http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50325
--- Comment #22 from rguenther at suse dot de <rguenther at suse dot de> 2011-12-01 09:22:19 UTC --- On Thu, 17 Nov 2011, krebbel at gcc dot gnu.org wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50325 > > --- Comment #14 from Andreas Krebbel <krebbel at gcc dot gnu.org> 2011-11-17 > 15:23:26 UTC --- > As the tests from Ian Sandoe and Dominique d'Humieres show, the Darwin/AIX > regressions disappear when limiting the extract_bit_field invocation to > fieldmode == BLKmode (as it was in the "Experimental fix" attached to the > bugzilla). > > But I'm not sure this is the right fix. In general also the other modes need > correct handling here. If the correct extraction of the source operand really > depends on things like function arg padding the handling in store_bit_field is > doomed to be incomplete. > > Richard, could you please have a look! Well, store_bit_field is supposed to do generic memory fiddling, dependency on function arg padding is unwanted - and thus such dependency has to be reflected by argument adjustments in the caller. [I can smell some weirdness we might have here though, but surely latent - if you have such argument (small C testcase I can look at with a cross?), take its address and perform aggregate assignment through a pointer - does that still work? Thus, does the memory layout of s and q in foo (struct S s) { struct S q; } really differ?
