On Fri, Jan 3, 2020 at 9:23 AM Jakub Jelinek <ja...@redhat.com> wrote:
>
> Hi!
>
> The newly added absdi2 expander doesn't work well on ia32, because it
> requires a xordi3 pattern, which is available even for !TARGET_64BIT,
> but only if TARGET_STV && TARGET_SSE2.
>
> The following patch just uses expand_simple_binop which is able to handle
> the splitting of it into two xorsi3 patterns if needed etc., plus is shorter
> in the expander. Also, there is no need to build a DImode shift amount and
> then convert_modes it.
>
> Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, on the
> testcase we now get identical code to what GCC 9 emitted in all of -m32
> -mno-stv -mno-sse, -m32 -msse2 -mstv and -m64 modes, ok for trunk?
>
> 2020-01-03 Jakub Jelinek <ja...@redhat.com>
>
> PR target/93110
> * config/i386/i386.md (abs<mode>2): Use expand_simple_binop instead of
> emitting ASHIFTRT, XOR and MINUS by hand. Use gen_int_mode with
> QImode
> instead of gen_int_shift_amount + convert_modes.
>
> * gcc.dg/torture/pr93110.c: New test.
OK.
Thanks,
Uros.
> --- gcc/config/i386/i386.md.jj 2020-01-01 12:16:10.071276261 +0100
> +++ gcc/config/i386/i386.md 2020-01-02 10:47:26.638399487 +0100
> @@ -9711,30 +9711,16 @@ (define_expand "abs<mode>2"
>
> /* Generate rtx abs using abs (x) = (((signed) x >> (W-1)) ^ x) -
> ((signed) x >> (W-1)) */
> - rtx shift_amount = gen_int_shift_amount (mode,
> - GET_MODE_PRECISION (mode)
> - - 1);
> - shift_amount = convert_modes (E_QImode, GET_MODE (shift_amount),
> - shift_amount, 1);
> - rtx shift_dst = gen_reg_rtx (mode);
> - rtx shift_op = gen_rtx_SET (shift_dst,
> - gen_rtx_fmt_ee (ASHIFTRT, mode,
> - operands[1], shift_amount));
> - rtx clobber = gen_rtx_CLOBBER (VOIDmode, gen_rtx_REG (CCmode,
> - FLAGS_REG));
> - emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, shift_op,
> - clobber)));
> -
> - rtx xor_op = gen_rtx_SET (operands[0],
> - gen_rtx_fmt_ee (XOR, mode, shift_dst,
> - operands[1]));
> - emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, xor_op, clobber)));
> -
> - rtx minus_op = gen_rtx_SET (operands[0],
> - gen_rtx_fmt_ee (MINUS, mode,
> - operands[0], shift_dst));
> - emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, minus_op,
> - clobber)));
> + rtx shift_amount = gen_int_mode (GET_MODE_PRECISION (mode) - 1, QImode);
> + rtx shift_dst = expand_simple_binop (mode, ASHIFTRT, operands[1],
> + shift_amount, NULL_RTX,
> + 0, OPTAB_DIRECT);
> + rtx xor_dst = expand_simple_binop (mode, XOR, shift_dst, operands[1],
> + operands[0], 0, OPTAB_DIRECT);
> + rtx minus_dst = expand_simple_binop (mode, MINUS, xor_dst, shift_dst,
> + operands[0], 0, OPTAB_DIRECT);
> + if (!rtx_equal_p (minus_dst, operands[0]))
> + emit_move_insn (operands[0], minus_dst);
> DONE;
> })
>
> --- gcc/testsuite/gcc.dg/torture/pr93110.c.jj 2020-01-02 10:50:10.335895988
> +0100
> +++ gcc/testsuite/gcc.dg/torture/pr93110.c 2020-01-02 10:49:54.248142020
> +0100
> @@ -0,0 +1,9 @@
> +/* PR target/93110 */
> +/* { dg-do compile } */
> +/* { dg-additional-options "-mtune=core2 -mno-stv" { target { i?86-*-*
> x86_64-*-* } } } */
> +
> +long long
> +foo (long long a)
> +{
> + return a > 0 ? a : -a;
> +}
>
> Jakub
>
