--- /dev/null
+/*
+ * Copyright © 2010 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 ir_vec_index_to_cond_assign.cpp
+ *
+ * Turns indexing into vector types to a series of conditional moves
+ * of each channel's swizzle into a temporary.
+ *
+ * Most GPUs don't have a native way to do this operation, and this
+ * works around that. For drivers using both this pass and
+ * ir_vec_index_to_swizzle, there's a risk that this pass will happen
+ * before sufficient constant folding to find that the array index is
+ * constant. However, we hope that other optimization passes,
+ * particularly constant folding of assignment conditions and copy
+ * propagation, will result in the same code in the end.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_optimization.h"
+#include "glsl_types.h"
+
+/**
+ * Visitor class for replacing expressions with ir_constant values.
+ */
+
+class ir_vec_index_to_cond_assign_visitor : public ir_hierarchical_visitor {
+public:
+ ir_vec_index_to_cond_assign_visitor()
+ {
+ progress = false;
+ }
+
+ ir_rvalue *convert_vec_index_to_cond_assign(ir_rvalue *val);
+
+ virtual ir_visitor_status visit_enter(ir_expression *);
+ virtual ir_visitor_status visit_enter(ir_swizzle *);
+ virtual ir_visitor_status visit_enter(ir_assignment *);
+ virtual ir_visitor_status visit_enter(ir_return *);
+ virtual ir_visitor_status visit_enter(ir_call *);
+ virtual ir_visitor_status visit_enter(ir_if *);
+
+ bool progress;
+};
+
+ir_rvalue *
+ir_vec_index_to_cond_assign_visitor::convert_vec_index_to_cond_assign(ir_rvalue *ir)
+{
+ ir_dereference_array *orig_deref = ir->as_dereference_array();
+ ir_assignment *assign;
+ ir_variable *index, *var;
+ ir_dereference *deref;
+ ir_expression *condition;
+ ir_swizzle *swizzle;
+ int i;
+
+ if (!orig_deref)
+ return ir;
+
+ if (orig_deref->array->type->is_matrix() ||
+ orig_deref->array->type->is_array())
+ return ir;
+
+ assert(orig_deref->array_index->type->base_type == GLSL_TYPE_INT);
+
+ /* Store the index to a temporary to avoid reusing its tree. */
+ index = new(base_ir) ir_variable(glsl_type::int_type,
+ "vec_index_tmp_i");
+ base_ir->insert_before(index);
+ deref = new(base_ir) ir_dereference_variable(index);
+ assign = new(base_ir) ir_assignment(deref, orig_deref->array_index, NULL);
+ base_ir->insert_before(assign);
+
+ /* Temporary where we store whichever value we swizzle out. */
+ var = new(base_ir) ir_variable(ir->type, "vec_index_tmp_v");
+ base_ir->insert_before(var);
+
+ /* Generate a conditional move of each vector element to the temp. */
+ for (i = 0; i < orig_deref->array->type->vector_elements; i++) {
+ deref = new(base_ir) ir_dereference_variable(index);
+ condition = new(base_ir) ir_expression(ir_binop_equal,
+ glsl_type::bool_type,
+ deref,
+ new(base_ir) ir_constant(i));
+
+ /* Just clone the rest of the deref chain when trying to get at the
+ * underlying variable.
+ */
+ deref = (ir_dereference *)orig_deref->array->clone(NULL);
+ swizzle = new(base_ir) ir_swizzle(deref, i, 0, 0, 0, 1);
+
+ deref = new(base_ir) ir_dereference_variable(var);
+ assign = new(base_ir) ir_assignment(deref, swizzle, condition);
+ base_ir->insert_before(assign);
+ }
+
+ this->progress = true;
+ return new(base_ir) ir_dereference_variable(var);
+}
+
+ir_visitor_status
+ir_vec_index_to_cond_assign_visitor::visit_enter(ir_expression *ir)
+{
+ unsigned int i;
+
+ for (i = 0; i < ir->get_num_operands(); i++) {
+ ir->operands[i] = convert_vec_index_to_cond_assign(ir->operands[i]);
+ }
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_vec_index_to_cond_assign_visitor::visit_enter(ir_swizzle *ir)
+{
+ /* Can't be hit from normal GLSL, since you can't swizzle a scalar (which
+ * the result of indexing a vector is. But maybe at some point we'll end up
+ * using swizzling of scalars for vector construction.
+ */
+ ir->val = convert_vec_index_to_cond_assign(ir->val);
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_vec_index_to_cond_assign_visitor::visit_enter(ir_assignment *ir)
+{
+ /* FINISHME: Handle it on the LHS. */
+ ir->rhs = convert_vec_index_to_cond_assign(ir->rhs);
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_vec_index_to_cond_assign_visitor::visit_enter(ir_call *ir)
+{
+ foreach_iter(exec_list_iterator, iter, *ir) {
+ ir_rvalue *param = (ir_rvalue *)iter.get();
+ ir_rvalue *new_param = convert_vec_index_to_cond_assign(param);
+
+ if (new_param != param) {
+ param->insert_before(new_param);
+ param->remove();
+ }
+ }
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_vec_index_to_cond_assign_visitor::visit_enter(ir_return *ir)
+{
+ if (ir->value) {
+ ir->value = convert_vec_index_to_cond_assign(ir->value);
+ }
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_vec_index_to_cond_assign_visitor::visit_enter(ir_if *ir)
+{
+ ir->condition = convert_vec_index_to_cond_assign(ir->condition);
+
+ return visit_continue;
+}
+
+bool
+do_vec_index_to_cond_assign(exec_list *instructions)
+{
+ ir_vec_index_to_cond_assign_visitor v;
+
+ visit_list_elements(&v, instructions);
+
+ return v.progress;
+}
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