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/*
* Copyright © 2018 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.h"
#include "nir_builder.h"
#include "nir_deref.h"
#include "util/hash_table.h"
void
nir_deref_path_init(nir_deref_path *path,
nir_deref_instr *deref, void *mem_ctx)
{
assert(deref != NULL);
/* The length of the short path is at most ARRAY_SIZE - 1 because we need
* room for the NULL terminator.
*/
static const int max_short_path_len = ARRAY_SIZE(path->_short_path) - 1;
int count = 0;
nir_deref_instr **tail = &path->_short_path[max_short_path_len];
nir_deref_instr **head = tail;
*tail = NULL;
for (nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
count++;
if (count <= max_short_path_len)
*(--head) = d;
}
if (count <= max_short_path_len) {
/* If we're under max_short_path_len, just use the short path. */
path->path = head;
goto done;
}
#ifndef NDEBUG
/* Just in case someone uses short_path by accident */
for (unsigned i = 0; i < ARRAY_SIZE(path->_short_path); i++)
path->_short_path[i] = (void *)0xdeadbeef;
#endif
path->path = ralloc_array(mem_ctx, nir_deref_instr *, count + 1);
head = tail = path->path + count;
*tail = NULL;
for (nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d))
*(--head) = d;
done:
assert(head == path->path);
assert(tail == head + count);
assert((*head)->deref_type == nir_deref_type_var);
assert(*tail == NULL);
}
void
nir_deref_path_finish(nir_deref_path *path)
{
if (path->path < &path->_short_path[0] ||
path->path > &path->_short_path[ARRAY_SIZE(path->_short_path) - 1])
ralloc_free(path->path);
}
/**
* Recursively removes unused deref instructions
*/
bool
nir_deref_instr_remove_if_unused(nir_deref_instr *instr)
{
bool progress = false;
for (nir_deref_instr *d = instr; d; d = nir_deref_instr_parent(d)) {
/* If anyone is using this deref, leave it alone */
assert(d->dest.is_ssa);
if (!list_empty(&d->dest.ssa.uses))
break;
nir_instr_remove(&d->instr);
progress = true;
}
return progress;
}
bool
nir_deref_instr_has_indirect(nir_deref_instr *instr)
{
while (instr->deref_type != nir_deref_type_var) {
/* Consider casts to be indirects */
if (instr->deref_type == nir_deref_type_cast)
return true;
if (instr->deref_type == nir_deref_type_array &&
!nir_src_is_const(instr->arr.index))
return true;
instr = nir_deref_instr_parent(instr);
}
return false;
}
static unsigned
type_get_array_stride(const struct glsl_type *elem_type,
glsl_type_size_align_func size_align)
{
unsigned elem_size, elem_align;
glsl_get_natural_size_align_bytes(elem_type, &elem_size, &elem_align);
return ALIGN_POT(elem_size, elem_align);
}
static unsigned
struct_type_get_field_offset(const struct glsl_type *struct_type,
glsl_type_size_align_func size_align,
unsigned field_idx)
{
assert(glsl_type_is_struct(struct_type));
unsigned offset = 0;
for (unsigned i = 0; i <= field_idx; i++) {
unsigned elem_size, elem_align;
glsl_get_natural_size_align_bytes(glsl_get_struct_field(struct_type, i),
&elem_size, &elem_align);
offset = ALIGN_POT(offset, elem_align);
if (i < field_idx)
offset += elem_size;
}
return offset;
}
unsigned
nir_deref_instr_get_const_offset(nir_deref_instr *deref,
glsl_type_size_align_func size_align)
{
nir_deref_path path;
nir_deref_path_init(&path, deref, NULL);
assert(path.path[0]->deref_type == nir_deref_type_var);
unsigned offset = 0;
for (nir_deref_instr **p = &path.path[1]; *p; p++) {
if ((*p)->deref_type == nir_deref_type_array) {
offset += nir_src_as_uint((*p)->arr.index) *
type_get_array_stride((*p)->type, size_align);
} else if ((*p)->deref_type == nir_deref_type_struct) {
/* p starts at path[1], so this is safe */
nir_deref_instr *parent = *(p - 1);
offset += struct_type_get_field_offset(parent->type, size_align,
(*p)->strct.index);
} else {
unreachable("Unsupported deref type");
}
}
nir_deref_path_finish(&path);
return offset;
}
nir_ssa_def *
nir_build_deref_offset(nir_builder *b, nir_deref_instr *deref,
glsl_type_size_align_func size_align)
{
nir_deref_path path;
nir_deref_path_init(&path, deref, NULL);
assert(path.path[0]->deref_type == nir_deref_type_var);
nir_ssa_def *offset = nir_imm_int(b, 0);
for (nir_deref_instr **p = &path.path[1]; *p; p++) {
if ((*p)->deref_type == nir_deref_type_array) {
nir_ssa_def *index = nir_ssa_for_src(b, (*p)->arr.index, 1);
nir_ssa_def *stride =
nir_imm_int(b, type_get_array_stride((*p)->type, size_align));
offset = nir_iadd(b, offset, nir_imul(b, index, stride));
} else if ((*p)->deref_type == nir_deref_type_struct) {
/* p starts at path[1], so this is safe */
nir_deref_instr *parent = *(p - 1);
unsigned field_offset =
struct_type_get_field_offset(parent->type, size_align,
(*p)->strct.index);
nir_iadd(b, offset, nir_imm_int(b, field_offset));
} else {
unreachable("Unsupported deref type");
}
}
nir_deref_path_finish(&path);
return offset;
}
bool
nir_remove_dead_derefs_impl(nir_function_impl *impl)
{
bool progress = false;
nir_foreach_block(block, impl) {
nir_foreach_instr_safe(instr, block) {
if (instr->type == nir_instr_type_deref &&
nir_deref_instr_remove_if_unused(nir_instr_as_deref(instr)))
progress = true;
}
}
if (progress)
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
return progress;
}
bool
nir_remove_dead_derefs(nir_shader *shader)
{
bool progress = false;
nir_foreach_function(function, shader) {
if (function->impl && nir_remove_dead_derefs_impl(function->impl))
progress = true;
}
return progress;
}
void
nir_fixup_deref_modes(nir_shader *shader)
{
nir_foreach_function(function, shader) {
if (!function->impl)
continue;
nir_foreach_block(block, function->impl) {
nir_foreach_instr(instr, block) {
if (instr->type != nir_instr_type_deref)
continue;
nir_deref_instr *deref = nir_instr_as_deref(instr);
nir_variable_mode parent_mode;
if (deref->deref_type == nir_deref_type_var) {
parent_mode = deref->var->data.mode;
} else {
assert(deref->parent.is_ssa);
nir_deref_instr *parent =
nir_instr_as_deref(deref->parent.ssa->parent_instr);
parent_mode = parent->mode;
}
deref->mode = parent_mode;
}
}
}
}
nir_deref_compare_result
nir_compare_deref_paths(nir_deref_path *a_path,
nir_deref_path *b_path)
{
if (a_path->path[0]->var != b_path->path[0]->var)
return nir_derefs_do_not_alias;
/* Start off assuming they fully compare. We ignore equality for now. In
* the end, we'll determine that by containment.
*/
nir_deref_compare_result result = nir_derefs_may_alias_bit |
nir_derefs_a_contains_b_bit |
nir_derefs_b_contains_a_bit;
nir_deref_instr **a_p = &a_path->path[1];
nir_deref_instr **b_p = &b_path->path[1];
while (*a_p != NULL && *b_p != NULL) {
nir_deref_instr *a_tail = *(a_p++);
nir_deref_instr *b_tail = *(b_p++);
if (a_tail == b_tail)
continue;
switch (a_tail->deref_type) {
case nir_deref_type_array:
case nir_deref_type_array_wildcard: {
assert(b_tail->deref_type == nir_deref_type_array ||
b_tail->deref_type == nir_deref_type_array_wildcard);
if (a_tail->deref_type == nir_deref_type_array_wildcard) {
if (b_tail->deref_type != nir_deref_type_array_wildcard)
result &= ~nir_derefs_b_contains_a_bit;
} else if (b_tail->deref_type == nir_deref_type_array_wildcard) {
if (a_tail->deref_type != nir_deref_type_array_wildcard)
result &= ~nir_derefs_a_contains_b_bit;
} else {
assert(a_tail->deref_type == nir_deref_type_array &&
b_tail->deref_type == nir_deref_type_array);
assert(a_tail->arr.index.is_ssa && b_tail->arr.index.is_ssa);
if (nir_src_is_const(a_tail->arr.index) &&
nir_src_is_const(b_tail->arr.index)) {
/* If they're both direct and have different offsets, they
* don't even alias much less anything else.
*/
if (nir_src_as_uint(a_tail->arr.index) !=
nir_src_as_uint(b_tail->arr.index))
return nir_derefs_do_not_alias;
} else if (a_tail->arr.index.ssa == b_tail->arr.index.ssa) {
/* They're the same indirect, continue on */
} else {
/* They're not the same index so we can't prove anything about
* containment.
*/
result &= ~(nir_derefs_a_contains_b_bit | nir_derefs_b_contains_a_bit);
}
}
break;
}
case nir_deref_type_struct: {
/* If they're different struct members, they don't even alias */
if (a_tail->strct.index != b_tail->strct.index)
return nir_derefs_do_not_alias;
break;
}
default:
unreachable("Invalid deref type");
}
}
/* If a is longer than b, then it can't contain b */
if (*a_p != NULL)
result &= ~nir_derefs_a_contains_b_bit;
if (*b_p != NULL)
result &= ~nir_derefs_b_contains_a_bit;
/* If a contains b and b contains a they must be equal. */
if ((result & nir_derefs_a_contains_b_bit) && (result & nir_derefs_b_contains_a_bit))
result |= nir_derefs_equal_bit;
return result;
}
nir_deref_compare_result
nir_compare_derefs(nir_deref_instr *a, nir_deref_instr *b)
{
if (a == b) {
return nir_derefs_equal_bit | nir_derefs_may_alias_bit |
nir_derefs_a_contains_b_bit | nir_derefs_b_contains_a_bit;
}
nir_deref_path a_path, b_path;
nir_deref_path_init(&a_path, a, NULL);
nir_deref_path_init(&b_path, b, NULL);
assert(a_path.path[0]->deref_type == nir_deref_type_var);
assert(b_path.path[0]->deref_type == nir_deref_type_var);
nir_deref_compare_result result = nir_compare_deref_paths(&a_path, &b_path);
nir_deref_path_finish(&a_path);
nir_deref_path_finish(&b_path);
return result;
}
struct rematerialize_deref_state {
bool progress;
nir_builder builder;
nir_block *block;
struct hash_table *cache;
};
static nir_deref_instr *
rematerialize_deref_in_block(nir_deref_instr *deref,
struct rematerialize_deref_state *state)
{
if (deref->instr.block == state->block)
return deref;
if (!state->cache) {
state->cache = _mesa_hash_table_create(NULL, _mesa_hash_pointer,
_mesa_key_pointer_equal);
}
struct hash_entry *cached = _mesa_hash_table_search(state->cache, deref);
if (cached)
return cached->data;
nir_builder *b = &state->builder;
nir_deref_instr *new_deref =
nir_deref_instr_create(b->shader, deref->deref_type);
new_deref->mode = deref->mode;
new_deref->type = deref->type;
if (deref->deref_type == nir_deref_type_var) {
new_deref->var = deref->var;
} else {
nir_deref_instr *parent = nir_src_as_deref(deref->parent);
if (parent) {
parent = rematerialize_deref_in_block(parent, state);
new_deref->parent = nir_src_for_ssa(&parent->dest.ssa);
} else {
nir_src_copy(&new_deref->parent, &deref->parent, new_deref);
}
}
switch (deref->deref_type) {
case nir_deref_type_var:
case nir_deref_type_array_wildcard:
case nir_deref_type_cast:
/* Nothing more to do */
break;
case nir_deref_type_array:
assert(!nir_src_as_deref(deref->arr.index));
nir_src_copy(&new_deref->arr.index, &deref->arr.index, new_deref);
break;
case nir_deref_type_struct:
new_deref->strct.index = deref->strct.index;
break;
default:
unreachable("Invalid deref instruction type");
}
nir_ssa_dest_init(&new_deref->instr, &new_deref->dest,
deref->dest.ssa.num_components,
deref->dest.ssa.bit_size,
deref->dest.ssa.name);
nir_builder_instr_insert(b, &new_deref->instr);
return new_deref;
}
static bool
rematerialize_deref_src(nir_src *src, void *_state)
{
struct rematerialize_deref_state *state = _state;
nir_deref_instr *deref = nir_src_as_deref(*src);
if (!deref)
return true;
nir_deref_instr *block_deref = rematerialize_deref_in_block(deref, state);
if (block_deref != deref) {
nir_instr_rewrite_src(src->parent_instr, src,
nir_src_for_ssa(&block_deref->dest.ssa));
nir_deref_instr_remove_if_unused(deref);
state->progress = true;
}
return true;
}
/** Re-materialize derefs in every block
*
* This pass re-materializes deref instructions in every block in which it is
* used. After this pass has been run, every use of a deref will be of a
* deref in the same block as the use. Also, all unused derefs will be
* deleted as a side-effect.
*/
bool
nir_rematerialize_derefs_in_use_blocks_impl(nir_function_impl *impl)
{
struct rematerialize_deref_state state = { 0 };
nir_builder_init(&state.builder, impl);
nir_foreach_block(block, impl) {
state.block = block;
/* Start each block with a fresh cache */
if (state.cache)
_mesa_hash_table_clear(state.cache, NULL);
nir_foreach_instr_safe(instr, block) {
if (instr->type == nir_instr_type_deref) {
nir_deref_instr_remove_if_unused(nir_instr_as_deref(instr));
continue;
}
state.builder.cursor = nir_before_instr(instr);
nir_foreach_src(instr, rematerialize_deref_src, &state);
}
#ifndef NDEBUG
nir_if *following_if = nir_block_get_following_if(block);
if (following_if)
assert(!nir_src_as_deref(following_if->condition));
#endif
}
_mesa_hash_table_destroy(state.cache, NULL);
return state.progress;
}
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