------- Comment #2 from rob1weld at aol dot com 2007-06-03 13:16 ------- Did GSL and Paranoia with -ffloat-store for gcc 4.3.0, same result.
Instead of "the normal x87 issue" it might be a "libm issue" since it works with Cygwin's gcc but fails with all the Linux gcc's. Here is something that gsl configure prints: checking for inline... inline checking for extern inline... yes checking ieeefp.h usability... no checking ieeefp.h presence... no checking for ieeefp.h... no checking for vprintf... yes checking for _doprnt... no ... checking for cos in -lm... yes checking whether feenableexcept is declared... yes checking whether fesettrapenable is declared... no checking whether hypot is declared... yes checking whether expm1 is declared... yes checking whether acosh is declared... yes checking whether asinh is declared... yes checking whether atanh is declared... yes checking whether ldexp is declared... yes checking whether frexp is declared... yes checking whether isinf is declared... yes checking whether finite is declared... yes checking whether isfinite is declared... no checking whether isnan is declared... yes checking whether log1p is declared... yes checking for long double stdio... yes checking for extended floating point registers... yes checking for IEEE arithmetic interface type... gnux86 checking for FPU_SETCW... yes checking for IEEE compiler flags... none checking for IEEE comparisons... yes checking for IEEE denormalized values... yes ... When Cygwin builds gcc it answers yes to these questions: checking ieeefp.h usability... no checking ieeefp.h presence... no It is good to see that GSL check the need for FPU_SETCW. GSL, like GCC, uses "-lm" whereas GCC's libjava builds and uses it's own libfdlibm.a (but unfortunately _seems_ to use "-lm" in a few places). If these programs CAN be compiled on target i686-pc-cygwin (old gcc) WITHOUT errors and can NOT be compiled on target i686-pc-linux-gnu (newer gcc) WITHOUT errors then NEWER gcc is not implementing it's math with the same accuracy as the older gcc does. I am using the same computer to run both tests so, in theory, it would be possible to alter GCC 4.3.0 (and 4.2.1, etc.) so that it's math results were as accurate as they once were. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32180
