------- Comment #17 from jakub at gcc dot gnu dot org 2010-09-16 14:08 ------- That's true. But many expanders can make use of DECL_ALIGN information, e.g. to choose faster code. If cfgexpand keeps doing what it does now, namely bumping DECL_ALIGN of variables up to PREFERRED_STACK_BOUNDARY even when in the end the stack block doesn't end up being aligned that way, then it lies to the expander and that will hit us again and again. On x86-64/i686, I don't think we want to prevent memcpy folding as your patch does, at least not for CPUs where movu* is fast.
-- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45678
