Fix file index verifier when there is no file name in the prologue. (#77004)

If there is no file name in the prologue of a line table, the verifier
will try to verify the file index, which will be set to 1 by default.
This will cause the DWARF verifier to throw an error even if there is no
error.

rdar://114476503
rdar://114343624

2 files changed, 363 insertions, 2 deletions

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp b/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
index 43ed60d7f977..18377815c78b 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
@@ -940,8 +940,13 @@ void DWARFVerifier::verifyDebugLineRows() {
         OS << '\n';
       }
 
-      // Verify file index.
-      if (!LineTable->hasFileAtIndex(Row.File)) {
+      // 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() == 0 &&
+            LineTable->Rows.size() == 1) &&
+          !LineTable->hasFileAtIndex(Row.File)) {
         ++NumDebugLineErrors;
         error() << ".debug_line["
                 << format("0x%08" PRIx64,
diff --git a/llvm/test/tools/llvm-dwarfdump/verify-no-file.yaml b/llvm/test/tools/llvm-dwarfdump/verify-no-file.yaml
new file mode 100644
index 000000000000..e43bb8808216
--- /dev/null
+++ b/llvm/test/tools/llvm-dwarfdump/verify-no-file.yaml
@@ -0,0 +1,356 @@
+# RUN: rm -rf %t && mkdir -p %t
+# RUN: yaml2obj %s -o %t/test.o
+# RUN: llvm-dwarfdump --debug-line --verify %t/test.o 2>&1 | FileCheck %s
+
+# CHECK-NOT: error: .debug_line[0x{{[0-9a-f]+}}][0] has invalid file index 1 (valid values are [1,0]):
+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACF
+  cputype:         0x100000C
+  cpusubtype:      0x0
+  filetype:        0x1
+  ncmds:           4
+  sizeofcmds:      1000
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+  reserved:        0x0
+LoadCommands:
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+    cmdsize:         872
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+    filesize:        635
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+        reserved2:       0x0
+        reserved3:       0x0
+        content:         C0035FD6
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+        segname:         __DWARF
+        addr:            0x4
+        size:            50
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