On Mon, 2014-12-15 at 11:39 +0000, Richard Earnshaw wrote: > On 12/12/14 23:50, Florian Weimer wrote: > > On 12/12/2014 08:02 PM, Jeff Law wrote: > > > >> It'd probably work for the specific cases Florian wants to tackle, but > >> I'd consider it highly non-portable. > > > > I agree, that's why I asked for something “GCC-portable”. > > > > Don't go this way. Seriously, you can't assume that a future platform > ABI won't break if you do. ABI's at this level really aren't controlled > by GCC, which just has to conform to whatever the platform ABI requires. > We were very close in AArch64 to defining the ABI for variadics to push > all variadic (from the ... onwards) arguments onto the stack - it leads > to a very simple ABI from an implementation viewpoint and eliminates > much of the grotty code around reconstructing the parameter list. FYI, that's what the Renesas ABI does on SH. Makes capturing and forwarding va arg lists more efficient. Cheers, Oleg
