Summary:
This patch will obtain the section name for symbols that refer to a section. Prior to this patch the Name field for STT_SECTIONs was blank, now it is populated.
Before:
```
Symbol table '.symtab' contains 6 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 SECTION LOCAL DEFAULT 1
2: 0000000000000000 0 SECTION LOCAL DEFAULT 3
3: 0000000000000000 0 SECTION LOCAL DEFAULT 4
4: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND _GLOBAL_OFFSET_TABLE_
5: 0000000000000000 0 TLS GLOBAL DEFAULT UND sym
```
With this patch:
```
Symbol table '.symtab' contains 6 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 SECTION LOCAL DEFAULT 1 .text
2: 0000000000000000 0 SECTION LOCAL DEFAULT 3 .data
3: 0000000000000000 0 SECTION LOCAL DEFAULT 4 .bss
4: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND _GLOBAL_OFFSET_TABLE_
5: 0000000000000000 0 TLS GLOBAL DEFAULT UND sym
```
This fixes PR40788
Reviewers: jhenderson, rupprecht, espindola
Reviewed By: rupprecht
Subscribers: emaste, javed.absar, arichardson, MaskRay, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58796
llvm-svn: 355207
Section symbols exist as an optimization: instead of having multiple relocations
point to different symbols, many of them can point to a single section symbol.
When that optimization is unused, a section symbol is also unused and adds no
extra information to the object file.
This saves a bit of space on the object files and makes the output of
llvm-objdump -t easier to read and consequently some tests get quite a bit
simpler.
llvm-svn: 239045
The ELF spec is very clear:
-----------------------------------------------------------------------------
If the value is non-zero, it represents a string table index that gives the
symbol name. Otherwise, the symbol table entry has no name.
--------------------------------------------------------------------------
In particular, a st_name of 0 most certainly doesn't mean that the symbol has
the same name as the section.
llvm-svn: 238899
ELF has no restrictions on where undefined symbols go relative to other defined
symbols. In fact, gas just sorts them together. Do the same.
This was there since r111174 probably just because the MachO writer has it.
llvm-svn: 238513
Many of these predate llvm-readobj. With elf-dump we had to match
a relocation to symbol number and symbol number to symbol name or
section number.
llvm-svn: 235015
Matt Davis