[llvm] r263971 - [llvm-objdump] Printing relocations in executable and shared object files. This partially reverts r215844 by removing test objdump-reloc-shared.test which stated GNU objdump doesn't print relocations, it does.

[Rafael Espíndola via llvm-commits]

> +uint64_t ELFObjectFile<ELFT>::getRelocationOffset(DataRefImpl Rel) const {
> +  const Elf_Shdr *sec = getRelSection(Rel);
> +  uint64_t Offset = sec->sh_type == ELF::SHT_REL ?
> +                    getRel(Rel)->r_offset :
> +                    getRela(Rel)->r_offset;
> +  if (EF.getHeader()->e_type == ELF::ET_EXEC ||
> +      EF.getHeader()->e_type == ELF::ET_DYN) {
> +    // For an executable file or a shared object, the value is the virtual
> +    // address of the storage unit affected by the relocation.
> +    auto SectionIter = getRelocatedSection(toDRI(sec));
> +    if (SectionIter != section_end())
> +      Offset -= SectionIter->getAddress();

This is completely wrong. You simply return the wrong value if the
section has no associated relocated section.


For example:
-----------------------------------------------------
$ cat test.c
__attribute__((visibility("hidden"))) int a = 42;
int *b = &a;
$ clang -c test.c
$ ld test.o -o test.so -shared
$ objdump  -r test.so

test.so:     file format elf64-x86-64

$ ./build/bin/llvm-objdump -r test.so

test.so:        file format ELF64-x86-64

RELOCATION RECORDS FOR [.rela.dyn]:
./build/bin/llvm-objdump: error reading file: Invalid data was
encountered while parsing the file.
-------------------------------------------------------


Reverting and adding the above test.


Cheers,
Rafael