Paolo Carlini wrote: > Therefore, I'm not sure... I would certainly like to see method 2 > becoming the default everywhere, on the other hand, I'm not sure if > method 2 isn't too slow as default for C89 (outside fast-math, I > repeat). Shall we carry out performance tests perhaps, or peak > performance outside fast-math aren't really an issue here? I don't know.
Performance tests would certainly be useful. > In case of doubt, I would still switch to method 2 as default together > with C++0x, in that case the reference C language is C99 and things are > very neat... The problem is that this isn't how users think about it. If a user does: gcc test.c g++ test.c and gets different performance between the two, I think we're going to have a "C++ is slow" bug report. In a certain sense, the user may be right, in that C99/C++ mandate a slower approach than is used by GNU C89. But, because GNU C89 is the default, we still have a problem. Since C99 has defined semantics for this, and C++ is following, it seems reasonable to me to change C89 to always use these semantics. Then, some GNU C89 programs may go a bit slower, but we don't have weird differences between the languages. And, users can use -ffast-math to get the performance back -- in all languages, uniformly. -- Mark Mitchell CodeSourcery [EMAIL PROTECTED] (650) 331-3385 x713