diff options
Diffstat (limited to 'src/compiler/glsl/loop_unroll.cpp')
| -rw-r--r-- | src/compiler/glsl/loop_unroll.cpp | 172 |
1 files changed, 134 insertions, 38 deletions
diff --git a/src/compiler/glsl/loop_unroll.cpp b/src/compiler/glsl/loop_unroll.cpp index 358cbf10af4..6e06a30fb91 100644 --- a/src/compiler/glsl/loop_unroll.cpp +++ b/src/compiler/glsl/loop_unroll.cpp @@ -42,7 +42,9 @@ public: virtual ir_visitor_status visit_leave(ir_loop *ir); void simple_unroll(ir_loop *ir, int iterations); void complex_unroll(ir_loop *ir, int iterations, - bool continue_from_then_branch); + bool continue_from_then_branch, + bool limiting_term_first, + bool lt_continue_from_then_branch); void splice_post_if_instructions(ir_if *ir_if, exec_list *splice_dest); loop_state *state; @@ -176,6 +178,51 @@ void loop_unroll_visitor::simple_unroll(ir_loop *ir, int iterations) { void *const mem_ctx = ralloc_parent(ir); + loop_variable_state *const ls = this->state->get(ir); + + ir_instruction *first_ir = + (ir_instruction *) ir->body_instructions.get_head(); + + if (!first_ir) { + /* The loop is empty remove it and return */ + ir->remove(); + return; + } + + ir_if *limit_if = NULL; + bool exit_branch_has_instructions = false; + if (ls->limiting_terminator) { + limit_if = ls->limiting_terminator->ir; + ir_instruction *ir_if_last = (ir_instruction *) + limit_if->then_instructions.get_tail(); + + if (is_break(ir_if_last)) { + if (ir_if_last != limit_if->then_instructions.get_head()) + exit_branch_has_instructions = true; + + splice_post_if_instructions(limit_if, &limit_if->else_instructions); + ir_if_last->remove(); + } else { + ir_if_last = (ir_instruction *) + limit_if->else_instructions.get_tail(); + assert(is_break(ir_if_last)); + + if (ir_if_last != limit_if->else_instructions.get_head()) + exit_branch_has_instructions = true; + + splice_post_if_instructions(limit_if, &limit_if->then_instructions); + ir_if_last->remove(); + } + } + + /* Because 'iterations' is the number of times we pass over the *entire* + * loop body before hitting the first break, we need to bump the number of + * iterations if the limiting terminator is not the first instruction in + * the loop, or it the exit branch contains instructions. This ensures we + * execute any instructions before the terminator or in its exit branch. + */ + if (limit_if != first_ir->as_if() || exit_branch_has_instructions) + iterations++; for (int i = 0; i < iterations; i++) { exec_list copy_list; @@ -227,11 +274,22 @@ loop_unroll_visitor::simple_unroll(ir_loop *ir, int iterations) */ void loop_unroll_visitor::complex_unroll(ir_loop *ir, int iterations, - bool continue_from_then_branch) + bool second_term_then_continue, + bool extra_iteration_required, + bool first_term_then_continue) { void *const mem_ctx = ralloc_parent(ir); ir_instruction *ir_to_replace = ir; + /* Because 'iterations' is the number of times we pass over the *entire* + * loop body before hitting the first break, we need to bump the number of + * iterations if the limiting terminator is not the first instruction in + * the loop, or it the exit branch contains instructions. This ensures we + * execute any instructions before the terminator or in its exit branch. + */ + if (extra_iteration_required) + iterations++; + for (int i = 0; i < iterations; i++) { exec_list copy_list; @@ -241,6 +299,10 @@ loop_unroll_visitor::complex_unroll(ir_loop *ir, int iterations, ir_if *ir_if = ((ir_instruction *) copy_list.get_tail())->as_if(); assert(ir_if != NULL); + exec_list *const first_list = first_term_then_continue + ? &ir_if->then_instructions : &ir_if->else_instructions; + ir_if = ((ir_instruction *) first_list->get_tail())->as_if(); + ir_to_replace->insert_before(©_list); ir_to_replace->remove(); @@ -248,10 +310,10 @@ loop_unroll_visitor::complex_unroll(ir_loop *ir, int iterations, ir_to_replace = new(mem_ctx) ir_loop_jump(ir_loop_jump::jump_continue); - exec_list *const list = (continue_from_then_branch) + exec_list *const second_term_continue_list = second_term_then_continue ? &ir_if->then_instructions : &ir_if->else_instructions; - list->push_tail(ir_to_replace); + second_term_continue_list->push_tail(ir_to_replace); } ir_to_replace->remove(); @@ -293,6 +355,21 @@ loop_unroll_visitor::splice_post_if_instructions(ir_if *ir_if, } } +static bool +exit_branch_has_instructions(ir_if *term_if, bool lt_then_continue) +{ + if (lt_then_continue) { + if (term_if->else_instructions.get_head() == + term_if->else_instructions.get_tail()) + return false; + } else { + if (term_if->then_instructions.get_head() == + term_if->then_instructions.get_tail()) + return false; + } + + return true; +} ir_visitor_status loop_unroll_visitor::visit_leave(ir_loop *ir) @@ -417,7 +494,6 @@ loop_unroll_visitor::visit_leave(ir_loop *ir) return visit_continue; if (predicted_num_loop_jumps == 0) { - ls->limiting_terminator->ir->remove(); simple_unroll(ir, iterations); return visit_continue; } @@ -432,51 +508,71 @@ loop_unroll_visitor::visit_leave(ir_loop *ir) */ last_ir->remove(); - ls->limiting_terminator->ir->remove(); simple_unroll(ir, 1); return visit_continue; } - /* recognize loops in the form produced by ir_lower_jumps */ - foreach_in_list(ir_instruction, cur_ir, &ir->body_instructions) { - /* Skip the limiting terminator, since it will go away when we - * unroll. - */ - if (cur_ir == ls->limiting_terminator->ir) - continue; + /* Complex unrolling can only handle two terminators. One with an unknown + * iteration count and one with a known iteration count. We have already + * made sure we have a known iteration count above and removed any + * unreachable terminators with a known count. Here we make sure there + * isn't any additional unknown terminators, or any other jumps nested + * inside futher ifs. + */ + if (ls->num_loop_jumps != 2) + return visit_continue; - ir_if *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(); + ir_instruction *first_ir = + (ir_instruction *) ir->body_instructions.get_head(); + unsigned term_count = 0; + bool first_term_then_continue = false; + foreach_in_list(loop_terminator, t, &ls->terminators) { + assert(term_count < 2); + + ir_if *ir_if = t->ir->as_if(); + assert(ir_if != NULL); + + ir_instruction *ir_if_last = + (ir_instruction *) ir_if->then_instructions.get_tail(); + + if (is_break(ir_if_last)) { + splice_post_if_instructions(ir_if, &ir_if->else_instructions); + ir_if_last->remove(); + if (term_count == 1) { + bool ebi = + exit_branch_has_instructions(ls->limiting_terminator->ir, + first_term_then_continue); + complex_unroll(ir, iterations, false, + first_ir->as_if() != ls->limiting_terminator->ir || + ebi, + first_term_then_continue); + return visit_continue; + } + } else { + ir_if_last = + (ir_instruction *) ir_if->else_instructions.get_tail(); + + assert(is_break(ir_if_last)); if (is_break(ir_if_last)) { - ls->limiting_terminator->ir->remove(); - splice_post_if_instructions(ir_if, &ir_if->else_instructions); + splice_post_if_instructions(ir_if, &ir_if->then_instructions); ir_if_last->remove(); - complex_unroll(ir, iterations, false); - return visit_continue; - } else { - ir_if_last = - (ir_instruction *) ir_if->else_instructions.get_tail(); - - if (is_break(ir_if_last)) { - ls->limiting_terminator->ir->remove(); - splice_post_if_instructions(ir_if, &ir_if->then_instructions); - ir_if_last->remove(); - complex_unroll(ir, iterations, true); + if (term_count == 1) { + bool ebi = + exit_branch_has_instructions(ls->limiting_terminator->ir, + first_term_then_continue); + complex_unroll(ir, iterations, true, + first_ir->as_if() != ls->limiting_terminator->ir || + ebi, + first_term_then_continue); return visit_continue; + } else { + first_term_then_continue = true; } } } + + term_count++; } /* Did not find the break statement. It must be in a complex if-nesting, |