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/*
* Copyright © 2019 Collabora, Ltd.
*
* 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 (Collabora):
* Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
*/
#include "nir.h"
#include "nir_builder.h"
/*
* Lowers SSBOs to globals, for hardware that lack native SSBO support. When
* lowering, *_ssbo_* instructions will become *_global_* instructions,
* augmented with load_ssbo_address.
*
* DOES NOT PERFORM BOUNDS CHECKING. DO NOT USE IN PRODUCTION ON UNTRUSTED
* CONTEXTS INCLUDING WEBGL 2.
*/
static nir_intrinsic_op
lower_ssbo_op(nir_intrinsic_op op)
{
switch (op) {
case nir_intrinsic_load_ssbo:
return nir_intrinsic_load_global;
case nir_intrinsic_store_ssbo:
return nir_intrinsic_store_global;
default:
unreachable("Invalid SSBO op");
}
}
/* Like SSBO property sysvals, though SSBO index may be indirect. C.f.
* nir_load_system_value */
static inline nir_ssa_def *
nir_load_ssbo_prop(nir_builder *b, nir_intrinsic_op op,
nir_src *idx, unsigned bitsize)
{
nir_intrinsic_instr *load = nir_intrinsic_instr_create(b->shader, op);
load->num_components = 1;
nir_src_copy(&load->src[0], idx, load);
nir_ssa_dest_init(&load->instr, &load->dest, 1, bitsize, NULL);
nir_builder_instr_insert(b, &load->instr);
return &load->dest.ssa;
}
#define nir_ssbo_prop(b, prop, index, bitsize) \
nir_load_ssbo_prop(b, nir_intrinsic_##prop, index, bitsize)
static nir_ssa_def *
lower_ssbo_instr(nir_builder *b, nir_intrinsic_instr *intr)
{
nir_intrinsic_op op = lower_ssbo_op(intr->intrinsic);
bool is_store = op == nir_intrinsic_store_global;
/* We have to calculate the address:
*
* &(SSBO[offset]) = &SSBO + offset
*/
nir_src index = intr->src[is_store ? 1 : 0];
nir_src *offset_src = nir_get_io_offset_src(intr);
nir_ssa_def *offset = nir_ssa_for_src(b, *offset_src, 1);
nir_ssa_def *address =
nir_iadd(b,
nir_ssbo_prop(b, load_ssbo_address, &index, 64),
nir_u2u64(b, offset));
/* Create the replacement intrinsic */
nir_intrinsic_instr *global =
nir_intrinsic_instr_create(b->shader, op);
global->num_components = intr->num_components;
global->src[is_store ? 1 : 0] = nir_src_for_ssa(address);
if (is_store) {
nir_src_copy(&global->src[0], &intr->src[0], global);
nir_intrinsic_set_write_mask(global, nir_intrinsic_write_mask(intr));
} else {
nir_ssa_dest_init(&global->instr, &global->dest,
intr->dest.ssa.num_components,
intr->dest.ssa.bit_size, NULL);
}
nir_builder_instr_insert(b, &global->instr);
return is_store ? NULL : &global->dest.ssa;
}
static bool
should_lower_ssbo_instr(const nir_instr *instr)
{
if (instr->type != nir_instr_type_intrinsic)
return false;
const nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
switch (intr->intrinsic) {
case nir_intrinsic_load_ssbo:
case nir_intrinsic_store_ssbo:
return true;
default:
return false;
}
return false;
}
bool
nir_lower_ssbo(nir_shader *shader)
{
bool progress = false;
nir_foreach_function(function, shader) {
nir_function_impl *impl = function->impl;
nir_builder b;
nir_builder_init(&b, impl);
nir_foreach_block(block, impl) {
nir_foreach_instr_safe(instr, block) {
if (!should_lower_ssbo_instr(instr)) continue;
progress = true;
b.cursor = nir_before_instr(instr);
nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
nir_ssa_def *replace = lower_ssbo_instr(&b, intr);
if (replace) {
nir_ssa_def_rewrite_uses(&intr->dest.ssa,
nir_src_for_ssa(replace));
}
nir_instr_remove(instr);
}
}
}
return progress;
}
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