On 05/05/15 13:54, Jakub Jelinek wrote: > On Tue, May 05, 2015 at 01:49:55PM +0100, Richard Earnshaw wrote: >> The real question here is why is TYPE the type of the value, rather than >> the type of the formal as expressed by the prototype (or implicit >> prototype in the case of variadics or K&R)? Surely this is the mid-end >> passing the wrong information to the back-end. > > There is nothing else for unnamed arguments (K&R, stdarg). > For named arguments, the backend has the option to save the fntype in > CUMULATIVE_ARGS and look it up when it needs that. But, that will > still mean K&R and stdarg will be just broken on arm. > > Jakub >
In a literal sense, yes. However, even K&R & stdarg have standard promotion and conversion rules (size < int => int, floats promoted to double, etc). What are those rules for GCC's overaligned types (ie where in the docs does it say what happens and how a back-end should interpret them)? Shouldn't the mid-end be doing that work so as to create a consistent view of the values passed into the back-end? It seems to me that at present the back-end has to be psychic as to what is really happening. R.
