[Mesa-dev] [RFC] nir: add pass to lower atomic counters to SSBO
Rob Clark
robdclark at gmail.com
Thu Apr 13 15:47:18 UTC 2017
On Thu, Apr 13, 2017 at 11:44 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> Nice! This may let us delete some back-end code too. I'll review later.
I looked a bit at i965, and I think it could.. we may want to
introduce ssbo_inc and ssbo_dec instructions so you can keep using hw
inc/dec instructions (but then lower to add if hw doesn't have atomic
inc/dec instructions)
BR,
-R
> On Thu, Apr 13, 2017 at 8:23 AM, Rob Clark <robdclark at gmail.com> wrote:
>>
>> This is equivalent to what mesa/st does in glsl_to_tgsi. For most hw
>> there isn't a particularly good reason to treat these differently.
>>
>> Signed-off-by: Rob Clark <robdclark at gmail.com>
>> ---
>> This is part of a larger patchset I'm working on to add SSBO and compute
>> shader support in mesa/st glsl_to_nir path, and compute/SSBO support in
>> freedreno. Still working on a few things and some cleanup on the rest
>> of it, but I figured I should send this out to get some early comments.
>>
>> src/compiler/Makefile.sources | 1 +
>> src/compiler/nir/nir.h | 1 +
>> src/compiler/nir/nir_lower_atomics_to_ssbo.c | 215
>> +++++++++++++++++++++++++++
>> 3 files changed, 217 insertions(+)
>> create mode 100644 src/compiler/nir/nir_lower_atomics_to_ssbo.c
>>
>> diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
>> index 2455d4e..b2a3a42 100644
>> --- a/src/compiler/Makefile.sources
>> +++ b/src/compiler/Makefile.sources
>> @@ -208,6 +208,7 @@ NIR_FILES = \
>> nir/nir_lower_64bit_packing.c \
>> nir/nir_lower_alu_to_scalar.c \
>> nir/nir_lower_atomics.c \
>> + nir/nir_lower_atomics_to_ssbo.c \
>> nir/nir_lower_bitmap.c \
>> nir/nir_lower_clamp_color_outputs.c \
>> nir/nir_lower_clip.c \
>> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
>> index ce5b434..be35930 100644
>> --- a/src/compiler/nir/nir.h
>> +++ b/src/compiler/nir/nir.h
>> @@ -2546,6 +2546,7 @@ void nir_lower_bitmap(nir_shader *shader, const
>> nir_lower_bitmap_options *option
>>
>> bool nir_lower_atomics(nir_shader *shader,
>> const struct gl_shader_program *shader_program);
>> +bool nir_lower_atomics_to_ssbo(nir_shader *shader, unsigned ssbo_offset);
>> bool nir_lower_to_source_mods(nir_shader *shader);
>>
>> bool nir_lower_gs_intrinsics(nir_shader *shader);
>> diff --git a/src/compiler/nir/nir_lower_atomics_to_ssbo.c
>> b/src/compiler/nir/nir_lower_atomics_to_ssbo.c
>> new file mode 100644
>> index 0000000..f382e29
>> --- /dev/null
>> +++ b/src/compiler/nir/nir_lower_atomics_to_ssbo.c
>> @@ -0,0 +1,215 @@
>> +/*
>> + * Copyright © 2017 Red Hat
>> + *
>> + * Permission is hereby granted, free of charge, to any person obtaining
>> a
>> + * copy of this software and associated documentation files (the
>> "Software"),
>> + * to deal in the Software without restriction, including without
>> limitation
>> + * the rights to use, copy, modify, merge, publish, distribute,
>> sublicense,
>> + * and/or sell copies of the Software, and to permit persons to whom the
>> + * Software is furnished to do so, subject to the following conditions:
>> + *
>> + * The above copyright notice and this permission notice (including the
>> next
>> + * paragraph) shall be included in all copies or substantial portions of
>> the
>> + * Software.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
>> EXPRESS OR
>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
>> MERCHANTABILITY,
>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
>> SHALL
>> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
>> OTHER
>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
>> ARISING
>> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
>> DEALINGS
>> + * IN THE SOFTWARE.
>> + *
>> + * Authors:
>> + * Rob Clark <robclark at freedesktop.org>
>> + */
>> +
>> +#include "nir.h"
>> +#include "nir_builder.h"
>> +
>> +/*
>> + * Remap atomic counters to SSBOs. Atomic counters get remapped to
>> + * SSBO binding points [0..ssbo_offset) and the original SSBOs are
>> + * remapped to [ssbo_offset..n) (mostly to align with what mesa/st
>> + * does.
>> + */
>> +
>> +static bool
>> +lower_instr(nir_intrinsic_instr *instr, unsigned ssbo_offset, nir_builder
>> *b)
>> +{
>> + nir_intrinsic_op op;
>> + switch (instr->intrinsic) {
>> + case nir_intrinsic_ssbo_atomic_add:
>> + case nir_intrinsic_ssbo_atomic_imin:
>> + case nir_intrinsic_ssbo_atomic_umin:
>> + case nir_intrinsic_ssbo_atomic_imax:
>> + case nir_intrinsic_ssbo_atomic_umax:
>> + case nir_intrinsic_ssbo_atomic_and:
>> + case nir_intrinsic_ssbo_atomic_or:
>> + case nir_intrinsic_ssbo_atomic_xor:
>> + case nir_intrinsic_ssbo_atomic_exchange:
>> + case nir_intrinsic_ssbo_atomic_comp_swap:
>> + case nir_intrinsic_store_ssbo:
>> + case nir_intrinsic_load_ssbo:
>> + /* keep same opcode, remap buffer_index */
>> + op = instr->intrinsic;
>> + break;
>> + case nir_intrinsic_atomic_counter_inc:
>> + case nir_intrinsic_atomic_counter_add:
>> + case nir_intrinsic_atomic_counter_dec:
>> + /* inc and dec get remapped to add: */
>> + op = nir_intrinsic_ssbo_atomic_add;
>> + break;
>> + case nir_intrinsic_atomic_counter_read:
>> + op = nir_intrinsic_load_ssbo;
>> + break;
>> + case nir_intrinsic_atomic_counter_min:
>> + op = nir_intrinsic_ssbo_atomic_umin;
>> + break;
>> + case nir_intrinsic_atomic_counter_max:
>> + op = nir_intrinsic_ssbo_atomic_umax;
>> + break;
>> + case nir_intrinsic_atomic_counter_and:
>> + op = nir_intrinsic_ssbo_atomic_and;
>> + break;
>> + case nir_intrinsic_atomic_counter_or:
>> + op = nir_intrinsic_ssbo_atomic_or;
>> + break;
>> + case nir_intrinsic_atomic_counter_xor:
>> + op = nir_intrinsic_ssbo_atomic_xor;
>> + break;
>> + case nir_intrinsic_atomic_counter_exchange:
>> + op = nir_intrinsic_ssbo_atomic_exchange;
>> + break;
>> + case nir_intrinsic_atomic_counter_comp_swap:
>> + op = nir_intrinsic_ssbo_atomic_comp_swap;
>> + break;
>> + default:
>> + return false;
>> + }
>> +
>> + b->cursor = nir_before_instr(&instr->instr);
>> +
>> + /* easy case, just remap SSBO buffer index: */
>> + if (op == instr->intrinsic) {
>> + unsigned srcn = (op == nir_intrinsic_store_ssbo) ? 1 : 0;
>> + nir_ssa_def *old_idx = nir_ssa_for_src(b, instr->src[srcn], 1);
>> + nir_ssa_def *new_idx = nir_iadd(b, old_idx, nir_imm_int(b,
>> ssbo_offset));
>> + nir_instr_rewrite_src(&instr->instr,
>> + &instr->src[srcn],
>> + nir_src_for_ssa(new_idx));
>> +
>> + return true;
>> + }
>> +
>> + nir_ssa_def *buffer = nir_imm_int(b, nir_intrinsic_base(instr));
>> + nir_ssa_def *temp = NULL;
>> + nir_intrinsic_instr *new_instr =
>> + nir_intrinsic_instr_create(ralloc_parent(instr), op);
>> +
>> + /* a couple instructions need special handling since they don't map
>> + * 1:1 with ssbo atomics
>> + */
>> + switch (instr->intrinsic) {
>> + case nir_intrinsic_atomic_counter_inc:
>> + /* remapped to ssbo_atomic_add: { buffer_idx, offset, +1 } */
>> + temp = nir_imm_int(b, +1);
>> + new_instr->src[0] = nir_src_for_ssa(buffer);
>> + new_instr->src[1] = instr->src[0];
>> + new_instr->src[2] = nir_src_for_ssa(temp);
>> + break;
>> + case nir_intrinsic_atomic_counter_dec:
>> + /* remapped to ssbo_atomic_add: { buffer_idx, offset, -1 } */
>> + /* NOTE semantic difference so we adjust the return value below */
>> + temp = nir_imm_int(b, -1);
>> + new_instr->src[0] = nir_src_for_ssa(buffer);
>> + new_instr->src[1] = instr->src[0];
>> + new_instr->src[2] = nir_src_for_ssa(temp);
>> + break;
>> + case nir_intrinsic_atomic_counter_read:
>> + /* remapped to load_ssbo: { buffer_idx, offset } */
>> + new_instr->src[0] = nir_src_for_ssa(buffer);
>> + new_instr->src[1] = instr->src[0];
>> + break;
>> + default:
>> + /* remapped to ssbo_atomic_x: { buffer_idx, offset, data,
>> (compare)? } */
>> + new_instr->src[0] = nir_src_for_ssa(buffer);
>> + new_instr->src[1] = instr->src[0];
>> + new_instr->src[2] = instr->src[1];
>> + if (op == nir_intrinsic_ssbo_atomic_comp_swap)
>> + new_instr->src[3] = instr->src[2];
>> + break;
>> + }
>> +
>> + nir_ssa_dest_init(&new_instr->instr, &new_instr->dest,
>> + instr->dest.ssa.num_components,
>> + instr->dest.ssa.bit_size, NULL);
>> + nir_instr_insert_before(&instr->instr, &new_instr->instr);
>> + nir_instr_remove(&instr->instr);
>> +
>> + if (instr->intrinsic == nir_intrinsic_atomic_counter_dec) {
>> + b->cursor = nir_after_instr(&new_instr->instr);
>> + nir_ssa_def *result = nir_iadd(b, &new_instr->dest.ssa, temp);
>> + nir_ssa_def_rewrite_uses(&instr->dest.ssa,
>> nir_src_for_ssa(result));
>> + } else {
>> + nir_ssa_def_rewrite_uses(&instr->dest.ssa,
>> nir_src_for_ssa(&new_instr->dest.ssa));
>> + }
>> +
>> + return true;
>> +}
>> +
>> +bool
>> +nir_lower_atomics_to_ssbo(nir_shader *shader, unsigned ssbo_offset)
>> +{
>> + bool progress = false;
>> +
>> + nir_foreach_function(function, shader) {
>> + if (function->impl) {
>> + nir_builder builder;
>> + nir_builder_init(&builder, function->impl);
>> + nir_foreach_block(block, function->impl) {
>> + nir_foreach_instr_safe(instr, block) {
>> + if (instr->type == nir_instr_type_intrinsic)
>> + progress |= lower_instr(nir_instr_as_intrinsic(instr),
>> + ssbo_offset, &builder);
>> + }
>> + }
>> +
>> + nir_metadata_preserve(function->impl, nir_metadata_block_index |
>> + nir_metadata_dominance);
>> + }
>> + }
>> +
>> + if (progress) {
>> + /* replace atomic_uint uniforms with ssbo's: */
>> + unsigned replaced = 0;
>> + nir_foreach_variable_safe(var, &shader->uniforms) {
>> + if (glsl_get_base_type(var->type) == GLSL_TYPE_ATOMIC_UINT) {
>> + exec_node_remove(&var->node);
>> +
>> + if (replaced & (1 << var->data.binding))
>> + continue;
>> +
>> + nir_variable *ssbo;
>> + char name[16];
>> +
>> + // TODO can we declare an array without size? Or do we have
>> + // to find all the atomic_uint's in one pass and figure out
>> + // max offset??
>> + const struct glsl_type *type =
>> + glsl_array_type(glsl_uint_type(), 256);
>> +
>> + snprintf(name, sizeof(name), "counter%d", var->data.binding);
>> +
>> + ssbo = nir_variable_create(shader, nir_var_shader_storage,
>> + type, name);
>> + ssbo->data.binding = var->data.binding;
>> +
>> + replaced |= (1 << var->data.binding);
>> + }
>> + }
>> + }
>> +
>> + return progress;
>> +}
>> +
>> --
>> 2.9.3
>>
>
More information about the mesa-dev
mailing list