+++ /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 opt_redundant_jumps.cpp
- * Remove certain types of redundant jumps
- */
-
-#include "ir.h"
-
-namespace {
-
-class redundant_jumps_visitor : public ir_hierarchical_visitor {
-public:
- redundant_jumps_visitor()
- {
- this->progress = false;
- }
-
- virtual ir_visitor_status visit_leave(ir_if *);
- virtual ir_visitor_status visit_leave(ir_loop *);
- virtual ir_visitor_status visit_enter(ir_assignment *);
-
- bool progress;
-};
-
-} /* unnamed namespace */
-
-/* We only care about the top level instructions, so don't descend
- * into expressions.
- */
-ir_visitor_status
-redundant_jumps_visitor::visit_enter(ir_assignment *)
-{
- return visit_continue_with_parent;
-}
-
-ir_visitor_status
-redundant_jumps_visitor::visit_leave(ir_if *ir)
-{
- /* If the last instruction in both branches is a 'break' or a 'continue',
- * pull it out of the branches and insert it after the if-statment. Note
- * that both must be the same type (either 'break' or 'continue').
- */
- ir_instruction *const last_then =
- (ir_instruction *) ir->then_instructions.get_tail();
- ir_instruction *const last_else =
- (ir_instruction *) ir->else_instructions.get_tail();
-
- if ((last_then == NULL) || (last_else == NULL))
- return visit_continue;
-
- if ((last_then->ir_type != ir_type_loop_jump)
- || (last_else->ir_type != ir_type_loop_jump))
- return visit_continue;
-
- ir_loop_jump *const then_jump = (ir_loop_jump *) last_then;
- ir_loop_jump *const else_jump = (ir_loop_jump *) last_else;
-
- if (then_jump->mode != else_jump->mode)
- return visit_continue;
-
- then_jump->remove();
- else_jump->remove();
- this->progress = true;
-
- ir->insert_after(then_jump);
-
- /* If both branchs of the if-statement are now empty, remove the
- * if-statement.
- */
- if (ir->then_instructions.is_empty() && ir->else_instructions.is_empty())
- ir->remove();
-
- return visit_continue;
-}
-
-
-ir_visitor_status
-redundant_jumps_visitor::visit_leave(ir_loop *ir)
-{
- /* If the last instruction of a loop body is a 'continue', remove it.
- */
- ir_instruction *const last =
- (ir_instruction *) ir->body_instructions.get_tail();
-
- if (last && (last->ir_type == ir_type_loop_jump)
- && (((ir_loop_jump *) last)->mode == ir_loop_jump::jump_continue)) {
- last->remove();
- this->progress = true;
- }
-
- return visit_continue;
-}
-
-
-bool
-optimize_redundant_jumps(exec_list *instructions)
-{
- redundant_jumps_visitor v;
-
- v.run(instructions);
- return v.progress;
-}