On Wed, 28 Feb 2024, Jakub Jelinek wrote:
> Hi!
>
> The following patch changes the memcpy etc. folding to use bitwise vector
> types rather than huge INTEGER_TYPEs for copying of > MAX_FIXED_MODE_SIZE
> lengths. The problem with the huge INTEGER_TYPEs is that they aren't
> supported very much, usually there are just optabs to handle moves of them,
> perhaps misaligned moves and that is it, so they pose problems e.g. to
> BITINT_TYPE lowering.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
I guess the int_mode_for_size (ilen * BITS_PER_UNIT, 0).exists (&imode)
could then be removed in stage1?
Thanks,
Richard.
> 2024-02-28 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/113988
> * stor-layout.h (bitwise_mode_for_size): Declare.
> * stor-layout.cc (bitwise_mode_for_size): New function.
> * gimple-fold.cc (gimple_fold_builtin_memory_op): Use it.
> Use bitwise_type_for_mode instead of build_nonstandard_integer_type.
> Use BITS_PER_UNIT instead of 8.
>
> * gcc.dg/bitint-91.c: New test.
>
> --- gcc/stor-layout.h.jj 2024-01-03 11:51:28.103778767 +0100
> +++ gcc/stor-layout.h 2024-02-27 12:32:17.716535079 +0100
> @@ -102,6 +102,8 @@ extern opt_machine_mode mode_for_size_tr
>
> extern tree bitwise_type_for_mode (machine_mode);
>
> +extern opt_machine_mode bitwise_mode_for_size (poly_uint64);
> +
> /* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of
> a previous call to layout_decl and calls it again. */
> extern void relayout_decl (tree);
> --- gcc/stor-layout.cc.jj 2024-01-17 13:53:13.160176498 +0100
> +++ gcc/stor-layout.cc 2024-02-27 12:27:20.876647298 +0100
> @@ -476,6 +476,32 @@ bitwise_type_for_mode (machine_mode mode
> return inner_type;
> }
>
> +/* Find a mode that can be used for efficient bitwise operations on SIZE
> + bits, if one exists. */
> +
> +opt_machine_mode
> +bitwise_mode_for_size (poly_uint64 size)
> +{
> + if (known_le (size, (unsigned int) MAX_FIXED_MODE_SIZE))
> + return mode_for_size (size, MODE_INT, true);
> +
> + machine_mode mode, ret = VOIDmode;
> + FOR_EACH_MODE_FROM (mode, MIN_MODE_VECTOR_INT)
> + if (known_eq (GET_MODE_BITSIZE (mode), size)
> + && (ret == VOIDmode || GET_MODE_INNER (mode) == QImode)
> + && have_regs_of_mode[mode]
> + && targetm.vector_mode_supported_p (mode))
> + {
> + if (GET_MODE_INNER (mode) == QImode)
> + return mode;
> + else if (ret == VOIDmode)
> + ret = mode;
> + }
> + if (ret != VOIDmode)
> + return ret;
> + return opt_machine_mode ();
> +}
> +
> /* Find a mode that is suitable for representing a vector with NUNITS
> elements of mode INNERMODE, if one exists. The returned mode can be
> either an integer mode or a vector mode. */
> --- gcc/gimple-fold.cc.jj 2024-02-20 10:25:26.297760979 +0100
> +++ gcc/gimple-fold.cc 2024-02-27 12:42:38.338925573 +0100
> @@ -995,9 +995,12 @@ gimple_fold_builtin_memory_op (gimple_st
> if (warning != OPT_Wrestrict)
> return false;
>
> - scalar_int_mode mode;
> - if (int_mode_for_size (ilen * 8, 0).exists (&mode)
> - && GET_MODE_SIZE (mode) * BITS_PER_UNIT == ilen * 8
> + scalar_int_mode imode;
> + machine_mode mode;
> + if (int_mode_for_size (ilen * BITS_PER_UNIT, 0).exists (&imode)
> + && bitwise_mode_for_size (ilen
> + * BITS_PER_UNIT).exists (&mode)
> + && known_eq (GET_MODE_BITSIZE (mode), ilen * BITS_PER_UNIT)
> /* If the destination pointer is not aligned we must be able
> to emit an unaligned store. */
> && (dest_align >= GET_MODE_ALIGNMENT (mode)
> @@ -1005,7 +1008,7 @@ gimple_fold_builtin_memory_op (gimple_st
> || (optab_handler (movmisalign_optab, mode)
> != CODE_FOR_nothing)))
> {
> - tree type = build_nonstandard_integer_type (ilen * 8, 1);
> + tree type = bitwise_type_for_mode (mode);
> tree srctype = type;
> tree desttype = type;
> if (src_align < GET_MODE_ALIGNMENT (mode))
> --- gcc/testsuite/gcc.dg/bitint-91.c.jj 2024-02-27 12:08:15.230481756
> +0100
> +++ gcc/testsuite/gcc.dg/bitint-91.c 2024-02-27 12:08:15.230481756 +0100
> @@ -0,0 +1,38 @@
> +/* PR tree-optimization/113988 */
> +/* { dg-do compile { target bitint } } */
> +/* { dg-options "-O2" } */
> +/* { dg-additional-options "-mavx512f" { target i?86-*-* x86_64-*-* } } */
> +
> +int i;
> +
> +#if __BITINT_MAXWIDTH__ >= 256
> +void
> +foo (void *p, _BitInt(256) x)
> +{
> + __builtin_memcpy (p, &x, sizeof x);
> +}
> +
> +_BitInt(256)
> +bar (void *p, _BitInt(256) x)
> +{
> + _BitInt(246) y = x + 1;
> + __builtin_memcpy (p, &y, sizeof y);
> + return x;
> +}
> +#endif
> +
> +#if __BITINT_MAXWIDTH__ >= 512
> +void
> +baz (void *p, _BitInt(512) x)
> +{
> + __builtin_memcpy (p, &x, sizeof x);
> +}
> +
> +_BitInt(512)
> +qux (void *p, _BitInt(512) x)
> +{
> + _BitInt(512) y = x + 1;
> + __builtin_memcpy (p, &y, sizeof y);
> + return x;
> +}
> +#endif
>
> 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)
