[BOLT][DWARF] Avoid invalid work if DWO id is zero #154749
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@llvm/pr-subscribers-bolt Author: Jinjie Huang (Jinjie-Huang) ChangesDWOs with a DWOId of 0 are considered invalid. Currently, createRangeLocListAddressWriters() is called before these invalid DWOs are skipped, which seems unnecessary. Perhaps we can check the DWOId beforehand? BTW, this may lead to an assertion failure inside createRangeLocListAddressWriters("RangeLists writer for DWO unit already exists.), when a duplicate DWO ID of 0 is encountered. I hit this case when using the compiler built prior to this commit with -fsplit-dwarf-inlining enabled, which generates a large number of Compile Units with a DWO ID == 0. I'm not sure if other scenarios could also trigger this issue. Full diff: https://github.com/llvm/llvm-project/pull/154749.diff 1 Files Affected:
diff --git a/bolt/lib/Rewrite/DWARFRewriter.cpp b/bolt/lib/Rewrite/DWARFRewriter.cpp
index 0c1a1bac6c72e..e8f6189eb5a69 100644
--- a/bolt/lib/Rewrite/DWARFRewriter.cpp
+++ b/bolt/lib/Rewrite/DWARFRewriter.cpp
@@ -729,13 +729,13 @@ void DWARFRewriter::updateDebugInfo() {
ThreadPoolInterface &ThreadPool =
ParallelUtilities::getThreadPool(ThreadCount);
for (DWARFUnit *CU : DIEBlder.getProcessedCUs()) {
- createRangeLocListAddressWriters(*CU);
std::optional<DWARFUnit *> SplitCU;
std::optional<uint64_t> DWOId = CU->getDWOId();
if (DWOId)
SplitCU = BC.getDWOCU(*DWOId);
if (!SplitCU)
continue;
+ createRangeLocListAddressWriters(*CU);
DebugAddrWriter &AddressWriter =
*AddressWritersByCU[CU->getOffset()].get();
DebugRangesSectionWriter &TempRangesSectionWriter =
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That sounds like a broken DWARF. Maybe better approach is to detect it and not to update debug information at all. |
Perhaps we can skip mapping the RangeListsWriters for those DWOs with a DWOId of 0, since currently "0" is considered invalid?
Btw, multiple DWOIds of 0 may lead to an assertion failure inside createRangeLocListAddressWriters("RangeLists writer for DWO unit already exists"). I hit this case when using the compiler built prior to this commit with -fsplit-dwarf-inlining enabled, which generates a large number of Compile Units with a DWO ID == 0. I'm not sure if there are other cases could also trigger this issue.