On Tue, Mar 10, 2009 at 10:41 AM, Sylvain Pion <sylvain.p...@sophia.inria.fr> wrote: > Richard Guenther wrote: >> >> The middle-end knows about an explicit association barrier (only >> used from the Fortran FE sofar), a PAREN_EXPR. Would exposing >> that to C/C++ be of any help? For example it would, even with >> -ffast-math, avoid constant folding for (x + FLT_EPS) - FLT_EPS >> (which FLT_EPS such that proper rounding to the nearest integer >> value is performed). > > Off the top of my head, I don't see anything both really useful > and not-surprising in C/C++ here, but I may well miss something. > > There are some C++0x features, axiom and constexpr, which are > related to this area. It's not clear yet to me how all this > will interact, but I have good hope to see some connections > there (like modeling some associativity rules with axioms).
Note that axioms do not change the behaviour of a program -- assuming the program contains `no bugs'. -- Gaby
