/*
* Copyright © 2012 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.
*/
/**
* \file lower_ubo_reference.cpp
*
* IR lower pass to replace dereferences of variables in a uniform
* buffer object with usage of ir_binop_ubo_load expressions, each of
* which can read data up to the size of a vec4.
*
* This relieves drivers of the responsibility to deal with tricky UBO
* layout issues like std140 structures and row_major matrices on
* their own.
*/
#include "ir.h"
#include "ir_builder.h"
#include "ir_rvalue_visitor.h"
#include "main/macros.h"
using namespace ir_builder;
namespace {
class lower_ubo_reference_visitor : public ir_rvalue_enter_visitor {
public:
lower_ubo_reference_visitor(struct gl_shader *shader)
: shader(shader)
{
}
void handle_rvalue(ir_rvalue **rvalue);
void emit_ubo_loads(ir_dereference *deref, ir_variable *base_offset,
unsigned int deref_offset);
ir_expression *ubo_load(const struct glsl_type *type,
ir_rvalue *offset);
void *mem_ctx;
struct gl_shader *shader;
struct gl_uniform_buffer_variable *ubo_var;
unsigned uniform_block;
bool progress;
};
/**
* Determine the name of the interface block field
*
* This is the name of the specific member as it would appear in the
* \c gl_uniform_buffer_variable::Name field in the shader's
* \c UniformBlocks array.
*/
static const char *
interface_field_name(void *mem_ctx, char *base_name, ir_dereference *d)
{
ir_constant *previous_index = NULL;
while (d != NULL) {
switch (d->ir_type) {
case ir_type_dereference_variable: {
ir_dereference_variable *v = (ir_dereference_variable *) d;
if (previous_index
&& v->var->is_interface_instance()
&& v->var->type->is_array())
return ralloc_asprintf(mem_ctx,
"%s[%d]",
base_name,
previous_index->get_uint_component(0));
else
return base_name;
break;
}
case ir_type_dereference_record: {
ir_dereference_record *r = (ir_dereference_record *) d;
d = r->record->as_dereference();
break;
}
case ir_type_dereference_array: {
ir_dereference_array *a = (ir_dereference_array *) d;
d = a->array->as_dereference();
previous_index = a->array_index->as_constant();
break;
}
default:
assert(!"Should not get here.");
break;
}
}
assert(!"Should not get here.");
return NULL;
}
void
lower_ubo_reference_visitor::handle_rvalue(ir_rvalue **rvalue)
{
if (!*rvalue)
return;
ir_dereference *deref = (*rvalue)->as_dereference();
if (!deref)
return;
ir_variable *var = deref->variable_referenced();
if (!var || !var->is_in_uniform_block())
return;
mem_ctx = ralloc_parent(*rvalue);
const char *const field_name =
interface_field_name(mem_ctx, (char *) var->interface_type->name, deref);
this->uniform_block = -1;
for (unsigned i = 0; i < shader->NumUniformBlocks; i++) {
if (strcmp(field_name, shader->UniformBlocks[i].Name) == 0) {
this->uniform_block = i;
struct gl_uniform_block *block = &shader->UniformBlocks[i];
this->ubo_var = var->is_interface_instance()
? &block->Uniforms[0] : &block->Uniforms[var->location];
break;
}
}
assert(this->uniform_block != (unsigned) -1);
ir_rvalue *offset = new(mem_ctx) ir_constant(0u);
unsigned const_offset = 0;
bool row_major = ubo_var->RowMajor;
/* Calculate the offset to the start of the region of the UBO
* dereferenced by *rvalue. This may be a variable offset if an
* array dereference has a variable index.
*/
while (deref) {
switch (deref->ir_type) {
case ir_type_dereference_variable: {
const_offset += ubo_var->Offset;
deref = NULL;
break;
}
case ir_type_dereference_array: {
ir_dereference_array *deref_array = (ir_dereference_array *)deref;
unsigned array_stride;
if (deref_array->array->type->is_matrix() && row_major) {
/* When loading a vector out of a row major matrix, the
* step between the columns (vectors) is the size of a
* float, while the step between the rows (elements of a
* vector) is handled below in emit_ubo_loads.
*/
array_stride = 4;
} else if (deref_array->type->is_interface()) {
/* We're processing an array dereference of an interface instance
* array. The thing being dereferenced *must* be a variable
* dereference because intefaces cannot be embedded an other
* types. In terms of calculating the offsets for the lowering
* pass, we don't care about the array index. All elements of an
* interface instance array will have the same offsets relative to
* the base of the block that backs them.
*/
assert(deref_array->array->as_dereference_variable());
deref = deref_array->array->as_dereference();
break;
} else {
array_stride = deref_array->type->std140_size(row_major);
array_stride = glsl_align(array_stride, 16);
}
ir_constant *const_index = deref_array->array_index->as_constant();
if (const_index) {
const_offset += array_stride * const_index->value.i[0];
} else {
offset = add(offset,
mul(deref_array->array_index,
new(mem_ctx) ir_constant(array_stride)));
}
deref = deref_array->array->as_dereference();
break;
}
case ir_type_dereference_record: {
ir_dereference_record *deref_record = (ir_dereference_record *)deref;
const glsl_type *struct_type = deref_record->record->type;
unsigned intra_struct_offset = 0;
unsigned max_field_align = 16;
for (unsigned int i = 0; i < struct_type->length; i++) {
const glsl_type *type = struct_type->fields.structure[i].type;
unsigned field_align = type->std140_base_alignment(row_major);
max_field_align = MAX2(field_align, max_field_align);
intra_struct_offset = glsl_align(intra_struct_offset, field_align);
if (strcmp(struct_type->fields.structure[i].name,
deref_record->field) == 0)
break;
intra_struct_offset += type->std140_size(row_major);
}
const_offset = glsl_align(const_offset, max_field_align);
const_offset += intra_struct_offset;
deref = deref_record->record->as_dereference();
break;
}
default:
assert(!"not reached");
deref = NULL;
break;
}
}
/* Now that we've calculated the offset to the start of the
* dereference, walk over the type and emit loads into a temporary.
*/
const glsl_type *type = (*rvalue)->type;
ir_variable *load_var = new(mem_ctx) ir_variable(type,
"ubo_load_temp",
ir_var_temporary);
base_ir->insert_before(load_var);
ir_variable *load_offset = new(mem_ctx) ir_variable(glsl_type::uint_type,
"ubo_load_temp_offset",
ir_var_temporary);
base_ir->insert_before(load_offset);
base_ir->insert_before(assign(load_offset, offset));
deref = new(mem_ctx) ir_dereference_variable(load_var);
emit_ubo_loads(deref, load_offset, const_offset);
*rvalue = deref;
progress = true;
}
ir_expression *
lower_ubo_reference_visitor::ubo_load(const glsl_type *type,
ir_rvalue *offset)
{
return new(mem_ctx)
ir_expression(ir_binop_ubo_load,
type,
new(mem_ctx) ir_constant(this->uniform_block),
offset);
}
/**
* Takes LHS and emits a series of assignments into its components
* from the UBO variable at variable_offset + deref_offset.
*
* Recursively calls itself to break the deref down to the point that
* the ir_binop_ubo_load expressions generated are contiguous scalars
* or vectors.
*/
void
lower_ubo_reference_visitor::emit_ubo_loads(ir_dereference *deref,
ir_variable *base_offset,
unsigned int deref_offset)
{
if (deref->type->is_record()) {
unsigned int field_offset = 0;
for (unsigned i = 0; i < deref->type->length; i++) {
const struct glsl_struct_field *field =
&deref->type->fields.structure[i];
ir_dereference *field_deref =
new(mem_ctx) ir_dereference_record(deref->clone(mem_ctx, NULL),
field->name);
field_offset =
glsl_align(field_offset,
field->type->std140_base_alignment(ubo_var->RowMajor));
emit_ubo_loads(field_deref, base_offset, deref_offset + field_offset);
field_offset += field->type->std140_size(ubo_var->RowMajor);
}
return;
}
if (deref->type->is_array()) {
unsigned array_stride =
glsl_align(deref->type->fields.array->std140_size(ubo_var->RowMajor),
16);
for (unsigned i = 0; i < deref->type->length; i++) {
ir_constant *element = new(mem_ctx) ir_constant(i);
ir_dereference *element_deref =
new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL),
element);
emit_ubo_loads(element_deref, base_offset,
deref_offset + i * array_stride);
}
return;
}
if (deref->type->is_matrix()) {
for (unsigned i = 0; i < deref->type->matrix_columns; i++) {
ir_constant *col = new(mem_ctx) ir_constant(i);
ir_dereference *col_deref =
new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL),
col);
/* std140 always rounds the stride of arrays (and matrices)
* to a vec4, so matrices are always 16 between columns/rows.
*/
emit_ubo_loads(col_deref, base_offset, deref_offset + i * 16);
}
return;
}
assert(deref->type->is_scalar() ||
deref->type->is_vector());
if (!ubo_var->RowMajor) {
ir_rvalue *offset = add(base_offset,
new(mem_ctx) ir_constant(deref_offset));
base_ir->insert_before(assign(deref->clone(mem_ctx, NULL),
ubo_load(deref->type, offset)));
} else {
/* We're dereffing a column out of a row-major matrix, so we
* gather the vector from each stored row.
*/
assert(deref->type->base_type == GLSL_TYPE_FLOAT);
/* Matrices, row_major or not, are stored as if they were
* arrays of vectors of the appropriate size in std140.
* Arrays have their strides rounded up to a vec4, so the
* matrix stride is always 16.
*/
unsigned matrix_stride = 16;
for (unsigned i = 0; i < deref->type->vector_elements; i++) {
ir_rvalue *chan_offset =
add(base_offset,
new(mem_ctx) ir_constant(deref_offset + i * matrix_stride));
base_ir->insert_before(assign(deref->clone(mem_ctx, NULL),
ubo_load(glsl_type::float_type,
chan_offset),
(1U << i)));
}
}
}
} /* unnamed namespace */
void
lower_ubo_reference(struct gl_shader *shader, exec_list *instructions)
{
lower_ubo_reference_visitor v(shader);
/* Loop over the instructions lowering references, because we take
* a deref of a UBO array using a UBO dereference as the index will
* produce a collection of instructions all of which have cloned
* UBO dereferences for that array index.
*/
do {
v.progress = false;
visit_list_elements(&v, instructions);
} while (v.progress);
}