[DWARF v5] improved support for .debug_rnglists/consumer

[wolfgangp]

Summary

This patch is intended to significantly improve the support for DWARF v5 range lists (in the .debug_rnglists section) on the consumer side. Basically, it enables any consumer to extract a DWARF v5 encoded rangelist (via DIE::getAddressRanges()).
Still missing for full support are the DW_RLE-* encodings that use an index into the .debug_addr section to designate address ranges (e.g. DW_RLE_startx_endx). These will be supported at a later stage.

This patch does the following:

1. Adds a method to the DebugRnglist class to return a DWARFAddressRangesVector based on it.
2. Adds methods to the DebugRnglistTable class to a) retrieve a rangelist based on an offset and if needed extract it from the section b) given an index, retrieve an entry into the table's offset table (which represents an offset to a range list). c) add a format property to the table class to designate which dwarf format the table is encoded in (only DWARF32 supported at the moment).
   1. Adds a range list table to the DWARFUnit class which holds the DebugRnglistTable that belongs to the unit.
   2. Adding 3 methods to DWARFUnit to a) obtain DWARFAddressRangesVectors given either a range list offset or an index. The former is used with DW_FORM_sec_offset, the latter with DW_FORM_rnglistx, when handling the DW_AT_ranges attribute in DIEs. b) retrieve the range list offset that results from using an index supplied with DW_FORM_rnglistx. This is used only to dump the offset.

5. Slightly refactor the dumping code in DWARFContext in the face of dumping both .debug_rnglists and .debug_rnglists.dwo.

6. Using getRelocatedAddress() instead of getAddress() when extracting range lists.

7. When dumping a rangelist referenced from a DIE, and the DW_AT_ranges attribute uses FORM_rnglistx, add some code to dump the offset that is retrieved via the index.

8. Change DWARFDie::getAddressRanges() to use the interface now provided by DWARFUnit to obtain a DWARFAddressRangesVector via DW_AT_ranges.

9. Some additions to DWARFFormValue to deal with DW_Form_rnglistx.

10. DWARFUnit now parses the range list table header in version 5 and tries to set up the range list table based on the DW_AT_rnglists_base attribute in the CU DIE. It does this in both split and full CUs (though no DW_AT_rnglists_base in split units).

[JDevlieghere]

include/llvm/DebugInfo/DWARF/DWARFDebugRnglists.h

120 ↗

(On Diff #142094)

Is Format checked before this function is called? If not, this should probably also be an Optional as it can fail due to bad input. Otherwise I'd add a comment specifying this as a pre-condition.

lib/DebugInfo/DWARF/DWARFDebugRnglists.cpp

200 ↗

(On Diff #142094)

Same as my other comment, we shouldn't crash on bad input.

lib/DebugInfo/DWARF/DWARFUnit.cpp

152 ↗

(On Diff #142094)

Would it make sense to turn this into an Expected and propagate the Error from extractHeaderAndOffsets?

[aprantl]

This looks generally good to me.

include/llvm/DebugInfo/DWARF/DWARFDebugRnglists.h

120 ↗

(On Diff #142094)

Nit: By moving the unreachable outside of the switch statement, we could benefit from the incomplete-switch warning if a new enumerator is added.

lib/DebugInfo/DWARF/DWARFContext.cpp

255 ↗

(On Diff #142094)

Not your code, but since you touched it: IIRC there's supposed to be a helper function that prints "error:" in color somewhere in libDebugInfo.

lib/DebugInfo/DWARF/DWARFUnit.cpp

381 ↗

(On Diff #142094)

That's a matter of taste, but I would have put the Version <= 4 case up front since its shorter.

[dblaikie]

test/DebugInfo/X86/dwarfdump-rnglists.s

6–8 ↗

(On Diff #142094)

You could use one CU with rnglists_base (but maybe it's better to test the case where there is no rnglists_base, as you are doing?) - the spec says that rnglistx /may/ be used in the presence of rngilsts_base, but doesn't have to be used.

(the indirection of indexing into a table of offsets in rnglists, and the fact that the rnglists_base points to the bytes /after/ the header seem both a bit weird/unfortunate, but I guess they were picked that way for a reason (the latter seems problematic because it looks to me like that would mean the section can't be versioned effectively - if a newer version of the table changed the layout, how would that be parsed? The header would have to remain the same size & the parser would have to walk backwards from rnglists_base to see if the version is the same? :/)

135 ↗

(On Diff #142094)

This comment should be DW_RLE_end_of_list, perhaps?

155–176 ↗

(On Diff #142094)

Usually we put the CHECK lines at the start, or sometimes interleaved with the content they're checking - perhaps you could do that? (you can even have multiple section chunks so you could keep the ranges for a specific CU next to the CU to make the tests relatively isolated rather than interleaved, perhaps?)

[wolfgangp]

Addressed review comments:

1. Changed parseRngListTableHeader to return an Expected<> rather than Optional<> to allow reporting of errors we find during initial parsing of a range list table.
2. Use helper routines to use color encoding with error reporting.

include/llvm/DebugInfo/DWARF/DWARFDebugRnglists.h

120 ↗

(On Diff #142094)

Is Format checked before this function is called? If not, this should probably also > be an Optional as it can fail due to bad input. Otherwise I'd add a comment
specifying this as a pre-condition.

Actually, format is (or rather, will be once DWARF64 support is added) derived from parsing the table, and it really can only be either DWARF32 or DWARF64 (or something else to be added in the future). If it isn't it's clearly an internal error. I'll add a comment to that effect.

lib/DebugInfo/DWARF/DWARFContext.cpp

255 ↗

(On Diff #142094)

Found it. So far it seems to be only used by the verifier.

lib/DebugInfo/DWARF/DWARFDebugRnglists.cpp

200 ↗

(On Diff #142094)

Same as my other comment, we shouldn't crash on bad input.

Any unsupported encodings should have been found during the initial extraction of the range list, which would have prevented the list from being internalized. So at this point we expect a list with only supported encodings. I'll add a comment to that effect.

lib/DebugInfo/DWARF/DWARFUnit.cpp

152 ↗

(On Diff #142094)

Good idea. This allows reporting of errors when we first parse the range list table.

[JDevlieghere]

lib/DebugInfo/DWARF/DWARFContext.cpp

255 ↗

(On Diff #142094)

I've added convenience methods in WithColor (rL330091) and I've updated the other uses in libDebugInfo (rL330092).

[wolfgangp]

Sorry for the long delay on this (I was out of the country with sketchy internet connections). I'm using the 'WithColor' convenience functions as Jonas suggested. Otherwise, I believe all review comments have been addressed.

[JDevlieghere]

Looks good to me, thanks Wolfgang!

lib/DebugInfo/DWARF/DWARFDebugRnglists.cpp

366 ↗

(On Diff #146643)

Would it be worth propagating the error and have this function return an Expected<>?

[wolfgangp]

lib/DebugInfo/DWARF/DWARFDebugRnglists.cpp

366 ↗

(On Diff #146643)

Would it be worth propagating the error and have this function return an Expected<>?

It would improve the reporting on invalid DW_AT_ranges attributes in the DIEs. Seems to require a few more changes in DWARFDie.cpp, but it would be worthwhile. I'll take a look at it.

[jhenderson]

lib/DebugInfo/DWARF/DWARFDebugRnglists.cpp

366 ↗

(On Diff #146643)

This would be a nice parallel to the work I did on improving the debug line error handling in D44560, and probably something we should keep in mind for any further changes/additions to the DWARF implementation.

[wolfgangp]

lib/DebugInfo/DWARF/DWARFDebugRnglists.cpp

366 ↗

(On Diff #146643)

I'm inclined to do this in a follow-on patch to keep the number of changes smaller.

llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFDebugRnglists.h

 //===- DWARFDebugRnglists.h -------------------------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_DEBUGINFO_DWARFDEBUGRNGLISTS_H
 #define LLVM_DEBUGINFO_DWARFDEBUGRNGLISTS_H
 
+#include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/DebugInfo/DIContext.h"
 #include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugRangeList.h"
 #include <cstdint>
 #include <map>
 #include <vector>
 
 namespace llvm {
 
 class Error;
 class raw_ostream;
 
 /// A class representing a single rangelist.
 class DWARFDebugRnglist {
 public:
   struct RangeListEntry {
     /// The offset at which the entry is located in the section.
     uint32_t Offset;
     /// The DWARF encoding (DW_RLE_*).
     uint8_t EntryKind;
+    /// The index of the section this range belongs to.
+    uint64_t SectionIndex;
     /// The values making up the range list entry. Most represent a range with
     /// a start and end address or a start address and a length. Others are
     /// single value base addresses or end-of-list with no values. The unneeded
     /// values are semantically undefined, but initialized to 0.
     uint64_t Value0;
     uint64_t Value1;
 
     Error extract(DWARFDataExtractor Data, uint32_t End, uint32_t *OffsetPtr);
   };
 
   using RngListEntries = std::vector<RangeListEntry>;
 
 private:
   RngListEntries Entries;
 
 public:
   const RngListEntries &getEntries() const { return Entries; }
   bool empty() const { return Entries.empty(); }
   void clear() { Entries.clear(); }
   Error extract(DWARFDataExtractor Data, uint32_t HeaderOffset, uint32_t End,
                 uint32_t *OffsetPtr);
+  /// Build a DWARFAddressRangesVector from a rangelist.
+  DWARFAddressRangesVector
+  getAbsoluteRanges(llvm::Optional<BaseAddress> BaseAddr) const;
 };
 
 /// A class representing a table of range lists as specified in DWARF v5.
 /// The table consists of a header followed by an array of offsets into the
 /// .debug_rnglists section, followed by one or more rangelists. The rangelists
 /// are kept in a map where the keys are the lists' section offsets.
 class DWARFDebugRnglistTable {
 public:
struct Header {
     /// The size in bytes of a segment selector on the target architecture.
     /// If the target system uses a flat address space, this value is 0.
     uint8_t SegSize;
     /// The number of offsets that follow the header before the range lists.
     uint32_t OffsetEntryCount;
   };
 
 private:
+  dwarf::DwarfFormat Format;
   uint32_t HeaderOffset;
   Header HeaderData;
   std::vector<uint32_t> Offsets;
   std::map<uint32_t, DWARFDebugRnglist> Ranges;
 
 public:
   void clear();
   /// Extract the table header and the array of offsets.
   Error extractHeaderAndOffsets(DWARFDataExtractor Data, uint32_t *OffsetPtr);
   /// Extract an entire table, including all rangelists.
   Error extract(DWARFDataExtractor Data, uint32_t *OffsetPtr);
+  /// Look up a rangelist based on a given offset. Extract it and enter it into
+  /// the ranges map if necessary.
+  Optional<DWARFDebugRnglist> findRangeList(DWARFDataExtractor Data,
+                                            uint32_t Offset);
   uint32_t getHeaderOffset() const { return HeaderOffset; }
+  uint8_t getAddrSize() const { return HeaderData.AddrSize; }
   void dump(raw_ostream &OS, DIDumpOptions DumpOpts) const;
+  /// Return the contents of the offset entry designated by a given index.
+  Optional<uint32_t> getOffsetEntry(uint32_t Index) const {
+    if (Index < Offsets.size())
+      return Offsets[Index];
+    return None;
+  }
+  /// Return the size of the table header including the length but not including
+  /// the offsets. This is dependent on the table format, which is unambiguously
+  /// derived from parsing the table.
+  uint8_t getHeaderSize() const {
+    switch (Format) {
+    case dwarf::DwarfFormat::DWARF32:
+      return 12;
+    case dwarf::DwarfFormat::DWARF64:
+      return 20;
+    }
+    llvm_unreachable("Invalid DWARF format (expected DWARF32 or DWARF64");
+  }
 
   /// Returns the length of this table, including the length field, or 0 if the
   /// length has not been determined (e.g. because the table has not yet been
   /// parsed, or there was a problem in parsing).
   uint32_t length() const;
 };
 
 } // end namespace llvm
 
 #endif // LLVM_DEBUGINFO_DWARFDEBUGRNGLISTS_H

llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFObject.h

public:
   virtual StringRef getAbbrevDWOSection() const { return ""; }
   virtual const DWARFSection &getLineDWOSection() const { return Dummy; }
   virtual const DWARFSection &getLocDWOSection() const { return Dummy; }
   virtual StringRef getStringDWOSection() const { return ""; }
   virtual const DWARFSection &getStringOffsetDWOSection() const {
     return Dummy;
   }
   virtual const DWARFSection &getRangeDWOSection() const { return Dummy; }
+  virtual const DWARFSection &getRnglistsDWOSection() const { return Dummy; }
   virtual const DWARFSection &getAddrSection() const { return Dummy; }
   virtual const DWARFSection &getAppleNamesSection() const { return Dummy; }
   virtual const DWARFSection &getAppleTypesSection() const { return Dummy; }
   virtual const DWARFSection &getAppleNamespacesSection() const {
     return Dummy;
   }
   virtual const DWARFSection &getDebugNamesSection() const { return Dummy; }
   virtual const DWARFSection &getAppleObjCSection() const { return Dummy; }

llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFUnit.h

 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugRangeList.h"
+#include "llvm/DebugInfo/DWARF/DWARFDebugRnglists.h"
 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
 #include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
 #include "llvm/DebugInfo/DWARF/DWARFSection.h"
 #include "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
 #include "llvm/Support/DataExtractor.h"
 #include <algorithm>
 #include <cassert>
class DWARFUnit {
   bool isLittleEndian;
   bool isDWO;
   const DWARFUnitSectionBase &UnitSection;
 
   /// Start, length, and DWARF format of the unit's contribution to the string
   /// offsets table (DWARF v5).
   Optional<StrOffsetsContributionDescriptor> StringOffsetsTableContribution;
 
+  /// A table of range lists (DWARF v5 and later).
+  Optional<DWARFDebugRnglistTable> RngListTable;
+
   mutable const DWARFAbbreviationDeclarationSet *Abbrevs;
   llvm::Optional<BaseAddress> BaseAddr;
   /// The compile unit debug information entry items.
   std::vector<DWARFDebugInfoEntry> DieArray;
 
   /// Map from range's start address to end address and corresponding DIE.
   /// IntervalMap does not support range removal, as a result, we use the
   /// std::map::upper_bound for address range lookup.
DWARFDie getUnitDIE(bool ExtractUnitDIEOnly = true) {
     if (DieArray.empty())
       return DWARFDie();
     return DWARFDie(this, &DieArray[0]);
   }
 
   const char *getCompilationDir();
   Optional<uint64_t> getDWOId();
 
+  /// Return a vector of address ranges resulting from a (possibly encoded)
+  /// range list starting at a given offset in the appropriate ranges section.
+  DWARFAddressRangesVector findRnglistFromOffset(uint32_t Offset);
+
+  /// Return a vector of address ranges retrieved from an encoded range
+  /// list whose offset is found via a table lookup given an index (DWARF v5
+  /// and later).
+  DWARFAddressRangesVector findRnglistFromIndex(uint32_t Index);
+
+  /// Return a rangelist's offset based on an index. The index designates
+  /// an entry in the rangelist table's offset array and is supplied by
+  /// DW_FORM_rnglistx.
+  Optional<uint32_t> getRnglistOffset(uint32_t Index) {
+    if (RngListTable)
+      return RngListTable->getOffsetEntry(Index);
+    return None;
+  }
+
   void collectAddressRanges(DWARFAddressRangesVector &CURanges);
 
   /// Returns subprogram DIE with address range encompassing the provided
   /// address. The pointer is alive as long as parsed compile unit DIEs are not
   /// cleared.
   DWARFDie getSubroutineForAddress(uint64_t Address);
 
   /// getInlinedChainForAddress - fetches inlined chain for a given address.

llvm/trunk/lib/DebugInfo/DWARF/DWARFContext.cpp

while (offset < size) {
       const char *S = StrData.getCStr(&StringOffset);
       if (S)
         OS << format("\"%s\"", S);
       OS << "\n";
     }
   }
 }
 
+// Dump the .debug_rnglists or .debug_rnglists.dwo section (DWARF v5).
+static void dumpRnglistsSection(raw_ostream &OS,
+                                DWARFDataExtractor &rnglistData,
+                                DIDumpOptions DumpOpts) {
+  uint32_t Offset = 0;
+  while (rnglistData.isValidOffset(Offset)) {
+    llvm::DWARFDebugRnglistTable Rnglists;
+    uint32_t TableOffset = Offset;
+    if (Error Err = Rnglists.extract(rnglistData, &Offset)) {
+      WithColor::error() << toString(std::move(Err)) << '\n';
+      uint64_t Length = Rnglists.length();
+      // Keep going after an error, if we can, assuming that the length field
+      // could be read. If it couldn't, stop reading the section.
+      if (Length == 0)
+        break;
+      Offset = TableOffset + Length;
+    } else {
+      Rnglists.dump(OS, DumpOpts);
+    }
+  }
+}
+
 void DWARFContext::dump(
     raw_ostream &OS, DIDumpOptions DumpOpts,
     std::array<Optional<uint64_t>, DIDT_ID_Count> DumpOffsets) {
 
   Optional<uint64_t> DumpOffset;
   uint64_t DumpType = DumpOpts.DumpType;
 
   StringRef Extension = sys::path::extension(DObj->getFileName());
if (shouldDump(Explicit, ".debug_ranges", DIDT_ID_DebugRanges,
     uint32_t offset = 0;
     DWARFDebugRangeList rangeList;
     while (rangeList.extract(rangesData, &offset))
       rangeList.dump(OS);
   }
 
   if (shouldDump(Explicit, ".debug_rnglists", DIDT_ID_DebugRnglists,
                  DObj->getRnglistsSection().Data)) {
-    DWARFDataExtractor rnglistData(*DObj, DObj->getRnglistsSection(),
+    DWARFDataExtractor RnglistData(*DObj, DObj->getRnglistsSection(),
                                    isLittleEndian(), 0);
-    uint32_t Offset = 0;
-    while (rnglistData.isValidOffset(Offset)) {
-      DWARFDebugRnglistTable Rnglists;
-      uint32_t TableOffset = Offset;
-      if (Error Err = Rnglists.extract(rnglistData, &Offset)) {
-        WithColor::error() << toString(std::move(Err)) << '\n';
-        uint64_t Length = Rnglists.length();
-        // Keep going after an error, if we can, assuming that the length field
-        // could be read. If it couldn't, stop reading the section.
-        if (Length == 0)
-          break;
-        Offset = TableOffset + Length;
-      } else {
-        Rnglists.dump(OS, DumpOpts);
-      }
-    }
+    dumpRnglistsSection(OS, RnglistData, DumpOpts);
+
+  if (shouldDump(ExplicitDWO, ".debug_rnglists.dwo", DIDT_ID_DebugRnglists,
+                 DObj->getRnglistsDWOSection().Data)) {
+    DWARFDataExtractor RnglistData(*DObj, DObj->getRnglistsDWOSection(),
+                                   isLittleEndian(), 0);
+    dumpRnglistsSection(OS, RnglistData, DumpOpts);
   }
 
   if (shouldDump(Explicit, ".debug_pubnames", DIDT_ID_DebugPubnames,
                  DObj->getPubNamesSection()))
     DWARFDebugPubTable(DObj->getPubNamesSection(), isLittleEndian(), false)
         .dump(OS);
 
   if (shouldDump(Explicit, ".debug_pubtypes", DIDT_ID_DebugPubtypes,
class DWARFObjInMemory final : public DWARFObject {
   DWARFSectionMap RangeSection;
   DWARFSectionMap RnglistsSection;
   DWARFSectionMap StringOffsetSection;
   DWARFSectionMap InfoDWOSection;
   DWARFSectionMap LineDWOSection;
   DWARFSectionMap LocDWOSection;
   DWARFSectionMap StringOffsetDWOSection;
   DWARFSectionMap RangeDWOSection;
+  DWARFSectionMap RnglistsDWOSection;
   DWARFSectionMap AddrSection;
   DWARFSectionMap AppleNamesSection;
   DWARFSectionMap AppleTypesSection;
   DWARFSectionMap AppleNamespacesSection;
   DWARFSectionMap AppleObjCSection;
   DWARFSectionMap DebugNamesSection;
 
   DWARFSectionMap *mapNameToDWARFSection(StringRef Name) {
     return StringSwitch<DWARFSectionMap *>(Name)
         .Case("debug_info", &InfoSection)
         .Case("debug_loc", &LocSection)
         .Case("debug_line", &LineSection)
         .Case("debug_str_offsets", &StringOffsetSection)
         .Case("debug_ranges", &RangeSection)
         .Case("debug_rnglists", &RnglistsSection)
         .Case("debug_info.dwo", &InfoDWOSection)
         .Case("debug_loc.dwo", &LocDWOSection)
         .Case("debug_line.dwo", &LineDWOSection)
         .Case("debug_names", &DebugNamesSection)
+        .Case("debug_rnglists.dwo", &RnglistsDWOSection)
         .Case("debug_str_offsets.dwo", &StringOffsetDWOSection)
         .Case("debug_addr", &AddrSection)
         .Case("apple_names", &AppleNamesSection)
         .Case("apple_types", &AppleTypesSection)
         .Case("apple_namespaces", &AppleNamespacesSection)
         .Case("apple_namespac", &AppleNamespacesSection)
         .Case("apple_objc", &AppleObjCSection)
         .Default(nullptr);
public:
   }
   StringRef getStringDWOSection() const override { return StringDWOSection; }
   const DWARFSection &getStringOffsetDWOSection() const override {
     return StringOffsetDWOSection;
   }
   const DWARFSection &getRangeDWOSection() const override {
     return RangeDWOSection;
   }
+  const DWARFSection &getRnglistsDWOSection() const override {
+    return RnglistsDWOSection;
+  }
   const DWARFSection &getAddrSection() const override { return AddrSection; }
   StringRef getCUIndexSection() const override { return CUIndexSection; }
   StringRef getGdbIndexSection() const override { return GdbIndexSection; }
   StringRef getTUIndexSection() const override { return TUIndexSection; }
 
   // DWARF v5
   const DWARFSection &getStringOffsetSection() const override {
     return StringOffsetSection;

llvm/trunk/lib/DebugInfo/DWARF/DWARFDebugRnglists.cpp

 //===- DWARFDebugRnglists.cpp ---------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/DWARF/DWARFDebugRnglists.h"
-
 #include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 
 void DWARFDebugRnglistTable::clear() {
   HeaderData = {};
return createError("section is not large enough to contain a "
                        ".debug_rnglists table length at offset 0x%" PRIx32,
                        *OffsetPtr);
   // TODO: Add support for DWARF64.
   HeaderData.Length = Data.getU32(OffsetPtr);
   if (HeaderData.Length == 0xffffffffu)
     return createError(
         "DWARF64 is not supported in .debug_rnglists at offset 0x%" PRIx32,
         HeaderOffset);
+  Format = dwarf::DwarfFormat::DWARF32;
   if (HeaderData.Length + sizeof(uint32_t) < sizeof(Header))
     return createError(".debug_rnglists table at offset 0x%" PRIx32
                        " has too small length (0x%" PRIx32
                        ") to contain a complete header",
                        HeaderOffset, length());
   uint32_t End = HeaderOffset + length();
   if (!Data.isValidOffsetForDataOfSize(HeaderOffset, End - HeaderOffset))
     return createError(
for (uint32_t I = 0; I < HeaderData.OffsetEntryCount; ++I)
     Offsets.push_back(Data.getU32(OffsetPtr));
   return Error::success();
 }
 
 Error DWARFDebugRnglist::RangeListEntry::extract(DWARFDataExtractor Data,
                                                  uint32_t End,
                                                  uint32_t *OffsetPtr) {
   Offset = *OffsetPtr;
+  SectionIndex = -1ULL;
   // The caller should guarantee that we have at least 1 byte available, so
   // we just assert instead of revalidate.
   assert(*OffsetPtr < End &&
          "not enough space to extract a rangelist encoding");
   uint8_t Encoding = Data.getU8(OffsetPtr);
 
   switch (Encoding) {
   case dwarf::DW_RLE_end_of_list:
if (End < *OffsetPtr)
                          PreviousOffset);
     break;
   }
   case dwarf::DW_RLE_base_address: {
     if ((End - *OffsetPtr) < Data.getAddressSize())
       return createError("insufficient space remaining in table for "
                          "DW_RLE_base_address encoding at offset 0x%" PRIx32,
                          *OffsetPtr - 1);
-    Value0 = Data.getAddress(OffsetPtr);
+    Value0 = Data.getRelocatedAddress(OffsetPtr, &SectionIndex);
     break;
   }
   case dwarf::DW_RLE_start_end: {
     if ((End - *OffsetPtr) < unsigned(Data.getAddressSize() * 2))
       return createError("insufficient space remaining in table for "
                          "DW_RLE_start_end encoding "
                          "at offset 0x%" PRIx32,
                          *OffsetPtr - 1);
-    Value0 = Data.getAddress(OffsetPtr);
-    Value1 = Data.getAddress(OffsetPtr);
+    Value0 = Data.getRelocatedAddress(OffsetPtr, &SectionIndex);
+    Value1 = Data.getRelocatedAddress(OffsetPtr);
     break;
   }
   case dwarf::DW_RLE_start_length: {
     uint32_t PreviousOffset = *OffsetPtr - 1;
-    Value0 = Data.getAddress(OffsetPtr);
+    Value0 = Data.getRelocatedAddress(OffsetPtr, &SectionIndex);
     Value1 = Data.getULEB128(OffsetPtr);
     if (End < *OffsetPtr)
       return createError("read past end of table when reading "
                          "DW_RLE_start_length encoding at offset 0x%" PRIx32,
                          PreviousOffset);
     break;
   }
   default:
     return createError("unknown rnglists encoding 0x%" PRIx32
                        " at offset 0x%" PRIx32,
                        uint32_t(Encoding), *OffsetPtr - 1);
   }
 
   EntryKind = Encoding;
   return Error::success();
 }
 
+DWARFAddressRangesVector DWARFDebugRnglist::getAbsoluteRanges(
+    llvm::Optional<BaseAddress> BaseAddr) const {
+  DWARFAddressRangesVector Res;
+  for (const RangeListEntry &RLE : Entries) {
+    if (RLE.EntryKind == dwarf::DW_RLE_end_of_list)
+      break;
+    if (RLE.EntryKind == dwarf::DW_RLE_base_address) {
+      BaseAddr = {RLE.Value0, RLE.SectionIndex};
+      continue;
+    }
+
+    DWARFAddressRange E;
+    E.SectionIndex = RLE.SectionIndex;
+    if (BaseAddr && E.SectionIndex == -1ULL)
+      E.SectionIndex = BaseAddr->SectionIndex;
+
+    switch (RLE.EntryKind) {
+    case dwarf::DW_RLE_offset_pair:
+      E.LowPC = RLE.Value0;
+      E.HighPC = RLE.Value1;
+      if (BaseAddr) {
+        E.LowPC += BaseAddr->Address;
+        E.HighPC += BaseAddr->Address;
+      }
+      break;
+    case dwarf::DW_RLE_start_end:
+      E.LowPC = RLE.Value0;
+      E.HighPC = RLE.Value1;
+      break;
+    case dwarf::DW_RLE_start_length:
+      E.LowPC = RLE.Value0;
+      E.HighPC = E.LowPC + RLE.Value1;
+      break;
+    default:
+      // Unsupported encodings should have been reported during extraction,
+      // so we should not run into any here.
+      llvm_unreachable("Unsupported range list encoding");
+    }
+    Res.push_back(E);
+  }
+  return Res;
+}
+
 Error DWARFDebugRnglist::extract(DWARFDataExtractor Data, uint32_t HeaderOffset,
                                  uint32_t End, uint32_t *OffsetPtr) {
   Entries.clear();
   while (*OffsetPtr < End) {
     RangeListEntry Entry{0, 0, 0, 0};
     if (Error E = Entry.extract(Data, End, OffsetPtr))
       return E;
     Entries.push_back(Entry);

 }
 
 uint32_t DWARFDebugRnglistTable::length() const {
   if (HeaderData.Length == 0)
     return 0;
   // TODO: DWARF64 support.
   return HeaderData.Length + sizeof(uint32_t);
 }
+
+Optional<DWARFDebugRnglist>
+DWARFDebugRnglistTable::findRangeList(DWARFDataExtractor Data,
+                                      uint32_t Offset) {
+  auto Entry = Ranges.find(Offset);
+  if (Entry != Ranges.end())
+    return Entry->second;
+
+  // Extract the rangelist from the section and enter it into the ranges map.
+  DWARFDebugRnglist RngList;
+  uint32_t End = HeaderOffset + length();
+  uint32_t StartingOffset = Offset;
+  if (Error E = RngList.extract(Data, HeaderOffset, End, &Offset)) {
+    llvm::consumeError(std::move(E));
+    return None;
+  }
+  Ranges[StartingOffset] = RngList;
+  return RngList;
+}

llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp

if (Attr == DW_AT_specification || Attr == DW_AT_abstract_origin) {
     OS << " \"";
     dumpTypeName(OS, Die);
     OS << '"';
   } else if (Attr == DW_AT_APPLE_property_attribute) {
     if (Optional<uint64_t> OptVal = formValue.getAsUnsignedConstant())
       dumpApplePropertyAttribute(OS, *OptVal);
   } else if (Attr == DW_AT_ranges) {
     const DWARFObject &Obj = Die.getDwarfUnit()->getContext().getDWARFObj();
+    // For DW_FORM_rnglistx we need to dump the offset separately, since
+    // we have only dumped the index so far.
+    Optional<DWARFFormValue> Value = Die.find(DW_AT_ranges);
+    if (Value && Value->getForm() == DW_FORM_rnglistx)
+      if (auto RangeListOffset =
+              U->getRnglistOffset(*Value->getAsSectionOffset())) {
+        DWARFFormValue FV(dwarf::DW_FORM_sec_offset);
+        FV.setUValue(*RangeListOffset);
+        FV.dump(OS, DumpOpts);
+      }
     dumpRanges(Obj, OS, Die.getAddressRanges(), U->getAddressByteSize(),
                sizeof(BaseIndent) + Indent + 4, DumpOpts);
   }
 
   OS << ")\n";
 }
 
 bool DWARFDie::isSubprogramDIE() const { return getTag() == DW_TAG_subprogram; }

 DWARFAddressRangesVector DWARFDie::getAddressRanges() const {
   if (isNULL())
     return DWARFAddressRangesVector();
   // Single range specified by low/high PC.
   uint64_t LowPC, HighPC, Index;
   if (getLowAndHighPC(LowPC, HighPC, Index))
     return {{LowPC, HighPC, Index}};
 
-  // Multiple ranges from .debug_ranges section.
-  auto RangesOffset = toSectionOffset(find(DW_AT_ranges));
-  if (RangesOffset) {
-    DWARFDebugRangeList RangeList;
-    if (U->extractRangeList(*RangesOffset, RangeList))
-      return RangeList.getAbsoluteRanges(U->getBaseAddress());
+  Optional<DWARFFormValue> Value = find(DW_AT_ranges);
+  if (Value) {
+    if (Value->getForm() == DW_FORM_rnglistx)
+      return U->findRnglistFromIndex(*Value->getAsSectionOffset());
+    return U->findRnglistFromOffset(*Value->getAsSectionOffset());
   }
   return DWARFAddressRangesVector();
 }
 
 void DWARFDie::collectChildrenAddressRanges(
     DWARFAddressRangesVector &Ranges) const {
   if (isNULL())
     return;

llvm/trunk/lib/DebugInfo/DWARF/DWARFFormValue.cpp

case DW_FORM_data16:
       Value.uval = 16;
       IsBlock = true;
       break;
     case DW_FORM_sdata:
       Value.sval = Data.getSLEB128(OffsetPtr);
       break;
     case DW_FORM_udata:
     case DW_FORM_ref_udata:
+    case DW_FORM_rnglistx:
       Value.uval = Data.getULEB128(OffsetPtr);
       break;
     case DW_FORM_string:
       Value.cstr = Data.getCStr(OffsetPtr);
       break;
     case DW_FORM_indirect:
       Form = static_cast<dwarf::Form>(Data.getULEB128(OffsetPtr));
       Indirect = true;
case DW_FORM_GNU_ref_alt:
     break;
 
   // All DW_FORM_indirect attributes should be resolved prior to calling
   // this function
   case DW_FORM_indirect:
     OS << "DW_FORM_indirect";
     break;
 
+  case DW_FORM_rnglistx:
+    OS << format("indexed (0x%x) rangelist = ", (uint32_t)UValue);
+    break;
+
   // Should be formatted to 64-bit for DWARF64.
   case DW_FORM_sec_offset:
     AddrOS << format("0x%08x", (uint32_t)UValue);
     break;
 
   default:
     OS << format("DW_FORM(0x%4.4x)", Form);
     break;

llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp

 //===- DWARFUnit.cpp ------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h"
 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
+#include "llvm/DebugInfo/DWARF/DWARFDebugRnglists.h"
 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
 #include "llvm/Support/DataExtractor.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/WithColor.h"
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
bool DWARFUnitHeader::extract(DWARFContext &Context,
   if (!LengthOK || !VersionOK || !AddrSizeOK || !TypeOffsetOK)
     return false;
 
   // Keep track of the highest DWARF version we encounter across all units.
   Context.setMaxVersionIfGreater(getVersion());
   return true;
 }
 
+// Parse the rangelist table header, including the optional array of offsets
+// following it (DWARF v5 and later).
+static Expected<DWARFDebugRnglistTable>
+parseRngListTableHeader(DWARFDataExtractor &DA, uint32_t Offset) {
+  // TODO: Support DWARF64
+  // We are expected to be called with Offset 0 or pointing just past the table
+  // header, which is 12 bytes long for DWARF32.
+  if (Offset > 0) {
+    if (Offset < 12U) {
+      std::string Buffer;
+      raw_string_ostream Stream(Buffer);
+      Stream << format(
+          "Did not detect a valid range list table with base = 0x%x", Offset);
+      return make_error<StringError>(Stream.str(), inconvertibleErrorCode());
+    }
+    Offset -= 12U;
+  }
+  llvm::DWARFDebugRnglistTable Table;
+  if (Error E = Table.extractHeaderAndOffsets(DA, &Offset))
+    return E;
+  return Table;
+}
+
 bool DWARFUnit::extractRangeList(uint32_t RangeListOffset,
                                  DWARFDebugRangeList &RangeList) const {
   // Require that compile unit is extracted.
   assert(!DieArray.empty());
   DWARFDataExtractor RangesData(Context.getDWARFObj(), *RangeSection,
                                 isLittleEndian, getAddressByteSize());
   uint32_t ActualRangeListOffset = RangeSectionBase + RangeListOffset;
   return RangeList.extract(RangesData, &ActualRangeListOffset);
if (!HasCUDie) {
     if (isDWO)
       StringOffsetsTableContribution =
           determineStringOffsetsTableContributionDWO(
               DA, StringOffsetsContributionBase);
     else if (getVersion() >= 5)
       StringOffsetsTableContribution = determineStringOffsetsTableContribution(
           DA, StringOffsetsContributionBase);
 
+    // DWARF v5 uses the .debug_rnglists and .debug_rnglists.dwo sections to
+    // describe address ranges.
+    if (getVersion() >= 5) {
+      if (isDWO)
+        setRangesSection(&Context.getDWARFObj().getRnglistsDWOSection(), 0);
+      else
+        setRangesSection(&Context.getDWARFObj().getRnglistsSection(),
+                         toSectionOffset(UnitDie.find(DW_AT_rnglists_base), 0));
+      // Parse the range list table header. Individual range lists are
+      // extracted lazily.
+      DWARFDataExtractor RangesDA(Context.getDWARFObj(), *RangeSection,
+                                  isLittleEndian, 0);
+      if (auto TableOrError =
+              parseRngListTableHeader(RangesDA, RangeSectionBase))
+        RngListTable = TableOrError.get();
+      else
+        WithColor::error() << "parsing a range list table: "
+                           << toString(std::move(TableOrError.takeError()))
+                           << '\n';
+
+      // In a split dwarf unit, there is no DW_AT_rnglists_base attribute.
+      // Adjust RangeSectionBase to point past the table header.
+      if (isDWO && RngListTable)
+        RangeSectionBase = RngListTable->getHeaderSize();
+    }
+
     // Don't fall back to DW_AT_GNU_ranges_base: it should be ignored for
     // skeleton CU DIE, so that DWARF users not aware of it are not broken.
   }
 
   return DieArray.size();
 }
 
 bool DWARFUnit::parseDWO() {
if (!DWOContext)
     return false;
 
   DWARFCompileUnit *DWOCU = DWOContext->getDWOCompileUnitForHash(*DWOId);
   if (!DWOCU)
     return false;
   DWO = std::shared_ptr<DWARFCompileUnit>(std::move(DWOContext), DWOCU);
   // Share .debug_addr and .debug_ranges section with compile unit in .dwo
   DWO->setAddrOffsetSection(AddrOffsetSection, AddrOffsetSectionBase);
+  if (getVersion() >= 5) {
+    DWO->setRangesSection(&Context.getDWARFObj().getRnglistsDWOSection(), 0);
+    DWARFDataExtractor RangesDA(Context.getDWARFObj(), *RangeSection,
+                                isLittleEndian, 0);
+    if (auto TableOrError = parseRngListTableHeader(RangesDA, RangeSectionBase))
+      DWO->RngListTable = TableOrError.get();
+    else
+      WithColor::error() << "parsing a range list table: "
+                         << toString(std::move(TableOrError.takeError()))
+                         << '\n';
+    if (DWO->RngListTable)
+      DWO->RangeSectionBase = DWO->RngListTable->getHeaderSize();
+  } else {
     auto DWORangesBase = UnitDie.getRangesBaseAttribute();
     DWO->setRangesSection(RangeSection, DWORangesBase ? *DWORangesBase : 0);
+  }
+
   return true;
 }
 
 void DWARFUnit::clearDIEs(bool KeepCUDie) {
   if (DieArray.size() > (unsigned)KeepCUDie) {
     DieArray.resize((unsigned)KeepCUDie);
     DieArray.shrink_to_fit();
   }
 }
 
+DWARFAddressRangesVector DWARFUnit::findRnglistFromOffset(uint32_t Offset) {
+  if (getVersion() <= 4) {
+    DWARFDebugRangeList RangeList;
+    if (extractRangeList(Offset, RangeList))
+      return RangeList.getAbsoluteRanges(getBaseAddress());
+    return DWARFAddressRangesVector();
+  }
+  if (RngListTable) {
+    DWARFDataExtractor RangesData(Context.getDWARFObj(), *RangeSection,
+                                  isLittleEndian, RngListTable->getAddrSize());
+    if (auto RangeList = RngListTable->findRangeList(RangesData, Offset))
+      return RangeList->getAbsoluteRanges(getBaseAddress());
+  }
+  return DWARFAddressRangesVector();
+}
+
+DWARFAddressRangesVector DWARFUnit::findRnglistFromIndex(uint32_t Index) {
+  if (auto Offset = getRnglistOffset(Index))
+    return findRnglistFromOffset(*Offset + RangeSectionBase);
+  return DWARFAddressRangesVector();
+}
+
 void DWARFUnit::collectAddressRanges(DWARFAddressRangesVector &CURanges) {
   DWARFDie UnitDie = getUnitDIE();
   if (!UnitDie)
     return;
   // First, check if unit DIE describes address ranges for the whole unit.
   const auto &CUDIERanges = UnitDie.getAddressRanges();
   if (!CUDIERanges.empty()) {
     CURanges.insert(CURanges.end(), CUDIERanges.begin(), CUDIERanges.end());

llvm/trunk/test/DebugInfo/X86/dwarfdump-rnglists.s

+# RUN: llvm-mc -triple x86_64-unknown-linux %s -filetype=obj -o %t.o
+# RUN: llvm-dwarfdump -v -debug-info %t.o 2> %t.err | FileCheck %s
+# RUN: FileCheck %s --input-file %t.err --check-prefix=ERR
+
+# Test object to verify dwarfdump handles v5 range lists.
+# We use very simplified compile unit dies.
+# There are 2 full CUs with DW_AT_rnglists_base, one with a DW_AT_ranges
+# attribute using DW_FORM_sec_offset, the other with DW_AT_ranges using
+# DW_FORM_rnglistx.
+
+        .section .debug_abbrev,"",@progbits
+        .byte 0x01  # Abbrev code
+        .byte 0x11  # DW_TAG_compile_unit
+        .byte 0x00  # DW_CHILDREN_no
+        .byte 0x74  # DW_AT_rnglists_base
+        .byte 0x17  # DW_FORM_sec_offset
+        .byte 0x55  # DW_AT_ranges
+        .byte 0x17  # DW_FORM_sec_offset
+        .byte 0x00  # EOM(1)
+        .byte 0x00  # EOM(2)
+        .byte 0x02  # Abbrev code
+        .byte 0x11  # DW_TAG_compile_unit
+        .byte 0x00  # DW_CHILDREN_no
+        .byte 0x74  # DW_AT_rnglists_base
+        .byte 0x17  # DW_FORM_sec_offset
+        .byte 0x55  # DW_AT_ranges
+        .byte 0x23  # DW_FORM_rnglistx
+        .byte 0x00  # EOM(1)
+        .byte 0x00  # EOM(2)
+        .byte 0x00  # EOM(3)
+
+# The split CU uses DW_FORM_rnglistx (the only correct option).
+# There is no DW_AT_rnglists_base in split units.
+        .section .debug_abbrev.dwo,"",@progbits
+        .byte 0x01  # Abbrev code
+        .byte 0x11  # DW_TAG_compile_unit
+        .byte 0x00  # DW_CHILDREN_no
+        .byte 0x55  # DW_AT_ranges
+        .byte 0x23  # DW_FORM_rnglistx
+        .byte 0x00  # EOM(1)
+        .byte 0x00  # EOM(2)
+        .byte 0x00  # EOM(3)
+        
+        .section .debug_info,"",@progbits
+# DWARF v5 CU header.
+        .long  CU1_5_end-CU1_5_version  # Length of Unit
+CU1_5_version:
+        .short 5               # DWARF version number
+        .byte 1                # DWARF Unit Type
+        .byte 4                # Address Size (in bytes)
+        .long .debug_abbrev    # Offset Into Abbrev. Section
+# The compile-unit DIE, which has DW_AT_rnglists_base and DW_AT_ranges.
+        .byte 1                # Abbreviation code
+        .long Rnglist_Table0_base     # DW_AT_rnglists_base
+        .long Rnglist_Table0_Rnglist0 # DW_AT_ranges
+        .byte 0 # NULL
+        .byte 0 # NULL
+CU1_5_end:
+
+# DWARF v5 CU header
+        .long  CU2_5_end-CU2_5_version  # Length of Unit
+CU2_5_version:
+        .short 5               # DWARF version number
+        .byte 1                # DWARF Unit Type
+        .byte 4                # Address Size (in bytes)
+        .long .debug_abbrev    # Offset Into Abbrev. Section
+# The compile-unit DIE, which has DW_AT_rnglists_base and DW_AT_ranges.
+        .byte 2                # Abbreviation code
+        .long Rnglist_Table0_base   # DW_AT_rnglists_base
+        .uleb128 1             # DW_AT_ranges
+        .byte 0                # NULL
+CU2_5_end:
+# A CU with an invalid DW_AT_rnglists_base attribute
+        .long  CU3_5_end-CU3_5_version  # Length of Unit
+CU3_5_version:
+        .short 5               # DWARF version number
+        .byte 1                # DWARF Unit Type
+        .byte 4                # Address Size (in bytes)
+        .long .debug_abbrev    # Offset Into Abbrev. Section
+# The compile-unit DIE, which has DW_AT_rnglists_base and DW_AT_ranges.
+        .byte 2                # Abbreviation code
+        .long 0x8              # DW_AT_rnglists_base
+        .long 0                # DW_AT_ranges
+        .byte 0                # NULL
+CU3_5_end:
+
+        .section .debug_info.dwo,"",@progbits
+
+# DWARF v5 split CU header.
+        .long  CU_split_5_end-CU_split_5_version  # Length of Unit
+CU_split_5_version:
+        .short 5               # DWARF version number
+        .byte 5                # DWARF Unit Type
+        .byte 4                # Address Size (in bytes)
+        .long 0                # Offset Into Abbrev Section
+# The compile-unit DIE, which has DW_AT_rnglists_base and DW_AT_ranges.
+        .byte 1                # Abbreviation code
+        .uleb128 1             # DW_AT_ranges
+        .byte 0                # NULL
+CU_split_5_end:
+
+        .section .debug_rnglists,"",@progbits
+# A rnglist table with 2 range lists. The first one uses DW_RLE_start_end
+# and DW_RLE_start_length. The second one uses DW_RLE_base_address and
+# DW_RLE_offset_pair. The range lists have entries in the offset table.
+        .long Rnglist_Table0_end - Rnglist_Table0   # table length
+Rnglist_Table0:
+        .short 5                                    # version
+        .byte 4                                     # address size
+        .byte 0                                     # segment selector size
+        .long 2                                     # offset entry count
+Rnglist_Table0_base:
+# 2 offset entries which can be used by DW_FORM_rnglistx.
+        .long Rnglist_Table0_Rnglist0 - Rnglist_Table0_base
+        .long Rnglist_Table0_Rnglist1 - Rnglist_Table0_base
+Rnglist_Table0_Rnglist0:
+        .byte 6                                     # DW_RLE_start_end
+        .long Range0_start
+        .long Range0_end
+        .byte 7                                     # DW_RLE_start_length
+        .long Range1_start
+        .uleb128 Range1_end - Range1_start 
+        .byte 0                                     # DW_RLE_end_of_list
+Rnglist_Table0_Rnglist1:
+        .byte 5                                     # DW_RLE_base_address
+        .long Range0_start
+        .byte 4                                     # DW_RLE_offset_pair
+        .uleb128 Range1_start - Range0_start
+        .uleb128 Range1_end - Range0_start
+        .byte 0                                     # DW_RLE_end_of_list
+Rnglist_Table0_end:
+
+# A rnglist table for the split unit with an empty rangelist and one that
+# uses DW_RLE_base_address and DW_RLE_offset_pair. The ranges have entries
+# in the offset table. We use the empty range list so we can test 
+# DW_FORM_rnglistx with an index other than 0.
+        .section .debug_rnglists.dwo,"",@progbits
+        .long Rnglist_Table0_dwo_end - Rnglist_Table0_dwo   # table length
+Rnglist_Table0_dwo:
+        .short 5                                    # version
+        .byte 4                                     # address size
+        .byte 0                                     # segment selector size
+        .long 2                                     # offset entry count
+Rnglist_Table0_base_dwo:
+# 2 offset entries which can be used by DW_FORM_rnglistx.
+        .long Rnglist_Table0_Rnglist0_dwo - Rnglist_Table0_base_dwo
+        .long Rnglist_Table0_Rnglist1_dwo - Rnglist_Table0_base_dwo
+Rnglist_Table0_Rnglist0_dwo:
+        .byte 0                                     # DW_RLE_start_end
+Rnglist_Table0_Rnglist1_dwo:
+        .byte 5                                     # DW_RLE_base_address
+        .long Range0_start - .text
+        .byte 4                                     # DW_RLE_offset_pair
+        .uleb128 Range1_start - Range0_start
+        .uleb128 Range1_end - Range0_start
+        .byte 0                                     # DW_RLE_end_of_list
+Rnglist_Table0_dwo_end:
+
+.text
+        .space 20
+Range0_start:               # Range0: 0x14 - 0x1c
+        .space 10
+Range0_end:
+        .space 12
+Range1_start:               # Range1: 0x2a - 0x34
+        .space 10
+Range1_end:
+
+# CHECK:      .debug_info contents:
+# CHECK:      Compile Unit: 
+# CHECK-NOT:  Compile Unit:
+# CHECK:      DW_TAG_compile_unit
+# CHECK-NEXT: DW_AT_rnglists_base [DW_FORM_sec_offset]  (0x0000000c)
+# CHECK-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000014
+# CHECK-NEXT: [0x00000014, 0x0000001e) ".text"
+# CHECK-NEXT: [0x0000002a, 0x00000034) ".text")
+
+# CHECK:      Compile Unit:
+# CHECK-NOT:  Compile Unit:
+# CHECK:      DW_TAG_compile_unit
+# CHECK-NEXT: DW_AT_rnglists_base [DW_FORM_sec_offset]  (0x0000000c)
+# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000018
+# CHECK-NEXT: [0x0000002a, 0x00000034) ".text")
+
+# CHECK:      .debug_info.dwo contents:
+# CHECK:      Compile Unit:
+# CHECK-NOT:  contents:
+# CHECK:      DW_TAG_compile_unit
+# CHECK-NEXT: DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x1) rangelist = 0x00000009
+# CHECK-NEXT: [0x0000002a, 0x00000034))
+
+#ERR: error: parsing a range list table: Did not detect a valid range list table with base = 0x8