/*
* 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.
*
* Authors:
* Jason Ekstrand (jason@jlekstrand.net)
*
*/
#include "nir.h"
struct locals_to_regs_state {
nir_shader *shader;
nir_function_impl *impl;
/* A hash table mapping derefs to registers */
struct hash_table *regs_table;
bool progress;
};
/* The following two functions implement a hash and equality check for
* variable dreferences. When the hash or equality function encounters an
* array, it ignores the offset and whether it is direct or indirect
* entirely.
*/
static uint32_t
hash_deref(const void *void_deref)
{
uint32_t hash = _mesa_fnv32_1a_offset_bias;
const nir_deref_var *deref_var = void_deref;
hash = _mesa_fnv32_1a_accumulate(hash, deref_var->var);
for (const nir_deref *deref = deref_var->deref.child;
deref; deref = deref->child) {
if (deref->deref_type == nir_deref_type_struct) {
const nir_deref_struct *deref_struct = nir_deref_as_struct(deref);
hash = _mesa_fnv32_1a_accumulate(hash, deref_struct->index);
}
}
return hash;
}
static bool
derefs_equal(const void *void_a, const void *void_b)
{
const nir_deref_var *a_var = void_a;
const nir_deref_var *b_var = void_b;
if (a_var->var != b_var->var)
return false;
for (const nir_deref *a = a_var->deref.child, *b = b_var->deref.child;
a != NULL; a = a->child, b = b->child) {
if (a->deref_type != b->deref_type)
return false;
if (a->deref_type == nir_deref_type_struct) {
if (nir_deref_as_struct(a)->index != nir_deref_as_struct(b)->index)
return false;
}
/* Do nothing for arrays. They're all the same. */
assert((a->child == NULL) == (b->child == NULL));
if((a->child == NULL) != (b->child == NULL))
return false;
}
return true;
}
static nir_register *
get_reg_for_deref(nir_deref_var *deref, struct locals_to_regs_state *state)
{
uint32_t hash = hash_deref(deref);
assert(deref->var->constant_initializer == NULL);
struct hash_entry *entry =
_mesa_hash_table_search_pre_hashed(state->regs_table, hash, deref);
if (entry)
return entry->data;
unsigned array_size = 1;
nir_deref *tail = &deref->deref;
while (tail->child) {
if (tail->child->deref_type == nir_deref_type_array)
array_size *= glsl_get_length(tail->type);
tail = tail->child;
}
assert(glsl_type_is_vector(tail->type) || glsl_type_is_scalar(tail->type));
nir_register *reg = nir_local_reg_create(state->impl);
reg->num_components = glsl_get_vector_elements(tail->type);
reg->num_array_elems = array_size > 1 ? array_size : 0;
reg->bit_size = glsl_get_bit_size(tail->type);
_mesa_hash_table_insert_pre_hashed(state->regs_table, hash, deref, reg);
return reg;
}
static nir_src
get_deref_reg_src(nir_deref_var *deref, nir_instr *instr,
struct locals_to_regs_state *state)
{
nir_src src;
src.is_ssa = false;
src.reg.reg = get_reg_for_deref(deref, state);
src.reg.base_offset = 0;
src.reg.indirect = NULL;
/* It is possible for a user to create a shader that has an array with a
* single element and then proceed to access it indirectly. Indirectly
* accessing a non-array register is not allowed in NIR. In order to
* handle this case we just convert it to a direct reference.
*/
if (src.reg.reg->num_array_elems == 0)
return src;
nir_deref *tail = &deref->deref;
while (tail->child != NULL) {
const struct glsl_type *parent_type = tail->type;
tail = tail->child;
if (tail->deref_type != nir_deref_type_array)
continue;
nir_deref_array *deref_array = nir_deref_as_array(tail);
src.reg.base_offset *= glsl_get_length(parent_type);
src.reg.base_offset += deref_array->base_offset;
if (src.reg.indirect) {
nir_load_const_instr *load_const =
nir_load_const_instr_create(state->shader, 1, 32);
load_const->value.u32[0] = glsl_get_length(parent_type);
nir_instr_insert_before(instr, &load_const->instr);
nir_alu_instr *mul = nir_alu_instr_create(state->shader, nir_op_imul);
mul->src[0].src = *src.reg.indirect;
mul->src[1].src.is_ssa = true;
mul->src[1].src.ssa = &load_const->def;
mul->dest.write_mask = 1;
nir_ssa_dest_init(&mul->instr, &mul->dest.dest, 1, 32, NULL);
nir_instr_insert_before(instr, &mul->instr);
src.reg.indirect->is_ssa = true;
src.reg.indirect->ssa = &mul->dest.dest.ssa;
}
if (deref_array->deref_array_type == nir_deref_array_type_indirect) {
if (src.reg.indirect == NULL) {
src.reg.indirect = ralloc(state->shader, nir_src);
nir_src_copy(src.reg.indirect, &deref_array->indirect,
state->shader);
} else {
nir_alu_instr *add = nir_alu_instr_create(state->shader,
nir_op_iadd);
add->src[0].src = *src.reg.indirect;
nir_src_copy(&add->src[1].src, &deref_array->indirect, add);
add->dest.write_mask = 1;
nir_ssa_dest_init(&add->instr, &add->dest.dest, 1, 32, NULL);
nir_instr_insert_before(instr, &add->instr);
src.reg.indirect->is_ssa = true;
src.reg.indirect->ssa = &add->dest.dest.ssa;
}
}
}
return src;
}
static bool
lower_locals_to_regs_block(nir_block *block,
struct locals_to_regs_state *state)
{
nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
switch (intrin->intrinsic) {
case nir_intrinsic_load_var: {
if (intrin->variables[0]->var->data.mode != nir_var_local)
continue;
nir_alu_instr *mov = nir_alu_instr_create(state->shader, nir_op_imov);
mov->src[0].src = get_deref_reg_src(intrin->variables[0],
&intrin->instr, state);
mov->dest.write_mask = (1 << intrin->num_components) - 1;
if (intrin->dest.is_ssa) {
nir_ssa_dest_init(&mov->instr, &mov->dest.dest,
intrin->num_components,
intrin->dest.ssa.bit_size, NULL);
nir_ssa_def_rewrite_uses(&intrin->dest.ssa,
nir_src_for_ssa(&mov->dest.dest.ssa));
} else {
nir_dest_copy(&mov->dest.dest, &intrin->dest, &mov->instr);
}
nir_instr_insert_before(&intrin->instr, &mov->instr);
nir_instr_remove(&intrin->instr);
state->progress = true;
break;
}
case nir_intrinsic_store_var: {
if (intrin->variables[0]->var->data.mode != nir_var_local)
continue;
nir_src reg_src = get_deref_reg_src(intrin->variables[0],
&intrin->instr, state);
nir_alu_instr *mov = nir_alu_instr_create(state->shader, nir_op_imov);
nir_src_copy(&mov->src[0].src, &intrin->src[0], mov);
mov->dest.write_mask = nir_intrinsic_write_mask(intrin);
mov->dest.dest.is_ssa = false;
mov->dest.dest.reg.reg = reg_src.reg.reg;
mov->dest.dest.reg.base_offset = reg_src.reg.base_offset;
mov->dest.dest.reg.indirect = reg_src.reg.indirect;
nir_instr_insert_before(&intrin->instr, &mov->instr);
nir_instr_remove(&intrin->instr);
state->progress = true;
break;
}
case nir_intrinsic_copy_var:
unreachable("There should be no copies whatsoever at this point");
break;
default:
continue;
}
}
return true;
}
static bool
nir_lower_locals_to_regs_impl(nir_function_impl *impl)
{
struct locals_to_regs_state state;
state.shader = impl->function->shader;
state.impl = impl;
state.progress = false;
state.regs_table = _mesa_hash_table_create(NULL, hash_deref, derefs_equal);
nir_metadata_require(impl, nir_metadata_dominance);
nir_foreach_block(block, impl) {
lower_locals_to_regs_block(block, &state);
}
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
_mesa_hash_table_destroy(state.regs_table, NULL);
return state.progress;
}
bool
nir_lower_locals_to_regs(nir_shader *shader)
{
bool progress = false;
nir_foreach_function(function, shader) {
if (function->impl)
progress = nir_lower_locals_to_regs_impl(function->impl) || progress;
}
return progress;
}