https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97205
--- Comment #7 from rguenther at suse dot de <rguenther at suse dot de> --- On Wed, 28 Oct 2020, bernd.edlinger at hotmail dot de wrote: > 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 ... Ah, OK - only now looked at the testcase ;) Yes, I think for registers we should ignore decl/type alignment and _always_ use the natural (mode) alignment. That is, static unsigned int align_local_variable (tree decl, bool really_expand) { unsigned int align; if (TREE_CODE (decl) == SSA_NAME) align = TYPE_ALIGN (TREE_TYPE (decl)); should probably use GET_MODE_ALIGNMENT (TYPE_MODE (TREE_TYPE (decl))) unless it is a BLKmode var. There's a duplicate code in expand_one_stack_var_1, not sure why it special-cases SSA_NAMEs there. Also, when an SSA name gets a stack location, we should instead use the underlying decl for the MEM_EXPR, not the SSA name. > 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; > >
