On Fri, Sep 9, 2016 at 10:12 AM, Nicolai Hähnle <nhaeh...@gmail.com> wrote:
> From: Nicolai Hähnle <nicolai.haeh...@amd.com>
>
> Not sure if it's possible to avoid programming the block size twice (once for
> the userdata and once for the dispatch).
>
> Since the shaders are compiled with a pessimistic upper limit on the number of
> registers, asynchronously compiling variants may be worth considering in the
> future if we observe the shaders to be dispatched with small block sizes.
> ---
> I think this is sufficient to support variable group sizes on radeonsi, but
> it's completely untested. Do you keep the latest version of your series in a
> public repository somewhere?
>
> src/gallium/drivers/radeonsi/si_compute.c | 10 +++++++++-
> src/gallium/drivers/radeonsi/si_shader.c | 29 ++++++++++++++++++++---------
> src/gallium/drivers/radeonsi/si_shader.h | 4 +++-
> 3 files changed, 32 insertions(+), 11 deletions(-)
>
> diff --git a/src/gallium/drivers/radeonsi/si_compute.c
> b/src/gallium/drivers/radeonsi/si_compute.c
> index 5041761..26e096c 100644
> --- a/src/gallium/drivers/radeonsi/si_compute.c
> +++ b/src/gallium/drivers/radeonsi/si_compute.c
> @@ -379,25 +379,33 @@ static void si_setup_tgsi_grid(struct si_context *sctx,
> for (i = 0; i < 3; ++i) {
> radeon_emit(cs, PKT3(PKT3_COPY_DATA, 4, 0));
> radeon_emit(cs, COPY_DATA_SRC_SEL(COPY_DATA_MEM) |
> COPY_DATA_DST_SEL(COPY_DATA_REG));
> radeon_emit(cs, (va + 4 * i));
> radeon_emit(cs, (va + 4 * i) >> 32);
> radeon_emit(cs, (grid_size_reg >> 2) + i);
> radeon_emit(cs, 0);
> }
> } else {
> + struct si_compute *program = sctx->cs_shader_state.program;
> + bool variable_group_size =
> +
> program->shader.selector->info.properties[TGSI_PROPERTY_CS_FIXED_BLOCK_WIDTH]
> == 0;
>
> - radeon_set_sh_reg_seq(cs, grid_size_reg, 3);
> + radeon_set_sh_reg_seq(cs, grid_size_reg, variable_group_size
> ? 6 : 3);
> radeon_emit(cs, info->grid[0]);
> radeon_emit(cs, info->grid[1]);
> radeon_emit(cs, info->grid[2]);
> + if (variable_group_size) {
> + radeon_emit(cs, info->block[0]);
> + radeon_emit(cs, info->block[1]);
> + radeon_emit(cs, info->block[2]);
> + }
> }
> }
>
> static void si_emit_dispatch_packets(struct si_context *sctx,
> const struct pipe_grid_info *info)
> {
> struct radeon_winsys_cs *cs = sctx->b.gfx.cs;
> bool render_cond_bit = sctx->b.render_cond &&
> !sctx->b.render_cond_force_off;
> unsigned waves_per_threadgroup =
> DIV_ROUND_UP(info->block[0] * info->block[1] *
> info->block[2], 64);
> diff --git a/src/gallium/drivers/radeonsi/si_shader.c
> b/src/gallium/drivers/radeonsi/si_shader.c
> index 0b7de18..730ee21 100644
> --- a/src/gallium/drivers/radeonsi/si_shader.c
> +++ b/src/gallium/drivers/radeonsi/si_shader.c
> @@ -1783,30 +1783,35 @@ static void declare_system_value(
>
> case TGSI_SEMANTIC_GRID_SIZE:
> value = LLVMGetParam(radeon_bld->main_fn, SI_PARAM_GRID_SIZE);
> break;
>
> case TGSI_SEMANTIC_BLOCK_SIZE:
> {
> LLVMValueRef values[3];
> unsigned i;
> unsigned *properties = ctx->shader->selector->info.properties;
> - unsigned sizes[3] = {
> - properties[TGSI_PROPERTY_CS_FIXED_BLOCK_WIDTH],
> - properties[TGSI_PROPERTY_CS_FIXED_BLOCK_HEIGHT],
> - properties[TGSI_PROPERTY_CS_FIXED_BLOCK_DEPTH]
> - };
>
> - for (i = 0; i < 3; ++i)
> - values[i] = lp_build_const_int32(gallivm, sizes[i]);
> + if (properties[TGSI_PROPERTY_CS_FIXED_BLOCK_WIDTH] != 0) {
> + unsigned sizes[3] = {
> +
> properties[TGSI_PROPERTY_CS_FIXED_BLOCK_WIDTH],
> +
> properties[TGSI_PROPERTY_CS_FIXED_BLOCK_HEIGHT],
> + properties[TGSI_PROPERTY_CS_FIXED_BLOCK_DEPTH]
> + };
> +
> + for (i = 0; i < 3; ++i)
> + values[i] = lp_build_const_int32(gallivm,
> sizes[i]);
>
> - value = lp_build_gather_values(gallivm, values, 3);
> + value = lp_build_gather_values(gallivm, values, 3);
> + } else {
> + value = LLVMGetParam(radeon_bld->main_fn,
> SI_PARAM_BLOCK_SIZE);
> + }
> break;
> }
>
> case TGSI_SEMANTIC_BLOCK_ID:
> value = LLVMGetParam(radeon_bld->main_fn, SI_PARAM_BLOCK_ID);
> break;
>
> case TGSI_SEMANTIC_THREAD_ID:
> value = LLVMGetParam(radeon_bld->main_fn, SI_PARAM_THREAD_ID);
> break;
> @@ -5705,20 +5710,21 @@ static void create_function(struct si_shader_context
> *ctx)
>
> for (i = 0; i < num_return_sgprs; i++)
> returns[i] = ctx->i32;
> for (; i < num_returns; i++)
> returns[i] = ctx->f32;
> }
> break;
>
> case PIPE_SHADER_COMPUTE:
> params[SI_PARAM_GRID_SIZE] = v3i32;
> + params[SI_PARAM_BLOCK_SIZE] = v3i32;
> params[SI_PARAM_BLOCK_ID] = v3i32;
> last_sgpr = SI_PARAM_BLOCK_ID;
>
> params[SI_PARAM_THREAD_ID] = v3i32;
> num_params = SI_PARAM_THREAD_ID + 1;
> break;
> default:
> assert(0 && "unimplemented shader");
> return;
> }
> @@ -5741,21 +5747,26 @@ static void create_function(struct si_shader_context
> *ctx)
> S_0286D0_LINEAR_CENTROID_ENA(1) |
> S_0286D0_FRONT_FACE_ENA(1) |
> S_0286D0_POS_FIXED_PT_ENA(1));
> } else if (ctx->type == PIPE_SHADER_COMPUTE) {
> const unsigned *properties =
> shader->selector->info.properties;
> unsigned max_work_group_size =
> properties[TGSI_PROPERTY_CS_FIXED_BLOCK_WIDTH]
> *
>
> properties[TGSI_PROPERTY_CS_FIXED_BLOCK_HEIGHT] *
> properties[TGSI_PROPERTY_CS_FIXED_BLOCK_DEPTH];
>
> - assert(max_work_group_size);
> + if (!max_work_group_size) {
> + /* This is a variable group size compute shader,
> + * compile it for the maximum possible group size.
> + */
> + max_work_group_size = 2048;
> + }
The VGPR limit is 32. That's too limiting. I'd prefer it if
GL_MAX_COMPUTE_VARIABLE_WORK_GROUP_INVOCATIONS_ARB was set to 512 or
1024. That should move the limit to 128 or 64, respectively.
Marek
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