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nir/lower_io_to_vector: add flat mode 

This has lower_io_to_vector try to turn variables into arrays of 4-sized
vectors when possible and fall back to the old approach when that isn't
possible.

This is so that lower_io_to_vector can guarantee that only one variable is
used for each fragment shader output.

v2: handle dual-source blending
v3: don't try to merge structs and non-32-bit types in get_flat_type()
v3: fix per-vertex inputs
v3: fix and cleanup location advancement in get_flat_type() and it's
    calling code
v4: prioritize the original mode over the flat mode
v4: don't create flat variables to merge only one variable
v5: don't skip an entire slot when encountering structs in the old mode

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
This commit is contained in:
Rhys Perry 2019-05-17 15:04:39 +01:00 committed by Rhys Perry
parent 300e758b7c
commit bcd14756ee
1 changed files with 204 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

251
src/compiler/nir/nir_lower_io_to_vector.c
View File

@ -47,6 +47,22 @@ get_slot(const nir_variable *var)
return var->data.location + var->data.index;
}
static const struct glsl_type *
get_per_vertex_type(const nir_shader *shader, const nir_variable *var,
unsigned *num_vertices)
{
if (nir_is_per_vertex_io(var, shader->info.stage)) {
assert(glsl_type_is_array(var->type));
if (num_vertices)
*num_vertices = glsl_get_length(var->type);
return glsl_get_array_element(var->type);
} else {
if (num_vertices)
*num_vertices = 0;
return var->type;
}
}
static const struct glsl_type *
resize_array_vec_type(const struct glsl_type *type, unsigned num_components)
{
@ -61,43 +77,45 @@ resize_array_vec_type(const struct glsl_type *type, unsigned num_components)
}
static bool
variable_can_rewrite(const nir_variable *var)
{
/* Skip complex types we don't split in the first place */
if (!glsl_type_is_vector_or_scalar(glsl_without_array(var->type)))
return false;
/* TODO: add 64/16bit support ? */
if (glsl_get_bit_size(glsl_without_array(var->type)) != 32)
return false;
return true;
}
static bool
variables_can_merge(nir_shader *shader,
const nir_variable *a, const nir_variable *b)
variables_can_merge(const nir_shader *shader,
const nir_variable *a, const nir_variable *b,
bool same_array_structure)
{
const struct glsl_type *a_type_tail = a->type;
const struct glsl_type *b_type_tail = b->type;
if (nir_is_per_vertex_io(a, shader->info.stage) !=
nir_is_per_vertex_io(b, shader->info.stage))
return false;
/* They must have the same array structure */
while (glsl_type_is_array(a_type_tail)) {
if (!glsl_type_is_array(b_type_tail))
return false;
if (same_array_structure) {
while (glsl_type_is_array(a_type_tail)) {
if (!glsl_type_is_array(b_type_tail))
return false;
if (glsl_get_length(a_type_tail) != glsl_get_length(b_type_tail))
return false;
if (glsl_get_length(a_type_tail) != glsl_get_length(b_type_tail))
return false;
a_type_tail = glsl_get_array_element(a_type_tail);
b_type_tail = glsl_get_array_element(b_type_tail);
a_type_tail = glsl_get_array_element(a_type_tail);
b_type_tail = glsl_get_array_element(b_type_tail);
}
if (glsl_type_is_array(b_type_tail))
return false;
} else {
a_type_tail = glsl_without_array(a_type_tail);
b_type_tail = glsl_without_array(b_type_tail);
}
if (!glsl_type_is_vector_or_scalar(a_type_tail) ||
!glsl_type_is_vector_or_scalar(b_type_tail))
return false;
if (glsl_get_base_type(a->type) != glsl_get_base_type(b->type))
if (glsl_get_base_type(a_type_tail) != glsl_get_base_type(b_type_tail))
return false;
/* TODO: add 64/16bit support ? */
if (glsl_get_bit_size(a_type_tail) != 32)
return false;
assert(a->data.mode == b->data.mode);
@ -114,26 +132,75 @@ variables_can_merge(nir_shader *shader,
return true;
}
static const struct glsl_type *
get_flat_type(const nir_shader *shader, nir_variable *old_vars[MAX_SLOTS][4],
unsigned *loc, nir_variable **first_var, unsigned *num_vertices)
{
unsigned todo = 1;
unsigned slots = 0;
unsigned num_vars = 0;
enum glsl_base_type base;
*num_vertices = 0;
*first_var = NULL;
while (todo) {
assert(*loc < MAX_SLOTS);
for (unsigned frac = 0; frac < 4; frac++) {
nir_variable *var = old_vars[*loc][frac];
if (!var)
continue;
if ((*first_var &&
!variables_can_merge(shader, var, *first_var, false)) ||
var->data.compact) {
(*loc)++;
return NULL;
}
if (!*first_var) {
if (!glsl_type_is_vector_or_scalar(glsl_without_array(var->type))) {
(*loc)++;
return NULL;
}
*first_var = var;
base = glsl_get_base_type(
glsl_without_array(get_per_vertex_type(shader, var, NULL)));
}
bool vs_in = shader->info.stage == MESA_SHADER_VERTEX &&
var->data.mode == nir_var_shader_in;
unsigned var_slots = glsl_count_attribute_slots(
get_per_vertex_type(shader, var, num_vertices), vs_in);
todo = MAX2(todo, var_slots);
num_vars++;
}
todo--;
slots++;
(*loc)++;
}
if (num_vars <= 1)
return NULL;
return glsl_array_type(glsl_vector_type(base, 4), slots, 0);
}
static bool
create_new_io_vars(nir_shader *shader, struct exec_list *io_list,
nir_variable *old_vars[MAX_SLOTS][4],
nir_variable *new_vars[MAX_SLOTS][4])
nir_variable *new_vars[MAX_SLOTS][4],
bool flat_vars[MAX_SLOTS])
{
if (exec_list_is_empty(io_list))
return false;
nir_variable *old_vars[MAX_SLOTS][4] = {{0}};
nir_foreach_variable(var, io_list) {
if (variable_can_rewrite(var)) {
unsigned frac = var->data.location_frac;
old_vars[get_slot(var)][frac] = var;
}
unsigned frac = var->data.location_frac;
old_vars[get_slot(var)][frac] = var;
}
bool merged_any_vars = false;
/* We don't handle combining vars of different type e.g. different array
* lengths.
*/
for (unsigned loc = 0; loc < MAX_SLOTS; loc++) {
unsigned frac = 0;
while (frac < 4) {
@ -152,7 +219,7 @@ create_new_io_vars(nir_shader *shader, struct exec_list *io_list,
break;
if (var != first_var) {
if (!variables_can_merge(shader, first_var, var))
if (!variables_can_merge(shader, first_var, var, true))
break;
found_merge = true;
@ -160,6 +227,11 @@ create_new_io_vars(nir_shader *shader, struct exec_list *io_list,
const unsigned num_components =
glsl_get_components(glsl_without_array(var->type));
if (!num_components) {
assert(frac == 0);
frac++;
break; /* The type was a struct. */
}
/* We had better not have any overlapping vars */
for (unsigned i = 1; i < num_components; i++)
@ -178,11 +250,44 @@ create_new_io_vars(nir_shader *shader, struct exec_list *io_list,
var->type = resize_array_vec_type(var->type, frac - first);
nir_shader_add_variable(shader, var);
for (unsigned i = first; i < frac; i++)
for (unsigned i = first; i < frac; i++) {
new_vars[loc][i] = var;
old_vars[loc][i] = NULL;
}
old_vars[loc][first] = var;
}
}
/* "flat" mode: tries to ensure there is at most one variable per slot by
* merging variables into vec4s
*/
for (unsigned loc = 0; loc < MAX_SLOTS;) {
nir_variable *first_var;
unsigned num_vertices;
unsigned new_loc = loc;
const struct glsl_type *flat_type =
get_flat_type(shader, old_vars, &new_loc, &first_var, &num_vertices);
if (flat_type) {
merged_any_vars = true;
nir_variable *var = nir_variable_clone(first_var, shader);
var->data.location_frac = 0;
if (num_vertices)
var->type = glsl_array_type(flat_type, num_vertices, 0);
else
var->type = flat_type;
nir_shader_add_variable(shader, var);
for (unsigned i = 0; i < glsl_get_length(flat_type); i++) {
for (unsigned j = 0; j < 4; j++)
new_vars[loc + i][j] = var;
flat_vars[loc + i] = true;
}
}
loc = new_loc;
}
return merged_any_vars;
}
@ -199,6 +304,45 @@ build_array_deref_of_new_var(nir_builder *b, nir_variable *new_var,
return nir_build_deref_follower(b, parent, leader);
}
static nir_ssa_def *
build_array_index(nir_builder *b, nir_deref_instr *deref, nir_ssa_def *base,
bool vs_in)
{
switch (deref->deref_type) {
case nir_deref_type_var:
return base;
case nir_deref_type_array: {
nir_ssa_def *index = nir_i2i(b, deref->arr.index.ssa,
deref->dest.ssa.bit_size);
return nir_iadd(
b, build_array_index(b, nir_deref_instr_parent(deref), base, vs_in),
nir_imul_imm(b, index, glsl_count_attribute_slots(deref->type, vs_in)));
}
default:
unreachable("Invalid deref instruction type");
}
}
static nir_deref_instr *
build_array_deref_of_new_var_flat(nir_shader *shader,
nir_builder *b, nir_variable *new_var,
nir_deref_instr *leader, unsigned base)
{
nir_deref_instr *deref = nir_build_deref_var(b, new_var);
if (nir_is_per_vertex_io(new_var, shader->info.stage)) {
assert(leader->deref_type == nir_deref_type_array);
nir_ssa_def *index = leader->arr.index.ssa;
leader = nir_deref_instr_parent(leader);
deref = nir_build_deref_array(b, deref, index);
}
bool vs_in = shader->info.stage == MESA_SHADER_VERTEX &&
new_var->data.mode == nir_var_shader_in;
return nir_build_deref_array(
b, deref, build_array_index(b, leader, nir_imm_int(b, base), vs_in));
}
static bool
nir_lower_io_to_vector_impl(nir_function_impl *impl, nir_variable_mode modes)
{
@ -210,10 +354,10 @@ nir_lower_io_to_vector_impl(nir_function_impl *impl, nir_variable_mode modes)
nir_metadata_require(impl, nir_metadata_dominance);
nir_shader *shader = impl->function->shader;
nir_variable *old_inputs[MAX_SLOTS][4] = {{0}};
nir_variable *new_inputs[MAX_SLOTS][4] = {{0}};
nir_variable *old_outputs[MAX_SLOTS][4] = {{0}};
nir_variable *new_outputs[MAX_SLOTS][4] = {{0}};
bool flat_inputs[MAX_SLOTS] = {0};
bool flat_outputs[MAX_SLOTS] = {0};
if (modes & nir_var_shader_in) {
/* Vertex shaders support overlapping inputs. We don't do those */
@ -223,7 +367,7 @@ nir_lower_io_to_vector_impl(nir_function_impl *impl, nir_variable_mode modes)
* so we don't bother doing extra non-work.
*/
if (!create_new_io_vars(shader, &shader->inputs,
old_inputs, new_inputs))
new_inputs, flat_inputs))
modes &= ~nir_var_shader_in;
}
@ -232,7 +376,7 @@ nir_lower_io_to_vector_impl(nir_function_impl *impl, nir_variable_mode modes)
* so we don't bother doing extra non-work.
*/
if (!create_new_io_vars(shader, &shader->outputs,
old_outputs, new_outputs))
new_outputs, flat_outputs))
modes &= ~nir_var_shader_out;
}
@ -274,10 +418,11 @@ nir_lower_io_to_vector_impl(nir_function_impl *impl, nir_variable_mode modes)
nir_variable *new_var = old_deref->mode == nir_var_shader_in ?
new_inputs[loc][old_frac] :
new_outputs[loc][old_frac];
bool flat = old_deref->mode == nir_var_shader_in ?
flat_inputs[loc] : flat_outputs[loc];
if (!new_var)
break;
assert(get_slot(new_var) == loc);
const unsigned new_frac = new_var->data.location_frac;
nir_component_mask_t vec4_comp_mask =
@ -288,9 +433,15 @@ nir_lower_io_to_vector_impl(nir_function_impl *impl, nir_variable_mode modes)
/* Rewrite the load to use the new variable and only select a
* portion of the result.
*/
nir_deref_instr *new_deref =
build_array_deref_of_new_var(&b, new_var, old_deref);
assert(glsl_type_is_vector(new_deref->type));
nir_deref_instr *new_deref;
if (flat) {
new_deref = build_array_deref_of_new_var_flat(
shader, &b, new_var, old_deref, loc - get_slot(new_var));
} else {
assert(get_slot(new_var) == loc);
new_deref = build_array_deref_of_new_var(&b, new_var, old_deref);
assert(glsl_type_is_vector(new_deref->type));
}
nir_instr_rewrite_src(&intrin->instr, &intrin->src[0],
nir_src_for_ssa(&new_deref->dest.ssa));
@ -320,18 +471,24 @@ nir_lower_io_to_vector_impl(nir_function_impl *impl, nir_variable_mode modes)
const unsigned loc = get_slot(old_var);
const unsigned old_frac = old_var->data.location_frac;
nir_variable *new_var = new_outputs[loc][old_frac];
bool flat = flat_outputs[loc];
if (!new_var)
break;
assert(get_slot(new_var) == loc);
const unsigned new_frac = new_var->data.location_frac;
b.cursor = nir_before_instr(&intrin->instr);
/* Rewrite the store to be a masked store to the new variable */
nir_deref_instr *new_deref =
build_array_deref_of_new_var(&b, new_var, old_deref);
assert(glsl_type_is_vector(new_deref->type));
nir_deref_instr *new_deref;
if (flat) {
new_deref = build_array_deref_of_new_var_flat(
shader, &b, new_var, old_deref, loc - get_slot(new_var));
} else {
assert(get_slot(new_var) == loc);
new_deref = build_array_deref_of_new_var(&b, new_var, old_deref);
assert(glsl_type_is_vector(new_deref->type));
}
nir_instr_rewrite_src(&intrin->instr, &intrin->src[0],
nir_src_for_ssa(&new_deref->dest.ssa));