From: Stan Shebs To: Norman Gray Cc: fortran-dev@lists.apple.com Subject: Re: Link problems: restFP/saveFP and -lcc_dynamic -- why? Date: Tue, 27 Jul 2004 12:04:25 -0700 Message-ID: <4106A739.1070808@apple.com> References: In-Reply-To: Norman Gray wrote: >Greetings, > >Can anyone explain to me what the story is with the restFP/saveFP >symbols, which cause such inexplicable link problems with (some? all?) >combinations of g77 and gcc code? [I posted this query on >macosx-dev@omnigroup.com a few days ago, but nobody wanted to bite]. > The underlying situation is that saveFP/restFP are entry points to special assembly language routines that some versions of the compiler will call instead of issuing a long string of floating-point register loads and stores when calling a function; saves a little space in code. Normally the definitions get compiled into GCC's own library libgcc, aka libcc_dynamic, and normally the compiler adds the library to the link line automagically. Problems come up because not every version of GCC issues the saveFP/restFP calls in preference to issuing the loads/stores directly, so if you mix-n-match compilers and don't link a libgcc that defines these, you get undefines. Another thing to watch out for is random libraries that were compiled by a GCC that assumes these, but linking with a libgcc that doesn't. In particular, restFP/saveFP has been one of the differences between FSF GCC and Apple GCC. Stan