Don't get confused with sections whose section number is reserved.

It is perfectly possible for SHNDX to contain indexes that have the same value
as reserved st_shndx values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240544 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Object/ELF.h

@@ -401,7 +401,7 @@ public:
 
   uint64_t getNumSections() const;
   uintX_t getStringTableIndex() const;
-  ELF::Elf64_Word getSymbolTableIndex(const Elf_Sym *symb) const;
+  ELF::Elf64_Word getExtendedSymbolTableIndex(const Elf_Sym *symb) const;
   const Elf_Ehdr *getHeader() const { return Header; }
   const Elf_Shdr *getSection(const Elf_Sym *symb) const;
   const Elf_Shdr *getSection(uint32_t Index) const;
@@ -510,10 +510,10 @@ void ELFFile<ELFT>::LoadVersionMap() const {
 }
 
 template <class ELFT>
-ELF::Elf64_Word ELFFile<ELFT>::getSymbolTableIndex(const Elf_Sym *symb) const {
-  if (symb->st_shndx == ELF::SHN_XINDEX)
-    return ExtendedSymbolTable.lookup(symb);
-  return symb->st_shndx;
+ELF::Elf64_Word
+ELFFile<ELFT>::getExtendedSymbolTableIndex(const Elf_Sym *symb) const {
+  assert(symb->st_shndx == ELF::SHN_XINDEX);
+  return ExtendedSymbolTable.lookup(symb);
 }
 
 template <class ELFT>

include/llvm/Object/ELFObjectFile.h

@@ -278,7 +278,7 @@ template <class ELFT>
 std::error_code ELFObjectFile<ELFT>::getSymbolAddress(DataRefImpl Symb,
                                                       uint64_t &Result) const {
   const Elf_Sym *ESym = getSymbol(Symb);
-  switch (EF.getSymbolTableIndex(ESym)) {
+  switch (ESym->st_shndx) {
   case ELF::SHN_COMMON:
   case ELF::SHN_UNDEF:
     Result = UnknownAddress;
@@ -383,11 +383,10 @@ uint32_t ELFObjectFile<ELFT>::getSymbolFlags(DataRefImpl Symb) const {
       EIter == EF.begin_symbols() || EIter == EF.begin_dynamic_symbols())
     Result |= SymbolRef::SF_FormatSpecific;
 
-  if (EF.getSymbolTableIndex(ESym) == ELF::SHN_UNDEF)
+  if (ESym->st_shndx == ELF::SHN_UNDEF)
     Result |= SymbolRef::SF_Undefined;
 
-  if (ESym->getType() == ELF::STT_COMMON ||
-      EF.getSymbolTableIndex(ESym) == ELF::SHN_COMMON)
+  if (ESym->getType() == ELF::STT_COMMON || ESym->st_shndx == ELF::SHN_COMMON)
     Result |= SymbolRef::SF_Common;
 
   if (isExportedToOtherDSO(ESym))

test/MC/ELF/many-sections-3.s

@@ -0,0 +1,107 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o %t
+// RUN: llvm-readobj -t %t | FileCheck --check-prefix=SYMBOLS %s
+// RUN: llvm-nm %t | FileCheck --check-prefix=NM %s
+
+// Test that symbol a has a section that could be confused with common (0xFFF2)
+// SYMBOLS:         Name: a
+// SYMBOLS-NEXT:    Value: 0x0
+// SYMBOLS-NEXT:    Size: 0
+// SYMBOLS-NEXT:    Binding: Local (0x0)
+// SYMBOLS-NEXT:    Type: None (0x0)
+// SYMBOLS-NEXT:    Other: 0
+// SYMBOLS-NEXT:    Section: bar (0xFFF2)
+// SYMBOLS-NEXT:  }
+
+// Test that we don't get confused
+// NM: 0000000000000000 r a
+
+.macro gen_sections4 x
+        .section a\x
+        .section b\x
+        .section c\x
+        .section d\x
+.endm
+
+.macro gen_sections8 x
+        gen_sections4 a\x
+        gen_sections4 b\x
+.endm
+
+.macro gen_sections16 x
+        gen_sections8 a\x
+        gen_sections8 b\x
+.endm
+
+.macro gen_sections32 x
+        gen_sections16 a\x
+        gen_sections16 b\x
+.endm
+
+.macro gen_sections64 x
+        gen_sections32 a\x
+        gen_sections32 b\x
+.endm
+
+.macro gen_sections128 x
+        gen_sections64 a\x
+        gen_sections64 b\x
+.endm
+
+.macro gen_sections256 x
+        gen_sections128 a\x
+        gen_sections128 b\x
+.endm
+
+.macro gen_sections512 x
+        gen_sections256 a\x
+        gen_sections256 b\x
+.endm
+
+.macro gen_sections1024 x
+        gen_sections512 a\x
+        gen_sections512 b\x
+.endm
+
+.macro gen_sections2048 x
+        gen_sections1024 a\x
+        gen_sections1024 b\x
+.endm
+
+.macro gen_sections4096 x
+        gen_sections2048 a\x
+        gen_sections2048 b\x
+.endm
+
+.macro gen_sections8192 x
+        gen_sections4096 a\x
+        gen_sections4096 b\x
+.endm
+
+.macro gen_sections16384 x
+        gen_sections8192 a\x
+        gen_sections8192 b\x
+.endm
+
+.macro gen_sections32768 x
+        gen_sections16384 a\x
+        gen_sections16384 b\x
+.endm
+
+gen_sections32768 a
+gen_sections16384 b
+gen_sections8192 c
+gen_sections4096 d
+gen_sections2048 e
+gen_sections1024 f
+gen_sections512 g
+gen_sections256 h
+gen_sections128 i
+gen_sections64 j
+gen_sections32 k
+gen_sections8 l
+gen_sections4 m
+
+        .section foo
+        .section bar, "a"
+
+a:

tools/llvm-readobj/ELFDumper.cpp

@@ -156,9 +156,7 @@ getSectionNameIndex(const ELFO &Obj, typename ELFO::Elf_Sym_Iter Symbol,
     SectionName = "Reserved";
   else {
     if (SectionIndex == SHN_XINDEX)
-      SectionIndex = Obj.getSymbolTableIndex(&*Symbol);
-    assert(SectionIndex != SHN_XINDEX &&
-           "getSymbolTableIndex should handle this");
+      SectionIndex = Obj.getExtendedSymbolTableIndex(&*Symbol);
     const typename ELFO::Elf_Shdr *Sec = Obj.getSection(SectionIndex);
     SectionName = errorOrDefault(Obj.getSectionName(Sec));
   }