g++(1) -fpic
GNU project C and C++ compiler
-fpic
    Generate position-independent code (PIC) suitable for use in a shared library, if supported for the
    target machine.  Such code accesses all constant addresses through a global offset table (GOT).  The
    dynamic loader resolves the GOT entries when the program starts (the dynamic loader is not part of
    GCC; it is part of the operating system).  If the GOT size for the linked executable exceeds a
    machine-specific maximum size, you get an error message from the linker indicating that -fpic does
    not work; in that case, recompile with -fPIC instead.  (These maximums are 8k on the SPARC and 32k on
    the m68k and RS/6000.  The 386 has no such limit.)

    Position-independent code requires special support, and therefore works only on certain machines.
    For the 386, GCC supports PIC for System V but not for the Sun 386i.  Code generated for the IBM
    RS/6000 is always position-independent.

    When this flag is set, the macros "__pic__" and "__PIC__" are defined to 1.
source manpages: g++