This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Miscompilation of remainder expressions


Gabriel Dos Reis wrote:

I would say that is a bit extreme.  I don't think we're going to
implement any of the solutions without giving people options to
disable the correct instruction generation when they don't care about
it.

I would hesitate a bit about options in this general class of


generate-wrong-code-i-don't-care

I think such options should only be in place if you can really
show a substantial effect.

Point in case, GNAT put in a truly horrible overflow detection
circuit very early on, that works by doing everything in double
precision and range checking the results. This seemed so very
inefficient that we made overflow checks off by default and
provided an option (-gnato) to turn them on.

But in practice, most large applications find that -gnato is
not noticeably expensive, and probably at the very least it
should have been made the default.

P.S. it would seem that -ftrapv would be just what Ada needs,
but our local gcc folks claim that -ftrapv is completely
broken and unusable :-(


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]