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/*
* Copyright (c) 2015 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_buffer_access.cpp
*
* Helper for IR lowering pass to replace dereferences of buffer object based
* shader variables with intrinsic function calls.
*
* This helper is used by lowering passes for UBOs, SSBOs and compute shader
* shared variables.
*/
#include "lower_buffer_access.h"
#include "ir_builder.h"
#include "main/macros.h"
#include "util/list.h"
#include "glsl_parser_extras.h"
#include "linker.h"
using namespace ir_builder;
namespace lower_buffer_access {
static inline int
writemask_for_size(unsigned n)
{
return ((1 << n) - 1);
}
/**
* Takes a deref and recursively calls itself to break the deref down to the
* point that the reads or writes generated are contiguous scalars or vectors.
*/
void
lower_buffer_access::emit_access(void *mem_ctx,
bool is_write,
ir_dereference *deref,
ir_variable *base_offset,
unsigned int deref_offset,
bool row_major,
const glsl_type *matrix_type,
enum glsl_interface_packing packing,
unsigned int write_mask)
{
if (deref->type->is_struct()) {
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);
unsigned field_align;
if (packing == GLSL_INTERFACE_PACKING_STD430)
field_align = field->type->std430_base_alignment(row_major);
else
field_align = field->type->std140_base_alignment(row_major);
field_offset = glsl_align(field_offset, field_align);
emit_access(mem_ctx, is_write, field_deref, base_offset,
deref_offset + field_offset,
row_major, NULL, packing,
writemask_for_size(field_deref->type->vector_elements));
if (packing == GLSL_INTERFACE_PACKING_STD430)
field_offset += field->type->std430_size(row_major);
else
field_offset += field->type->std140_size(row_major);
}
return;
}
if (deref->type->is_array()) {
unsigned array_stride = packing == GLSL_INTERFACE_PACKING_STD430 ?
deref->type->fields.array->std430_array_stride(row_major) :
glsl_align(deref->type->fields.array->std140_size(row_major), 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_access(mem_ctx, is_write, element_deref, base_offset,
deref_offset + i * array_stride,
row_major, NULL, packing,
writemask_for_size(element_deref->type->vector_elements));
}
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);
/* For a row-major matrix, the next column starts at the next
* element. Otherwise it is offset by the matrix stride.
*/
const unsigned size_mul = row_major
? (deref->type->is_double() ? 8 : 4)
: link_calculate_matrix_stride(deref->type, row_major, packing);
emit_access(mem_ctx, is_write, col_deref, base_offset,
deref_offset + i * size_mul,
row_major, deref->type, packing,
writemask_for_size(col_deref->type->vector_elements));
}
return;
}
assert(deref->type->is_scalar() || deref->type->is_vector());
if (!row_major) {
ir_rvalue *offset =
add(base_offset, new(mem_ctx) ir_constant(deref_offset));
unsigned mask =
is_write ? write_mask : (1 << deref->type->vector_elements) - 1;
insert_buffer_access(mem_ctx, deref, deref->type, offset, mask, -1);
} else {
/* We're dereffing a column out of a row-major matrix, so we
* gather the vector from each stored row.
*/
assert(deref->type->is_float() || deref->type->is_double());
assert(matrix_type != NULL);
const unsigned matrix_stride =
link_calculate_matrix_stride(matrix_type, row_major, packing);
const glsl_type *deref_type = deref->type->get_scalar_type();
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));
if (!is_write || ((1U << i) & write_mask))
insert_buffer_access(mem_ctx, deref, deref_type, chan_offset,
(1U << i), i);
}
}
}
/**
* Determine if a thing being dereferenced is row-major
*
* There is some trickery here.
*
* If the thing being dereferenced is a member of uniform block \b without an
* instance name, then the name of the \c ir_variable is the field name of an
* interface type. If this field is row-major, then the thing referenced is
* row-major.
*
* If the thing being dereferenced is a member of uniform block \b with an
* instance name, then the last dereference in the tree will be an
* \c ir_dereference_record. If that record field is row-major, then the
* thing referenced is row-major.
*/
bool
lower_buffer_access::is_dereferenced_thing_row_major(const ir_rvalue *deref)
{
bool matrix = false;
const ir_rvalue *ir = deref;
while (true) {
matrix = matrix || ir->type->without_array()->is_matrix();
switch (ir->ir_type) {
case ir_type_dereference_array: {
const ir_dereference_array *const array_deref =
(const ir_dereference_array *) ir;
ir = array_deref->array;
break;
}
case ir_type_dereference_record: {
const ir_dereference_record *const record_deref =
(const ir_dereference_record *) ir;
ir = record_deref->record;
const int idx = record_deref->field_idx;
assert(idx >= 0);
const enum glsl_matrix_layout matrix_layout =
glsl_matrix_layout(ir->type->fields.structure[idx].matrix_layout);
switch (matrix_layout) {
case GLSL_MATRIX_LAYOUT_INHERITED:
break;
case GLSL_MATRIX_LAYOUT_COLUMN_MAJOR:
return false;
case GLSL_MATRIX_LAYOUT_ROW_MAJOR:
return matrix || deref->type->without_array()->is_struct();
}
break;
}
case ir_type_dereference_variable: {
const ir_dereference_variable *const var_deref =
(const ir_dereference_variable *) ir;
const enum glsl_matrix_layout matrix_layout =
glsl_matrix_layout(var_deref->var->data.matrix_layout);
switch (matrix_layout) {
case GLSL_MATRIX_LAYOUT_INHERITED: {
/* For interface block matrix variables we handle inherited
* layouts at HIR generation time, but we don't do that for shared
* variables, which are always column-major
*/
ASSERTED ir_variable *var = deref->variable_referenced();
assert((var->is_in_buffer_block() && !matrix) ||
var->data.mode == ir_var_shader_shared);
return false;
}
case GLSL_MATRIX_LAYOUT_COLUMN_MAJOR:
return false;
case GLSL_MATRIX_LAYOUT_ROW_MAJOR:
return matrix || deref->type->without_array()->is_struct();
}
unreachable("invalid matrix layout");
break;
}
default:
return false;
}
}
/* The tree must have ended with a dereference that wasn't an
* ir_dereference_variable. That is invalid, and it should be impossible.
*/
unreachable("invalid dereference tree");
return false;
}
/**
* This function initializes various values that will be used later by
* emit_access when actually emitting loads or stores.
*
* Note: const_offset is an input as well as an output, clients must
* initialize it to the offset of the variable in the underlying block, and
* this function will adjust it by adding the constant offset of the member
* being accessed into that variable.
*/
void
lower_buffer_access::setup_buffer_access(void *mem_ctx,
ir_rvalue *deref,
ir_rvalue **offset,
unsigned *const_offset,
bool *row_major,
const glsl_type **matrix_type,
const glsl_struct_field **struct_field,
enum glsl_interface_packing packing)
{
*offset = new(mem_ctx) ir_constant(0u);
*row_major = is_dereferenced_thing_row_major(deref);
*matrix_type = NULL;
/* 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: {
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_vector()) {
/* We get this when storing or loading a component out of a vector
* with a non-constant index. This happens for v[i] = f where v is
* a vector (or m[i][j] = f where m is a matrix). If we don't
* lower that here, it gets turned into v = vector_insert(v, i,
* f), which loads the entire vector, modifies one component and
* then write the entire thing back. That breaks if another
* thread or SIMD channel is modifying the same vector.
*/
array_stride = 4;
if (deref_array->array->type->is_64bit())
array_stride *= 2;
} else 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;
if (deref_array->array->type->is_64bit())
array_stride *= 2;
*matrix_type = deref_array->array->type;
} else if (deref_array->type->without_array()->is_interface()) {
/* We're processing an array dereference of an interface instance
* array. The thing being dereferenced *must* be a variable
* dereference because interfaces cannot be embedded in 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.
*/
deref = deref_array->array->as_dereference();
break;
} else {
/* Whether or not the field is row-major (because it might be a
* bvec2 or something) does not affect the array itself. We need
* to know whether an array element in its entirety is row-major.
*/
const bool array_row_major =
is_dereferenced_thing_row_major(deref_array);
/* The array type will give the correct interface packing
* information
*/
if (packing == GLSL_INTERFACE_PACKING_STD430) {
array_stride = deref_array->type->std430_array_stride(array_row_major);
} else {
array_stride = deref_array->type->std140_size(array_row_major);
array_stride = glsl_align(array_stride, 16);
}
}
ir_rvalue *array_index = deref_array->array_index;
if (array_index->type->base_type == GLSL_TYPE_INT)
array_index = i2u(array_index);
ir_constant *const_index =
array_index->constant_expression_value(mem_ctx, NULL);
if (const_index) {
*const_offset += array_stride * const_index->value.u[0];
} else {
*offset = add(*offset,
mul(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;
for (unsigned int i = 0; i < struct_type->length; i++) {
const glsl_type *type = struct_type->fields.structure[i].type;
ir_dereference_record *field_deref = new(mem_ctx)
ir_dereference_record(deref_record->record,
struct_type->fields.structure[i].name);
const bool field_row_major =
is_dereferenced_thing_row_major(field_deref);
ralloc_free(field_deref);
unsigned field_align = 0;
if (packing == GLSL_INTERFACE_PACKING_STD430)
field_align = type->std430_base_alignment(field_row_major);
else
field_align = type->std140_base_alignment(field_row_major);
if (struct_type->fields.structure[i].offset != -1) {
intra_struct_offset = struct_type->fields.structure[i].offset;
}
intra_struct_offset = glsl_align(intra_struct_offset, field_align);
assert(deref_record->field_idx >= 0);
if (i == (unsigned) deref_record->field_idx) {
if (struct_field)
*struct_field = &struct_type->fields.structure[i];
break;
}
if (packing == GLSL_INTERFACE_PACKING_STD430)
intra_struct_offset += type->std430_size(field_row_major);
else
intra_struct_offset += type->std140_size(field_row_major);
/* If the field just examined was itself a structure, apply rule
* #9:
*
* "The structure may have padding at the end; the base offset
* of the member following the sub-structure is rounded up to
* the next multiple of the base alignment of the structure."
*/
if (type->without_array()->is_struct()) {
intra_struct_offset = glsl_align(intra_struct_offset,
field_align);
}
}
*const_offset += intra_struct_offset;
deref = deref_record->record->as_dereference();
break;
}
case ir_type_swizzle: {
ir_swizzle *deref_swizzle = (ir_swizzle *) deref;
assert(deref_swizzle->mask.num_components == 1);
*const_offset += deref_swizzle->mask.x * sizeof(int);
deref = deref_swizzle->val->as_dereference();
break;
}
default:
assert(!"not reached");
deref = NULL;
break;
}
}
}
} /* namespace lower_buffer_access */