Fix DWARFDie::getDeclFile(...) to work with DW_AT_specification.

[clayborg]

Summary

DWARFDie::getDeclFile(...) previously only supported getting the DW_AT_decl_file if the DIE itself contained the DW_AT_decl_file attribute, or if the DIE had a DW_AT_abstract_origin that pointed to another DIE that had a DW_AT_decl_file. This patch allows the function to get the right attribute value if there is a DW_AT_specification that points to another DIE. We also test that if a DW_AT_abtract_origin or DW_AT_specification points to a DIE in another CU with a DW_FORM_ref_addr, that the right line table is used to extract the file index.

Full tests were added for the following cases:

• DIE has a DW_AT_decl_file attribute
• DIE has a DW_AT_abtract_origin that points to another die in the same CU
• DIE has a DW_AT_abtract_origin that points to another die in another CU
• DIE has a DW_AT_specification that points to another die in the same CU
• DIE has a DW_AT_specification that points to another die in another CU

[dblaikie]

Given the textual overhead of DWARF unit test yaml at the moment, I think it might be reasonable to put the various examples in one test file/one YAML rather than multiple separate tests with all the overhead of describing standalone DWARF in each test. Or, at least, trimming them down substantially to just the bare necessities.

llvm/unittests/DebugInfo/DWARF/DWARFDieTest.cpp

114–135

Could probably strip most of this out - keep just the DW_TAG_compile_unit's DW_AT_stmt_list, and the DW_TAG_subprogram's DW_AT_decl_file?

174–202

Can this all be stripped, or does it have to be here for some reason? (maybe it can just be the single end_sequence?)

[clayborg]

Reduced DWARF yaml to absolute minimum needed as suggested in review.

[dblaikie]

Sounds alright

llvm/include/llvm/DebugInfo/DWARF/DWARFFormValue.h

public:
   Optional<int64_t> getAsSignedConstant() const;
   Optional<const char *> getAsCString() const;
   Optional<uint64_t> getAsAddress() const;
   Optional<object::SectionedAddress> getAsSectionedAddress() const;
   Optional<uint64_t> getAsSectionOffset() const;
   Optional<ArrayRef<uint8_t>> getAsBlock() const;
   Optional<uint64_t> getAsCStringOffset() const;
   Optional<uint64_t> getAsReferenceUVal() const;
+  /// Correctly extract any file paths from a form value.
+  ///
+  /// These attributes can be in the from DW_AT_decl_file or DW_AT_call_file
+  /// attributes. We need to use the file index in the correct DWARFUnit's line
+  /// table prologue, and each DWARFFormValue has the DWARFUnit the form value
+  /// was extracted from.
+  ///
+  /// \param Kind The kind of path to extract.
+  ///
+  /// \returns A valid string value on success, or llvm::None if the form class
+  /// is not FC_Constant, or if the file index is not valid.
+  Optional<std::string>
+  getAsFile(DILineInfoSpecifier::FileLineInfoKind Kind) const;
 
   /// Skip a form's value in \p DebugInfoData at the offset specified by
   /// \p OffsetPtr.
   ///
   /// Skips the bytes for the current form and updates the offset.
   ///
   /// \param DebugInfoData The data where we want to skip the value.
   /// \param OffsetPtr A reference to the offset that will be updated.

llvm/lib/DebugInfo/DWARF/DWARFDie.cpp

 }
 
 uint64_t DWARFDie::getDeclLine() const {
   return toUnsigned(findRecursively(DW_AT_decl_line), 0);
 }
 
 std::string
 DWARFDie::getDeclFile(DILineInfoSpecifier::FileLineInfoKind Kind) const {
-  auto D = getAttributeValueAsReferencedDie(DW_AT_abstract_origin);
-  if (!D)
-    D = *this;
-  std::string FileName;
-  if (auto DeclFile = toUnsigned(D.find(DW_AT_decl_file))) {
-    if (const auto *LineTable =
-            getDwarfUnit()->getContext().getLineTableForUnit(
-                D.getDwarfUnit()->getLinkedUnit()))
-      LineTable->getFileNameByIndex(
-          *DeclFile, D.getDwarfUnit()->getCompilationDir(), Kind, FileName);
-  }
-  return FileName;
+  if (auto FormValue = findRecursively(DW_AT_decl_file))
+    if (auto OptString = FormValue->getAsFile(Kind))
+      return *OptString;
+  return {};
 }
 
 void DWARFDie::getCallerFrame(uint32_t &CallFile, uint32_t &CallLine,
                               uint32_t &CallColumn,
                               uint32_t &CallDiscriminator) const {
   CallFile = toUnsigned(find(DW_AT_call_file), 0);
   CallLine = toUnsigned(find(DW_AT_call_line), 0);
   CallColumn = toUnsigned(find(DW_AT_call_column), 0);

llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp

DWARFFormValue::getAsSectionedAddress() const {
   return {{Value.uval, Value.SectionIndex}};
 }
 
 Optional<uint64_t> DWARFFormValue::getAsReference() const {
   if (auto R = getAsRelativeReference())
     return R->Unit ? R->Unit->getOffset() + R->Offset : R->Offset;
   return None;
 }
-  
 Optional<DWARFFormValue::UnitOffset> DWARFFormValue::getAsRelativeReference() const {
   if (!isFormClass(FC_Reference))
     return None;
   switch (Form) {
   case DW_FORM_ref1:
   case DW_FORM_ref2:
   case DW_FORM_ref4:
   case DW_FORM_ref8:
Optional<uint64_t> DWARFFormValue::getAsCStringOffset() const {
   return Value.uval;
 }
 
 Optional<uint64_t> DWARFFormValue::getAsReferenceUVal() const {
   if (!isFormClass(FC_Reference))
     return None;
   return Value.uval;
 }
+
+Optional<std::string>
+DWARFFormValue::getAsFile(DILineInfoSpecifier::FileLineInfoKind Kind) const {
+  if (U == nullptr || !isFormClass(FC_Constant))
+    return None;
+  DWARFUnit *DU = const_cast<DWARFUnit *>(U);
+  if (auto *LT = U->getContext().getLineTableForUnit(DU->getLinkedUnit())) {
+    std::string FileName;
+    if (LT->getFileNameByIndex(Value.uval, DU->getCompilationDir(), Kind,
+                               FileName))
+      return FileName;
+  }
+  return None;
+}

llvm/unittests/DebugInfo/DWARF/DWARFDieTest.cpp

EXPECT_THAT_EXPECTED(
           "unexpected end of data at offset 0x20 while reading [0x20, 0x21)"));
 
   EXPECT_THAT_EXPECTED(
       Die.getLocations(DW_AT_call_data_value),
       Failed<ErrorInfoBase>(testing::Property(&ErrorInfoBase::message,
                                               "No DW_AT_call_data_value")));
 }
 
+TEST(DWARFDie, getDeclFile) {
+  const char *yamldata = R"(
+  debug_str:
+    - ''
+  debug_abbrev:
+    - ID:              0
+      Table:
+        - Code:            0x1
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_yes
+          Attributes:
+            - Attribute:       DW_AT_stmt_list
+              Form:            DW_FORM_sec_offset
+        - Code:            0x2
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_decl_file
+              Form:            DW_FORM_data1
+  debug_info:
+    - Length:          0xF
+      Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x1
+          Values:
+            - Value:           0x0
+        - AbbrCode:        0x2
+          Values:
+            - Value:           0x1
+        - AbbrCode:        0x0
+  debug_line:
+    - Length:          42
+      Version:         2
+      PrologueLength:  36
+      MinInstLength:   1
+      DefaultIsStmt:   1
+      LineBase:        251
+      LineRange:       14
+      OpcodeBase:      13
+      StandardOpcodeLengths: [ 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1 ]
+      IncludeDirs:
+        - '/tmp'
+      Files:
+        - Name:            main.cpp
+          DirIdx:          1
+          ModTime:         0
+          Length:          0
+  )";
+
+  // Given DWARF like this:
+  //
+  // 0x0000000b: DW_TAG_compile_unit
+  //               DW_AT_stmt_list (0x00000000)
+  //
+  // 0x00000010:   DW_TAG_subprogram
+  //                 DW_AT_decl_file ("/tmp/main.cpp")
+  //
+  // 0x00000012:   NULL
+  //
+  // This tests that we can extract the right DW_AT_decl_file from a DIE that
+  // has a DW_AT_decl_file attribute.
+
+  Expected<StringMap<std::unique_ptr<MemoryBuffer>>> Sections =
+      DWARFYAML::emitDebugSections(StringRef(yamldata),
+                                   /*IsLittleEndian=*/true,
+                                   /*Is64BitAddrSize=*/true);
+  ASSERT_THAT_EXPECTED(Sections, Succeeded());
+  std::unique_ptr<DWARFContext> Ctx =
+      DWARFContext::create(*Sections, 4, /*isLittleEndian=*/true);
+  DWARFCompileUnit *CU = Ctx->getCompileUnitForOffset(0);
+  ASSERT_NE(nullptr, CU);
+  DWARFDie Die = CU->getUnitDIE(/*ExtractUnitDIEOnly=*/false);
+  ASSERT_TRUE(Die.isValid());
+
+  DWARFDie MainDie = Die.getFirstChild();
+  ASSERT_TRUE(MainDie.isValid());
+
+  std::string DeclFile = MainDie.getDeclFile(
+      DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath);
+
+  EXPECT_EQ(DeclFile, "/tmp/main.cpp");
+}
+
+TEST(DWARFDie, getDeclFileAbstractOrigin) {
+  const char *yamldata = R"(
+  debug_str:
+    - ''
+  debug_abbrev:
+    - ID:              0
+      Table:
+        - Code:            0x1
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_yes
+          Attributes:
+            - Attribute:       DW_AT_stmt_list
+              Form:            DW_FORM_sec_offset
+        - Code:            0x2
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_abstract_origin
+              Form:            DW_FORM_ref_addr
+        - Code:            0x3
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_decl_file
+              Form:            DW_FORM_data1
+  debug_info:
+    - Length:          0x14
+      Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x1
+          Values:
+            - Value:           0x0
+        - AbbrCode:        0x2
+          Values:
+            - Value:           0x15
+        - AbbrCode:        0x3
+          Values:
+            - Value:           0x1
+        - AbbrCode:        0x0
+  debug_line:
+    - Length:          42
+      Version:         2
+      PrologueLength:  36
+      MinInstLength:   1
+      DefaultIsStmt:   1
+      LineBase:        251
+      LineRange:       14
+      OpcodeBase:      13
+      StandardOpcodeLengths: [ 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1 ]
+      IncludeDirs:
+        - '/tmp'
+      Files:
+        - Name:            main.cpp
+          DirIdx:          1
+          ModTime:         0
+          Length:          0
+  )";
+
+  // Given DWARF like this:
+  //
+  // 0x0000000b: DW_TAG_compile_unit
+  //               DW_AT_stmt_list (0x00000000)
+  //
+  // 0x00000010:   DW_TAG_subprogram
+  //                 DW_AT_abstract_origin (0x0000000000000015)
+  //
+  // 0x00000015:   DW_TAG_subprogram
+  //                 DW_AT_decl_file ("/tmp/main.cpp")
+  //
+  // 0x00000017:   NULL
+  //
+  //
+  // The DIE at 0x00000010 uses a DW_AT_abstract_origin to point to the DIE at
+  // 0x00000015, make sure that DWARFDie::getDeclFile() succeeds by extracting
+  // the right file name of "/tmp/main.cpp".
+  //
+  // This tests that when we have a DW_AT_abstract_origin with a compile unit
+  // relative form (DW_FORM_ref4) to another DIE that we get the right
+  // DW_AT_decl_file value.
+
+  Expected<StringMap<std::unique_ptr<MemoryBuffer>>> Sections =
+      DWARFYAML::emitDebugSections(StringRef(yamldata),
+                                   /*IsLittleEndian=*/true,
+                                   /*Is64BitAddrSize=*/true);
+  ASSERT_THAT_EXPECTED(Sections, Succeeded());
+  std::unique_ptr<DWARFContext> Ctx =
+      DWARFContext::create(*Sections, 4, /*isLittleEndian=*/true);
+  DWARFCompileUnit *CU = Ctx->getCompileUnitForOffset(0);
+  ASSERT_NE(nullptr, CU);
+  DWARFDie Die = CU->getUnitDIE(/*ExtractUnitDIEOnly=*/false);
+  ASSERT_TRUE(Die.isValid());
+
+  DWARFDie MainDie = Die.getFirstChild();
+  ASSERT_TRUE(MainDie.isValid());
+
+  std::string DeclFile = MainDie.getDeclFile(
+      DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath);
+
+  EXPECT_EQ(DeclFile, "/tmp/main.cpp");
+}
+
+TEST(DWARFDie, getDeclFileSpecification) {
+  const char *yamldata = R"(
+  debug_str:
+    - ''
+  debug_abbrev:
+    - ID:              0
+      Table:
+        - Code:            0x1
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_yes
+          Attributes:
+            - Attribute:       DW_AT_stmt_list
+              Form:            DW_FORM_sec_offset
+        - Code:            0x2
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_specification
+              Form:            DW_FORM_ref_addr
+        - Code:            0x3
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_decl_file
+              Form:            DW_FORM_data1
+  debug_info:
+    - Length:          0x14
+      Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x1
+          Values:
+            - Value:           0x0
+        - AbbrCode:        0x2
+          Values:
+            - Value:           0x15
+        - AbbrCode:        0x3
+          Values:
+            - Value:           0x1
+        - AbbrCode:        0x0
+  debug_line:
+    - Length:          42
+      Version:         2
+      PrologueLength:  36
+      MinInstLength:   1
+      DefaultIsStmt:   1
+      LineBase:        251
+      LineRange:       14
+      OpcodeBase:      13
+      StandardOpcodeLengths: [ 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1 ]
+      IncludeDirs:
+        - '/tmp'
+      Files:
+        - Name:            main.cpp
+          DirIdx:          1
+          ModTime:         0
+          Length:          0
+  )";
+
+  // Given DWARF like this:
+  //
+  // 0x0000000b: DW_TAG_compile_unit
+  //               DW_AT_stmt_list   (0x00000000)
+  //
+  // 0x00000010:   DW_TAG_subprogram
+  //                 DW_AT_specification     (0x0000000000000015)
+  //
+  // 0x00000015:   DW_TAG_subprogram
+  //                 DW_AT_decl_file ("/tmp/main.cpp")
+  //
+  // 0x00000017:   NULL
+  //
+  // The DIE at 0x00000010 uses a DW_AT_specification to point to the DIE at
+  // 0x00000015, make sure that DWARFDie::getDeclFile() succeeds by extracting
+  // the right file name of "/tmp/main.cpp".
+  //
+  // This tests that when we have a DW_AT_specification with a compile unit
+  // relative form (DW_FORM_ref4) to another DIE that we get the right
+  // DW_AT_decl_file value.
+
+  Expected<StringMap<std::unique_ptr<MemoryBuffer>>> Sections =
+      DWARFYAML::emitDebugSections(StringRef(yamldata),
+                                   /*IsLittleEndian=*/true,
+                                   /*Is64BitAddrSize=*/true);
+  ASSERT_THAT_EXPECTED(Sections, Succeeded());
+  std::unique_ptr<DWARFContext> Ctx =
+      DWARFContext::create(*Sections, 4, /*isLittleEndian=*/true);
+  DWARFCompileUnit *CU = Ctx->getCompileUnitForOffset(0);
+  ASSERT_NE(nullptr, CU);
+  DWARFDie Die = CU->getUnitDIE(/*ExtractUnitDIEOnly=*/false);
+  ASSERT_TRUE(Die.isValid());
+
+  DWARFDie MainDie = Die.getFirstChild();
+  ASSERT_TRUE(MainDie.isValid());
+
+  std::string DeclFile = MainDie.getDeclFile(
+      DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath);
+
+  EXPECT_EQ(DeclFile, "/tmp/main.cpp");
+}
+
+TEST(DWARFDie, getDeclFileAbstractOriginAcrossCUBoundary) {
+  const char *yamldata = R"(
+  debug_str:
+    - ''
+  debug_abbrev:
+    - ID:              0
+      Table:
+        - Code:            0x1
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_yes
+        - Code:            0x2
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_abstract_origin
+              Form:            DW_FORM_ref_addr
+        - Code:            0x3
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_yes
+          Attributes:
+            - Attribute:       DW_AT_stmt_list
+              Form:            DW_FORM_sec_offset
+        - Code:            0x4
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_decl_file
+              Form:            DW_FORM_data1
+  debug_info:
+    - Length:          0xE
+      Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x1
+        - AbbrCode:        0x2
+          Values:
+            - Value:           0x22
+        - AbbrCode:        0x0
+    - Length:          0xF
+      Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x3
+          Values:
+            - Value:           0x0
+        - AbbrCode:        0x4
+          Values:
+            - Value:           0x1
+        - AbbrCode:        0x0
+  debug_line:
+    - Length:          42
+      Version:         2
+      PrologueLength:  36
+      MinInstLength:   1
+      DefaultIsStmt:   1
+      LineBase:        251
+      LineRange:       14
+      OpcodeBase:      13
+      StandardOpcodeLengths: [ 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1 ]
+      IncludeDirs:
+        - '/tmp'
+      Files:
+        - Name:            main.cpp
+          DirIdx:          1
+          ModTime:         0
+          Length:          0
+  )";
+
+  // Given DWARF like this:
+  //
+  // 0x0000000b: DW_TAG_compile_unit
+  //
+  // 0x0000000c:   DW_TAG_subprogram
+  //                 DW_AT_abstract_origin (0x0000000000000022)
+  //
+  // 0x00000011:   NULL
+  //
+  // 0x0000001d: DW_TAG_compile_unit
+  //               DW_AT_stmt_list (0x00000000)
+  //
+  // 0x00000022:   DW_TAG_subprogram
+  //                 DW_AT_decl_file ("/tmp/main.cpp")
+  //
+  // 0x00000024:   NULL
+  //
+  // This tests that when we have a DW_AT_abstract_origin with a
+  // DW_FORM_ref_addr to another DIE in another compile unit that we use the
+  // right file table when converting the file index of the DW_AT_decl_file.
+  //
+  // The DIE at 0x0000000c uses a DW_AT_abstract_origin to point to the DIE at
+  // 0x00000022, make sure that DWARFDie::getDeclFile() succeeds by extracting
+  // the right file name of "/tmp/main.cpp". The DW_AT_decl_file must grab the
+  // file from the line table prologue of the compile unit at offset
+  // 0x0000001d.
+
+  Expected<StringMap<std::unique_ptr<MemoryBuffer>>> Sections =
+      DWARFYAML::emitDebugSections(StringRef(yamldata),
+                                   /*IsLittleEndian=*/true,
+                                   /*Is64BitAddrSize=*/true);
+  ASSERT_THAT_EXPECTED(Sections, Succeeded());
+  std::unique_ptr<DWARFContext> Ctx =
+      DWARFContext::create(*Sections, 4, /*isLittleEndian=*/true);
+  DWARFCompileUnit *CU = Ctx->getCompileUnitForOffset(0);
+  ASSERT_NE(nullptr, CU);
+  DWARFDie Die = CU->getUnitDIE(/*ExtractUnitDIEOnly=*/false);
+  ASSERT_TRUE(Die.isValid());
+
+  DWARFDie MainDie = Die.getFirstChild();
+  ASSERT_TRUE(MainDie.isValid());
+
+  std::string DeclFile = MainDie.getDeclFile(
+      DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath);
+
+  EXPECT_EQ(DeclFile, "/tmp/main.cpp");
+}
+
+TEST(DWARFDie, getDeclFileSpecificationAcrossCUBoundary) {
+  const char *yamldata = R"(
+  debug_str:
+    - ''
+  debug_abbrev:
+    - ID:              0
+      Table:
+        - Code:            0x1
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_yes
+        - Code:            0x2
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_specification
+              Form:            DW_FORM_ref_addr
+        - Code:            0x3
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_yes
+          Attributes:
+            - Attribute:       DW_AT_stmt_list
+              Form:            DW_FORM_sec_offset
+        - Code:            0x4
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_decl_file
+              Form:            DW_FORM_data1
+  debug_info:
+    - Length:          0xE
+      Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x1
+        - AbbrCode:        0x2
+          Values:
+            - Value:           0x22
+        - AbbrCode:        0x0
+    - Length:          0xF
+      Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x3
+          Values:
+            - Value:           0x0
+        - AbbrCode:        0x4
+          Values:
+            - Value:           0x1
+        - AbbrCode:        0x0
+  debug_line:
+    - Length:          42
+      Version:         2
+      PrologueLength:  36
+      MinInstLength:   1
+      DefaultIsStmt:   1
+      LineBase:        251
+      LineRange:       14
+      OpcodeBase:      13
+      StandardOpcodeLengths: [ 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1 ]
+      IncludeDirs:
+        - '/tmp'
+      Files:
+        - Name:            main.cpp
+          DirIdx:          1
+          ModTime:         0
+          Length:          0
+  )";
+
+  // Given DWARF like this:
+  //
+  // 0x0000000b: DW_TAG_compile_unit
+  //
+  // 0x0000000c:   DW_TAG_subprogram
+  //                 DW_AT_specification     (0x0000000000000022)
+  //
+  // 0x00000011:   NULL
+  //
+  // 0x0000001d: DW_TAG_compile_unit
+  //               DW_AT_stmt_list   (0x00000000)
+  //
+  // 0x00000022:   DW_TAG_subprogram
+  //                 DW_AT_decl_file ("/tmp/main.cpp")
+  //
+  // 0x00000024:   NULL
+  //
+  // This tests that when we have a DW_AT_specification with a
+  // DW_FORM_ref_addr to another DIE in another compile unit that we use the
+  // right file table when converting the file index of the DW_AT_decl_file.
+  //
+  // The DIE at 0x0000000c uses a DW_AT_specification to point to the DIE at
+  // 0x00000022, make sure that DWARFDie::getDeclFile() succeeds by extracting
+  // the right file name of "/tmp/main.cpp". The DW_AT_decl_file must grab the
+  // file from the line table prologue of the compile unit at offset
+  // 0x0000001d.
+
+  Expected<StringMap<std::unique_ptr<MemoryBuffer>>> Sections =
+      DWARFYAML::emitDebugSections(StringRef(yamldata),
+                                   /*IsLittleEndian=*/true,
+                                   /*Is64BitAddrSize=*/true);
+  ASSERT_THAT_EXPECTED(Sections, Succeeded());
+  std::unique_ptr<DWARFContext> Ctx =
+      DWARFContext::create(*Sections, 4, /*isLittleEndian=*/true);
+  DWARFCompileUnit *CU = Ctx->getCompileUnitForOffset(0);
+  ASSERT_NE(nullptr, CU);
+  DWARFDie Die = CU->getUnitDIE(/*ExtractUnitDIEOnly=*/false);
+  ASSERT_TRUE(Die.isValid());
+
+  DWARFDie MainDie = Die.getFirstChild();
+  ASSERT_TRUE(MainDie.isValid());
+
+  std::string DeclFile = MainDie.getDeclFile(
+      DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath);
+
+  EXPECT_EQ(DeclFile, "/tmp/main.cpp");
+}
+
 } // end anonymous namespace