On Thu, 18 Jan 2024, Jakub Jelinek wrote:
> On Thu, Jan 18, 2024 at 01:34:53PM +0100, Richard Biener wrote:
> > So - if we simply do
> >
> > /* If the input and output modes are both the same, we are done. */
> > if (mode == GET_MODE (op0) || (mode == BLKmode && MEM_P (op0))
> > ;
> >
> > ? After all if we want BLKmode we want a MEM, and if we have one
> > we should be done already. V_C_E isn't supposed to do any value
> > transform.
>
> We'd need to make sure that op0 is actually MEM, which is not the case.
>
> The following patch seems to work though, the
> discover_nonconstant_array_refs_r
> part helps for -O2, the expr.cc part is needed at all optimization levels.
>
> 2024-01-18 Jakub Jelinek <ja...@redhat.com>
>
> * cfgexpand.cc (discover_nonconstant_array_refs_r): Force non-BLKmode
> VAR_DECLs referenced in BLKmode VIEW_CONVERT_EXPRs into memory.
> * expr.cc (expand_expr_real_1) <case VIEW_CONVERT_EXPR>: If mode is
> BLKmode and type a BITINT_TYPE from a non-BLKmode VAR_P with MEM
> DECL_RTL, use adjust_address to BLKmode for it instead of expand_expr.
>
> --- gcc/cfgexpand.cc.jj 2024-01-16 11:45:16.159326506 +0100
> +++ gcc/cfgexpand.cc 2024-01-18 13:41:54.579551282 +0100
> @@ -6380,11 +6380,16 @@ discover_nonconstant_array_refs_r (tree
> /* References of size POLY_INT_CST to a fixed-size object must go
> through memory. It's more efficient to force that here than
> to create temporary slots on the fly.
> - RTL expansion expectes TARGET_MEM_REF to always address actual memory.
> */
> + RTL expansion expectes TARGET_MEM_REF to always address actual memory.
> + Also, force to stack non-BLKmode vars accessed through VIEW_CONVERT_EXPR
> + to BLKmode BITINT_TYPEs. */
> else if (TREE_CODE (t) == TARGET_MEM_REF
> || (TREE_CODE (t) == MEM_REF
> && TYPE_SIZE (TREE_TYPE (t))
> - && POLY_INT_CST_P (TYPE_SIZE (TREE_TYPE (t)))))
> + && POLY_INT_CST_P (TYPE_SIZE (TREE_TYPE (t))))
> + || (TREE_CODE (t) == VIEW_CONVERT_EXPR
> + && TREE_CODE (TREE_TYPE (t)) == BITINT_TYPE
> + && TYPE_MODE (TREE_TYPE (t)) == BLKmode))
I'm still not getting what's special about BITINT_TYPE here so
shouldn't that apply to all BLKmode V_C_E? But sure we can for
now just handle BITINT_TYPE.
That hunk looks OK to me.
> {
> tree base = get_base_address (t);
> if (base
> --- gcc/expr.cc.jj 2024-01-12 10:07:58.194851657 +0100
> +++ gcc/expr.cc 2024-01-18 13:38:19.677556646 +0100
> @@ -12382,6 +12382,17 @@ expand_expr_real_1 (tree exp, rtx target
> }
> }
>
> + /* Ensure non-BLKmode array VAR_DECLs VCEd to BLKmode BITINT_TYPE
> + aren't promoted to registers. */
> + if (op0 == NULL_RTX
> + && mode == BLKmode
> + && TREE_CODE (type) == BITINT_TYPE
> + && VAR_P (treeop0)
> + && DECL_MODE (treeop0) != BLKmode
> + && DECL_RTL_SET_P (treeop0)
> + && MEM_P (DECL_RTL (treeop0)))
> + op0 = adjust_address (DECL_RTL (treeop0), BLKmode, 0);
> +
> if (!op0)
> op0 = expand_expr_real (treeop0, NULL_RTX, VOIDmode, modifier,
> NULL, inner_reference_p);
So we're now sure we have MEM_P (op0) after expand_expr_real,
even without this change, right? What's wrong with the
suggestion to use
if (mode == GET_MODE (op0) || (mode == BLKmode && MEM_P (op0))
thus not run into any of the special-casing? We're doing just
op0 = adjust_address (op0, mode, 0);
then which is basically what you do above?
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
