On 3/2/06, H. J. Lu <[EMAIL PROTECTED]> wrote: > On Thu, Mar 02, 2006 at 04:44:50PM +0100, Jakub Jelinek wrote: > > On Thu, Mar 02, 2006 at 07:38:47AM -0800, H. J. Lu wrote: > > > Yes. That is for float and double functions in libm. > > > > > > > to touch x387 > > > > flags for XFmode long long operations. > > > > > > I assume you meant long double. If the library knows it doesn't long > > > double, it doesn't need to touch x87 unit control. > > > > But if you call one of the standard fenv.h functions, they > > are supposed to affect not just the calling routine (where you > > could through preprocessor magic tell what it uses, though e.g. > > not for inline asm), but for the whole process. And I don't understand > > how you can prove that if you call fesetround or similar from > > -mfpmath=sse compiled source file that the program doesn't anywhere > > in some other library or in the main binary use x87 unit (or vice versa). > > I was talking about glibc. sysdeps/ieee754/flt-32/e_expf.c has > > feholdexcept (&oldenv); > #ifdef FE_TONEAREST > fesetround (FE_TONEAREST); > #endif > > ... > > /* Return result. */ > fesetenv (&oldenv); > > I don't see why it has to touch x87 unit. The same applies to most, > if not all, float/double functions in glibc.
Right, but here a __builtin_fesetround and friends would be more appropriate that helping glibc with preprocessor magic. Richard.
