On Wed, Nov 17, 2021 at 1:39 AM Richard Sandiford via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > apinski--- via Gcc-patches <gcc-patches@gcc.gnu.org> writes: > > From: Andrew Pinski <apin...@marvell.com> > > > > The problem here is with -mstrict-align, aarch64_expand_setmem needs > > to check the alginment of the mode to make sure we can use it for > > doing the stores. > > > > gcc/ChangeLog: > > > > PR target/103100 > > * config/aarch64/aarch64.c (aarch64_expand_setmem): > > Add check for alignment of the mode if STRICT_ALIGNMENT is true. > > --- > > gcc/config/aarch64/aarch64.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c > > index fdf05505846..2c00583e12c 100644 > > --- a/gcc/config/aarch64/aarch64.c > > +++ b/gcc/config/aarch64/aarch64.c > > @@ -23738,7 +23738,9 @@ aarch64_expand_setmem (rtx *operands) > > over writing. */ > > opt_scalar_int_mode mode_iter; > > FOR_EACH_MODE_IN_CLASS (mode_iter, MODE_INT) > > - if (GET_MODE_BITSIZE (mode_iter.require ()) <= MIN (n, copy_limit)) > > + if (GET_MODE_BITSIZE (mode_iter.require ()) <= MIN (n, copy_limit) > > + && (!STRICT_ALIGNMENT > > + || MEM_ALIGN (dst) >= GET_MODE_ALIGNMENT (mode_iter.require > > ()))) > > Sorry for the slow review. I think instead we should have keep > track of the alignment of the start byte. This will be MEM_ALIGN > for the first iteration but could decrease after writing some bytes. > > The net effect should be the same in practice. It just seems > more robust.
So looking into this loop further, I think it really needs a rewrite :). Currently it is not a greedy loop, instead it iterates for each copy it does and loops over the modes each time too. Let me rewrite the loop so it is better. Thanks, Andrew > > Thanks, > Richard > > > cur_mode = mode_iter.require (); > > > > gcc_assert (cur_mode != BLKmode);
