--- /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_tree_grafting.cpp
+ *
+ * Takes assignments to variables that are dereferenced only once and
+ * pastes the RHS expression into where the variable is dereferenced.
+ *
+ * In the process of various operations like function inlining and
+ * tertiary op handling, we'll end up with our expression trees having
+ * been chopped up into a series of assignments of short expressions
+ * to temps. Other passes like ir_algebraic.cpp would prefer to see
+ * the deepest expression trees they can to try to optimize them.
+ *
+ * This is a lot like copy propagaton. In comparison, copy
+ * propagation only acts on plain copies, not arbitrary expressions on
+ * the RHS. Generally, we wouldn't want to go pasting some
+ * complicated expression everywhere it got used, though, so we don't
+ * handle expressions in that pass.
+ *
+ * The hard part is making sure we don't move an expression across
+ * some other assignments that would change the value of the
+ * expression. So we split this into two passes: First, find the
+ * variables in our scope which are written to once and read once, and
+ * then go through basic blocks seeing if we find an opportunity to
+ * move those expressions safely.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_variable_refcount.h"
+#include "ir_basic_block.h"
+#include "ir_optimization.h"
+#include "glsl_types.h"
+
+static bool debug = false;
+
+class ir_tree_grafting_visitor : public ir_hierarchical_visitor {
+public:
+ ir_tree_grafting_visitor(ir_assignment *graft_assign,
+ ir_variable *graft_var)
+ {
+ this->progress = false;
+ this->graft_assign = graft_assign;
+ this->graft_var = graft_var;
+ }
+
+ virtual ir_visitor_status visit_leave(class ir_assignment *);
+ virtual ir_visitor_status visit_enter(class ir_call *);
+ virtual ir_visitor_status visit_enter(class ir_expression *);
+ virtual ir_visitor_status visit_enter(class ir_function *);
+ virtual ir_visitor_status visit_enter(class ir_function_signature *);
+ virtual ir_visitor_status visit_enter(class ir_if *);
+ virtual ir_visitor_status visit_enter(class ir_loop *);
+ virtual ir_visitor_status visit_enter(class ir_swizzle *);
+ virtual ir_visitor_status visit_enter(class ir_texture *);
+
+ bool do_graft(ir_rvalue **rvalue);
+
+ bool progress;
+ ir_variable *graft_var;
+ ir_assignment *graft_assign;
+};
+
+struct find_deref_info {
+ ir_variable *var;
+ bool found;
+};
+
+void
+dereferences_variable_callback(ir_instruction *ir, void *data)
+{
+ struct find_deref_info *info = (struct find_deref_info *)data;
+
+ if (ir == info->var)
+ info->found = true;
+}
+
+static bool
+dereferences_variable(ir_instruction *ir, ir_variable *var)
+{
+ struct find_deref_info info;
+
+ info.var = var;
+ info.found = false;
+
+ visit_tree(ir, dereferences_variable_callback, &info);
+
+ return info.found;
+}
+
+bool
+ir_tree_grafting_visitor::do_graft(ir_rvalue **rvalue)
+{
+ if (!*rvalue)
+ return false;
+
+ ir_dereference_variable *deref = (*rvalue)->as_dereference_variable();
+
+ if (!deref || deref->var != this->graft_var)
+ return false;
+
+ if (debug) {
+ printf("GRAFTING:\n");
+ this->graft_assign->rhs->print();
+ printf("\n");
+ printf("TO:\n");
+ (*rvalue)->print();
+ printf("\n");
+ }
+
+ this->graft_assign->remove();
+ *rvalue = this->graft_assign->rhs;
+
+ this->progress = true;
+ return true;
+}
+
+ir_visitor_status
+ir_tree_grafting_visitor::visit_enter(ir_loop *ir)
+{
+ (void)ir;
+ /* Do not traverse into the body of the loop since that is a
+ * different basic block.
+ */
+ return visit_stop;
+}
+
+ir_visitor_status
+ir_tree_grafting_visitor::visit_leave(ir_assignment *ir)
+{
+ if (do_graft(&ir->rhs) ||
+ do_graft(&ir->condition))
+ return visit_stop;
+
+ /* If this assignment updates a variable used in the assignment
+ * we're trying to graft, then we're done.
+ */
+ if (dereferences_variable(this->graft_assign->rhs,
+ ir->lhs->variable_referenced())) {
+ if (debug) {
+ printf("graft killed by: ");
+ ir->print();
+ printf("\n");
+ }
+ return visit_stop;
+ }
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_tree_grafting_visitor::visit_enter(ir_function *ir)
+{
+ (void) ir;
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+ir_tree_grafting_visitor::visit_enter(ir_function_signature *ir)
+{
+ (void)ir;
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+ir_tree_grafting_visitor::visit_enter(ir_call *ir)
+{
+ /* Reminder: iterating ir_call iterates its parameters. */
+ foreach_iter(exec_list_iterator, iter, *ir) {
+ ir_rvalue *ir = (ir_rvalue *)iter.get();
+ ir_rvalue *new_ir = ir;
+
+ if (do_graft(&new_ir)) {
+ ir->replace_with(new_ir);
+ return visit_stop;
+ }
+ }
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_tree_grafting_visitor::visit_enter(ir_expression *ir)
+{
+ for (unsigned int i = 0; i < ir->get_num_operands(); i++) {
+ if (do_graft(&ir->operands[i]))
+ return visit_stop;
+ }
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_tree_grafting_visitor::visit_enter(ir_if *ir)
+{
+ if (do_graft(&ir->condition))
+ return visit_stop;
+
+ /* Do not traverse into the body of the if-statement since that is a
+ * different basic block.
+ */
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+ir_tree_grafting_visitor::visit_enter(ir_swizzle *ir)
+{
+ if (do_graft(&ir->val))
+ return visit_stop;
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_tree_grafting_visitor::visit_enter(ir_texture *ir)
+{
+ if (do_graft(&ir->coordinate) ||
+ do_graft(&ir->projector) ||
+ do_graft(&ir->shadow_comparitor))
+ return visit_stop;
+
+ switch (ir->op) {
+ case ir_tex:
+ break;
+ case ir_txb:
+ if (do_graft(&ir->lod_info.bias))
+ return visit_stop;
+ break;
+ case ir_txf:
+ case ir_txl:
+ if (do_graft(&ir->lod_info.lod))
+ return visit_stop;
+ break;
+ case ir_txd:
+ if (do_graft(&ir->lod_info.grad.dPdx) ||
+ do_graft(&ir->lod_info.grad.dPdy))
+ return visit_stop;
+ break;
+ }
+
+ return visit_continue;
+}
+
+struct tree_grafting_info {
+ ir_variable_refcount_visitor *refs;
+ bool progress;
+};
+
+static bool
+try_tree_grafting(ir_assignment *start,
+ ir_variable *lhs_var,
+ ir_instruction *bb_last)
+{
+ ir_tree_grafting_visitor v(start, lhs_var);
+
+ if (debug) {
+ printf("trying to graft: ");
+ lhs_var->print();
+ printf("\n");
+ }
+
+ for (ir_instruction *ir = (ir_instruction *)start->next;
+ ir != bb_last->next;
+ ir = (ir_instruction *)ir->next) {
+
+ if (debug) {
+ printf("- ");
+ ir->print();
+ printf("\n");
+ }
+
+ ir_visitor_status s = ir->accept(&v);
+ if (s == visit_stop)
+ return v.progress;
+ }
+
+ return false;
+}
+
+static void
+tree_grafting_basic_block(ir_instruction *bb_first,
+ ir_instruction *bb_last,
+ void *data)
+{
+ struct tree_grafting_info *info = (struct tree_grafting_info *)data;
+ ir_instruction *ir, *next;
+
+ for (ir = bb_first, next = (ir_instruction *)ir->next;
+ ir != bb_last->next;
+ ir = next, next = (ir_instruction *)ir->next) {
+ ir_assignment *assign = ir->as_assignment();
+
+ if (!assign)
+ continue;
+
+ ir_variable *lhs_var = assign->lhs->whole_variable_referenced();
+ if (!lhs_var)
+ continue;
+
+ struct variable_entry *entry = info->refs->get_variable_entry(lhs_var);
+
+ if (!entry->declaration ||
+ entry->assigned_count != 1 ||
+ entry->referenced_count != 2)
+ continue;
+
+ assert(assign == entry->assign);
+
+ /* Found a possibly graftable assignment. Now, walk through the
+ * rest of the BB seeing if the deref is here, and if nothing interfered with
+ * pasting its expression's values in between.
+ */
+ info->progress |= try_tree_grafting(assign, lhs_var, bb_last);
+ }
+}
+
+/**
+ * Does a copy propagation pass on the code present in the instruction stream.
+ */
+bool
+do_tree_grafting(exec_list *instructions)
+{
+ ir_variable_refcount_visitor refs;
+ struct tree_grafting_info info;
+
+ info.progress = false;
+ info.refs = &refs;
+
+ visit_list_elements(info.refs, instructions);
+
+ call_for_basic_blocks(instructions, tree_grafting_basic_block, &info);
+
+ return info.progress;
+}
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