Revert "[DWARF] Support for loclist.dwo section in llvm and llvm-dwarfdump."

This reverts commit 81b0a3284af1dcef26e56b0de9fd74002083c471.
Will Re-apply, with updated Differtial Revision, for automatic closure of
Phabricator review.

4 files changed, 26 insertions, 77 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 551e8a2751b..84444ca5174 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1158,12 +1158,11 @@ void DwarfDebug::finalizeModuleInfo() {
       if (U.hasRangeLists())
         U.addRnglistsBase();
 
-      if (!DebugLocs.getLists().empty()) {
+      if (!DebugLocs.getLists().empty() && !useSplitDwarf()) {
         DebugLocs.setSym(Asm->createTempSymbol("loclists_table_base"));
-        if (!useSplitDwarf())
-          U.addSectionLabel(U.getUnitDie(), dwarf::DW_AT_loclists_base,
-                            DebugLocs.getSym(),
-                            TLOF.getDwarfLoclistsSection()->getBeginSymbol());
+        U.addSectionLabel(U.getUnitDie(), dwarf::DW_AT_loclists_base,
+                          DebugLocs.getSym(),
+                          TLOF.getDwarfLoclistsSection()->getBeginSymbol());
       }
     }
 
@@ -1208,10 +1207,9 @@ void DwarfDebug::endModule() {
   emitDebugStr();
 
   if (useSplitDwarf())
-    // Handles debug_loc.dwo / debug_loclists.dwo section emission
     emitDebugLocDWO();
   else
-    // Handles debug_loc / debug_loclists section emission
+    // Emit info into a debug loc section.
     emitDebugLoc();
 
   // Corresponding abbreviations into a abbrev section.
@@ -2337,6 +2335,8 @@ static MCSymbol *emitLoclistsTableHeader(AsmPrinter *Asm,
 
   const auto &DebugLocs = DD.getDebugLocs();
 
+  // FIXME: Generate the offsets table and use DW_FORM_loclistx with the
+  // DW_AT_loclists_base attribute. Until then set the number of offsets to 0.
   Asm->OutStreamer->AddComment("Offset entry count");
   Asm->emitInt32(DebugLocs.getLists().size());
   Asm->OutStreamer->EmitLabel(DebugLocs.getSym());
@@ -2443,29 +2443,27 @@ static void emitRangeList(
   }
 }
 
-// Handles emission of both debug_loclist / debug_loclist.dwo
 static void emitLocList(DwarfDebug &DD, AsmPrinter *Asm, const DebugLocStream::List &List) {
-  emitRangeList(DD, Asm, List.Label, DD.getDebugLocs().getEntries(List),
-                *List.CU, dwarf::DW_LLE_base_addressx,
-                dwarf::DW_LLE_offset_pair, dwarf::DW_LLE_startx_length,
-                dwarf::DW_LLE_end_of_list, llvm::dwarf::LocListEncodingString,
-                /* ShouldUseBaseAddress */ true,
-                [&](const DebugLocStream::Entry &E) {
-                  DD.emitDebugLocEntryLocation(E, List.CU);
-                });
+  emitRangeList(
+      DD, Asm, List.Label, DD.getDebugLocs().getEntries(List), *List.CU,
+      dwarf::DW_LLE_base_addressx, dwarf::DW_LLE_offset_pair,
+      dwarf::DW_LLE_startx_length, dwarf::DW_LLE_end_of_list,
+      llvm::dwarf::LocListEncodingString,
+      /* ShouldUseBaseAddress */ true,
+      [&](const DebugLocStream::Entry &E) {
+        DD.emitDebugLocEntryLocation(E, List.CU);
+      });
 }
 
-// Emit locations into the .debug_loc/.debug_loclists section.
+// Emit locations into the .debug_loc/.debug_rnglists section.
 void DwarfDebug::emitDebugLoc() {
   if (DebugLocs.getLists().empty())
     return;
 
   MCSymbol *TableEnd = nullptr;
   if (getDwarfVersion() >= 5) {
-
     Asm->OutStreamer->SwitchSection(
         Asm->getObjFileLowering().getDwarfLoclistsSection());
-
     TableEnd = emitLoclistsTableHeader(Asm, *this);
   } else {
     Asm->OutStreamer->SwitchSection(
@@ -2479,29 +2477,11 @@ void DwarfDebug::emitDebugLoc() {
     Asm->OutStreamer->EmitLabel(TableEnd);
 }
 
-// Emit locations into the .debug_loc.dwo/.debug_loclists.dwo section.
 void DwarfDebug::emitDebugLocDWO() {
-  if (DebugLocs.getLists().empty())
-    return;
-
-  if (getDwarfVersion() >= 5) {
-    MCSymbol *TableEnd = nullptr;
-    Asm->OutStreamer->SwitchSection(
-        Asm->getObjFileLowering().getDwarfLoclistsDWOSection());
-    TableEnd = emitLoclistsTableHeader(Asm, *this);
-    for (const auto &List : DebugLocs.getLists())
-      emitLocList(*this, Asm, List);
-
-    if (TableEnd)
-      Asm->OutStreamer->EmitLabel(TableEnd);
-    return;
-  }
-
   for (const auto &List : DebugLocs.getLists()) {
     Asm->OutStreamer->SwitchSection(
         Asm->getObjFileLowering().getDwarfLocDWOSection());
     Asm->OutStreamer->EmitLabel(List.Label);
-
     for (const auto &Entry : DebugLocs.getEntries(List)) {
       // GDB only supports startx_length in pre-standard split-DWARF.
       // (in v5 standard loclists, it currently* /only/ supports base_address +
@@ -2514,6 +2494,7 @@ void DwarfDebug::emitDebugLocDWO() {
       unsigned idx = AddrPool.getIndex(Entry.Begin);
       Asm->EmitULEB128(idx);
       Asm->EmitLabelDifference(Entry.End, Entry.Begin, 4);
+
       emitDebugLocEntryLocation(Entry, List.CU);
     }
     Asm->emitInt8(dwarf::DW_LLE_end_of_list);
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
index 012bab35460..f7b3fb495f9 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -404,14 +404,6 @@ void DWARFContext::dump(
     dumpLoclistsSection(OS, LLDumpOpts, Data, getRegisterInfo(), *Off);
   }
   if (const auto *Off =
-          shouldDump(ExplicitDWO, ".debug_loclists.dwo", DIDT_ID_DebugLoclists,
-                     DObj->getLoclistsDWOSection().Data)) {
-    DWARFDataExtractor Data(*DObj, DObj->getLoclistsDWOSection(),
-                            isLittleEndian(), 0);
-    dumpLoclistsSection(OS, LLDumpOpts, Data, getRegisterInfo(), *Off);
-  }
-
-  if (const auto *Off =
           shouldDump(ExplicitDWO, ".debug_loc.dwo", DIDT_ID_DebugLoc,
                      DObj->getLocDWOSection().Data)) {
     DWARFDataExtractor Data(*DObj, DObj->getLocDWOSection(), isLittleEndian(),
@@ -1393,7 +1385,6 @@ class DWARFObjInMemory final : public DWARFObject {
 
   DWARFSectionMap LocSection;
   DWARFSectionMap LoclistsSection;
-  DWARFSectionMap LoclistsDWOSection;
   DWARFSectionMap LineSection;
   DWARFSectionMap RangesSection;
   DWARFSectionMap RnglistsSection;
@@ -1420,7 +1411,6 @@ class DWARFObjInMemory final : public DWARFObject {
     return StringSwitch<DWARFSectionMap *>(Name)
         .Case("debug_loc", &LocSection)
         .Case("debug_loclists", &LoclistsSection)
-        .Case("debug_loclists.dwo", &LoclistsDWOSection)
         .Case("debug_line", &LineSection)
         .Case("debug_frame", &FrameSection)
         .Case("eh_frame", &EHFrameSection)
@@ -1751,9 +1741,6 @@ public:
   const DWARFSection &getRnglistsDWOSection() const override {
     return RnglistsDWOSection;
   }
-  const DWARFSection &getLoclistsDWOSection() const override {
-    return LoclistsDWOSection;
-  }
   const DWARFSection &getAddrSection() const override { return AddrSection; }
   StringRef getCUIndexSection() const override { return CUIndexSection; }
   StringRef getGdbIndexSection() const override { return GdbIndexSection; }
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
index b662e88816f..e5d33e13644 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
@@ -186,16 +186,9 @@ DWARFUnit::DWARFUnit(DWARFContext &DC, const DWARFSection &Section,
     if (auto *IndexEntry = Header.getIndexEntry())
       if (const auto *C = IndexEntry->getOffset(DW_SECT_LOC))
         Data = Data.substr(C->Offset, C->Length);
-
-    DWARFDataExtractor DWARFData =
-        Header.getVersion() >= 5
-            ? DWARFDataExtractor(Context.getDWARFObj(),
-                                 Context.getDWARFObj().getLoclistsDWOSection(),
-                                 isLittleEndian, getAddressByteSize())
-            : DWARFDataExtractor(Data, isLittleEndian, getAddressByteSize());
-    LocTable =
-        std::make_unique<DWARFDebugLoclists>(DWARFData, Header.getVersion());
-
+    LocTable = std::make_unique<DWARFDebugLoclists>(
+        DWARFDataExtractor(Data, isLittleEndian, getAddressByteSize()),
+        Header.getVersion());
   } else if (Header.getVersion() >= 5) {
     LocTable = std::make_unique<DWARFDebugLoclists>(
         DWARFDataExtractor(Context.getDWARFObj(),
@@ -509,23 +502,14 @@ Error DWARFUnit::tryExtractDIEsIfNeeded(bool CUDieOnly) {
         RangeSectionBase = RngListTable->getHeaderSize();
     }
 
-    // In a split dwarf unit, there is no DW_AT_loclists_base attribute.
-    // Setting LocSectionBase to point past the table header.
-    if (IsDWO)
-      setLocSection(&Context.getDWARFObj().getLoclistsDWOSection(),
-                    DWARFListTableHeader::getHeaderSize(Header.getFormat()));
-    else
-      setLocSection(&Context.getDWARFObj().getLoclistsSection(),
-                    toSectionOffset(UnitDie.find(DW_AT_loclists_base), 0));
+    // FIXME: add loclists.dwo support
+    setLocSection(&Context.getDWARFObj().getLoclistsSection(),
+                  toSectionOffset(UnitDie.find(DW_AT_loclists_base), 0));
 
     if (LocSection->Data.size()) {
-      if (IsDWO)
-        LoclistTableHeader.emplace(".debug_loclists.dwo", "locations");
-      else
-        LoclistTableHeader.emplace(".debug_loclists", "locations");
-
+      LoclistTableHeader.emplace(".debug_loclists", "locations");
+      uint64_t Offset = LocSectionBase;
       uint64_t HeaderSize = DWARFListTableHeader::getHeaderSize(Header.getFormat());
-      uint64_t Offset = getLocSectionBase();
       DWARFDataExtractor Data(Context.getDWARFObj(), *LocSection,
                               isLittleEndian, getAddressByteSize());
       if (Offset < HeaderSize)
diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index 5b4da1998c4..53a9467041c 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -464,9 +464,6 @@ void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T, bool Large) {
   DwarfRnglistsDWOSection =
       Ctx->getELFSection(".debug_rnglists.dwo", DebugSecType, ELF::SHF_EXCLUDE);
 
-  DwarfLoclistsDWOSection =
-      Ctx->getELFSection(".debug_loclists.dwo", DebugSecType, ELF::SHF_EXCLUDE);
-
   // DWP Sections
   DwarfCUIndexSection =
       Ctx->getELFSection(".debug_cu_index", DebugSecType, 0);