Is there any way to check if an object file(.o file) is PIC-enabled?
Not sure how portable this is, but for x86 and x86_64, ELF format, you can use readelf -r and look at the relocation types.
For 32bit PIC code, you should have a R_386_GOTPC relocation section:
Relocation section '.rel.text' at offset 0x38c contains 3 entries:
Offset Info Type Sym.Value Sym. Name
00000004 00000902 R_386_PC32 00000000 __i686.get_pc_thunk.cx
0000000a 00000a0a R_386_GOTPC 00000000 _GLOBAL_OFFSET_TABLE_
00000010 00000803 R_386_GOT32 00000000 f
No such section section should exists for non-PIC .os. (You'll also see a global offset table in the readelf -s output.)
For 64bit, same thing but with a R_X86_64_GOTPCREL relocation type. I'm pretty sure all the relocation type names are directly indicative of whether the code is PIC or not, but I can't find a reference right now.