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/*
* Copyright (C) 2020-2021 Collabora, Ltd.
* Copyright © 2020 Valve Corporation
*
* 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.
*/
#include "compiler/nir/nir.h"
#include "compiler/nir/nir_builder.h"
static bool
lower(nir_builder *b, nir_instr *instr, void *data)
{
if (instr->type != nir_instr_type_intrinsic)
return false;
nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
bool *lower_plain_stores = data;
switch (intr->intrinsic) {
case nir_intrinsic_global_atomic:
case nir_intrinsic_global_atomic_swap:
case nir_intrinsic_image_atomic:
case nir_intrinsic_image_atomic_swap:
break;
case nir_intrinsic_store_global:
case nir_intrinsic_image_store:
if (!(*lower_plain_stores))
return false;
else
break;
default:
return false;
}
b->cursor = nir_before_instr(instr);
bool has_dest = nir_intrinsic_infos[intr->intrinsic].has_dest;
nir_ssa_def *undef = NULL;
nir_ssa_def *helper = nir_load_helper_invocation(b, 1);
nir_push_if(b, nir_inot(b, helper));
nir_instr_remove(instr);
nir_builder_instr_insert(b, instr);
/* Per the spec, it does not matter what we return for helper threads.
* Represent this by an ssa_undef in the hopes the backend will be clever
* enough to optimize out the phi.
*
* Fragment shader helper invocations execute the same shader code as
* non-helper invocations, but will not have side effects that modify the
* framebuffer or other shader-accessible memory. In particular:
*
* ...
*
* Atomic operations to image, buffer, or atomic counter variables
* performed by helper invocations have no effect on the underlying
* image or buffer memory. The values returned by such atomic
* operations are undefined.
*/
if (has_dest) {
nir_push_else(b, NULL);
undef = nir_ssa_undef(b, nir_dest_num_components(intr->dest),
nir_dest_bit_size(intr->dest));
}
nir_pop_if(b, NULL);
if (has_dest) {
assert(intr->dest.is_ssa);
nir_ssa_def *phi = nir_if_phi(b, &intr->dest.ssa, undef);
/* We can't use nir_ssa_def_rewrite_uses_after on phis, so use the global
* version and fixup the phi manually
*/
nir_ssa_def_rewrite_uses(&intr->dest.ssa, phi);
nir_instr *phi_instr = phi->parent_instr;
nir_phi_instr *phi_as_phi = nir_instr_as_phi(phi_instr);
nir_phi_src *phi_src = nir_phi_get_src_from_block(phi_as_phi,
instr->block);
nir_instr_rewrite_src_ssa(phi->parent_instr, &phi_src->src,
&intr->dest.ssa);
}
return true;
}
bool
nir_lower_helper_writes(nir_shader *shader, bool lower_plain_stores)
{
assert(shader->info.stage == MESA_SHADER_FRAGMENT);
return nir_shader_instructions_pass(shader, lower, nir_metadata_none,
&lower_plain_stores);
}
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