On 2005-05-29 13:22:55 +0300, Michael Veksler wrote: > Two examples come in mind: > 1. Non conformance of x86 to the standard FP due to > its extra precision.
Wrong. The IEEE-754 standard allows extended precision. > This includes different results between -O2 and -O0 even with > -fsave-temps. Getting different results is not the problem (and indeed, some bug reports are invalid, but *some* of them only). > Several PR about this issue were marked invalid in > the past. > This is a bug in two places: > i. x86 FP which implements wrong precision. As I've said above, this is not a wrong precision; this is allowed by the IEEE-754 standard. So, this is definitely not a hardware bug. Perhaps just a bad design. > ii. glibc that claims in its headers that it sets to set > default precision to 64 bits, when in practice it > sets it to 80 bits. Where? Has there been a bug report about that? If you think of FLT_EVAL_METHOD, it is set to 2. It may be wrong (as said later in this thread), but it certainly does not mean that the default precision is the IEEE-754 double precision. -- Vincent Lefèvre <[EMAIL PROTECTED]> - Web: <http://www.vinc17.org/> 100% accessible validated (X)HTML - Blog: <http://www.vinc17.org/blog/> Work: CR INRIA - computer arithmetic / SPACES project at LORIA
