[PATCH] D62296: [Object] object::ELFObjectFile::symbol_begin(): skip symbol index 0

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added reviewers: chrisjackson, evgeny777, jhenderson, mtrent, rupprecht.
Herald added subscribers: llvm-commits, arphaman.
Herald added a project: LLVM.

For clients iterating the symbol table, none expects to handle index 0
(STN_UNDEF). Skip it to improve consistency with other binary formats.
Clients that need STN_UNDEF (e.g. lld) can use
getSectionContentsAsArray().


Repository:
  rL LLVM

https://reviews.llvm.org/D62296

Files:
  include/llvm/Object/ELFObjectFile.h
  tools/llvm-objdump/llvm-objdump.cpp


Index: tools/llvm-objdump/llvm-objdump.cpp
===================================================================
--- tools/llvm-objdump/llvm-objdump.cpp
+++ tools/llvm-objdump/llvm-objdump.cpp
@@ -1643,11 +1643,6 @@
 
   const StringRef FileName = O->getFileName();
   for (auto I = O->symbol_begin(), E = O->symbol_end(); I != E; ++I) {
-    // Skip printing the special zero symbol when dumping an ELF file.
-    // This makes the output consistent with the GNU objdump.
-    if (I == O->symbol_begin() && isa<ELFObjectFileBase>(O))
-      continue;
-
     const SymbolRef &Symbol = *I;
     uint64_t Address = unwrapOrError(Symbol.getAddress(), ArchiveName, FileName,
                                      ArchitectureName);
Index: include/llvm/Object/ELFObjectFile.h
===================================================================
--- include/llvm/Object/ELFObjectFile.h
+++ include/llvm/Object/ELFObjectFile.h
@@ -982,7 +982,9 @@
 
 template <class ELFT>
 basic_symbol_iterator ELFObjectFile<ELFT>::symbol_begin() const {
-  DataRefImpl Sym = toDRI(DotSymtabSec, 0);
+  DataRefImpl Sym =
+      toDRI(DotSymtabSec,
+            DotSymtabSec && DotSymtabSec->sh_size >= sizeof(Elf_Sym) ? 1 : 0);
   return basic_symbol_iterator(SymbolRef(Sym, this));
 }
 


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