Merge pull request #8163 from felipepiovezan/felipe/cherry-pick-empty-line-tables

[CherryPick][DWARFVerifier] Fix verification of empty line tables (llvm#81162)

Author: felipepiovezan

llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp

@@ -921,6 +921,11 @@ void DWARFVerifier::verifyDebugLineRows() {
       FileIndex++;
     }
 
+    // Nothing to verify in a line table with a single row containing the end
+    // sequence.
+    if (LineTable->Rows.size() == 1 && LineTable->Rows.front().EndSequence)
+      continue;
+
     // Verify rows.
     uint64_t PrevAddress = 0;
     uint32_t RowIndex = 0;
@@ -941,13 +946,7 @@ void DWARFVerifier::verifyDebugLineRows() {
         OS << '\n';
       }
 
-      // If the prologue contains no file names and the line table has only one
-      // row, do not verify the file index, this is a line table of an empty
-      // file with an end_sequence, but the DWARF standard sets the file number
-      // to 1 by default, otherwise verify file index.
-      if ((LineTable->Prologue.FileNames.size() ||
-           LineTable->Rows.size() != 1) &&
-          !LineTable->hasFileAtIndex(Row.File)) {
+      if (!LineTable->hasFileAtIndex(Row.File)) {
         ++NumDebugLineErrors;
         error() << ".debug_line["
                 << format("0x%08" PRIx64,

llvm/test/tools/llvm-dwarfdump/X86/verify_empty_debug_line_sequence.yaml

@@ -0,0 +1,55 @@
+# RUN: yaml2obj %s -o %t.o
+# RUN: llvm-dwarfdump -debug-line -verify %t.o | FileCheck %s
+
+# CHECK: Verifying .debug_line...
+# CHECK: No errors
+
+# In a line table like the one below, with no rows (other than the
+# end_sequence), we should never verify the file index because the state
+# machine initializes the file index to 1, which is invalid in DWARF 5 due to
+# its 0-based indexing.
+
+# file_names[  0]:
+#            name: "/home/umb/tests_2018/106_rnglists2"
+#       dir_index: 0
+# Address            Line   Column File   ISA Discriminator OpIndex Flags
+# ------------------ ------ ------ ------ --- ------------- ------- -------------
+# 0x0000000000000000      1      0      1   0             0       0  is_stmt end_sequence
+
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_EXEC
+DWARF:
+  debug_abbrev:
+    - ID:              0
+      Table:
+        - Code:            0x1
+          Tag:             DW_TAG_compile_unit
+          Children:        DW_CHILDREN_no
+          Attributes:
+            - Attribute:       DW_AT_stmt_list
+              Form:            DW_FORM_sec_offset
+  debug_info:
+    - Length:          0xd
+      Version:         5
+      UnitType:        DW_UT_compile
+      AbbrevTableID:   0
+      AbbrOffset:      0x0
+      AddrSize:        8
+      Entries:
+        - AbbrCode:        0x1
+          Values:
+            - Value:           0x0
+Sections:
+  - Name:            .debug_line
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x1
+    Content:         300000000500080025000000010101fb0e0d00010101010000000100000101011f010000000002011f020b010000000000000101
+  - Name:            .debug_line_str
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_MERGE, SHF_STRINGS ]
+    AddressAlign:    0x1
+    Content:         2F686F6D652F756D622F74657374735F323031382F3130365F726E676C697374733200746573742E63707000