/* * 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->get_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->data.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_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->as_constant(); 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; 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); }