[Piglit] [PATCH] Strengthen arb_shader_image_load_store-shader-mem-barrier test

[Francisco Jerez]

Nicolai Hähnle <nhaehnle at gmail.com> writes:

> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>
> By transposing the loop and the writer/reader branching, the effective level
> of parallelism in the test is increased for a typical wave-based architecture.
>
> Increasing the window size on top of that helps to reliably expose different
> implementation errors for AMD GCN.
>
> Cc: Francisco Jerez <currojerez at riseup.net>
> ---
> After trying a bunch of different things, it turns out that the combination
> of these rather small changes ends up covering all the cases.
>
Thanks!  I haven't tested yet whether I can still reproduce an inversion
with the control test on Intel hardware, but the change looks good
anyway so feel free to push:

Reviewed-by: Francisco Jerez <currojerez at riseup.net>

>  .../shader-mem-barrier.c                           | 32 ++++++++++------------
>  1 file changed, 15 insertions(+), 17 deletions(-)
>
> diff --git a/tests/spec/arb_shader_image_load_store/shader-mem-barrier.c b/tests/spec/arb_shader_image_load_store/shader-mem-barrier.c
> index 5fdd86b..ddf5da6 100644
> --- a/tests/spec/arb_shader_image_load_store/shader-mem-barrier.c
> +++ b/tests/spec/arb_shader_image_load_store/shader-mem-barrier.c
> @@ -48,7 +48,7 @@
>  #define W 256
>  
>  /** Window height. */
> -#define H 16
> +#define H 64
>  
>  /** Total number of pixels in the image. */
>  #define N (W * H)
> @@ -142,15 +142,15 @@ run_test(const struct image_test_info *test,
>                              "       int x = (idx.x % K) + (idx.x / (2 * K)) * (2 * K);\n"
>                              "       int i, n = 1000;\n"
>                              "\n"
> -                            "       if (check) {\n"
> -                            "              /*\n"
> -                            "               * Consumer: Monitor the evolution of a pair of\n"
> -                            "               * image locations until the test runs to\n"
> -                            "               * completion or an inconsistency is observed.\n"
> -                            "               */\n"
> -                            "              for (i = 0; i < n; ++i) {\n"
> -                            "                     uint u, v;\n"
> +                            "       for (i = 0; i < n; ++i) {\n"
> +                            "              uint u, v;\n"
>                              "\n"
> +                            "              if (check) {\n"
> +                            "                     /*\n"
> +                            "                      * Consumer: Monitor the evolution of a pair of\n"
> +                            "                      * image locations until the test runs to\n"
> +                            "                      * completion or an inconsistency is observed.\n"
> +                            "                      */\n"
>                              "                     v = imageLoad(img, ivec2(x, idx.y)).x;\n"
>                              "                     MEMORY_BARRIER();\n"
>                              "                     u = imageLoad(img, ivec2(x + K, idx.y)).x;\n"
> @@ -158,14 +158,12 @@ run_test(const struct image_test_info *test,
>                              "                     if (u < v)\n"
>                              "                             /* Fail. */\n"
>                              "                             return GRID_T(v << 16 | u, 0, 0, 1);\n"
> -                            "             }\n"
> -                            "       } else {\n"
> -                            "              /*\n"
> -                            "               * Producer: Update the same pair of image locations\n"
> -                            "               * sequentially with increasing values ordering the\n"
> -                            "               * stores with a barrier.\n"
> -                            "               */\n"
> -                            "              for (i = 0; i < n; ++i) {\n"
> +                            "             } else {\n"
> +                            "                     /*\n"
> +                            "                      * Producer: Update the same pair of image locations\n"
> +                            "                      * sequentially with increasing values ordering the\n"
> +                            "                      * stores with a barrier.\n"
> +                            "                      */\n"
>                              "                     imageStore(img, ivec2(x + K, idx.y), DATA_T(i));\n"
>                              "                     MEMORY_BARRIER();\n"
>                              "                     imageStore(img, ivec2(x, idx.y), DATA_T(i));\n"
> -- 
> 2.5.0
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