[DebugInfo] Improve error message text

[jhenderson]

Summary

Unlike most of our errors in the debug line parser, the "no end of sequence" message was missing any reference to which line table it refererred to. This change adds the offset to this message.

[jhenderson]

Update missed test.

[dblaikie]

Seems good

[jhenderson]

Rebase on master and add missed lld test.

lld/test/ELF/undef.s

 # CHECK:      error: undefined symbol: zed5
 # CHECK-NEXT: >>> referenced by undef-debug.s:11 (dir{{/|\\}}undef-debug.s:11)
 # CHECK-NEXT: >>>               {{.*}}.o:(.text.2+0x0)
 
 # Show that all line table problems are mentioned as soon as the object's line information
 # is requested, even if that particular part of the line information is not currently required.
 # Also show that the warnings are only printed once.
 # CHECK:      warning: parsing line table prologue at 0x00000000 should have ended at 0x00000038 but it ended at 0x00000037
-# CHECK-NEXT: warning: last sequence in debug line table is not terminated!
+# CHECK-NEXT: warning: last sequence in debug line table at offset 0x0000005b is not terminated
 # CHECK:      error: undefined symbol: zed6a
 # CHECK-NEXT: >>> referenced by {{.*}}tmp4.o:(.text+0x0)
 # CHECK:      error: undefined symbol: zed6b
 # CHECK-NEXT: >>> referenced by {{.*}}tmp4.o:(.text+0x8)
 
 # Show that a problem with one line table's information doesn't affect getting information from
 # a different one in the same object.
 # CHECK:      error: undefined symbol: zed7

llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp

if (Opcode == 0) {
 
       State.appendRowToMatrix();
     }
     if(OS)
       *OS << "\n";
   }
 
   if (!State.Sequence.Empty)
-    RecoverableErrorCallback(
-        createStringError(errc::illegal_byte_sequence,
-                    "last sequence in debug line table is not terminated!"));
+    RecoverableErrorCallback(createStringError(
+        errc::illegal_byte_sequence,
+        "last sequence in debug line table at offset 0x%8.8" PRIx64
+        " is not terminated",
+        DebugLineOffset));
 
   // Sort all sequences so that address lookup will work faster.
   if (!Sequences.empty()) {
     llvm::sort(Sequences, Sequence::orderByHighPC);
     // Note: actually, instruction address ranges of sequences should not
     // overlap (in shared objects and executables). If they do, the address
     // lookup would still work, though, but result would be ambiguous.
     // We don't report warning in this case. For example,

llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test

 # ALL:      warning: parsing line table prologue at offset 0x00000048 found unsupported version 0x00
 # ALL-NEXT: warning: parsing line table prologue at offset 0x0000004e found unsupported version 0x01
 # ALL-NEXT: warning: parsing line table prologue at 0x00000054 found an invalid directory or file table description at 0x00000073
 # ALL-NEXT: warning: failed to parse entry content descriptions because no path was found
 # FIXME - The latter offset in the next line should be 0xad. The filename parsing code does not notice a missing terminating byte.
 # ALL-NEXT: warning: parsing line table prologue at 0x00000081 should have ended at 0x000000b9 but it ended at 0x000000ba
 # ALL-NEXT: warning: parsing line table prologue at 0x000000c9 should have ended at 0x00000104 but it ended at 0x00000103
 # OTHER-NEXT: warning: unexpected line op length at offset 0x00000158 expected 0x02 found 0x01
-# OTHER-NEXT: warning: last sequence in debug line table is not terminated!
+# OTHER-NEXT: warning: last sequence in debug line table at offset 0x00000167 is not terminated
 # ALL-NEXT: warning: parsing line table prologue at 0x000001ad should have ended at 0x000001c8 but it ended at 0x000001df
 # ALL-NEXT: warning: parsing line table prologue at 0x000001ed should have ended at 0x00000218 but it ended at 0x0000021f
 # ALL-NEXT: warning: parsing line table prologue at 0x0000022d should have ended at 0x0000024f but it ended at 0x0000025f
 # ALL-NEXT: warning: parsing line table prologue at 0x0000026d found an invalid directory or file table description at 0x000002a2
 # ALL-NEXT: warning: failed to parse file entry because the MD5 hash is invalid
 # ALL-NOT:  warning:

llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp

TEST_F(DebugLineBasicFixture, CallbackUsedForUnterminatedSequence) {
   LT.addStandardOpcode(DW_LNS_copy, {});
   LT.addByte(0xbb);
   LT.addByte(0xcc);
 
   generate();
 
   auto ExpectedLineTable = Line.getOrParseLineTable(LineData, 0, *Context,
                                                     nullptr, RecordRecoverable);
-  checkError("last sequence in debug line table is not terminated!",
+  checkError("last sequence in debug line table at offset 0x00000000 is not "
+             "terminated",
              std::move(Recoverable));
   ASSERT_TRUE(ExpectedLineTable.operator bool());
   EXPECT_EQ((*ExpectedLineTable)->Rows.size(), 6u);
   // The unterminated sequence is not added to the sequence list.
   EXPECT_EQ((*ExpectedLineTable)->Sequences.size(), 1u);
 }
 
 TEST_F(DebugLineBasicFixture, ParserParsesCorrectly) {
checkError(
       "unexpected line op length at offset 0x00000030 expected 0x42 found 0x01",
       std::move(Unrecoverable));
 
   // Reset the error state so that it does not confuse the next set of checks.
   Unrecoverable = Error::success();
   Parser.parseNext(RecordRecoverable, RecordUnrecoverable);
 
   EXPECT_TRUE(Parser.done());
-  checkError("last sequence in debug line table is not terminated!",
+  checkError("last sequence in debug line table at offset 0x00000031 is not "
+             "terminated",
              std::move(Recoverable));
   EXPECT_FALSE(Unrecoverable);
 }
 
 TEST_F(DebugLineBasicFixture,
        ParserReportsPrologueErrorsInEachTableWhenSkipping) {
   if (!setupGenerator())
     return;