Re: [PATCH: PR target/44999] Replace "and r0, r0, #255" with uxtb in thumb2

[Carrot Wei <carrot@google.com>]

ping

On Thu, Jul 22, 2010 at 3:11 PM, Carrot Wei <carrot@google.com> wrote:
> In thumb2 "and r0, r0, #255" is 32 bit, uxtb is 16 bit and does the same
> operation. This patch simply detect the situation in pattern "andsi3" and call
> gen_thumb2_zero_extendqisi2_v6.
>
> Tested on arm qemu.
>
> ChangeLog:
> 2010-07-22  Wei Guozhi  <carrot@google.com>
>
>        PR target/44999
>        * config/arm/arm.md (andsi3): Change to zero extension if possible.
>        * config/arm/thumb2.md (thumb2_zero_extendqisi2_v6): Change the name.
>
> ChangeLog:
> 2010-07-22  Wei Guozhi  <carrot@google.com>
>
>        PR target/44999
>        * gcc.target/arm/pr44999.c: New testcase.
>
>
> Index: thumb2.md
> ===================================================================
> --- thumb2.md   (revision 162396)
> +++ thumb2.md   (working copy)
> @@ -970,7 +970,7 @@
>    (set_attr "neg_pool_range" "*,250")]
>  )
>
> -(define_insn "*thumb2_zero_extendqisi2_v6"
> +(define_insn "thumb2_zero_extendqisi2_v6"
>   [(set (match_operand:SI 0 "s_register_operand" "=r,r")
>        (zero_extend:SI (match_operand:QI 1 "nonimmediate_operand" "r,m")))]
>   "TARGET_THUMB2 && arm_arch6"
>
>
> Index: arm.md
> ===================================================================
> --- arm.md      (revision 162396)
> +++ arm.md      (working copy)
> @@ -1933,9 +1933,16 @@
>     {
>       if (GET_CODE (operands[2]) == CONST_INT)
>         {
> -          arm_split_constant (AND, SImode, NULL_RTX,
> -                             INTVAL (operands[2]), operands[0],
> -                             operands[1], optimize && can_create_pseudo_p ());
> +         if (INTVAL (operands[2]) == 255 && arm_arch6)
> +           {
> +             operands[1] = gen_rtx_SUBREG (QImode, operands[1], 0);
> +             gen_thumb2_zero_extendqisi2_v6 (operands[0], operands[1]);
> +           }
> +         else
> +           arm_split_constant (AND, SImode, NULL_RTX,
> +                               INTVAL (operands[2]), operands[0],
> +                               operands[1],
> +                               optimize && can_create_pseudo_p ());
>
>           DONE;
>         }
>
>
> Index: pr44999.c
> ===================================================================
> --- pr44999.c   (revision 0)
> +++ pr44999.c   (revision 0)
> @@ -0,0 +1,7 @@
> +/* { dg-options "-march=armv7-a -mthumb -Os" }  */
> +/* { dg-final { scan-assembler "uxtb" } } */
> +
> +int tp(int x, int y)
> +{
> +  return (x & 0xff) - (y & 0xffff);
> +}
>