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/*
* Copyright (C) 2005-2007 Brian Paul All Rights Reserved.
* Copyright (C) 2008 VMware, Inc. All Rights Reserved.
* Copyright © 2014 Intel 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 "nir/nir.h"
#include "nir_builder.h"
static void
lower_tex_src_to_offset(nir_builder *b,
nir_tex_instr *instr, unsigned src_idx)
{
nir_ssa_def *index = NULL;
unsigned base_index = 0;
unsigned array_elements = 1;
nir_tex_src *src = &instr->src[src_idx];
bool is_sampler = src->src_type == nir_tex_src_sampler_deref;
/* We compute first the offsets */
nir_deref_instr *deref = nir_instr_as_deref(src->src.ssa->parent_instr);
while (deref->deref_type != nir_deref_type_var) {
assert(deref->parent.is_ssa);
nir_deref_instr *parent =
nir_instr_as_deref(deref->parent.ssa->parent_instr);
assert(deref->deref_type == nir_deref_type_array);
if (nir_src_is_const(deref->arr.index) && index == NULL) {
/* We're still building a direct index */
unsigned index_in_array = nir_src_as_uint(deref->arr.index);
/* Section 5.11 (Out-of-Bounds Accesses) of the GLSL 4.60 spec says:
*
* In the subsections described above for array, vector, matrix and
* structure accesses, any out-of-bounds access produced undefined
* behavior.... Out-of-bounds reads return undefined values, which
* include values from other variables of the active program or zero.
*
* Robustness extensions suggest to return zero on out-of-bounds
* accesses, however it's not applicable to the arrays of samplers,
* so just clamp the index.
*
* Otherwise instr->sampler_index or instr->texture_index would be out
* of bounds, and they are used as an index to arrays of driver state.
*/
if (index_in_array < glsl_array_size(parent->type)) {
base_index += index_in_array * array_elements;
} else {
base_index = glsl_array_size(parent->type) - 1;
}
} else {
if (index == NULL) {
/* We used to be direct but not anymore */
index = nir_imm_int(b, base_index);
base_index = 0;
}
index = nir_iadd(b, index,
nir_imul(b, nir_imm_int(b, array_elements),
nir_ssa_for_src(b, deref->arr.index, 1)));
}
array_elements *= glsl_get_length(parent->type);
deref = parent;
}
if (index)
index = nir_umin(b, index, nir_imm_int(b, array_elements - 1));
/* We hit the deref_var. This is the end of the line */
assert(deref->deref_type == nir_deref_type_var);
base_index += deref->var->data.binding;
/* We have the offsets, we apply them, rewriting the source or removing
* instr if needed
*/
if (index) {
nir_instr_rewrite_src(&instr->instr, &src->src,
nir_src_for_ssa(index));
src->src_type = is_sampler ?
nir_tex_src_sampler_offset :
nir_tex_src_texture_offset;
} else {
nir_tex_instr_remove_src(instr, src_idx);
}
if (is_sampler) {
instr->sampler_index = base_index;
} else {
instr->texture_index = base_index;
}
}
static bool
lower_sampler(nir_builder *b, nir_instr *instr_, UNUSED void *cb_data)
{
if (instr_->type != nir_instr_type_tex)
return false;
nir_tex_instr *instr = nir_instr_as_tex(instr_);
int texture_idx =
nir_tex_instr_src_index(instr, nir_tex_src_texture_deref);
if (texture_idx >= 0) {
b->cursor = nir_before_instr(&instr->instr);
lower_tex_src_to_offset(b, instr, texture_idx);
}
int sampler_idx =
nir_tex_instr_src_index(instr, nir_tex_src_sampler_deref);
if (sampler_idx >= 0) {
lower_tex_src_to_offset(b, instr, sampler_idx);
}
if (texture_idx < 0 && sampler_idx < 0)
return false;
return true;
}
bool
nir_lower_samplers(nir_shader *shader)
{
return nir_shader_instructions_pass(shader, lower_sampler,
nir_metadata_block_index |
nir_metadata_dominance,
NULL);
}
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