https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97205
--- Comment #6 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
(In reply to rguent...@suse.de from comment #3)
> On Tue, 27 Oct 2020, bernd.edlinger at hotmail dot de wrote:
> > --- a/gcc/emit-rtl.c
> > +++ b/gcc/emit-rtl.c
> > @@ -2089,7 +2089,8 @@ set_mem_attributes_minus_bitpos (rtx ref, tree t, int
> > objectp,
> > {
> > gcc_assert (handled_component_p (t)
> > || TREE_CODE (t) == MEM_REF
> > - || TREE_CODE (t) == TARGET_MEM_REF);
> > + || TREE_CODE (t) == TARGET_MEM_REF
> > + || TREE_CODE (t) == SSA_NAME);
>
> Can you track down this? It's a red herring to have a MEM_EXPR
> that just is a SSA_NAME.
>
This happens here:
if (MEM_P (to_rtx))
{
/* If the field is at offset zero, we could have been given the
DECL_RTX of the parent struct. Don't munge it. */
to_rtx = shallow_copy_rtx (to_rtx);
set_mem_attributes_minus_bitpos (to_rtx, to, 0, bitpos);
if (volatilep)
MEM_VOLATILE_P (to_rtx) = 1;
}
since the patch allows the SSA_NAME to reach this block.
> > --- a/gcc/expr.c
> > +++ b/gcc/expr.c
> > @@ -5200,6 +5200,9 @@ expand_assignment (tree to, tree from, bool
> > nontemporal)
> > || (TREE_CODE (to) == MEM_REF
> > && (REF_REVERSE_STORAGE_ORDER (to)
> > || mem_ref_refers_to_non_mem_p (to)))
> > + || (TREE_CODE (to) == SSA_NAME
> > + && mode != BLKmode
> > + && TYPE_ALIGN (TREE_TYPE (to)) < GET_MODE_ALIGNMENT (mode))
>
> But an SSA name is a register, esp. one with non-BLKmode. And if
> expanded to a stack location that stack location should better
> be aligned... or be BLKmode. So I think the bug is elsewhere?
>
Hmm, to avoid the ICE the SSA_NAME would need a naturally
aligned type, maybe replace it somehow in make_ssa_name_fn ...
But isn't it possible that expand_expr_real_1
returns the original unaligned decl here?
case GIMPLE_SINGLE_RHS:
{
r = expand_expr_real (gimple_assign_rhs1 (g), target,
tmode, modifier, alt_rtl,
inner_reference_p);
break;
}
default:
gcc_unreachable ();
}
set_curr_insn_location (saved_loc);
if (REG_P (r) && !REG_EXPR (r))
set_reg_attrs_for_decl_rtl (SSA_NAME_VAR (exp), r);
return r;
