On 05/05/15 15:33, Richard Earnshaw wrote: > On 05/05/15 15:29, Jakub Jelinek wrote: >> On Tue, May 05, 2015 at 02:20:43PM +0100, Richard Earnshaw wrote: >>> On 05/05/15 14:06, Jakub Jelinek wrote: >>>> On Tue, May 05, 2015 at 02:02:19PM +0100, Richard Earnshaw wrote: >>>>> 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 >>>> >>>> For the middle-end, the TYPE_ALIGN info on expression types is considered >>>> useless, you can get there anything. There is no conversion rule to what >>>> you get for myalignedint + int, or (myalignedint) int, or (int) >>>> myalignedint, etc. >>>> >>>>> 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. >>>> >>>> No, the backend just shouldn't consider TYPE_ALIGN on the scalars, and it >>>> seems only arm ever looks at that. >>>> >>> >>> Nothing in the specification for TARGET_FUNCTION_ARG (or any of the >>> related functions) makes any mention of this... >> >> While this requirement isn't documented, it is clearly common sense or at >> least something any kind of testing would reveal immediately. > > Then clearly no such tests exist in the testsuite :-( >
Or, more precisely, no such tests existed in 2008, when the code went in. R. > R. > >> And it is nothing broken recently (except that with the SRA changes it hits >> much more often), looking e.g. at GCC 3.2, I'm seeing that expand_call is on >> that testcase also called with pretty random TYPE_ALIGN on the argument >> types; we didn't have GIMPLE then, so it is nothing that GIMPLE brought in. >> >> Jakub >> >
