[DWARF] - Take relocations in account when extracting ranges from .de…

…bug_ranges

I found this when investigated "Bug 32319 - .gdb_index is broken/incomplete" for LLD.

When we have object file with .debug_ranges section it may be filled with zeroes.
Relocations are exist in file to relocate this zeroes into real values later, but until that
a pair of zeroes is treated as terminator. And DWARF parser thinks there is no ranges at all
when I am trying to collect address ranges for building .gdb_index.

Solution implemented in this patch is to take relocations in account when parsing ranges.

Differential revision: https://reviews.llvm.org/D32228

llvm-svn: 301170

llvm/include/llvm/DebugInfo/DWARF/DWARFCompileUnit.h

@@ -18,9 +18,9 @@ namespace llvm {
 class DWARFCompileUnit : public DWARFUnit {
 public:
   DWARFCompileUnit(DWARFContext &Context, const DWARFSection &Section,
-                   const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
-                   StringRef SOS, StringRef AOS, StringRef LS, bool LE,
-                   bool IsDWO, const DWARFUnitSectionBase &UnitSection,
+                   const DWARFDebugAbbrev *DA, const DWARFSection *RS,
+                   StringRef SS, StringRef SOS, StringRef AOS, StringRef LS,
+                   bool LE, bool IsDWO, const DWARFUnitSectionBase &UnitSection,
                    const DWARFUnitIndex::Entry *Entry)
       : DWARFUnit(Context, Section, DA, RS, SS, SOS, AOS, LS, LE, IsDWO,
                   UnitSection, Entry) {}

llvm/include/llvm/DebugInfo/DWARF/DWARFContext.h

@@ -221,7 +221,7 @@ class DWARFContext : public DIContext {
   virtual StringRef getEHFrameSection() = 0;
   virtual const DWARFSection &getLineSection() = 0;
   virtual StringRef getStringSection() = 0;
-  virtual StringRef getRangeSection() = 0;
+  virtual const DWARFSection& getRangeSection() = 0;
   virtual StringRef getMacinfoSection() = 0;
   virtual StringRef getPubNamesSection() = 0;
   virtual StringRef getPubTypesSection() = 0;
@@ -236,7 +236,7 @@ class DWARFContext : public DIContext {
   virtual const DWARFSection &getLocDWOSection() = 0;
   virtual StringRef getStringDWOSection() = 0;
   virtual StringRef getStringOffsetDWOSection() = 0;
-  virtual StringRef getRangeDWOSection() = 0;
+  virtual const DWARFSection &getRangeDWOSection() = 0;
   virtual StringRef getAddrSection() = 0;
   virtual const DWARFSection& getAppleNamesSection() = 0;
   virtual const DWARFSection& getAppleTypesSection() = 0;
@@ -276,7 +276,7 @@ class DWARFContextInMemory : public DWARFContext {
   StringRef EHFrameSection;
   DWARFSection LineSection;
   StringRef StringSection;
-  StringRef RangeSection;
+  DWARFSection RangeSection;
   StringRef MacinfoSection;
   StringRef PubNamesSection;
   StringRef PubTypesSection;
@@ -291,7 +291,7 @@ class DWARFContextInMemory : public DWARFContext {
   DWARFSection LocDWOSection;
   StringRef StringDWOSection;
   StringRef StringOffsetDWOSection;
-  StringRef RangeDWOSection;
+  DWARFSection RangeDWOSection;
   StringRef AddrSection;
   DWARFSection AppleNamesSection;
   DWARFSection AppleTypesSection;
@@ -324,7 +324,7 @@ class DWARFContextInMemory : public DWARFContext {
   StringRef getEHFrameSection() override { return EHFrameSection; }
   const DWARFSection &getLineSection() override { return LineSection; }
   StringRef getStringSection() override { return StringSection; }
-  StringRef getRangeSection() override { return RangeSection; }
+  const DWARFSection &getRangeSection() override { return RangeSection; }
   StringRef getMacinfoSection() override { return MacinfoSection; }
   StringRef getPubNamesSection() override { return PubNamesSection; }
   StringRef getPubTypesSection() override { return PubTypesSection; }
@@ -351,7 +351,7 @@ class DWARFContextInMemory : public DWARFContext {
     return StringOffsetDWOSection;
   }
 
-  StringRef getRangeDWOSection() override { return RangeDWOSection; }
+  const DWARFSection &getRangeDWOSection() override { return RangeDWOSection; }
 
   StringRef getAddrSection() override {
     return AddrSection;

llvm/include/llvm/DebugInfo/DWARF/DWARFDebugRangeList.h

@@ -11,6 +11,8 @@
 #define LLVM_DEBUGINFO_DWARF_DWARFDEBUGRANGELIST_H
 
 #include "llvm/Support/DataExtractor.h"
+#include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
+
 #include <cassert>
 #include <cstdint>
 #include <utility>
@@ -71,7 +73,7 @@ class DWARFDebugRangeList {
 
   void clear();
   void dump(raw_ostream &OS) const;
-  bool extract(DataExtractor data, uint32_t *offset_ptr);
+  bool extract(DataExtractor data, uint32_t *offset_ptr, const RelocAddrMap& Relocs);
   const std::vector<RangeListEntry> &getEntries() { return Entries; }
 
   /// getAbsoluteRanges - Returns absolute address ranges defined by this range

llvm/include/llvm/DebugInfo/DWARF/DWARFTypeUnit.h

@@ -30,9 +30,9 @@ class DWARFTypeUnit : public DWARFUnit {
 
 public:
   DWARFTypeUnit(DWARFContext &Context, const DWARFSection &Section,
-                const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
-                StringRef SOS, StringRef AOS, StringRef LS, bool LE, bool IsDWO,
-                const DWARFUnitSectionBase &UnitSection,
+                const DWARFDebugAbbrev *DA, const DWARFSection *RS,
+                StringRef SS, StringRef SOS, StringRef AOS, StringRef LS,
+                bool LE, bool IsDWO, const DWARFUnitSectionBase &UnitSection,
                 const DWARFUnitIndex::Entry *Entry)
       : DWARFUnit(Context, Section, DA, RS, SS, SOS, AOS, LS, LE, IsDWO,
                   UnitSection, Entry) {}

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

@@ -56,9 +56,9 @@ class DWARFUnitSectionBase {
   ~DWARFUnitSectionBase() = default;
 
   virtual void parseImpl(DWARFContext &Context, const DWARFSection &Section,
-                         const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
-                         StringRef SOS, StringRef AOS, StringRef LS,
-                         bool isLittleEndian, bool isDWO) = 0;
+                         const DWARFDebugAbbrev *DA, const DWARFSection *RS,
+                         StringRef SS, StringRef SOS, StringRef AOS,
+                         StringRef LS, bool isLittleEndian, bool isDWO) = 0;
 };
 
 const DWARFUnitIndex &getDWARFUnitIndex(DWARFContext &Context,
@@ -88,9 +88,9 @@ class DWARFUnitSection final : public SmallVector<std::unique_ptr<UnitType>, 1>,
 
 private:
   void parseImpl(DWARFContext &Context, const DWARFSection &Section,
-                 const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
-                 StringRef SOS, StringRef AOS, StringRef LS, bool LE,
-                 bool IsDWO) override {
+                 const DWARFDebugAbbrev *DA, const DWARFSection *RS,
+                 StringRef SS, StringRef SOS, StringRef AOS, StringRef LS,
+                 bool LE, bool IsDWO) override {
     if (Parsed)
       return;
     const auto &Index = getDWARFUnitIndex(Context, UnitType::Section);
@@ -115,7 +115,7 @@ class DWARFUnit {
   const DWARFSection &InfoSection;
 
   const DWARFDebugAbbrev *Abbrev;
-  StringRef RangeSection;
+  const DWARFSection *RangeSection;
   uint32_t RangeSectionBase;
   StringRef LineSection;
   StringRef StringSection;
@@ -171,7 +171,7 @@ class DWARFUnit {
 
 public:
   DWARFUnit(DWARFContext &Context, const DWARFSection &Section,
-            const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
+            const DWARFDebugAbbrev *DA, const DWARFSection *RS, StringRef SS,
             StringRef SOS, StringRef AOS, StringRef LS, bool LE, bool IsDWO,
             const DWARFUnitSectionBase &UnitSection,
             const DWARFUnitIndex::Entry *IndexEntry = nullptr);
@@ -192,7 +192,7 @@ class DWARFUnit {
   // Recursively update address to Die map.
   void updateAddressDieMap(DWARFDie Die);
 
-  void setRangesSection(StringRef RS, uint32_t Base) {
+  void setRangesSection(const DWARFSection *RS, uint32_t Base) {
     RangeSection = RS;
     RangeSectionBase = Base;
   }

llvm/lib/DebugInfo/DWARF/DWARFContext.cpp

@@ -222,11 +222,11 @@ void DWARFContext::dump(raw_ostream &OS, DIDumpType DumpType, bool DumpEH,
     // sizes, but for simplicity we just use the address byte size of the last
     // compile unit (there is no easy and fast way to associate address range
     // list and the compile unit it describes).
-    DataExtractor rangesData(getRangeSection(), isLittleEndian(),
+    DataExtractor rangesData(getRangeSection().Data, isLittleEndian(),
                              savedAddressByteSize);
     offset = 0;
     DWARFDebugRangeList rangeList;
-    while (rangeList.extract(rangesData, &offset))
+    while (rangeList.extract(rangesData, &offset, getRangeSection().Relocs))
       rangeList.dump(OS);
   }
 
@@ -732,7 +732,7 @@ DWARFContextInMemory::DWARFContextInMemory(const object::ObjectFile &Obj,
       *SectionData = data;
       if (name == "debug_ranges") {
         // FIXME: Use the other dwo range section when we emit it.
-        RangeDWOSection = data;
+        RangeDWOSection.Data = data;
       }
     } else if (name == "debug_types") {
       // Find debug_types data by section rather than name as there are
@@ -773,6 +773,7 @@ DWARFContextInMemory::DWARFContextInMemory(const object::ObjectFile &Obj,
         .Case("debug_loc", &LocSection.Relocs)
         .Case("debug_info.dwo", &InfoDWOSection.Relocs)
         .Case("debug_line", &LineSection.Relocs)
+        .Case("debug_ranges", &RangeSection.Relocs)
         .Case("apple_names", &AppleNamesSection.Relocs)
         .Case("apple_types", &AppleTypesSection.Relocs)
         .Case("apple_namespaces", &AppleNamespacesSection.Relocs)
@@ -855,7 +856,7 @@ StringRef *DWARFContextInMemory::MapSectionToMember(StringRef Name) {
       .Case("debug_frame", &DebugFrameSection)
       .Case("eh_frame", &EHFrameSection)
       .Case("debug_str", &StringSection)
-      .Case("debug_ranges", &RangeSection)
+      .Case("debug_ranges", &RangeSection.Data)
       .Case("debug_macinfo", &MacinfoSection)
       .Case("debug_pubnames", &PubNamesSection)
       .Case("debug_pubtypes", &PubTypesSection)

llvm/lib/DebugInfo/DWARF/DWARFDebugRangeList.cpp

@@ -7,6 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugRangeList.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
@@ -22,7 +23,8 @@ void DWARFDebugRangeList::clear() {
   Entries.clear();
 }
 
-bool DWARFDebugRangeList::extract(DataExtractor data, uint32_t *offset_ptr) {
+bool DWARFDebugRangeList::extract(DataExtractor data, uint32_t *offset_ptr,
+                                  const RelocAddrMap &Relocs) {
   clear();
   if (!data.isValidOffset(*offset_ptr))
     return false;
@@ -33,8 +35,11 @@ bool DWARFDebugRangeList::extract(DataExtractor data, uint32_t *offset_ptr) {
   while (true) {
     RangeListEntry entry;
     uint32_t prev_offset = *offset_ptr;
-    entry.StartAddress = data.getAddress(offset_ptr);
-    entry.EndAddress = data.getAddress(offset_ptr);
+    entry.StartAddress =
+        getRelocatedValue(data, AddressSize, offset_ptr, &Relocs);
+    entry.EndAddress =
+        getRelocatedValue(data, AddressSize, offset_ptr, &Relocs);
+
     // Check that both values were extracted correctly.
     if (*offset_ptr != prev_offset + 2 * AddressSize) {
       clear();

llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp

@@ -32,24 +32,25 @@ using namespace llvm;
 using namespace dwarf;
 
 void DWARFUnitSectionBase::parse(DWARFContext &C, const DWARFSection &Section) {
-  parseImpl(C, Section, C.getDebugAbbrev(), C.getRangeSection(),
+  parseImpl(C, Section, C.getDebugAbbrev(), &C.getRangeSection(),
             C.getStringSection(), StringRef(), C.getAddrSection(),
             C.getLineSection().Data, C.isLittleEndian(), false);
 }
 
 void DWARFUnitSectionBase::parseDWO(DWARFContext &C,
                                     const DWARFSection &DWOSection,
                                     DWARFUnitIndex *Index) {
-  parseImpl(C, DWOSection, C.getDebugAbbrevDWO(), C.getRangeDWOSection(),
+  parseImpl(C, DWOSection, C.getDebugAbbrevDWO(), &C.getRangeDWOSection(),
             C.getStringDWOSection(), C.getStringOffsetDWOSection(),
             C.getAddrSection(), C.getLineDWOSection().Data, C.isLittleEndian(),
             true);
 }
 
 DWARFUnit::DWARFUnit(DWARFContext &DC, const DWARFSection &Section,
-                     const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
-                     StringRef SOS, StringRef AOS, StringRef LS, bool LE,
-                     bool IsDWO, const DWARFUnitSectionBase &UnitSection,
+                     const DWARFDebugAbbrev *DA, const DWARFSection *RS,
+                     StringRef SS, StringRef SOS, StringRef AOS, StringRef LS,
+                     bool LE, bool IsDWO,
+                     const DWARFUnitSectionBase &UnitSection,
                      const DWARFUnitIndex::Entry *IndexEntry)
     : Context(DC), InfoSection(Section), Abbrev(DA), RangeSection(RS),
       LineSection(LS), StringSection(SS), StringOffsetSection([&]() {
@@ -142,9 +143,10 @@ bool DWARFUnit::extractRangeList(uint32_t RangeListOffset,
                                         DWARFDebugRangeList &RangeList) const {
   // Require that compile unit is extracted.
   assert(!DieArray.empty());
-  DataExtractor RangesData(RangeSection, isLittleEndian, AddrSize);
+  DataExtractor RangesData(RangeSection->Data, isLittleEndian, AddrSize);
   uint32_t ActualRangeListOffset = RangeSectionBase + RangeListOffset;
-  return RangeList.extract(RangesData, &ActualRangeListOffset);
+  return RangeList.extract(RangesData, &ActualRangeListOffset,
+                           RangeSection->Relocs);
 }
 
 void DWARFUnit::clear() {

llvm/test/DebugInfo/dwarfdump-ranges-unrelocated.s

@@ -0,0 +1,70 @@
+# RUN: llvm-mc -triple x86_64-pc-linux -filetype=obj %s -o %t
+# RUN: llvm-dwarfdump %t | FileCheck %s
+
+# CHECK: .debug_ranges contents:
+# CHECK:   00000000 0000000000000000 0000000000000001
+# CHECK:   00000000 0000000000000000 0000000000000002
+# CHECK:   00000000 <End of list>
+
+## Asm code for testcase is a reduced output from next invocation and source:
+# clang test.cpp -S -o test.s -gmlt -ffunction-sections
+# test.cpp:
+#   void foo1() { }  
+#   void foo2() { }  
+
+.section .text.foo1,"ax",@progbits
+.Lfunc_begin0:
+ nop
+.Lfunc_end0:
+
+.section .text.foo2,"ax",@progbits
+.Lfunc_begin1:
+ nop
+ nop
+.Lfunc_end1:
+
+.section .debug_abbrev,"",@progbits
+.byte 1                       # Abbreviation Code
+.byte 17                      # DW_TAG_compile_unit
+.byte 0                       # DW_CHILDREN_no
+.byte 37                      # DW_AT_producer
+.byte 14                      # DW_FORM_strp
+.byte 19                      # DW_AT_language
+.byte 5                       # DW_FORM_data2
+.byte 3                       # DW_AT_name
+.byte 14                      # DW_FORM_strp
+.byte 16                      # DW_AT_stmt_list
+.byte 23                      # DW_FORM_sec_offset
+.byte 27                      # DW_AT_comp_dir
+.byte 14                      # DW_FORM_strp
+.byte 17                      # DW_AT_low_pc
+.byte 1                       # DW_FORM_addr
+.byte 85                      # DW_AT_ranges
+.byte 23                      # DW_FORM_sec_offset
+.byte 0                       # EOM(1)
+.byte 0                       # EOM(2)
+.byte 0                       # EOM(3)
+
+.section .debug_info,"",@progbits
+.Lcu_begin0:
+.long 38                      # Length of Unit
+.short 4                      # DWARF version number
+.long .debug_abbrev           # Offset Into Abbrev. Section
+.byte 8                       # Address Size (in bytes)
+.byte 1                       # Abbrev [1] 0xb:0x1f DW_TAG_compile_unit
+.long 0                       # DW_AT_producer
+.short 4                      # DW_AT_language
+.long 0                       # DW_AT_name
+.long 0                       # DW_AT_stmt_list
+.long 0                       # DW_AT_comp_dir
+.quad 0                       # DW_AT_low_pc
+.long .Ldebug_ranges0         # DW_AT_ranges
+
+.section .debug_ranges,"",@progbits
+.Ldebug_ranges0:
+.quad .Lfunc_begin0
+.quad .Lfunc_end0
+.quad .Lfunc_begin1
+.quad .Lfunc_end1
+.quad 0
+.quad 0

llvm/tools/dsymutil/DwarfLinker.cpp

@@ -2869,7 +2869,7 @@ void DwarfLinker::patchRangesForUnit(const CompileUnit &Unit,
   DWARFDebugRangeList RangeList;
   const auto &FunctionRanges = Unit.getFunctionRanges();
   unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
-  DataExtractor RangeExtractor(OrigDwarf.getRangeSection(),
+  DataExtractor RangeExtractor(OrigDwarf.getRangeSection().Data,
                                OrigDwarf.isLittleEndian(), AddressSize);
   auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
   DWARFUnit &OrigUnit = Unit.getOrigUnit();
@@ -2884,7 +2884,7 @@ void DwarfLinker::patchRangesForUnit(const CompileUnit &Unit,
   for (const auto &RangeAttribute : Unit.getRangesAttributes()) {
     uint32_t Offset = RangeAttribute.get();
     RangeAttribute.set(Streamer->getRangesSectionSize());
-    RangeList.extract(RangeExtractor, &Offset);
+    RangeList.extract(RangeExtractor, &Offset, OrigDwarf.getRangeSection().Relocs);
     const auto &Entries = RangeList.getEntries();
     if (!Entries.empty()) {
       const DWARFDebugRangeList::RangeListEntry &First = Entries.front();