[BOLT][DWARF] Fix handling of DWARF5 DWP (llvm#72729)

Fixed handling of DWP as input. Before BOLT crashed. Now it will write
out
correct CU, and all the TUs. Potential future improvement is to scan all
the TUs
used in this CU, and only include those.

Author: ayermolo

bolt/include/bolt/Core/DIEBuilder.h

@@ -273,7 +273,8 @@ class DIEBuilder {
   void buildCompileUnits(const std::vector<DWARFUnit *> &CUs);
   /// Preventing implicit conversions.
   template <class T> void buildCompileUnits(T) = delete;
-  void buildBoth();
+  /// Builds DWO Unit. For DWARF5 this includes the type units.
+  void buildDWOUnit(DWARFUnit &U);
 
   /// Returns DWARFUnitInfo for DWARFUnit
   DWARFUnitInfo &getUnitInfoByDwarfUnit(const DWARFUnit &DwarfUnit) {

bolt/lib/Core/DIEBuilder.cpp

@@ -193,12 +193,6 @@ void DIEBuilder::buildTypeUnits(const bool Init) {
   if (Init)
     BuilderState.reset(new State());
 
-  unsigned int CUNum = getCUNum(DwarfContext, IsDWO);
-  getState().CloneUnitCtxMap.resize(CUNum);
-  DWARFContext::unit_iterator_range CU4TURanges =
-      IsDWO ? DwarfContext->dwo_types_section_units()
-            : DwarfContext->types_section_units();
-
   const DWARFUnitIndex &TUIndex = DwarfContext->getTUIndex();
   if (!TUIndex.getRows().empty()) {
     for (auto &Row : TUIndex.getRows()) {
@@ -208,6 +202,11 @@ void DIEBuilder::buildTypeUnits(const bool Init) {
                                        true);
     }
   }
+  unsigned int CUNum = getCUNum(DwarfContext, IsDWO);
+  getState().CloneUnitCtxMap.resize(CUNum);
+  DWARFContext::unit_iterator_range CU4TURanges =
+      IsDWO ? DwarfContext->dwo_types_section_units()
+            : DwarfContext->types_section_units();
 
   getState().Type = ProcessingType::DWARF4TUs;
   for (std::unique_ptr<DWARFUnit> &DU : CU4TURanges)
@@ -278,11 +277,13 @@ void DIEBuilder::buildCompileUnits(const std::vector<DWARFUnit *> &CUs) {
     constructFromUnit(*DU);
 }
 
-void DIEBuilder::buildBoth() {
+void DIEBuilder::buildDWOUnit(DWARFUnit &U) {
   BuilderState.release();
   BuilderState = std::make_unique<State>();
   buildTypeUnits(false);
-  buildCompileUnits(false);
+  getState().Type = ProcessingType::CUs;
+  registerUnit(U, false);
+  constructFromUnit(U);
 }
 
 DIE *DIEBuilder::constructDIEFast(DWARFDie &DDie, DWARFUnit &U,

bolt/lib/Rewrite/DWARFRewriter.cpp

@@ -481,7 +481,7 @@ emitUnit(DIEBuilder &DIEBldr, DIEStreamer &Streamer, DWARFUnit &Unit) {
 
 static void emitDWOBuilder(const std::string &DWOName,
                            DIEBuilder &DWODIEBuilder, DWARFRewriter &Rewriter,
-                           const DWARFUnit &SplitCU, DWARFUnit &CU,
+                           DWARFUnit &SplitCU, DWARFUnit &CU,
                            DWARFRewriter::DWPState &State,
                            DebugLocWriter &LocWriter) {
   // Populate debug_info and debug_abbrev for current dwo into StringRef.
@@ -498,17 +498,15 @@ static void emitDWOBuilder(const std::string &DWOName,
   DWARFRewriter::UnitMetaVectorType TUMetaVector;
   DWARFRewriter::UnitMeta CUMI = {0, 0, 0};
   if (SplitCU.getContext().getMaxDWOVersion() >= 5) {
-    // TODO: Handle DWP as input. Right now it will iterate over all of CUs and
-    // TUs
     for (std::unique_ptr<llvm::DWARFUnit> &CU :
          SplitCU.getContext().dwo_info_section_units()) {
+      if (!CU->isTypeUnit())
+        continue;
       DWARFRewriter::UnitMeta MI =
           emitUnit(DWODIEBuilder, *Streamer, *CU.get());
-      if (CU->isTypeUnit())
-        TUMetaVector.emplace_back(MI);
-      else
-        CUMI = MI;
+      TUMetaVector.emplace_back(MI);
     }
+    CUMI = emitUnit(DWODIEBuilder, *Streamer, SplitCU);
   } else {
     for (std::unique_ptr<llvm::DWARFUnit> &CU :
          SplitCU.getContext().dwo_compile_units())
@@ -707,7 +705,7 @@ void DWARFRewriter::updateDebugInfo() {
     // Skipping CUs that failed to load.
     if (SplitCU) {
       DIEBuilder DWODIEBuilder(&(*SplitCU)->getContext(), true);
-      DWODIEBuilder.buildBoth();
+      DWODIEBuilder.buildDWOUnit(**SplitCU);
       std::string DWOName = updateDWONameCompDir(
           *Unit, *DIEBlder, *DIEBlder->getUnitDIEbyUnit(*Unit));