[Mesa-dev] [RFC PATCH 4/4] radv: add support for push constants inlining when possible
Bas Nieuwenhuizen
bas at basnieuwenhuizen.nl
Tue Feb 5 09:58:00 UTC 2019
On Fri, Jan 25, 2019 at 5:27 PM Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
>
> This removes some scalar loads from shaders, but it increases
> the number of SET_SH_REG packets. This is currently basic but
> it could be improved if needed. Inlining dynamic offsets might
> also help.
>
> Original idea from Dave Airlie.
>
> 29164 shaders in 15096 tests
> Totals:
> SGPRS: 1336072 -> 1365241 (2.18 %)
> VGPRS: 937784 -> 934592 (-0.34 %)
> Spilled SGPRs: 24751 -> 24796 (0.18 %)
> Code Size: 50001672 -> 49815524 (-0.37 %) bytes
> Max Waves: 208755 -> 208830 (0.04 %)
>
> Totals from affected shaders:
> SGPRS: 295018 -> 324187 (9.89 %)
> VGPRS: 243108 -> 239916 (-1.31 %)
> Spilled SGPRs: 1464 -> 1509 (3.07 %)
> Code Size: 8028188 -> 7842040 (-2.32 %) bytes
> Max Waves: 69580 -> 69655 (0.11 %)
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
> src/amd/common/ac_nir_to_llvm.c | 23 +++++++--
> src/amd/common/ac_shader_abi.h | 4 ++
> src/amd/vulkan/radv_cmd_buffer.c | 78 ++++++++++++++++++++++---------
> src/amd/vulkan/radv_nir_to_llvm.c | 54 +++++++++++++++++++++
> src/amd/vulkan/radv_shader.h | 10 ++--
> src/amd/vulkan/radv_shader_info.c | 4 ++
> 6 files changed, 145 insertions(+), 28 deletions(-)
>
> diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
> index f509fc31dff..db1574b5b35 100644
> --- a/src/amd/common/ac_nir_to_llvm.c
> +++ b/src/amd/common/ac_nir_to_llvm.c
> @@ -1392,10 +1392,27 @@ static LLVMValueRef visit_load_push_constant(struct ac_nir_context *ctx,
> nir_intrinsic_instr *instr)
> {
> LLVMValueRef ptr, addr;
> + LLVMValueRef src0 = get_src(ctx, instr->src[0]);
> + unsigned index = nir_intrinsic_base(instr);
>
> - addr = LLVMConstInt(ctx->ac.i32, nir_intrinsic_base(instr), 0);
> - addr = LLVMBuildAdd(ctx->ac.builder, addr,
> - get_src(ctx, instr->src[0]), "");
> + addr = LLVMConstInt(ctx->ac.i32, index, 0);
> + addr = LLVMBuildAdd(ctx->ac.builder, addr, src0, "");
> +
> + /* Load constant values from user SGPRS when possible, otherwise
> + * fallback to the default path that loads directly from memory.
> + */
> + if (LLVMIsConstant(src0) &&
> + index == 0 &&
> + instr->dest.ssa.bit_size == 32) {
> + unsigned offset = LLVMConstIntGetZExtValue(src0) / 4;
> + unsigned count = instr->dest.ssa.num_components;
> +
> + if (offset + count <= ctx->abi->num_inline_push_consts) {
> + return ac_build_gather_values(&ctx->ac,
> + ctx->abi->inline_push_consts + offset,
> + count);
> + }
> + }
>
> ptr = ac_build_gep0(&ctx->ac, ctx->abi->push_constants, addr);
>
> diff --git a/src/amd/common/ac_shader_abi.h b/src/amd/common/ac_shader_abi.h
> index ee18e6c1923..704c3d107c2 100644
> --- a/src/amd/common/ac_shader_abi.h
> +++ b/src/amd/common/ac_shader_abi.h
> @@ -32,6 +32,8 @@ struct nir_variable;
>
> #define AC_LLVM_MAX_OUTPUTS (VARYING_SLOT_VAR31 + 1)
>
> +#define AC_MAX_INLINE_PUSH_CONSTS 8
> +
> enum ac_descriptor_type {
> AC_DESC_IMAGE,
> AC_DESC_FMASK,
> @@ -66,6 +68,8 @@ struct ac_shader_abi {
>
> /* Vulkan only */
> LLVMValueRef push_constants;
> + LLVMValueRef inline_push_consts[AC_MAX_INLINE_PUSH_CONSTS];
> + unsigned num_inline_push_consts;
> LLVMValueRef view_index;
>
> LLVMValueRef outputs[AC_LLVM_MAX_OUTPUTS * 4];
> diff --git a/src/amd/vulkan/radv_cmd_buffer.c b/src/amd/vulkan/radv_cmd_buffer.c
> index aae90290841..f80e2078da0 100644
> --- a/src/amd/vulkan/radv_cmd_buffer.c
> +++ b/src/amd/vulkan/radv_cmd_buffer.c
> @@ -627,6 +627,23 @@ radv_emit_descriptor_pointers(struct radv_cmd_buffer *cmd_buffer,
> }
> }
>
> +static void
> +radv_emit_inline_push_consts(struct radv_cmd_buffer *cmd_buffer,
> + struct radv_pipeline *pipeline,
> + gl_shader_stage stage,
> + int idx, int count, uint32_t *values)
> +{
> + struct radv_userdata_info *loc = radv_lookup_user_sgpr(pipeline, stage, idx);
> + uint32_t base_reg = pipeline->user_data_0[stage];
> + if (loc->sgpr_idx == -1)
> + return;
> +
> + assert(loc->num_sgprs == count);
> +
> + radeon_set_sh_reg_seq(cmd_buffer->cs, base_reg + loc->sgpr_idx * 4, count);
> + radeon_emit_array(cmd_buffer->cs, values, count);
> +}
> +
> static void
> radv_update_multisample_state(struct radv_cmd_buffer *cmd_buffer,
> struct radv_pipeline *pipeline)
> @@ -1900,6 +1917,7 @@ radv_flush_constants(struct radv_cmd_buffer *cmd_buffer,
> radv_get_descriptors_state(cmd_buffer, bind_point);
> struct radv_pipeline_layout *layout = pipeline->layout;
> struct radv_shader_variant *shader, *prev_shader;
> + bool need_push_constants = false;
> unsigned offset;
> void *ptr;
> uint64_t va;
> @@ -1909,37 +1927,55 @@ radv_flush_constants(struct radv_cmd_buffer *cmd_buffer,
> (!layout->push_constant_size && !layout->dynamic_offset_count))
> return;
>
> - if (!radv_cmd_buffer_upload_alloc(cmd_buffer, layout->push_constant_size +
> - 16 * layout->dynamic_offset_count,
> - 256, &offset, &ptr))
> - return;
> + radv_foreach_stage(stage, stages) {
> + if (!pipeline->shaders[stage])
> + continue;
>
> - memcpy(ptr, cmd_buffer->push_constants, layout->push_constant_size);
> - memcpy((char*)ptr + layout->push_constant_size,
> - descriptors_state->dynamic_buffers,
> - 16 * layout->dynamic_offset_count);
> + need_push_constants |= pipeline->shaders[stage]->info.info.loads_push_constants;
> + need_push_constants |= pipeline->shaders[stage]->info.info.loads_dynamic_offsets;
>
> - va = radv_buffer_get_va(cmd_buffer->upload.upload_bo);
> - va += offset;
> + uint8_t count = pipeline->shaders[stage]->info.info.num_inline_push_consts;
>
> - MAYBE_UNUSED unsigned cdw_max = radeon_check_space(cmd_buffer->device->ws,
> - cmd_buffer->cs, MESA_SHADER_STAGES * 4);
> + radv_emit_inline_push_consts(cmd_buffer, pipeline, stage,
> + AC_UD_INLINE_PUSH_CONSTANTS,
> + count,
> + (uint32_t *)&cmd_buffer->push_constants[0]);
> + }
>
> - prev_shader = NULL;
> - radv_foreach_stage(stage, stages) {
> - shader = radv_get_shader(pipeline, stage);
> + if (need_push_constants) {
> + if (!radv_cmd_buffer_upload_alloc(cmd_buffer, layout->push_constant_size +
> + 16 * layout->dynamic_offset_count,
> + 256, &offset, &ptr))
> + return;
> +
> + memcpy(ptr, cmd_buffer->push_constants, layout->push_constant_size);
> + memcpy((char*)ptr + layout->push_constant_size,
> + descriptors_state->dynamic_buffers,
> + 16 * layout->dynamic_offset_count);
> +
> + va = radv_buffer_get_va(cmd_buffer->upload.upload_bo);
> + va += offset;
> +
> + MAYBE_UNUSED unsigned cdw_max =
> + radeon_check_space(cmd_buffer->device->ws,
> + cmd_buffer->cs, MESA_SHADER_STAGES * 4);
> +
> + prev_shader = NULL;
> + radv_foreach_stage(stage, stages) {
> + shader = radv_get_shader(pipeline, stage);
>
> - /* Avoid redundantly emitting the address for merged stages. */
> - if (shader && shader != prev_shader) {
> - radv_emit_userdata_address(cmd_buffer, pipeline, stage,
> - AC_UD_PUSH_CONSTANTS, va);
> + /* Avoid redundantly emitting the address for merged stages. */
> + if (shader && shader != prev_shader) {
> + radv_emit_userdata_address(cmd_buffer, pipeline, stage,
> + AC_UD_PUSH_CONSTANTS, va);
>
> - prev_shader = shader;
> + prev_shader = shader;
> + }
> }
> + assert(cmd_buffer->cs->cdw <= cdw_max);
> }
>
> cmd_buffer->push_constant_stages &= ~stages;
> - assert(cmd_buffer->cs->cdw <= cdw_max);
> }
>
> static void
> diff --git a/src/amd/vulkan/radv_nir_to_llvm.c b/src/amd/vulkan/radv_nir_to_llvm.c
> index 11417c5991b..1cffa748d15 100644
> --- a/src/amd/vulkan/radv_nir_to_llvm.c
> +++ b/src/amd/vulkan/radv_nir_to_llvm.c
> @@ -627,6 +627,47 @@ count_vs_user_sgprs(struct radv_shader_context *ctx)
> return count;
> }
>
> +static void allocate_inline_push_consts(struct radv_shader_context *ctx,
> + struct user_sgpr_info *user_sgpr_info)
> +{
> + uint8_t remaining_sgprs = user_sgpr_info->remaining_sgprs;
> +
> + /* Only supported if shaders don't have indirect push constants. */
> + if (ctx->shader_info->info.has_indirect_push_constants)
> + return;
> +
> + /* Only supported for 32-bit push constants. */
> + if (!ctx->shader_info->info.has_32bit_push_constants)
> + return;
> +
> + /* Only supported if base starts from 0. */
> + if (ctx->shader_info->info.min_push_constant_used != 0)
> + return;
> +
> + uint8_t num_push_consts =
> + (ctx->shader_info->info.max_push_constant_used -
> + ctx->shader_info->info.min_push_constant_used) / 4;
I think you need +1? if min_push_constant_used ==
max_push_constant_used you still use 1 push constant. (The code in the
info pass adds range, but that does not include the size of the loaded
thing?)
Now that I think about it, the shader info pass does not take into
account the size of the variable at all right? What happens with a
vec4? The range does not include the object itself right?
> +
> + /* Check if the number of user SGPRs is large enough. */
> + if (num_push_consts < remaining_sgprs) {
> + ctx->shader_info->info.num_inline_push_consts = num_push_consts;
> + } else {
> + ctx->shader_info->info.num_inline_push_consts = remaining_sgprs;
> + }
> +
> + /* Clamp to the maximum number of allowed inlined push constants. */
> + if (ctx->shader_info->info.num_inline_push_consts > AC_MAX_INLINE_PUSH_CONSTS)
> + ctx->shader_info->info.num_inline_push_consts = AC_MAX_INLINE_PUSH_CONSTS;
> +
> + if (ctx->shader_info->info.num_inline_push_consts == num_push_consts &&
> + !ctx->shader_info->info.loads_dynamic_offsets) {
This won't work, as we can reach here even if there are some accesses
which don't use inline push constants, e.g. some non 32-bit accesses.
> + /* Disable the default push constants path if all constants are
> + * inlined and if shaders don't use dynamic descriptors.
> + */
> + ctx->shader_info->info.loads_push_constants = false;
> + }
> +}
> +
> static void allocate_user_sgprs(struct radv_shader_context *ctx,
> gl_shader_stage stage,
> bool has_previous_stage,
> @@ -706,6 +747,8 @@ static void allocate_user_sgprs(struct radv_shader_context *ctx,
> } else {
> user_sgpr_info->remaining_sgprs = remaining_sgprs - num_desc_set;
> }
> +
> + allocate_inline_push_consts(ctx, user_sgpr_info);
> }
>
> static void
> @@ -735,6 +778,12 @@ declare_global_input_sgprs(struct radv_shader_context *ctx,
> add_arg(args, ARG_SGPR, type, &ctx->abi.push_constants);
> }
>
> + for (unsigned i = 0; i < ctx->shader_info->info.num_inline_push_consts; i++) {
> + add_arg(args, ARG_SGPR, ctx->ac.i32,
> + &ctx->abi.inline_push_consts[i]);
> + }
> + ctx->abi.num_inline_push_consts = ctx->shader_info->info.num_inline_push_consts;
> +
> if (ctx->shader_info->info.so.num_outputs) {
> add_arg(args, ARG_SGPR,
> ac_array_in_const32_addr_space(ctx->ac.v4i32),
> @@ -853,6 +902,11 @@ set_global_input_locs(struct radv_shader_context *ctx,
> set_loc_shader_ptr(ctx, AC_UD_PUSH_CONSTANTS, user_sgpr_idx);
> }
>
> + if (ctx->shader_info->info.num_inline_push_consts) {
> + set_loc_shader(ctx, AC_UD_INLINE_PUSH_CONSTANTS, user_sgpr_idx,
> + ctx->shader_info->info.num_inline_push_consts);
> + }
> +
> if (ctx->streamout_buffers) {
> set_loc_shader_ptr(ctx, AC_UD_STREAMOUT_BUFFERS,
> user_sgpr_idx);
> diff --git a/src/amd/vulkan/radv_shader.h b/src/amd/vulkan/radv_shader.h
> index 09bc5c2d4a9..d1bc467c5d9 100644
> --- a/src/amd/vulkan/radv_shader.h
> +++ b/src/amd/vulkan/radv_shader.h
> @@ -129,10 +129,11 @@ struct radv_nir_compiler_options {
> enum radv_ud_index {
> AC_UD_SCRATCH_RING_OFFSETS = 0,
> AC_UD_PUSH_CONSTANTS = 1,
> - AC_UD_INDIRECT_DESCRIPTOR_SETS = 2,
> - AC_UD_VIEW_INDEX = 3,
> - AC_UD_STREAMOUT_BUFFERS = 4,
> - AC_UD_SHADER_START = 5,
> + AC_UD_INLINE_PUSH_CONSTANTS = 2,
> + AC_UD_INDIRECT_DESCRIPTOR_SETS = 3,
> + AC_UD_VIEW_INDEX = 4,
> + AC_UD_STREAMOUT_BUFFERS = 5,
> + AC_UD_SHADER_START = 6,
> AC_UD_VS_VERTEX_BUFFERS = AC_UD_SHADER_START,
> AC_UD_VS_BASE_VERTEX_START_INSTANCE,
> AC_UD_VS_MAX_UD,
> @@ -167,6 +168,7 @@ struct radv_shader_info {
> uint8_t max_push_constant_used;
> bool has_32bit_push_constants;
> bool has_indirect_push_constants;
> + uint8_t num_inline_push_consts;
> uint32_t desc_set_used_mask;
> bool needs_multiview_view_index;
> bool uses_invocation_id;
> diff --git a/src/amd/vulkan/radv_shader_info.c b/src/amd/vulkan/radv_shader_info.c
> index cabe2a470a0..900bca1d097 100644
> --- a/src/amd/vulkan/radv_shader_info.c
> +++ b/src/amd/vulkan/radv_shader_info.c
> @@ -211,6 +211,10 @@ gather_push_constant_info(const nir_shader *nir,
> if (base < info->min_push_constant_used)
> info->min_push_constant_used = base;
>
> + /* TODO: handle base not 0. */
> + if (base != 0)
> + info->min_push_constant_used = -1;
> +
> info->loads_push_constants = true;
> }
>
> --
> 2.20.1
>
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