| /* |
| * 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_copy_propagation.cpp |
| * |
| * Moves usage of recently-copied variables to the previous copy of |
| * the variable. |
| * |
| * This should reduce the number of MOV instructions in the generated |
| * programs unless copy propagation is also done on the LIR, and may |
| * help anyway by triggering other optimizations that live in the HIR. |
| */ |
| |
| #include "ir.h" |
| #include "ir_visitor.h" |
| #include "ir_basic_block.h" |
| #include "ir_optimization.h" |
| #include "glsl_types.h" |
| |
| namespace { |
| |
| class acp_entry : public exec_node |
| { |
| public: |
| acp_entry(ir_variable *lhs, ir_variable *rhs) |
| { |
| assert(lhs); |
| assert(rhs); |
| this->lhs = lhs; |
| this->rhs = rhs; |
| } |
| |
| ir_variable *lhs; |
| ir_variable *rhs; |
| }; |
| |
| |
| class kill_entry : public exec_node |
| { |
| public: |
| kill_entry(ir_variable *var) |
| { |
| assert(var); |
| this->var = var; |
| } |
| |
| ir_variable *var; |
| }; |
| |
| class ir_copy_propagation_visitor : public ir_hierarchical_visitor { |
| public: |
| ir_copy_propagation_visitor() |
| { |
| progress = false; |
| mem_ctx = ralloc_context(0); |
| this->acp = new(mem_ctx) exec_list; |
| this->kills = new(mem_ctx) exec_list; |
| } |
| ~ir_copy_propagation_visitor() |
| { |
| ralloc_free(mem_ctx); |
| } |
| |
| virtual ir_visitor_status visit(class ir_dereference_variable *); |
| virtual ir_visitor_status visit_enter(class ir_loop *); |
| virtual ir_visitor_status visit_enter(class ir_function_signature *); |
| virtual ir_visitor_status visit_enter(class ir_function *); |
| 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_if *); |
| |
| void add_copy(ir_assignment *ir); |
| void kill(ir_variable *ir); |
| void handle_if_block(exec_list *instructions); |
| |
| /** List of acp_entry: The available copies to propagate */ |
| exec_list *acp; |
| /** |
| * List of kill_entry: The variables whose values were killed in this |
| * block. |
| */ |
| exec_list *kills; |
| |
| bool progress; |
| |
| bool killed_all; |
| |
| void *mem_ctx; |
| }; |
| |
| } /* unnamed namespace */ |
| |
| ir_visitor_status |
| ir_copy_propagation_visitor::visit_enter(ir_function_signature *ir) |
| { |
| /* Treat entry into a function signature as a completely separate |
| * block. Any instructions at global scope will be shuffled into |
| * main() at link time, so they're irrelevant to us. |
| */ |
| exec_list *orig_acp = this->acp; |
| exec_list *orig_kills = this->kills; |
| bool orig_killed_all = this->killed_all; |
| |
| this->acp = new(mem_ctx) exec_list; |
| this->kills = new(mem_ctx) exec_list; |
| this->killed_all = false; |
| |
| visit_list_elements(this, &ir->body); |
| |
| ralloc_free(this->acp); |
| ralloc_free(this->kills); |
| |
| this->kills = orig_kills; |
| this->acp = orig_acp; |
| this->killed_all = orig_killed_all; |
| |
| return visit_continue_with_parent; |
| } |
| |
| ir_visitor_status |
| ir_copy_propagation_visitor::visit_leave(ir_assignment *ir) |
| { |
| kill(ir->lhs->variable_referenced()); |
| |
| add_copy(ir); |
| |
| return visit_continue; |
| } |
| |
| ir_visitor_status |
| ir_copy_propagation_visitor::visit_enter(ir_function *ir) |
| { |
| (void) ir; |
| return visit_continue; |
| } |
| |
| /** |
| * Replaces dereferences of ACP RHS variables with ACP LHS variables. |
| * |
| * This is where the actual copy propagation occurs. Note that the |
| * rewriting of ir_dereference means that the ir_dereference instance |
| * must not be shared by multiple IR operations! |
| */ |
| ir_visitor_status |
| ir_copy_propagation_visitor::visit(ir_dereference_variable *ir) |
| { |
| if (this->in_assignee) |
| return visit_continue; |
| |
| ir_variable *var = ir->var; |
| |
| foreach_in_list(acp_entry, entry, this->acp) { |
| if (var == entry->lhs) { |
| ir->var = entry->rhs; |
| this->progress = true; |
| break; |
| } |
| } |
| |
| return visit_continue; |
| } |
| |
| |
| ir_visitor_status |
| ir_copy_propagation_visitor::visit_enter(ir_call *ir) |
| { |
| /* Do copy propagation on call parameters, but skip any out params */ |
| foreach_two_lists(formal_node, &ir->callee->parameters, |
| actual_node, &ir->actual_parameters) { |
| ir_variable *sig_param = (ir_variable *) formal_node; |
| ir_rvalue *ir = (ir_rvalue *) actual_node; |
| if (sig_param->data.mode != ir_var_function_out |
| && sig_param->data.mode != ir_var_function_inout) { |
| ir->accept(this); |
| } |
| } |
| |
| /* Since we're unlinked, we don't (necessarily) know the side effects of |
| * this call. So kill all copies. |
| */ |
| acp->make_empty(); |
| this->killed_all = true; |
| |
| return visit_continue_with_parent; |
| } |
| |
| void |
| ir_copy_propagation_visitor::handle_if_block(exec_list *instructions) |
| { |
| exec_list *orig_acp = this->acp; |
| exec_list *orig_kills = this->kills; |
| bool orig_killed_all = this->killed_all; |
| |
| this->acp = new(mem_ctx) exec_list; |
| this->kills = new(mem_ctx) exec_list; |
| this->killed_all = false; |
| |
| /* Populate the initial acp with a copy of the original */ |
| foreach_in_list(acp_entry, a, orig_acp) { |
| this->acp->push_tail(new(this->acp) acp_entry(a->lhs, a->rhs)); |
| } |
| |
| visit_list_elements(this, instructions); |
| |
| if (this->killed_all) { |
| orig_acp->make_empty(); |
| } |
| |
| exec_list *new_kills = this->kills; |
| this->kills = orig_kills; |
| ralloc_free(this->acp); |
| this->acp = orig_acp; |
| this->killed_all = this->killed_all || orig_killed_all; |
| |
| foreach_in_list(kill_entry, k, new_kills) { |
| kill(k->var); |
| } |
| |
| ralloc_free(new_kills); |
| } |
| |
| ir_visitor_status |
| ir_copy_propagation_visitor::visit_enter(ir_if *ir) |
| { |
| ir->condition->accept(this); |
| |
| handle_if_block(&ir->then_instructions); |
| handle_if_block(&ir->else_instructions); |
| |
| /* handle_if_block() already descended into the children. */ |
| return visit_continue_with_parent; |
| } |
| |
| ir_visitor_status |
| ir_copy_propagation_visitor::visit_enter(ir_loop *ir) |
| { |
| exec_list *orig_acp = this->acp; |
| exec_list *orig_kills = this->kills; |
| bool orig_killed_all = this->killed_all; |
| |
| /* FINISHME: For now, the initial acp for loops is totally empty. |
| * We could go through once, then go through again with the acp |
| * cloned minus the killed entries after the first run through. |
| */ |
| this->acp = new(mem_ctx) exec_list; |
| this->kills = new(mem_ctx) exec_list; |
| this->killed_all = false; |
| |
| visit_list_elements(this, &ir->body_instructions); |
| |
| if (this->killed_all) { |
| orig_acp->make_empty(); |
| } |
| |
| exec_list *new_kills = this->kills; |
| this->kills = orig_kills; |
| ralloc_free(this->acp); |
| this->acp = orig_acp; |
| this->killed_all = this->killed_all || orig_killed_all; |
| |
| foreach_in_list(kill_entry, k, new_kills) { |
| kill(k->var); |
| } |
| |
| ralloc_free(new_kills); |
| |
| /* already descended into the children. */ |
| return visit_continue_with_parent; |
| } |
| |
| void |
| ir_copy_propagation_visitor::kill(ir_variable *var) |
| { |
| assert(var != NULL); |
| |
| /* Remove any entries currently in the ACP for this kill. */ |
| foreach_in_list_safe(acp_entry, entry, acp) { |
| if (entry->lhs == var || entry->rhs == var) { |
| entry->remove(); |
| } |
| } |
| |
| /* Add the LHS variable to the list of killed variables in this block. |
| */ |
| this->kills->push_tail(new(this->kills) kill_entry(var)); |
| } |
| |
| /** |
| * Adds an entry to the available copy list if it's a plain assignment |
| * of a variable to a variable. |
| */ |
| void |
| ir_copy_propagation_visitor::add_copy(ir_assignment *ir) |
| { |
| acp_entry *entry; |
| |
| if (ir->condition) |
| return; |
| |
| ir_variable *lhs_var = ir->whole_variable_written(); |
| ir_variable *rhs_var = ir->rhs->whole_variable_referenced(); |
| |
| if ((lhs_var != NULL) && (rhs_var != NULL)) { |
| if (lhs_var == rhs_var) { |
| /* This is a dumb assignment, but we've conveniently noticed |
| * it here. Removing it now would mess up the loop iteration |
| * calling us. Just flag it to not execute, and someone else |
| * will clean up the mess. |
| */ |
| ir->condition = new(ralloc_parent(ir)) ir_constant(false); |
| this->progress = true; |
| } else { |
| entry = new(this->acp) acp_entry(lhs_var, rhs_var); |
| this->acp->push_tail(entry); |
| } |
| } |
| } |
| |
| /** |
| * Does a copy propagation pass on the code present in the instruction stream. |
| */ |
| bool |
| do_copy_propagation(exec_list *instructions) |
| { |
| ir_copy_propagation_visitor v; |
| |
| visit_list_elements(&v, instructions); |
| |
| return v.progress; |
| } |