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15.3.2 Compilers

The only compiler characteristics that affect libtool are the flags needed (if any) to generate PIC objects. In general, if a C compiler supports certain PIC flags, then any derivative compilers support the same flags. Until there are some noteworthy exceptions to this rule, this section will document only C compilers.

The following C compilers have standard command line options, regardless of the platform:


This is the GNU C compiler, which is also the system compiler for many free operating systems (FreeBSD, GNU/Hurd, GNU/Linux, Lites, NetBSD, and OpenBSD, to name a few).

The -fpic or -fPIC flags can be used to generate position-independent code. -fPIC is guaranteed to generate working code, but the code is slower on m68k, m88k, and SPARC chips. However, using -fpic on those chips imposes arbitrary size limits on the shared libraries.

The rest of this subsection lists compilers by the operating system that they are bundled with:


Most AIX compilers have no PIC flags, since AIX (with the exception of AIX for IA-64) runs on PowerPC and RS/6000 chips. 14


Use ‘+Z’ to generate PIC.


Digital/UNIX 3.x does not have PIC flags, at least not on the PowerPC platform.


Use -KPIC to generate PIC.


Use -PIC to generate PIC.



All code compiled for the PowerPC and RS/6000 chips (powerpc-*-*, powerpcle-*-*, and rs6000-*-*) is position-independent, regardless of the operating system or compiler suite. So, “regular objects” can be used to build shared libraries on these systems and no special PIC compiler flags are required.