[llvm-dwp] Abort when dwo_id is unset

[rupprecht]

Summary

An empty dwo_id indicates a degenerate .dwo file that should not have been generated in the first place. Instead of discovering this error later when merging with another degenerate .dwo file, print an error immediately when noticing an unset dwo_id, including the filename of the offending file.

Test case created by compiling a trivial file w/ -fno-split-dwarf-inlining -gmlt -gsplit-dwarf -c prior to r353771

[dblaikie]

llvm/test/tools/llvm-dwp/X86/missing_dwo_id.test

3 ↗

(On Diff #186361)

This error starts with a capital ("C") and the other ("top level DIE is not ..." ) does not. Might be good to pick one way for the convention - I think probably non-capitals is the norm in these sort of diagnostics?

llvm/tools/llvm-dwp/llvm-dwp.cpp

190–191 ↗

(On Diff #186361)

In theory a hash could be zero, I think (it's not a blessed/allocated non-value for a hash function, so far as I would know/think) - so I think this would need to be wrapped in Optional (perhaps an an implementation detail of this function, the result structure doesn't have to expose this detail, necessarily - though perhaps callers need to know if this is valid to use or not, even when getCUIdentifiers succeeds)

[rupprecht]

• Use optional
• Fix error message casing

[dblaikie]

Looks good!

llvm/trunk/test/tools/llvm-dwp/X86/invalid_string_form.test

 RUN: not llvm-dwp %p/../Inputs/invalid_string_form.dwo -o %t 2>&1 | FileCheck %s
 
-CHECK: error: string field encoded without DW_FORM_string or DW_FORM_GNU_str_index
+CHECK: error: {{.*}}invalid_string_form.dwo': string field encoded without DW_FORM_string or DW_FORM_GNU_str_index

llvm/trunk/test/tools/llvm-dwp/X86/missing_dwo_id.test

+RUN: not llvm-dwp %p/../Inputs/missing_dwo_id.dwo -o %t 2>&1 | FileCheck %s
+
+CHECK: error: {{.*}}missing_dwo_id.dwo': compile unit missing dwo_id

llvm/trunk/test/tools/llvm-dwp/X86/non_cu_top_level.test

 RUN: not llvm-dwp %p/../Inputs/non_cu_top_level.dwo -o %t 2>&1 | FileCheck %s
 
-CHECK: error: top level DIE is not a compile unit
+CHECK: error: {{.*}}non_cu_top_level.dwo': top level DIE is not a compile unit

llvm/trunk/tools/llvm-dwp/llvm-dwp.cpp

 //===-- llvm-dwp.cpp - Split DWARF merging tool for llvm ------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // A utility for merging DWARF 5 Split DWARF .dwo files into .dwp (DWARF
 // package files).
 //
 //===----------------------------------------------------------------------===//
 #include "DWPError.h"
 #include "DWPStringPool.h"
 #include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
 #include "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
 #include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCCodeEmitter.h"
 #include "llvm/MC/MCContext.h"
static Expected<CompileUnitIdentifiers> getCUIdentifiers(StringRef Abbrev,
   auto Tag = static_cast<dwarf::Tag>(AbbrevData.getULEB128(&AbbrevOffset));
   if (Tag != dwarf::DW_TAG_compile_unit)
     return make_error<DWPError>("top level DIE is not a compile unit");
   // DW_CHILDREN
   AbbrevData.getU8(&AbbrevOffset);
   uint32_t Name;
   dwarf::Form Form;
   CompileUnitIdentifiers ID;
+  Optional<uint64_t> Signature = None;
   while ((Name = AbbrevData.getULEB128(&AbbrevOffset)) |
          (Form = static_cast<dwarf::Form>(AbbrevData.getULEB128(&AbbrevOffset))) &&
          (Name != 0 || Form != 0)) {
     switch (Name) {
     case dwarf::DW_AT_name: {
       Expected<const char *> EName =
           getIndexedString(Form, InfoData, Offset, StrOffsets, Str);
       if (!EName)
         return EName.takeError();
       ID.Name = *EName;
       break;
     }
     case dwarf::DW_AT_GNU_dwo_name: {
       Expected<const char *> EName =
           getIndexedString(Form, InfoData, Offset, StrOffsets, Str);
       if (!EName)
         return EName.takeError();
       ID.DWOName = *EName;
       break;
     }
     case dwarf::DW_AT_GNU_dwo_id:
-      ID.Signature = InfoData.getU64(&Offset);
+      Signature = InfoData.getU64(&Offset);
       break;
     default:
       DWARFFormValue::skipValue(Form, InfoData, &Offset,
                                 dwarf::FormParams({Version, AddrSize, Format}));
     }
   }
+  if (!Signature)
+    return make_error<DWPError>("compile unit missing dwo_id");
+  ID.Signature = *Signature;
   return ID;
 }
 
 struct UnitIndexEntry {
   DWARFUnitIndex::Entry::SectionContribution Contributions[8];
   std::string Name;
   std::string DWOName;
   StringRef DWPName;
for (const auto &Input : Inputs) {
 
     writeStringsAndOffsets(Out, Strings, StrOffsetSection, CurStrSection,
                            CurStrOffsetSection);
 
     if (CurCUIndexSection.empty()) {
       Expected<CompileUnitIdentifiers> EID = getCUIdentifiers(
           AbbrevSection, InfoSection, CurStrOffsetSection, CurStrSection);
       if (!EID)
-        return EID.takeError();
+        return createFileError(Input, EID.takeError());
       const auto &ID = *EID;
       auto P = IndexEntries.insert(std::make_pair(ID.Signature, CurEntry));
       if (!P.second)
         return buildDuplicateError(*P.first, ID, "");
       P.first->second.Name = ID.Name;
       P.first->second.DWOName = ID.DWOName;
       addAllTypes(Out, TypeIndexEntries, TypesSection, CurTypesSection,
                   CurEntry, ContributionOffsets[DW_SECT_TYPES - DW_SECT_INFO]);
for (const DWARFUnitIndex::Entry &E : CUIndex.getRows()) {
         continue;
       auto P = IndexEntries.insert(std::make_pair(E.getSignature(), CurEntry));
       Expected<CompileUnitIdentifiers> EID = getCUIdentifiers(
           getSubsection(AbbrevSection, E, DW_SECT_ABBREV),
           getSubsection(InfoSection, E, DW_SECT_INFO),
           getSubsection(CurStrOffsetSection, E, DW_SECT_STR_OFFSETS),
           CurStrSection);
       if (!EID)
-        return EID.takeError();
+        return createFileError(Input, EID.takeError());
       const auto &ID = *EID;
       if (!P.second)
         return buildDuplicateError(*P.first, ID, Input);
       auto &NewEntry = P.first->second;
       NewEntry.Name = ID.Name;
       NewEntry.DWOName = ID.DWOName;
       NewEntry.DWPName = Input;
       for (auto Kind : CUIndex.getColumnKinds()) {