RE: [PATCH] aarch64: Fix up *aarch64_bfxilsi_uxtw [PR98853]

[Kyrylo Tkachov via Gcc-patches]

> -----Original Message-----
> From: Jakub Jelinek <ja...@redhat.com>
> Sent: 27 January 2021 19:11
> To: Richard Earnshaw <richard.earns...@arm.com>; Richard Sandiford
> <richard.sandif...@arm.com>; Marcus Shawcroft
> <marcus.shawcr...@arm.com>; Kyrylo Tkachov <kyrylo.tkac...@arm.com>
> Cc: gcc-patches@gcc.gnu.org
> Subject: [PATCH] aarch64: Fix up *aarch64_bfxilsi_uxtw [PR98853]
> 
> Hi!
> 
> The https://gcc.gnu.org/legacy-ml/gcc-patches/2018-07/msg01895.html
> patch that introduced this pattern claimed:
> Would generate:
> 
> combine_balanced_int:
>         bfxil   w0, w1, 0, 16
>         uxtw    x0, w0
>         ret
> 
> But with this patch generates:
> 
> combine_balanced_int:
>         bfxil   w0, w1, 0, 16
>         ret
> and it is indeed what it should generate, but it doesn't do that,
> it emits bfxil        x0, x1, 0, 16
> instead which doesn't zero extend from 32 to 64 bits, but preserves
> the bits from the destination register.
> 
> The following patch fixes that, bootstrapped/regtested on aarch64-linux,
> ok for trunk (and later backports)?

Ok.
Thanks,
Kyrill

> 
> 2021-01-27  Jakub Jelinek  <ja...@redhat.com>
> 
>       PR target/98853
>       * config/aarch64/aarch64.md (*aarch64_bfxilsi_uxtw): Use
>       %w0, %w1 and %2 instead of %0, %1 and %2.
> 
>       * gcc.c-torture/execute/pr98853-1.c: New test.
>       * gcc.c-torture/execute/pr98853-2.c: New test.
> 
> --- gcc/config/aarch64/aarch64.md.jj  2021-01-04 10:25:46.435147744
> +0100
> +++ gcc/config/aarch64/aarch64.md     2021-01-27 15:13:13.993275204
> +0100
> @@ -5724,10 +5724,10 @@ (define_insn "*aarch64_bfxilsi_uxtw"
>      {
>        case 0:
>       operands[3] = GEN_INT (ctz_hwi (~INTVAL (operands[3])));
> -     return "bfxil\\t%0, %1, 0, %3";
> +     return "bfxil\\t%w0, %w1, 0, %3";
>        case 1:
>       operands[3] = GEN_INT (ctz_hwi (~INTVAL (operands[4])));
> -     return "bfxil\\t%0, %2, 0, %3";
> +     return "bfxil\\t%w0, %w2, 0, %3";
>        default:
>       gcc_unreachable ();
>      }
> --- gcc/testsuite/gcc.c-torture/execute/pr98853-1.c.jj        2021-01-27
> 15:26:15.544335342 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr98853-1.c   2021-01-27
> 15:28:37.877710203 +0100
> @@ -0,0 +1,21 @@
> +/* PR target/98853 */
> +
> +#if __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8 &&
> __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> +__attribute__((__noipa__)) unsigned long long
> +foo (unsigned x, unsigned long long y, unsigned long long z)
> +{
> +  __builtin_memcpy (2 + (char *) &x, 2 + (char *) &y, 2);
> +  return x + z;
> +}
> +#endif
> +
> +int
> +main ()
> +{
> +#if __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8 &&
> __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> +  if (foo (0x44444444U, 0x1111111111111111ULL,
> 0x2222222222222222ULL)
> +      != 0x2222222233336666ULL)
> +    __builtin_abort ();
> +#endif
> +  return 0;
> +}
> --- gcc/testsuite/gcc.c-torture/execute/pr98853-2.c.jj        2021-01-27
> 19:35:52.312351623 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr98853-2.c   2021-01-27
> 19:37:51.369515183 +0100
> @@ -0,0 +1,19 @@
> +/* PR target/98853 */
> +
> +#if __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8
> +__attribute__((noipa)) unsigned long long
> +foo (unsigned long long x, unsigned int y)
> +{
> +  return ((unsigned) x & 0xfffe0000U) | (y & 0x1ffff);
> +}
> +#endif
> +
> +int
> +main ()
> +{
> +#if __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8
> +  if (foo (0xdeadbeefcaf2babeULL, 0xdeaffeedU) !=
> 0x00000000caf3feedULL)
> +    __builtin_abort ();
> +#endif
> +  return 0;
> +}
> 
>       Jakub