/* * 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" 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, int matrix_columns, unsigned int packing, unsigned int write_mask) { 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(row_major)); emit_access(mem_ctx, is_write, field_deref, base_offset, deref_offset + field_offset, row_major, 1, packing, writemask_for_size(field_deref->type->vector_elements)); 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, 1, 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); if (row_major) { /* For a row-major matrix, the next column starts at the next * element. */ int size_mul = deref->type->is_double() ? 8 : 4; emit_access(mem_ctx, is_write, col_deref, base_offset, deref_offset + i * size_mul, row_major, deref->type->matrix_columns, packing, writemask_for_size(col_deref->type->vector_elements)); } else { int size_mul; /* std430 doesn't round up vec2 size to a vec4 size */ if (packing == GLSL_INTERFACE_PACKING_STD430 && deref->type->vector_elements == 2 && !deref->type->is_double()) { size_mul = 8; } else { /* std140 always rounds the stride of arrays (and matrices) to a * vec4, so matrices are always 16 between columns/rows. With * doubles, they will be 32 apart when there are more than 2 rows. * * For both std140 and std430, if the member is a * three-'component vector with components consuming N basic * machine units, the base alignment is 4N. For vec4, base * alignment is 4N. */ size_mul = (deref->type->is_double() && deref->type->vector_elements > 2) ? 32 : 16; } emit_access(mem_ctx, is_write, col_deref, base_offset, deref_offset + i * size_mul, row_major, deref->type->matrix_columns, 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 { unsigned N = deref->type->is_double() ? 8 : 4; /* 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 || deref->type->base_type == GLSL_TYPE_DOUBLE); /* 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. However a double matrix may either be 16 * or 32 depending on the number of columns. */ assert(matrix_columns <= 4); unsigned matrix_stride = 0; /* Matrix stride for std430 mat2xY matrices are not rounded up to * vec4 size. From OpenGL 4.3 spec, section 7.6.2.2 "Standard Uniform * Block Layout": * * "2. If the member is a two- or four-component vector with components * consuming N basic machine units, the base alignment is 2N or 4N, * respectively." [...] * "4. If the member is an array of scalars or vectors, the base alignment * and array stride are set to match the base alignment of a single array * element, according to rules (1), (2), and (3), and rounded up to the * base alignment of a vec4." [...] * "7. If the member is a row-major matrix with C columns and R rows, the * matrix is stored identically to an array of R row vectors with C * components each, according to rule (4)." [...] * "When using the std430 storage layout, shader storage blocks will be * laid out in buffer storage identically to uniform and shader storage * blocks using the std140 layout, except that the base alignment and * stride of arrays of scalars and vectors in rule 4 and of structures in * rule 9 are not rounded up a multiple of the base alignment of a vec4." */ if (packing == GLSL_INTERFACE_PACKING_STD430 && matrix_columns == 2) matrix_stride = 2 * N; else matrix_stride = glsl_align(matrix_columns * N, 16); const glsl_type *deref_type = deref->type->base_type == GLSL_TYPE_FLOAT ? glsl_type::float_type : glsl_type::double_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 = ir->type->field_index(record_deref->field); 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_record(); } 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 */ 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_record(); } 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_variable *var, ir_rvalue *deref, ir_rvalue **offset, unsigned *const_offset, bool *row_major, int *matrix_columns, const glsl_struct_field **struct_field, unsigned packing) { *offset = new(mem_ctx) ir_constant(0u); *row_major = is_dereferenced_thing_row_major(deref); *matrix_columns = 1; /* 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_double()) 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_double()) array_stride *= 2; *matrix_columns = deref_array->array->type->matrix_columns; } 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(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); intra_struct_offset = glsl_align(intra_struct_offset, field_align); if (strcmp(struct_type->fields.structure[i].name, deref_record->field) == 0) { 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_record()) { 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 */