ebab47e1 100644
--- a/bolt/lib/Rewrite/DWARFRewriter.cpp
+++ b/bolt/lib/Rewrite/DWARFRewriter.cpp
@@ -668,20 +668,12 @@ void DWARFRewriter::updateDebugInfo() {
   auto processSplitCU = [&](DWARFUnit &Unit, DWARFUnit &SplitCU,
                             DIEBuilder &DIEBlder,
                             DebugRangesSectionWriter &TempRangesSectionWriter,
-                            DebugAddrWriter &AddressWriter) {
+                            DebugAddrWriter &AddressWriter,
+                            std::string &DWOName,
+                            std::optional<std::string> &DwarfOutputPath) {
     DIEBuilder DWODIEBuilder(BC, &(SplitCU).getContext(), DebugNamesTable,
                              &Unit);
     DWODIEBuilder.buildDWOUnit(SplitCU);
-    std::string DWOName = "";
-    std::optional<std::string> DwarfOutputPath =
-        opts::DwarfOutputPath.empty()
-            ? std::nullopt
-            : std::optional<std::string>(opts::DwarfOutputPath.c_str());
-    {
-      std::lock_guard<std::mutex> Lock(AccessMutex);
-      DWOName = DIEBlder.updateDWONameCompDir(
-          *StrOffstsWriter, *StrWriter, Unit, DwarfOutputPath, std::nullopt);
-    }
     DebugStrOffsetsWriter DWOStrOffstsWriter(BC);
     DebugStrWriter DWOStrWriter((SplitCU).getContext(), true);
     DWODIEBuilder.updateDWONameCompDirForTypes(
@@ -759,8 +751,16 @@ void DWARFRewriter::updateDebugInfo() {
       DebugRangesSectionWriter *TempRangesSectionWriter =
           CU->getVersion() >= 5 ? RangeListsWritersByCU[*DWOId].get()
                                 : LegacyRangesWritersByCU[*DWOId].get();
+      std::string DWOName = "";
+      std::optional<std::string> DwarfOutputPath =
+          opts::DwarfOutputPath.empty()
+              ? std::nullopt
+              : std::optional<std::string>(opts::DwarfOutputPath.c_str());
+      std::lock_guard<std::mutex> Lock(AccessMutex);
+      DWOName = DIEBlder.updateDWONameCompDir(*StrOffstsWriter, *StrWriter, *CU,
+                                              DwarfOutputPath, std::nullopt);
       processSplitCU(*CU, **SplitCU, DIEBlder, *TempRangesSectionWriter,
-                     AddressWriter);
+                     AddressWriter, DWOName, DwarfOutputPath);
     }
     for (DWARFUnit *CU : DIEBlder.getProcessedCUs())
       processMainBinaryCU(*CU, DIEBlder);

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[kevinfrei]

Why does hoisting this out of the lambda mean you don't need the lock anymore?

[sayhaan]

The lock was previously part of the old multithreading implementation which we weren't using. Previously the plan was to remove it in a followup PR but since we're moving it out of the lambda here it doesn't make sense to have the lock at all since DWOName is processed sequentially.

[ayermolo]

NIt. Change title to be more clear what you moved.
refer to other PR directly by URL.