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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(*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 ||
instr->deref_type == nir_deref_type_ptr_as_array) &&
!nir_src_is_const(instr->arr.index))
return true;
instr = nir_deref_instr_parent(instr);
}
return false;
}
bool
nir_deref_instr_is_known_out_of_bounds(nir_deref_instr *instr)
{
for (; instr; instr = nir_deref_instr_parent(instr)) {
if (instr->deref_type == nir_deref_type_array &&
nir_src_is_const(instr->arr.index) &&
nir_src_as_uint(instr->arr.index) >
glsl_get_length(nir_deref_instr_parent(instr)->type))
return true;
}
return false;
}
bool
nir_deref_instr_has_complex_use(nir_deref_instr *deref)
{
nir_foreach_use(use_src, &deref->dest.ssa) {
nir_instr *use_instr = use_src->parent_instr;
switch (use_instr->type) {
case nir_instr_type_deref: {
nir_deref_instr *use_deref = nir_instr_as_deref(use_instr);
/* A var deref has no sources */
assert(use_deref->deref_type != nir_deref_type_var);
/* If a deref shows up in an array index or something like that, it's
* a complex use.
*/
if (use_src != &use_deref->parent)
return true;
/* Anything that isn't a basic struct or array deref is considered to
* be a "complex" use. In particular, we don't allow ptr_as_array
* because we assume that opt_deref will turn any non-complex
* ptr_as_array derefs into regular array derefs eventually so passes
* which only want to handle simple derefs will pick them up in a
* later pass.
*/
if (use_deref->deref_type != nir_deref_type_struct &&
use_deref->deref_type != nir_deref_type_array_wildcard &&
use_deref->deref_type != nir_deref_type_array)
return true;
if (nir_deref_instr_has_complex_use(use_deref))
return true;
continue;
}
case nir_instr_type_intrinsic: {
nir_intrinsic_instr *use_intrin = nir_instr_as_intrinsic(use_instr);
switch (use_intrin->intrinsic) {
case nir_intrinsic_load_deref:
assert(use_src == &use_intrin->src[0]);
continue;
case nir_intrinsic_copy_deref:
assert(use_src == &use_intrin->src[0] ||
use_src == &use_intrin->src[1]);
continue;
case nir_intrinsic_store_deref:
/* A use in src[1] of a store means we're taking that pointer and
* writing it to a variable. Because we have no idea who will
* read that variable and what they will do with the pointer, it's
* considered a "complex" use. A use in src[0], on the other
* hand, is a simple use because we're just going to dereference
* it and write a value there.
*/
if (use_src == &use_intrin->src[0])
continue;
return true;
default:
return true;
}
unreachable("Switch default failed");
}
default:
return true;
}
}
nir_foreach_if_use(use, &deref->dest.ssa)
return true;
return false;
}
unsigned
nir_deref_instr_ptr_as_array_stride(nir_deref_instr *deref)
{
assert(deref->deref_type == nir_deref_type_ptr_as_array);
nir_deref_instr *parent = nir_deref_instr_parent(deref);
switch (parent->deref_type) {
case nir_deref_type_array:
return glsl_get_explicit_stride(nir_deref_instr_parent(parent)->type);
case nir_deref_type_ptr_as_array:
return nir_deref_instr_ptr_as_array_stride(parent);
case nir_deref_type_cast:
return parent->cast.ptr_stride;
default:
unreachable("Invalid parent for ptr_as_array deref");
}
}
static unsigned
type_get_array_stride(const struct glsl_type *elem_type,
glsl_type_size_align_func size_align)
{
unsigned elem_size, elem_align;
size_align(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_or_ifc(struct_type));
unsigned offset = 0;
for (unsigned i = 0; i <= field_idx; i++) {
unsigned elem_size, elem_align;
size_align(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);
int stride = type_get_array_stride((*p)->type, size_align);
offset = nir_iadd(b, offset, nir_imul_imm(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);
offset = nir_iadd_imm(b, offset, 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);
if (deref->deref_type == nir_deref_type_cast)
continue;
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;
}
}
}
}
static bool
modes_may_alias(nir_variable_mode a, nir_variable_mode b)
{
/* Generic pointers can alias with SSBOs */
if ((a == nir_var_mem_ssbo || a == nir_var_mem_global) &&
(b == nir_var_mem_ssbo || b == nir_var_mem_global))
return true;
/* In the general case, pointers can only alias if they have the same mode.
*
* NOTE: In future, with things like OpenCL generic pointers, this may not
* be true and will have to be re-evaluated. However, with graphics only,
* it should be safe.
*/
return a == b;
}
static bool
deref_path_contains_coherent_decoration(nir_deref_path *path)
{
assert(path->path[0]->deref_type == nir_deref_type_var);
if (path->path[0]->var->data.image.access & ACCESS_COHERENT)
return true;
for (nir_deref_instr **p = &path->path[1]; *p; p++) {
if ((*p)->deref_type != nir_deref_type_struct)
continue;
const struct glsl_type *struct_type = (*(p - 1))->type;
const struct glsl_struct_field *field =
glsl_get_struct_field_data(struct_type, (*p)->strct.index);
if (field->memory_coherent)
return true;
}
return false;
}
nir_deref_compare_result
nir_compare_deref_paths(nir_deref_path *a_path,
nir_deref_path *b_path)
{
if (!modes_may_alias(b_path->path[0]->mode, a_path->path[0]->mode))
return nir_derefs_do_not_alias;
if (a_path->path[0]->deref_type != b_path->path[0]->deref_type)
return nir_derefs_may_alias_bit;
if (a_path->path[0]->deref_type == nir_deref_type_var) {
if (a_path->path[0]->var != b_path->path[0]->var) {
/* Shader and function temporaries aren't backed by memory so two
* distinct variables never alias.
*/
static const nir_variable_mode temp_var_modes =
nir_var_shader_temp | nir_var_function_temp;
if ((a_path->path[0]->mode & temp_var_modes) ||
(b_path->path[0]->mode & temp_var_modes))
return nir_derefs_do_not_alias;
/* If they are both declared coherent or have coherent somewhere in
* their path (due to a member of an interface being declared
* coherent), we have to assume we that we could have any kind of
* aliasing. Otherwise, they could still alias but the client didn't
* tell us and that's their fault.
*/
if (deref_path_contains_coherent_decoration(a_path) &&
deref_path_contains_coherent_decoration(b_path))
return nir_derefs_may_alias_bit;
/* If we can chase the deref all the way back to the variable and
* they're not the same variable and at least one is not declared
* coherent, we know they can't possibly alias.
*/
return nir_derefs_do_not_alias;
}
} else {
assert(a_path->path[0]->deref_type == nir_deref_type_cast);
/* If they're not exactly the same cast, it's hard to compare them so we
* just assume they alias. Comparing casts is tricky as there are lots
* of things such as mode, type, etc. to make sure work out; for now, we
* just assume nit_opt_deref will combine them and compare the deref
* instructions.
*
* TODO: At some point in the future, we could be clever and understand
* that a float[] and int[] have the same layout and aliasing structure
* but double[] and vec3[] do not and we could potentially be a bit
* smarter here.
*/
if (a_path->path[0] != b_path->path[0])
return nir_derefs_may_alias_bit;
}
/* 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 && *a_p == *b_p) {
a_p++;
b_p++;
}
/* We're at either the tail or the divergence point between the two deref
* paths. Look to see if either contains a ptr_as_array deref. It it
* does we don't know how to safely make any inferences. Hopefully,
* nir_opt_deref will clean most of these up and we can start inferring
* things again.
*
* In theory, we could do a bit better. For instance, we could detect the
* case where we have exactly one ptr_as_array deref in the chain after the
* divergence point and it's matched in both chains and the two chains have
* different constant indices.
*/
for (nir_deref_instr **t_p = a_p; *t_p; t_p++) {
if ((*t_p)->deref_type == nir_deref_type_ptr_as_array)
return nir_derefs_may_alias_bit;
}
for (nir_deref_instr **t_p = b_p; *t_p; t_p++) {
if ((*t_p)->deref_type == nir_deref_type_ptr_as_array)
return nir_derefs_may_alias_bit;
}
while (*a_p != NULL && *b_p != NULL) {
nir_deref_instr *a_tail = *(a_p++);
nir_deref_instr *b_tail = *(b_p++);
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 ||
a_path.path[0]->deref_type == nir_deref_type_cast);
assert(b_path.path[0]->deref_type == nir_deref_type_var ||
b_path.path[0]->deref_type == nir_deref_type_cast);
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_pointer_hash_table_create(NULL);
}
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.
*
* Derefs used as sources of phi instructions are not rematerialized.
*/
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;
/* If a deref is used in a phi, we can't rematerialize it, as the new
* derefs would appear before the phi, which is not valid.
*/
if (instr->type == nir_instr_type_phi)
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;
}
static bool
is_trivial_deref_cast(nir_deref_instr *cast)
{
nir_deref_instr *parent = nir_src_as_deref(cast->parent);
if (!parent)
return false;
return cast->mode == parent->mode &&
cast->type == parent->type &&
cast->dest.ssa.num_components == parent->dest.ssa.num_components &&
cast->dest.ssa.bit_size == parent->dest.ssa.bit_size;
}
static bool
is_trivial_array_deref_cast(nir_deref_instr *cast)
{
assert(is_trivial_deref_cast(cast));
nir_deref_instr *parent = nir_src_as_deref(cast->parent);
if (parent->deref_type == nir_deref_type_array) {
return cast->cast.ptr_stride ==
glsl_get_explicit_stride(nir_deref_instr_parent(parent)->type);
} else if (parent->deref_type == nir_deref_type_ptr_as_array) {
return cast->cast.ptr_stride ==
nir_deref_instr_ptr_as_array_stride(parent);
} else {
return false;
}
}
static bool
is_deref_ptr_as_array(nir_instr *instr)
{
return instr->type == nir_instr_type_deref &&
nir_instr_as_deref(instr)->deref_type == nir_deref_type_ptr_as_array;
}
/**
* Remove casts that just wrap other casts.
*/
static bool
opt_remove_cast_cast(nir_deref_instr *cast)
{
nir_deref_instr *first_cast = cast;
while (true) {
nir_deref_instr *parent = nir_deref_instr_parent(first_cast);
if (parent == NULL || parent->deref_type != nir_deref_type_cast)
break;
first_cast = parent;
}
if (cast == first_cast)
return false;
nir_instr_rewrite_src(&cast->instr, &cast->parent,
nir_src_for_ssa(first_cast->parent.ssa));
return true;
}
/**
* Is this casting a struct to a contained struct.
* struct a { struct b field0 };
* ssa_5 is structa;
* deref_cast (structb *)ssa_5 (function_temp structb);
* converts to
* deref_struct &ssa_5->field0 (function_temp structb);
* This allows subsequent copy propagation to work.
*/
static bool
opt_replace_struct_wrapper_cast(nir_builder *b, nir_deref_instr *cast)
{
nir_deref_instr *parent = nir_src_as_deref(cast->parent);
if (!parent)
return false;
if (!glsl_type_is_struct(parent->type))
return false;
if (glsl_get_struct_field_offset(parent->type, 0) != 0)
return false;
if (cast->type != glsl_get_struct_field(parent->type, 0))
return false;
nir_deref_instr *replace = nir_build_deref_struct(b, parent, 0);
nir_ssa_def_rewrite_uses(&cast->dest.ssa, nir_src_for_ssa(&replace->dest.ssa));
nir_deref_instr_remove_if_unused(cast);
return true;
}
static bool
opt_deref_cast(nir_builder *b, nir_deref_instr *cast)
{
bool progress;
if (opt_replace_struct_wrapper_cast(b, cast))
return true;
progress = opt_remove_cast_cast(cast);
if (!is_trivial_deref_cast(cast))
return progress;
bool trivial_array_cast = is_trivial_array_deref_cast(cast);
assert(cast->dest.is_ssa);
assert(cast->parent.is_ssa);
nir_foreach_use_safe(use_src, &cast->dest.ssa) {
/* If this isn't a trivial array cast, we can't propagate into
* ptr_as_array derefs.
*/
if (is_deref_ptr_as_array(use_src->parent_instr) &&
!trivial_array_cast)
continue;
nir_instr_rewrite_src(use_src->parent_instr, use_src, cast->parent);
progress = true;
}
/* If uses would be a bit crazy */
assert(list_empty(&cast->dest.ssa.if_uses));
nir_deref_instr_remove_if_unused(cast);
return progress;
}
static bool
opt_deref_ptr_as_array(nir_builder *b, nir_deref_instr *deref)
{
assert(deref->deref_type == nir_deref_type_ptr_as_array);
nir_deref_instr *parent = nir_deref_instr_parent(deref);
if (nir_src_is_const(deref->arr.index) &&
nir_src_as_int(deref->arr.index) == 0) {
/* If it's a ptr_as_array deref with an index of 0, it does nothing
* and we can just replace its uses with its parent.
*
* The source of a ptr_as_array deref always has a deref_type of
* nir_deref_type_array or nir_deref_type_cast. If it's a cast, it
* may be trivial and we may be able to get rid of that too. Any
* trivial cast of trivial cast cases should be handled already by
* opt_deref_cast() above.
*/
if (parent->deref_type == nir_deref_type_cast &&
is_trivial_deref_cast(parent))
parent = nir_deref_instr_parent(parent);
nir_ssa_def_rewrite_uses(&deref->dest.ssa,
nir_src_for_ssa(&parent->dest.ssa));
nir_instr_remove(&deref->instr);
return true;
}
if (parent->deref_type != nir_deref_type_array &&
parent->deref_type != nir_deref_type_ptr_as_array)
return false;
assert(parent->parent.is_ssa);
assert(parent->arr.index.is_ssa);
assert(deref->arr.index.is_ssa);
nir_ssa_def *new_idx = nir_iadd(b, parent->arr.index.ssa,
deref->arr.index.ssa);
deref->deref_type = parent->deref_type;
nir_instr_rewrite_src(&deref->instr, &deref->parent, parent->parent);
nir_instr_rewrite_src(&deref->instr, &deref->arr.index,
nir_src_for_ssa(new_idx));
return true;
}
bool
nir_opt_deref_impl(nir_function_impl *impl)
{
bool progress = false;
nir_builder b;
nir_builder_init(&b, impl);
nir_foreach_block(block, impl) {
nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_deref)
continue;
b.cursor = nir_before_instr(instr);
nir_deref_instr *deref = nir_instr_as_deref(instr);
switch (deref->deref_type) {
case nir_deref_type_ptr_as_array:
if (opt_deref_ptr_as_array(&b, deref))
progress = true;
break;
case nir_deref_type_cast:
if (opt_deref_cast(&b, deref))
progress = true;
break;
default:
/* Do nothing */
break;
}
}
}
if (progress) {
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
} else {
#ifndef NDEBUG
impl->valid_metadata &= ~nir_metadata_not_properly_reset;
#endif
}
return progress;
}
bool
nir_opt_deref(nir_shader *shader)
{
bool progress = false;
nir_foreach_function(func, shader) {
if (func->impl && nir_opt_deref_impl(func->impl))
progress = true;
}
return progress;
}
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