> Note that I think the place of the check is unfortunate as you for example > will not remove the argument if it is unused. In fact I'm not yet sure > what transform exactly we are disabling. I am guessing we are > passing an aggregate by value that resides at a bit-aligned offset > of some outer object: > > foo (x.aggr); > > and the function then does > > foo (Aggr a) > { > int i = a.foo; > ... > } > > thus use only a part of the aggregate. Then IPA SRA would like to > pass x.aggr.foo instead of x.aggr and thus tries to materialize a > load from x.aggr.foo at all callers but fails to do that in a valid way.
Right, it's the usual MEM_EXPR business creating ADDR_EXPRs out of nowhere and miserably failing on something not addressable. > Erics fix did, at all callers > > Aggr tem = x.aggr; > foo (tem.foo); > > ? Yes, because the code wants to take &tem afterwards. > While we should be able to simply do > > foo (BIT_FIELD_REF <x.aggr, .....>) > > with the appropriate bit offset and size? (if that's of register type > you need to do the load in a separate stmt of couse). > > Thus similar to Erics fix but avoiding the aggregate copy. Yes, that should be doable, but I'm not sure it's worth the hassle. -- Eric Botcazou