| /* |
| * 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. |
| */ |
| |
| #include "glsl_types.h" |
| #include "loop_analysis.h" |
| #include "ir_hierarchical_visitor.h" |
| |
| class loop_unroll_visitor : public ir_hierarchical_visitor { |
| public: |
| loop_unroll_visitor(loop_state *state, unsigned max_iterations) |
| { |
| this->state = state; |
| this->progress = false; |
| this->max_iterations = max_iterations; |
| } |
| |
| virtual ir_visitor_status visit_leave(ir_loop *ir); |
| |
| loop_state *state; |
| |
| bool progress; |
| unsigned max_iterations; |
| }; |
| |
| |
| static bool |
| is_break(ir_instruction *ir) |
| { |
| return ir != NULL && ir->ir_type == ir_type_loop_jump |
| && ((ir_loop_jump *) ir)->is_break(); |
| } |
| |
| |
| ir_visitor_status |
| loop_unroll_visitor::visit_leave(ir_loop *ir) |
| { |
| loop_variable_state *const ls = this->state->get(ir); |
| int iterations; |
| |
| /* If we've entered a loop that hasn't been analyzed, something really, |
| * really bad has happened. |
| */ |
| if (ls == NULL) { |
| assert(ls != NULL); |
| return visit_continue; |
| } |
| |
| iterations = ls->max_iterations; |
| |
| /* Don't try to unroll loops where the number of iterations is not known |
| * at compile-time. |
| */ |
| if (iterations < 0) |
| return visit_continue; |
| |
| /* Don't try to unroll loops that have zillions of iterations either. |
| */ |
| if (iterations > (int) max_iterations) |
| return visit_continue; |
| |
| if (ls->num_loop_jumps > 1) |
| return visit_continue; |
| else if (ls->num_loop_jumps) { |
| ir_instruction *last_ir = (ir_instruction *) ir->body_instructions.get_tail(); |
| assert(last_ir != NULL); |
| |
| if (is_break(last_ir)) { |
| /* If the only loop-jump is a break at the end of the loop, the loop |
| * will execute exactly once. Remove the break, set the iteration |
| * count, and fall through to the normal unroller. |
| */ |
| last_ir->remove(); |
| iterations = 1; |
| |
| this->progress = true; |
| } else { |
| ir_if *ir_if = NULL; |
| ir_instruction *break_ir = NULL; |
| bool continue_from_then_branch = false; |
| |
| foreach_list(node, &ir->body_instructions) { |
| /* recognize loops in the form produced by ir_lower_jumps */ |
| ir_instruction *cur_ir = (ir_instruction *) node; |
| |
| ir_if = cur_ir->as_if(); |
| if (ir_if != NULL) { |
| /* Determine which if-statement branch, if any, ends with a |
| * break. The branch that did *not* have the break will get a |
| * temporary continue inserted in each iteration of the loop |
| * unroll. |
| * |
| * Note that since ls->num_loop_jumps is <= 1, it is impossible |
| * for both branches to end with a break. |
| */ |
| ir_instruction *ir_if_last = |
| (ir_instruction *) ir_if->then_instructions.get_tail(); |
| |
| if (is_break(ir_if_last)) { |
| continue_from_then_branch = false; |
| break_ir = ir_if_last; |
| break; |
| } else { |
| ir_if_last = |
| (ir_instruction *) ir_if->else_instructions.get_tail(); |
| |
| if (is_break(ir_if_last)) { |
| break_ir = ir_if_last; |
| continue_from_then_branch = true; |
| break; |
| } |
| } |
| } |
| } |
| |
| if (break_ir == NULL) |
| return visit_continue; |
| |
| /* move instructions after then if in the continue branch */ |
| while (!ir_if->get_next()->is_tail_sentinel()) { |
| ir_instruction *move_ir = (ir_instruction *) ir_if->get_next(); |
| |
| move_ir->remove(); |
| if (continue_from_then_branch) |
| ir_if->then_instructions.push_tail(move_ir); |
| else |
| ir_if->else_instructions.push_tail(move_ir); |
| } |
| |
| /* Remove the break from the if-statement. |
| */ |
| break_ir->remove(); |
| |
| void *const mem_ctx = hieralloc_parent(ir); |
| ir_instruction *ir_to_replace = ir; |
| |
| for (int i = 0; i < iterations; i++) { |
| exec_list copy_list; |
| |
| copy_list.make_empty(); |
| clone_ir_list(mem_ctx, ©_list, &ir->body_instructions); |
| |
| ir_if = ((ir_instruction *) copy_list.get_tail())->as_if(); |
| assert(ir_if != NULL); |
| |
| ir_to_replace->insert_before(©_list); |
| ir_to_replace->remove(); |
| |
| /* placeholder that will be removed in the next iteration */ |
| ir_to_replace = |
| new(mem_ctx) ir_loop_jump(ir_loop_jump::jump_continue); |
| |
| exec_list *const list = (continue_from_then_branch) |
| ? &ir_if->then_instructions : &ir_if->else_instructions; |
| |
| list->push_tail(ir_to_replace); |
| } |
| |
| ir_to_replace->remove(); |
| |
| this->progress = true; |
| return visit_continue; |
| } |
| } |
| |
| void *const mem_ctx = hieralloc_parent(ir); |
| |
| for (int i = 0; i < iterations; i++) { |
| exec_list copy_list; |
| |
| copy_list.make_empty(); |
| clone_ir_list(mem_ctx, ©_list, &ir->body_instructions); |
| |
| ir->insert_before(©_list); |
| } |
| |
| /* The loop has been replaced by the unrolled copies. Remove the original |
| * loop from the IR sequence. |
| */ |
| ir->remove(); |
| |
| this->progress = true; |
| return visit_continue; |
| } |
| |
| |
| bool |
| unroll_loops(exec_list *instructions, loop_state *ls, unsigned max_iterations) |
| { |
| loop_unroll_visitor v(ls, max_iterations); |
| |
| v.run(instructions); |
| |
| return v.progress; |
| } |