[ELF] Better error reporting for undefined symbols

This patch make lld show following details for undefined symbol errors:
- file (line)
- file (function name)
- file (section name + offset)

Differential revision: https://reviews.llvm.org/D25826

llvm-svn: 285186

1 files changed, 48 insertions, 0 deletions

diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index f03a5bdf05f..2dd34f0d5d8 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -18,6 +18,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/CodeGen/Analysis.h"
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/LTO/LTO.h"
@@ -35,6 +36,39 @@ using namespace lld::elf;
 
 std::vector<InputFile *> InputFile::Pool;
 
+template <class ELFT> DIHelper<ELFT>::DIHelper(elf::InputFile *F) {
+  Expected<std::unique_ptr<object::ObjectFile>> Obj =
+      object::ObjectFile::createObjectFile(F->MB);
+  if (!Obj)
+    return;
+
+  DWARFContextInMemory Dwarf(*Obj.get());
+  DwarfLine.reset(new DWARFDebugLine(&Dwarf.getLineSection().Relocs));
+  DataExtractor LineData(Dwarf.getLineSection().Data,
+                         ELFT::TargetEndianness == support::little,
+                         ELFT::Is64Bits ? 8 : 4);
+  // The second parameter is offset in .debug_line section
+  // for compilation unit (CU) of interest. We have only one
+  // CU (object file), so offset is always 0.
+  DwarfLine->getOrParseLineTable(LineData, 0);
+}
+
+template <class ELFT> std::string DIHelper<ELFT>::getLineInfo(uintX_t Offset) {
+  if (!DwarfLine)
+    return "";
+
+  DILineInfo LineInfo;
+  DILineInfoSpecifier Spec;
+  // The offset to CU is 0 (see DIHelper constructor).
+  const DWARFDebugLine::LineTable *LineTbl = DwarfLine->getLineTable(0);
+  if (!LineTbl)
+    return "";
+  LineTbl->getFileLineInfoForAddress(Offset, nullptr, Spec.FLIKind, LineInfo);
+  return LineInfo.Line != 0
+             ? LineInfo.FileName + " (" + std::to_string(LineInfo.Line) + ")"
+             : "";
+}
+
 // Deletes all InputFile instances created so far.
 void InputFile::freePool() {
   // Files are freed in reverse order so that files created
@@ -132,6 +166,13 @@ ArrayRef<SymbolBody *> elf::ObjectFile<ELFT>::getSymbols() {
   return makeArrayRef(this->SymbolBodies).slice(1);
 }
 
+template <class ELFT> DIHelper<ELFT> *elf::ObjectFile<ELFT>::getDIHelper() {
+  if (!DIH)
+    DIH.reset(new DIHelper<ELFT>(this));
+
+  return DIH.get();
+}
+
 template <class ELFT> uint32_t elf::ObjectFile<ELFT>::getMipsGp0() const {
   if (ELFT::Is64Bits && MipsOptions && MipsOptions->Reginfo)
     return MipsOptions->Reginfo->ri_gp_value;
@@ -432,6 +473,8 @@ SymbolBody *elf::ObjectFile<ELFT>::createSymbolBody(const Elf_Sym *Sym) {
   int Binding = Sym->getBinding();
   InputSectionBase<ELFT> *Sec = getSection(*Sym);
   if (Binding == STB_LOCAL) {
+    if (Sym->getType() == STT_FILE)
+      SourceFile = check(Sym->getName(this->StringTable));
     if (Sym->st_shndx == SHN_UNDEF)
       return new (this->Alloc)
           Undefined(Sym->st_name, Sym->st_other, Sym->getType(), this);
@@ -897,3 +940,8 @@ template InputFile *BinaryFile::createELF<ELF32LE>();
 template InputFile *BinaryFile::createELF<ELF32BE>();
 template InputFile *BinaryFile::createELF<ELF64LE>();
 template InputFile *BinaryFile::createELF<ELF64BE>();
+
+template class elf::DIHelper<ELF32LE>;
+template class elf::DIHelper<ELF32BE>;
+template class elf::DIHelper<ELF64LE>;
+template class elf::DIHelper<ELF64BE>;