[Mesa-dev] [RFC PATCH 4/4] radv: add support for push constants inlining when possible
Bas Nieuwenhuizen
bas at basnieuwenhuizen.nl
Tue Feb 5 10:29:53 UTC 2019
On Tue, Feb 5, 2019 at 11:07 AM Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
>
>
> On 2/5/19 10:58 AM, Bas Nieuwenhuizen wrote:
> > 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?)
>
> No, as min is 'base' and max is 'base + range'.
>
> >
> > 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?
>
> If it's a vec4 starting from base=0, range should be 16, that works for
> vec4.
hmm, so it includes the size of type. If I read the spir-v parser
correctly we set range very large though (looks like range is always
the total size of all push constants?)
>
> >
> >> +
> >> + /* 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.
>
> Good catch! One possible fix is to change 'has_32bit_push_constants' to
> 'has_only_32bit_push_constants' and bail out if it's false.
>
> What do you think?
That works.
>
> >
> >> + /* 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
> >>
> >> _______________________________________________
> >> mesa-dev mailing list
> >> mesa-dev at lists.freedesktop.org
> >> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
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