Fix line table lookups in line tables with multiple lines with the sa…

llvm/lib/DebugInfo/GSYM/LineTable.cpp

@@ -270,11 +270,6 @@ Expected<LineEntry> LineTable::lookup(DataExtractor &Data, uint64_t BaseAddr, ui
     if (Addr < Row.Addr)
       return false; // Stop parsing, result contains the line table row!
     Result = Row;
-    if (Addr == Row.Addr) {
-      // Stop parsing, this is the row we are looking for since the address
-      // matches.
-      return false;
-    }
     return true; // Keep parsing till we find the right row.
   });
   if (Err)

llvm/unittests/DebugInfo/GSYM/GSYMTest.cpp

@@ -4157,3 +4157,172 @@ TEST(GSYMTest, TestEmptyLinkageName) {
   // Make sure we don't see spurious errors in the output:
   EXPECT_TRUE(errors.find("error:") == std::string::npos);
 }
+
+TEST(GSYMTest, TestLineTablesWithEmptyRanges) {
+  // Test that lookups find the right line table entry when there are multiple
+  // line entries with the same address. When we have multiple line table
+  // entries with the same address, we need to pick the last one in the line
+  // table. We do this because a line entry's start address in the defined by
+  // the line table entry's address and the size is determined by the
+  // subtracting the next line table's address. If the current line table
+  // entry's address is the same as the next one, then there is no code
+  // assiciated with the current line table entry and it should be ignored.
+  //
+  // 0x0000000b: DW_TAG_compile_unit
+  //               DW_AT_name        ("/tmp/main.cpp")
+  //               DW_AT_language    (DW_LANG_C)
+  //               DW_AT_stmt_list   (0x00000000)
+  //
+  // 0x00000015:   DW_TAG_subprogram
+  //                 DW_AT_name      ("foo")
+  //                 DW_AT_low_pc    (0x0000000000001000)
+  //                 DW_AT_high_pc   (0x0000000000001050)
+  //
+  // 0x0000002a:   NULL
+  //
+  // The line table has a duplicate entry at 0x1010:
+  //
+  // Address    Line   Column File   ISA Discriminator Flags
+  // ---------- ------ ------ ------ --- ------------- -------------
+  // 0x00001000     10      0      1   0             0  is_stmt
+  // 0x00001010     11      0      1   0             0  is_stmt
+  // 0x00001010     12      0      1   0             0  is_stmt
+  // 0x00001050     13      0      1   0             0  is_stmt end_sequence
+
+  StringRef yamldata = R"(
+  debug_str:
+    - ''
+    - '/tmp/main.cpp'
+    - foo
+  debug_abbrev:
+    - ID:              0
+      Table:
+        - Code:            0x1
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_yes
+          Attributes:
+            - Attribute:       DW_AT_name
+              Form:            DW_FORM_strp
+            - Attribute:       DW_AT_language
+              Form:            DW_FORM_udata
+            - Attribute:       DW_AT_stmt_list
+              Form:            DW_FORM_sec_offset
+        - Code:            0x2
+          Tag:             DW_TAG_subprogram
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_name
+              Form:            DW_FORM_strp
+            - Attribute:       DW_AT_low_pc
+              Form:            DW_FORM_addr
+            - Attribute:       DW_AT_high_pc
+              Form:            DW_FORM_addr
+  debug_info:
+    - Length:          0x27
+      Version:         4
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x1
+          Values:
+            - Value:           0x1
+            - Value:           0x2
+            - Value:           0x0
+        - AbbrCode:        0x2
+          Values:
+            - Value:           0xF
+            - Value:           0x1000
+            - Value:           0x1050
+        - AbbrCode:        0x0
+  debug_line:
+    - Length:          71
+      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
+      Opcodes:
+        - Opcode:          DW_LNS_extended_op
+          ExtLen:          9
+          SubOpcode:       DW_LNE_set_address
+          Data:            4096
+        - Opcode:          DW_LNS_advance_line
+          SData:           9
+          Data:            0
+        - Opcode:          DW_LNS_copy
+          Data:            0
+        - Opcode:          DW_LNS_advance_pc
+          Data:            16
+        - Opcode:          DW_LNS_advance_line
+          SData:           1
+          Data:            0
+        - Opcode:          DW_LNS_copy
+          Data:            0
+        - Opcode:          DW_LNS_advance_line
+          SData:           1
+          Data:            0
+        - Opcode:          DW_LNS_copy
+          Data:            0
+        - Opcode:          DW_LNS_advance_pc
+          Data:            64
+        - Opcode:          DW_LNS_advance_line
+          SData:           1
+          Data:            0
+        - Opcode:          DW_LNS_extended_op
+          ExtLen:          1
+          SubOpcode:       DW_LNE_end_sequence
+          Data:            0
+  )";
+  auto ErrOrSections = DWARFYAML::emitDebugSections(yamldata);
+  ASSERT_THAT_EXPECTED(ErrOrSections, Succeeded());
+  std::unique_ptr<DWARFContext> DwarfContext =
+      DWARFContext::create(*ErrOrSections, 8);
+  ASSERT_TRUE(DwarfContext.get() != nullptr);
+  std::string errors;
+  raw_string_ostream OS(errors);
+  GsymCreator GC;
+  DwarfTransformer DT(*DwarfContext, GC);
+  const uint32_t ThreadCount = 1;
+  ASSERT_THAT_ERROR(DT.convert(ThreadCount, &OS), Succeeded());
+  ASSERT_THAT_ERROR(GC.finalize(OS), Succeeded());
+  OS.flush();
+  SmallString<512> Str;
+  raw_svector_ostream OutStrm(Str);
+  const auto ByteOrder = llvm::endianness::native;
+  FileWriter FW(OutStrm, ByteOrder);
+  ASSERT_THAT_ERROR(GC.encode(FW), Succeeded());
+  Expected<GsymReader> GR = GsymReader::copyBuffer(OutStrm.str());
+  ASSERT_THAT_EXPECTED(GR, Succeeded());
+  // There should be one function in our GSYM.
+  EXPECT_EQ(GR->getNumAddresses(), 1u);
+  // Verify "foo" is present and has a line table and no inline info.
+  auto ExpFI = GR->getFunctionInfo(0x1000);
+  ASSERT_THAT_EXPECTED(ExpFI, Succeeded());
+  ASSERT_EQ(ExpFI->Range, AddressRange(0x1000, 0x1050));
+  EXPECT_TRUE(ExpFI->OptLineTable.has_value());
+  EXPECT_FALSE(ExpFI->Inline.has_value());
+  StringRef FuncName = GR->getString(ExpFI->Name);
+  EXPECT_EQ(FuncName, "foo");
+
+  // Make sure we don't see spurious errors in the output:
+  EXPECT_TRUE(errors.find("error:") == std::string::npos);
+
+  // Make sure that when we lookup address 0x1010, that we get the entry that
+  // matches line 12, the second line entry that also has the address of
+  // 0x1010.
+  auto LR = GR->lookup(0x1010);
+  ASSERT_THAT_EXPECTED(LR, Succeeded());
+  SourceLocation src_loc = {"foo", "/tmp", "main.cpp", 12, 16};
+  EXPECT_THAT(LR->Locations, testing::ElementsAre(src_loc));
+git}