On Fri, 19 Dec 2014, Markos Chandras wrote: > > Obviously to use anything other than the 'm' constraint you are going > > to need to know when any given constraint was added to GCC. > > 'ZC' was only added to GCC in March 2013 r196828 which I believe it is a > > GCC 4.9 feature so you will have to use it conditionally if you use it at > > all. > > > > is this something desirable? check the gcc version, initialize a macro > and then use that macro as a constrain? i haven't thought this through, > but it could be a bit messy. There is prior art for this, see arch/mips/include/asm/compiler.h and then grep the tree for uses. Maciej
