--- /dev/null
+/*
+ * 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;
+};
+
+static inline unsigned int
+align(unsigned int a, unsigned int align)
+{
+ return (a + align - 1) / align * align;
+}
+
+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->uniform_block == -1)
+ return;
+
+ mem_ctx = ralloc_parent(*rvalue);
+ uniform_block = var->uniform_block;
+ struct gl_uniform_block *block = &shader->UniformBlocks[uniform_block];
+ this->ubo_var = &block->Uniforms[var->location];
+ 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 {
+ array_stride = deref_array->type->std140_size(row_major);
+ array_stride = 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 = 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 = 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 =
+ 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 =
+ 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 = new(mem_ctx) ir_constant((int)i);
+ ir_dereference *deref_chan =
+ new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL),
+ chan);
+
+ ir_rvalue *chan_offset =
+ add(base_offset,
+ new(mem_ctx) ir_constant(deref_offset + i * matrix_stride));
+
+ base_ir->insert_before(assign(deref_chan,
+ ubo_load(glsl_type::float_type,
+ chan_offset)));
+ }
+ }
+}
+
+} /* 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);
+}
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