[DWARFYAML][debug_info] Add support for error handling.

[Higuoxing]

Summary

This patch helps add support for error handling in DWARFYAML::emitDebugInfo().

[Higuoxing]

llvm/test/tools/yaml2obj/ELF/DWARF/debug-info.yaml

646

'a fatal error' -> 'an error'

Sorry I didn't notice it, I'll change it later

[jhenderson]

LGTM, with one nit.

llvm/lib/ObjectYAML/DWARFVisitor.h

16

Could you forward declare Error here, rather than having an extra include?

[Higuoxing]

llvm/lib/ObjectYAML/DWARFVisitor.h

16

Sure, I will do it later. Thanks!

[Higuoxing]

Address review comments.

llvm/lib/ObjectYAML/DWARFEmitter.cpp

 public:
   DumpVisitor(const DWARFYAML::Data &DI, raw_ostream &Out)
       : DWARFYAML::ConstVisitor(DI), OS(Out) {}
 };
 } // namespace
 
 Error DWARFYAML::emitDebugInfo(raw_ostream &OS, const DWARFYAML::Data &DI) {
   DumpVisitor Visitor(DI, OS);
-  Visitor.traverseDebugInfo();
-
-  return Error::success();
+  return Visitor.traverseDebugInfo();
 }
 
 static void emitFileEntry(raw_ostream &OS, const DWARFYAML::File &File) {
   OS.write(File.Name.data(), File.Name.size());
   OS.write('\0');
   encodeULEB128(File.DirIdx, OS);
   encodeULEB128(File.ModTime, OS);
   encodeULEB128(File.Length, OS);
DWARFYAML::emitDebugSections(StringRef YAMLString, bool ApplyFixups,
   DWARFYAML::Data DI;
   DI.IsLittleEndian = IsLittleEndian;
   YIn >> DI;
   if (YIn.error())
     return errorCodeToError(YIn.error());
 
   if (ApplyFixups) {
     DIEFixupVisitor DIFixer(DI);
-    DIFixer.traverseDebugInfo();
+    if (Error Err = DIFixer.traverseDebugInfo())
+      return std::move(Err);
   }
 
   StringMap<std::unique_ptr<MemoryBuffer>> DebugSections;
   Error Err = emitDebugSectionImpl(DI, &DWARFYAML::emitDebugInfo, "debug_info",
                                    DebugSections);
   Err = joinErrors(std::move(Err),
                    emitDebugSectionImpl(DI, &DWARFYAML::emitDebugLine,
                                         "debug_line", DebugSections));

llvm/lib/ObjectYAML/DWARFVisitor.h

 //===--- DWARFVisitor.h -----------------------------------------*- C++ -*-===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_OBJECTYAML_DWARFVISITOR_H
 #define LLVM_OBJECTYAML_DWARFVISITOR_H
 
 #include "llvm/ADT/StringRef.h"
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/Support/MemoryBuffer.h"
 
 namespace llvm {
+class Error;
 
 namespace DWARFYAML {
 
 struct Data;
 struct Unit;
 struct Entry;
 struct FormValue;
 struct AttributeAbbrev;
protected:
   virtual void onValue(const MemoryBufferRef MBR) {}
   /// @}
 
 public:
   VisitorImpl(T &DI) : DebugInfo(DI) {}
 
   virtual ~VisitorImpl() {}
 
-  void traverseDebugInfo();
+  Error traverseDebugInfo();
 
 private:
   void onVariableSizeValue(uint64_t U, unsigned Size);
 };
 
 // Making the visior instantiations extern and explicit in the cpp file. This
 // prevents them from being instantiated in every compile unit that uses the
 // visitors.

llvm/lib/ObjectYAML/DWARFVisitor.cpp

 //===--- DWARFVisitor.cpp ---------------------------------------*- C++ -*-===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 //===----------------------------------------------------------------------===//
 
 #include "DWARFVisitor.h"
 #include "llvm/ObjectYAML/DWARFYAML.h"
-#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Errc.h"
+#include "llvm/Support/Error.h"
 
 using namespace llvm;
 
 template <typename T>
 void DWARFYAML::VisitorImpl<T>::onVariableSizeValue(uint64_t U, unsigned Size) {
   switch (Size) {
   case 8:
     onValue((uint64_t)U);

 }
 
 static unsigned getRefSize(const DWARFYAML::Unit &Unit) {
   if (Unit.Version == 2)
     return Unit.AddrSize;
   return getOffsetSize(Unit);
 }
 
-template <typename T> void DWARFYAML::VisitorImpl<T>::traverseDebugInfo() {
+template <typename T> Error DWARFYAML::VisitorImpl<T>::traverseDebugInfo() {
   for (auto &Unit : DebugInfo.CompileUnits) {
     onStartCompileUnit(Unit);
     if (Unit.Entries.empty())
       continue;
 
     for (auto &Entry : Unit.Entries) {
       onStartDIE(Unit, Entry);
       uint32_t AbbrCode = Entry.AbbrCode;
       if (AbbrCode == 0 || Entry.Values.empty())
         continue;
 
       if (AbbrCode > DebugInfo.AbbrevDecls.size())
-        // TODO: Handle and test this error.
-        report_fatal_error(
+        return createStringError(
+            errc::invalid_argument,
             "abbrev code must be less than or equal to the number of "
             "entries in abbreviation table");
       const DWARFYAML::Abbrev &Abbrev = DebugInfo.AbbrevDecls[AbbrCode - 1];
       auto FormVal = Entry.Values.begin();
       auto AbbrForm = Abbrev.Attributes.begin();
       for (;
            FormVal != Entry.Values.end() && AbbrForm != Abbrev.Attributes.end();
            ++FormVal, ++AbbrForm) {
for (auto &Entry : Unit.Entries) {
             break;
           }
         } while (Indirect);
       }
       onEndDIE(Unit, Entry);
     }
     onEndCompileUnit(Unit);
   }
+
+  return Error::success();
 }
 
 // Explicitly instantiate the two template expansions.
 template class DWARFYAML::VisitorImpl<DWARFYAML::Data>;
 template class DWARFYAML::VisitorImpl<const DWARFYAML::Data>;

llvm/test/tools/yaml2obj/ELF/DWARF/debug-info.yaml

- Length:
           Values:
             - Value: 0x87654321
             - Value: 0x1234
         ## Test that yaml2obj ignores the contents of entries with abbrev code 0.
         - AbbrCode: 0
           Values:
             - Value: 0x1234
 
-## i) Test that yaml2obj reports a fatal error when 'debug_info' has values in its
+## i) Test that yaml2obj reports an error when 'debug_info' has values in its
 ## entries but 'debug_abbrev' doesn't have enough attributes for them.
 
-# RUN: not --crash yaml2obj --docnum=10 %s -o %t10.o 2>&1 | \
-# RUN:   FileCheck %s --check-prefixes=FATAL
+# RUN: not yaml2obj --docnum=10 %s -o %t10.o 2>&1 | \
+# RUN:   FileCheck %s --check-prefixes=ERROR
 
-# FATAL: LLVM ERROR: abbrev code must be less than or equal to the number of entries in abbreviation table
+# ERROR: yaml2obj: error: abbrev code must be less than or equal to the number of entries in abbreviation table
 
 --- !ELF
 FileHeader:
   Class:   ELFCLASS64
   Data:    ELFDATA2LSB
   Type:    ET_EXEC
   Machine: EM_X86_64
 DWARF: