diff options
Diffstat (limited to 'src/glsl/ir_copy_propagation.cpp')
| -rw-r--r-- | src/glsl/ir_copy_propagation.cpp | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/src/glsl/ir_copy_propagation.cpp b/src/glsl/ir_copy_propagation.cpp new file mode 100644 index 0000000000..46ef6679d9 --- /dev/null +++ b/src/glsl/ir_copy_propagation.cpp @@ -0,0 +1,256 @@ +/* + * 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_copy_propagation.cpp + * + * Moves usage of recently-copied variables to the previous copy of + * the variable within basic blocks. + * + * 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" + +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 ir_copy_propagation_visitor : public ir_hierarchical_visitor { +public: + ir_copy_propagation_visitor(exec_list *acp) + { + progress = false; + in_lhs = false; + this->acp = acp; + } + + 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_enter(class ir_assignment *); + virtual ir_visitor_status visit_enter(class ir_call *); + virtual ir_visitor_status visit_enter(class ir_if *); + + /** List of acp_entry */ + exec_list *acp; + bool progress; + + /** Currently in the LHS of an assignment? */ + bool in_lhs; +}; + + +ir_visitor_status +ir_copy_propagation_visitor::visit_enter(ir_loop *ir) +{ + (void)ir; + return visit_continue_with_parent; +} + +ir_visitor_status +ir_copy_propagation_visitor::visit_enter(ir_function_signature *ir) +{ + (void)ir; + return visit_continue_with_parent; +} + +ir_visitor_status +ir_copy_propagation_visitor::visit_enter(ir_assignment *ir) +{ + (void) ir; + this->in_lhs = true; + return visit_continue; +} + +ir_visitor_status +ir_copy_propagation_visitor::visit_enter(ir_function *ir) +{ + (void) ir; + return visit_continue_with_parent; +} + +/** + * 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) +{ + /* Ignores the LHS. Don't want to rewrite the LHS to point at some + * other storage! + */ + if (this->in_lhs) { + this->in_lhs = false; + return visit_continue; + } + + ir_variable *var = ir->variable_referenced(); + + foreach_iter(exec_list_iterator, iter, *this->acp) { + acp_entry *entry = (acp_entry *)iter.get(); + + 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) +{ + (void)ir; + + /* Note, if we were to do copy propagation to parameters of calls, we'd + * have to be careful about out params. + */ + return visit_continue_with_parent; +} + + +ir_visitor_status +ir_copy_propagation_visitor::visit_enter(ir_if *ir) +{ + ir->condition->accept(this); + + /* Do not traverse into the body of the if-statement since that is a + * different basic block. + */ + return visit_continue_with_parent; +} + +static bool +propagate_copies(ir_instruction *ir, exec_list *acp) +{ + ir_copy_propagation_visitor v(acp); + + ir->accept(&v); + + return v.progress; +} + +static void +kill_invalidated_copies(ir_assignment *ir, exec_list *acp) +{ + ir_variable *var = ir->lhs->variable_referenced(); + assert(var != NULL); + + foreach_iter(exec_list_iterator, iter, *acp) { + acp_entry *entry = (acp_entry *)iter.get(); + + if (entry->lhs == var || entry->rhs == var) { + entry->remove(); + } + } +} + +/** + * Adds an entry to the available copy list if it's a plain assignment + * of a variable to a variable. + */ +static void +add_copy(ir_assignment *ir, exec_list *acp) +{ + void *ctx = talloc_parent(ir); + acp_entry *entry; + + if (ir->condition) { + ir_constant *condition = ir->condition->as_constant(); + if (!condition || !condition->value.b[0]) + return; + } + + ir_variable *lhs_var = ir->lhs->whole_variable_referenced(); + ir_variable *rhs_var = ir->rhs->whole_variable_referenced(); + + if ((lhs_var != NULL) && (rhs_var != NULL)) { + entry = new(ctx) acp_entry(lhs_var, rhs_var); + acp->push_tail(entry); + } +} + +static void +copy_propagation_basic_block(ir_instruction *first, + ir_instruction *last, + void *data) +{ + ir_instruction *ir; + /* List of avaialble_copy */ + exec_list acp; + bool *out_progress = (bool *)data; + bool progress = false; + + for (ir = first;; ir = (ir_instruction *)ir->next) { + ir_assignment *ir_assign = ir->as_assignment(); + + progress = propagate_copies(ir, &acp) || progress; + + if (ir_assign) { + kill_invalidated_copies(ir_assign, &acp); + + add_copy(ir_assign, &acp); + } + if (ir == last) + break; + } + *out_progress = progress; +} + +/** + * Does a copy propagation pass on the code present in the instruction stream. + */ +bool +do_copy_propagation(exec_list *instructions) +{ + bool progress = false; + + call_for_basic_blocks(instructions, copy_propagation_basic_block, &progress); + + return progress; +} |