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+/*
+ * 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 opt_array_splitting.cpp
+ *
+ * If an array is always dereferenced with a constant index, then
+ * split it apart into its elements, making it more amenable to other
+ * optimization passes.
+ *
+ * This skips uniform/varying arrays, which would need careful
+ * handling due to their ir->location fields tying them to the GL API
+ * and other shader stages.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_rvalue_visitor.h"
+#include "ir_print_visitor.h"
+#include "glsl_types.h"
+
+static bool debug = false;
+
+namespace opt_array_splitting {
+
+class variable_entry : public exec_node
+{
+public:
+ variable_entry(ir_variable *var)
+ {
+ this->var = var;
+ this->whole_array_access = 0;
+ this->declaration = false;
+ this->components = NULL;
+ this->mem_ctx = NULL;
+ if (var->type->is_array())
+ this->size = var->type->length;
+ else
+ this->size = var->type->matrix_columns;
+ }
+
+ ir_variable *var; /* The key: the variable's pointer. */
+ unsigned size; /* array length or matrix columns */
+
+ /** Number of times the variable is referenced, including assignments. */
+ unsigned whole_array_access;
+
+ bool declaration; /* If the variable had a decl in the instruction stream */
+
+ ir_variable **components;
+
+ /** ralloc_parent(this->var) -- the shader's talloc context. */
+ void *mem_ctx;
+};
+
+} /* namespace */
+using namespace opt_array_splitting;
+
+/**
+ * This class does a walk over the tree, coming up with the set of
+ * variables that could be split by looking to see if they are arrays
+ * that are only ever constant-index dereferenced.
+ */
+class ir_array_reference_visitor : public ir_hierarchical_visitor {
+public:
+ ir_array_reference_visitor(void)
+ {
+ this->mem_ctx = ralloc_context(NULL);
+ this->variable_list.make_empty();
+ }
+
+ ~ir_array_reference_visitor(void)
+ {
+ ralloc_free(mem_ctx);
+ }
+
+ bool get_split_list(exec_list *instructions, bool linked);
+
+ virtual ir_visitor_status visit(ir_variable *);
+ virtual ir_visitor_status visit(ir_dereference_variable *);
+ virtual ir_visitor_status visit_enter(ir_dereference_array *);
+
+ variable_entry *get_variable_entry(ir_variable *var);
+
+ /* List of variable_entry */
+ exec_list variable_list;
+
+ void *mem_ctx;
+};
+
+variable_entry *
+ir_array_reference_visitor::get_variable_entry(ir_variable *var)
+{
+ assert(var);
+
+ if (var->mode != ir_var_auto &&
+ var->mode != ir_var_temporary)
+ return NULL;
+
+ if (!(var->type->is_array() || var->type->is_matrix()))
+ return NULL;
+
+ /* If the array hasn't been sized yet, we can't split it. After
+ * linking, this should be resolved.
+ */
+ if (var->type->is_array() && var->type->length == 0)
+ return NULL;
+
+ foreach_iter(exec_list_iterator, iter, this->variable_list) {
+ variable_entry *entry = (variable_entry *)iter.get();
+ if (entry->var == var)
+ return entry;
+ }
+
+ variable_entry *entry = new(mem_ctx) variable_entry(var);
+ this->variable_list.push_tail(entry);
+ return entry;
+}
+
+
+ir_visitor_status
+ir_array_reference_visitor::visit(ir_variable *ir)
+{
+ variable_entry *entry = this->get_variable_entry(ir);
+
+ if (entry)
+ entry->declaration = true;
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_array_reference_visitor::visit(ir_dereference_variable *ir)
+{
+ variable_entry *entry = this->get_variable_entry(ir->var);
+
+ /* If we made it to here, then the dereference of this array didn't
+ * have a constant index (see the visit_continue_with_parent
+ * below), so we can't split the variable.
+ */
+ if (entry)
+ entry->whole_array_access++;
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_array_reference_visitor::visit_enter(ir_dereference_array *ir)
+{
+ ir_dereference_variable *deref = ir->array->as_dereference_variable();
+ if (!deref)
+ return visit_continue;
+
+ variable_entry *entry = this->get_variable_entry(deref->var);
+
+ if (entry && !ir->array_index->as_constant())
+ entry->whole_array_access++;
+
+ return visit_continue_with_parent;
+}
+
+bool
+ir_array_reference_visitor::get_split_list(exec_list *instructions,
+ bool linked)
+{
+ visit_list_elements(this, instructions);
+
+ /* If the shaders aren't linked yet, we can't mess with global
+ * declarations, which need to be matched by name across shaders.
+ */
+ if (!linked) {
+ foreach_list(node, instructions) {
+ ir_variable *var = ((ir_instruction *)node)->as_variable();
+ if (var) {
+ variable_entry *entry = get_variable_entry(var);
+ if (entry)
+ entry->remove();
+ }
+ }
+ }
+
+ /* Trim out variables we found that we can't split. */
+ foreach_iter(exec_list_iterator, iter, variable_list) {
+ variable_entry *entry = (variable_entry *)iter.get();
+
+ if (debug) {
+ printf("array %s@%p: decl %d, whole_access %d\n",
+ entry->var->name, (void *) entry->var, entry->declaration,
+ entry->whole_array_access);
+ }
+
+ if (!entry->declaration || entry->whole_array_access) {
+ entry->remove();
+ }
+ }
+
+ return !variable_list.is_empty();
+}
+
+/** This is the class that does the actual work of splitting. */
+class ir_array_splitting_visitor : public ir_rvalue_visitor {
+public:
+ ir_array_splitting_visitor(exec_list *vars)
+ {
+ this->variable_list = vars;
+ }
+
+ virtual ~ir_array_splitting_visitor()
+ {
+ }
+
+ virtual ir_visitor_status visit_leave(ir_assignment *);
+
+ void split_deref(ir_dereference **deref);
+ void handle_rvalue(ir_rvalue **rvalue);
+ variable_entry *get_splitting_entry(ir_variable *var);
+
+ exec_list *variable_list;
+ void *mem_ctx;
+};
+
+variable_entry *
+ir_array_splitting_visitor::get_splitting_entry(ir_variable *var)
+{
+ assert(var);
+
+ foreach_iter(exec_list_iterator, iter, *this->variable_list) {
+ variable_entry *entry = (variable_entry *)iter.get();
+ if (entry->var == var) {
+ return entry;
+ }
+ }
+
+ return NULL;
+}
+
+void
+ir_array_splitting_visitor::split_deref(ir_dereference **deref)
+{
+ ir_dereference_array *deref_array = (*deref)->as_dereference_array();
+ if (!deref_array)
+ return;
+
+ ir_dereference_variable *deref_var = deref_array->array->as_dereference_variable();
+ if (!deref_var)
+ return;
+ ir_variable *var = deref_var->var;
+
+ variable_entry *entry = get_splitting_entry(var);
+ if (!entry)
+ return;
+
+ ir_constant *constant = deref_array->array_index->as_constant();
+ assert(constant);
+
+ if (constant->value.i[0] < (int)entry->size) {
+ *deref = new(entry->mem_ctx)
+ ir_dereference_variable(entry->components[constant->value.i[0]]);
+ } else {
+ /* There was a constant array access beyond the end of the
+ * array. This might have happened due to constant folding
+ * after the initial parse. This produces an undefined value,
+ * but shouldn't crash. Just give them an uninitialized
+ * variable.
+ */
+ ir_variable *temp = new(entry->mem_ctx) ir_variable(deref_array->type,
+ "undef",
+ ir_var_temporary);
+ entry->components[0]->insert_before(temp);
+ *deref = new(entry->mem_ctx) ir_dereference_variable(temp);
+ }
+}
+
+void
+ir_array_splitting_visitor::handle_rvalue(ir_rvalue **rvalue)
+{
+ if (!*rvalue)
+ return;
+
+ ir_dereference *deref = (*rvalue)->as_dereference();
+
+ if (!deref)
+ return;
+
+ split_deref(&deref);
+ *rvalue = deref;
+}
+
+ir_visitor_status
+ir_array_splitting_visitor::visit_leave(ir_assignment *ir)
+{
+ /* The normal rvalue visitor skips the LHS of assignments, but we
+ * need to process those just the same.
+ */
+ ir_rvalue *lhs = ir->lhs;
+
+ handle_rvalue(&lhs);
+ ir->lhs = lhs->as_dereference();
+
+ ir->lhs->accept(this);
+
+ handle_rvalue(&ir->rhs);
+ ir->rhs->accept(this);
+
+ if (ir->condition) {
+ handle_rvalue(&ir->condition);
+ ir->condition->accept(this);
+ }
+
+ return visit_continue;
+}
+
+bool
+optimize_split_arrays(exec_list *instructions, bool linked)
+{
+ ir_array_reference_visitor refs;
+ if (!refs.get_split_list(instructions, linked))
+ return false;
+
+ void *mem_ctx = ralloc_context(NULL);
+
+ /* Replace the decls of the arrays to be split with their split
+ * components.
+ */
+ foreach_iter(exec_list_iterator, iter, refs.variable_list) {
+ variable_entry *entry = (variable_entry *)iter.get();
+ const struct glsl_type *type = entry->var->type;
+ const struct glsl_type *subtype;
+
+ if (type->is_matrix())
+ subtype = glsl_type::get_instance(GLSL_TYPE_FLOAT,
+ type->vector_elements, 1);
+ else
+ subtype = type->fields.array;
+
+ entry->mem_ctx = ralloc_parent(entry->var);
+
+ entry->components = ralloc_array(mem_ctx,
+ ir_variable *,
+ entry->size);
+
+ for (unsigned int i = 0; i < entry->size; i++) {
+ const char *name = ralloc_asprintf(mem_ctx, "%s_%d",
+ entry->var->name, i);
+
+ entry->components[i] =
+ new(entry->mem_ctx) ir_variable(subtype, name, ir_var_temporary);
+ entry->var->insert_before(entry->components[i]);
+ }
+
+ entry->var->remove();
+ }
+
+ ir_array_splitting_visitor split(&refs.variable_list);
+ visit_list_elements(&split, instructions);
+
+ if (debug)
+ _mesa_print_ir(instructions, NULL);
+
+ ralloc_free(mem_ctx);
+
+ return true;
+
+}
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