[ELF] Return the section name when calling getSymbolName on a section symbol.

Summary:
Previously, llvm-nm would report symbols for .debug and .note sections as: '?' with an empty  section name:

```
00000000 ?
00000000 ?
...
```

With this patch the output more closely resembles GNU nm:
```
00000000 N .debug_abbrev
00000000 n .note.GNU-stack
...
```

This patch calls `getSectionName` for sections that belong to symbols of type `ELF::STT_SECTION`, which returns the name of the section from the section string table.

Reviewers: Bigcheese, davide, jhenderson

Reviewed By: davide, jhenderson

Subscribers: rupprecht, jhenderson, llvm-commits

Differential Revision: https://reviews.llvm.org/D57105

llvm-svn: 352785

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 87ed8bbe6ab..a82ed0974fb 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -941,8 +941,11 @@ static void disassembleObject(const Target *TheTarget, const ObjectFile *Obj,
       report_error(Obj->getFileName(), SectionOrErr.takeError());
 
     uint8_t SymbolType = ELF::STT_NOTYPE;
-    if (Obj->isELF())
+    if (Obj->isELF()) {
       SymbolType = getElfSymbolType(Obj, Symbol);
+      if (SymbolType == ELF::STT_SECTION)
+        continue;
+    }
 
     section_iterator SecI = *SectionOrErr;
     if (SecI != Obj->section_end())