On Tue, Nov 8, 2011 at 7:44 AM, Jakub Jelinek <[email protected]> wrote:
> Hi!
>
> Working virtually out of Pago Pago.
>
> Is there a reason why we don't prefer 32-byte integer vector modes
> even for AVX? If a vectorized loop needs some operation that is only
> supported by AVX2 we would retry whenever seeing such stmt, so
> what I think this costs us mainly some small amount of time
> during vectorization analysis. Examples of functions that can
> be vectorized with this patch using 32-byte vectors (and the runtime
> of the testcase decreased from ~ 0m2.876s to ~ 0m2.258s).
>
> #define N 1024
> int a[N], b[N];
> float c[N];
>
> __attribute__((noinline, noclone)) void
> f1 ()
> {
> int i;
> for (i = 0; i < N; i++)
> a[i] = b[i];
> }
>
> __attribute__((noinline, noclone)) void
> f2 ()
> {
> a[0] = b[0];
> a[1] = b[1];
> a[2] = b[2];
> a[3] = b[3];
> a[4] = b[4];
> a[5] = b[5];
> a[6] = b[6];
> a[7] = b[7];
> }
Other examples would for example be bitwise operations.
Richard.
> __attribute__((noinline, noclone)) void
> f3 ()
> {
> int i;
> for (i = 0; i < N; i++)
> c[i] = a[i];
> }
>
> __attribute__((noinline, noclone)) void
> f4 ()
> {
> int i;
> for (i = 0; i < N; i++)
> a[i] = 19;
> }
>
> int
> main ()
> {
> int i;
> for (i = 0; i < N; i++)
> b[i] = i;
> for (i = 0; i < 10000000; i++)
> {
> f1 ();
> f2 ();
> f3 ();
> f4 ();
> }
> return 0;
> }
>
>
> 2011-11-08 Jakub Jelinek <[email protected]>
>
> * config/i386/i386.c (ix86_preferred_simd_mode): Even for TARGET_AVX
> if not TARGET_PREFER_AVX128 return 32-byte SI/DI vectors.
>
> --- gcc/config/i386/i386.c.jj 2011-11-07 08:32:09.000000000 -1100
> +++ gcc/config/i386/i386.c 2011-11-07 19:19:57.000000000 -1100
> @@ -37881,9 +37881,9 @@ ix86_preferred_simd_mode (enum machine_m
> case HImode:
> return TARGET_AVX2 ? V16HImode : V8HImode;
> case SImode:
> - return TARGET_AVX2 ? V8SImode : V4SImode;
> + return (TARGET_AVX && !TARGET_PREFER_AVX128) ? V8SImode : V4SImode;
> case DImode:
> - return TARGET_AVX2 ? V4DImode : V2DImode;
> + return (TARGET_AVX && !TARGET_PREFER_AVX128) ? V4DImode : V2DImode;
>
> case SFmode:
> if (TARGET_AVX && !TARGET_PREFER_AVX128)
>
> Jakub
>
