[PATCH] D54361: [ELF] .gdb_index: fix CuOff when a .debug_info section more than 1 CU

[Fangrui Song via Phabricator via llvm-commits]

MaskRay updated this revision to Diff 173491.
MaskRay added a comment.

Use debug_info_offset to index into CUs


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D54361

Files:
  ELF/SyntheticSections.cpp


Index: ELF/SyntheticSections.cpp
===================================================================
--- ELF/SyntheticSections.cpp
+++ ELF/SyntheticSections.cpp
@@ -2413,28 +2413,45 @@
 }
 
 static std::vector<GdbIndexSection::NameTypeEntry>
-readPubNamesAndTypes(DWARFContext &Dwarf, uint32_t Idx) {
+readPubNamesAndTypes(DWARFContext &Dwarf,
+                     const std::vector<GdbIndexSection::CuEntry> &CUs) {
   StringRef Sec1 = Dwarf.getDWARFObj().getGnuPubNamesSection();
   StringRef Sec2 = Dwarf.getDWARFObj().getGnuPubTypesSection();
 
   std::vector<GdbIndexSection::NameTypeEntry> Ret;
   for (StringRef Sec : {Sec1, Sec2}) {
     DWARFDebugPubTable Table(Sec, Config->IsLE, true);
-    for (const DWARFDebugPubTable::Set &Set : Table.getData())
+    for (const DWARFDebugPubTable::Set &Set : Table.getData()) {
+      // The CU offset should be added to I when the entry is written into the
+      // constant pool.
+      uint32_t I =
+          std::lower_bound(CUs.begin(), CUs.end(), Set.Offset,
+                           [](const GdbIndexSection::CuEntry &CU,
+                              uint32_t Off) { return CU.CuOffset < Off; }) -
+          CUs.begin();
       for (const DWARFDebugPubTable::Entry &Ent : Set.Entries)
         Ret.push_back({{Ent.Name, computeGdbHash(Ent.Name)},
-                       (Ent.Descriptor.toBits() << 24) | Idx});
+                       (Ent.Descriptor.toBits() << 24) | I});
+    }
   }
   return Ret;
 }
 
 // Create a list of symbols from a given list of symbol names and types
 // by uniquifying them by name.
 static std::vector<GdbIndexSection::GdbSymbol>
-createSymbols(ArrayRef<std::vector<GdbIndexSection::NameTypeEntry>> NameTypes) {
+createSymbols(ArrayRef<std::vector<GdbIndexSection::NameTypeEntry>> NameTypes,
+              const std::vector<GdbIndexSection::GdbChunk> &Chunks) {
   typedef GdbIndexSection::GdbSymbol GdbSymbol;
   typedef GdbIndexSection::NameTypeEntry NameTypeEntry;
 
+  uint32_t CuOff = 0;
+  std::vector<uint32_t> CuOffs(Chunks.size());
+  for (uint32_t I = 0, E = Chunks.size(); I != E; ++I) {
+    CuOffs[I] = CuOff;
+    CuOff += Chunks[I].CompilationUnits.size();
+  }
+
   // The number of symbols we will handle in this function is of the order
   // of millions for very large executables, so we use multi-threading to
   // speed it up.
@@ -2451,21 +2468,24 @@
   // Instantiate GdbSymbols while uniqufying them by name.
   std::vector<std::vector<GdbSymbol>> Symbols(NumShards);
   parallelForEachN(0, Concurrency, [&](size_t ThreadId) {
+    uint32_t I = 0;
     for (ArrayRef<NameTypeEntry> Entries : NameTypes) {
       for (const NameTypeEntry &Ent : Entries) {
         size_t ShardId = Ent.Name.hash() >> Shift;
         if ((ShardId & (Concurrency - 1)) != ThreadId)
           continue;
 
+        uint32_t V = Ent.Type + CuOffs[I];
         size_t &Idx = Map[ShardId][Ent.Name];
         if (Idx) {
-          Symbols[ShardId][Idx - 1].CuVector.push_back(Ent.Type);
+          Symbols[ShardId][Idx - 1].CuVector.push_back(V);
           continue;
         }
 
         Idx = Symbols[ShardId].size() + 1;
-        Symbols[ShardId].push_back({Ent.Name, {Ent.Type}, 0, 0});
+        Symbols[ShardId].push_back({Ent.Name, {V}, 0, 0});
       }
+      ++I;
     }
   });
 
@@ -2517,12 +2537,12 @@
     Chunks[I].Sec = Sections[I];
     Chunks[I].CompilationUnits = readCuList(Dwarf);
     Chunks[I].AddressAreas = readAddressAreas(Dwarf, Sections[I]);
-    NameTypes[I] = readPubNamesAndTypes(Dwarf, I);
+    NameTypes[I] = readPubNamesAndTypes(Dwarf, Chunks[I].CompilationUnits);
   });
 
   auto *Ret = make<GdbIndexSection>();
   Ret->Chunks = std::move(Chunks);
-  Ret->Symbols = createSymbols(NameTypes);
+  Ret->Symbols = createSymbols(NameTypes, Ret->Chunks);
   Ret->initOutputSize();
   return Ret;
 }


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