0,0 → 1,350 |
/* |
* 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" |
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namespace { |
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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; |
}; |
|
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class kill_entry : public exec_node |
{ |
public: |
kill_entry(ir_variable *var) |
{ |
assert(var); |
this->var = var; |
} |
|
ir_variable *var; |
}; |
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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 *); |
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void add_copy(ir_assignment *ir); |
void kill(ir_variable *ir); |
void handle_if_block(exec_list *instructions); |
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/** 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; |
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void *mem_ctx; |
}; |
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} /* unnamed namespace */ |
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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; |
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this->acp = new(mem_ctx) exec_list; |
this->kills = new(mem_ctx) exec_list; |
this->killed_all = false; |
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visit_list_elements(this, &ir->body); |
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this->kills = orig_kills; |
this->acp = orig_acp; |
this->killed_all = orig_killed_all; |
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return visit_continue_with_parent; |
} |
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ir_visitor_status |
ir_copy_propagation_visitor::visit_leave(ir_assignment *ir) |
{ |
kill(ir->lhs->variable_referenced()); |
|
add_copy(ir); |
|
return visit_continue; |
} |
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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_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; |
} |
} |
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return visit_continue; |
} |
|
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ir_visitor_status |
ir_copy_propagation_visitor::visit_enter(ir_call *ir) |
{ |
/* Do copy propagation on call parameters, but skip any out params */ |
exec_list_iterator sig_param_iter = ir->callee->parameters.iterator(); |
foreach_iter(exec_list_iterator, iter, ir->actual_parameters) { |
ir_variable *sig_param = (ir_variable *)sig_param_iter.get(); |
ir_instruction *ir = (ir_instruction *)iter.get(); |
if (sig_param->mode != ir_var_function_out |
&& sig_param->mode != ir_var_function_inout) { |
ir->accept(this); |
} |
sig_param_iter.next(); |
} |
|
/* 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; |
} |
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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; |
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/* Populate the initial acp with a copy of the original */ |
foreach_iter(exec_list_iterator, iter, *orig_acp) { |
acp_entry *a = (acp_entry *)iter.get(); |
this->acp->push_tail(new(this->mem_ctx) acp_entry(a->lhs, a->rhs)); |
} |
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visit_list_elements(this, instructions); |
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if (this->killed_all) { |
orig_acp->make_empty(); |
} |
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exec_list *new_kills = this->kills; |
this->kills = orig_kills; |
this->acp = orig_acp; |
this->killed_all = this->killed_all || orig_killed_all; |
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foreach_iter(exec_list_iterator, iter, *new_kills) { |
kill_entry *k = (kill_entry *)iter.get(); |
kill(k->var); |
} |
} |
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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); |
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/* handle_if_block() already descended into the children. */ |
return visit_continue_with_parent; |
} |
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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(); |
} |
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exec_list *new_kills = this->kills; |
this->kills = orig_kills; |
this->acp = orig_acp; |
this->killed_all = this->killed_all || orig_killed_all; |
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foreach_iter(exec_list_iterator, iter, *new_kills) { |
kill_entry *k = (kill_entry *)iter.get(); |
kill(k->var); |
} |
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/* already descended into the children. */ |
return visit_continue_with_parent; |
} |
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void |
ir_copy_propagation_visitor::kill(ir_variable *var) |
{ |
assert(var != NULL); |
|
/* Remove any entries currently in the ACP for this kill. */ |
foreach_iter(exec_list_iterator, iter, *acp) { |
acp_entry *entry = (acp_entry *)iter.get(); |
|
if (entry->lhs == var || entry->rhs == var) { |
entry->remove(); |
} |
} |
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/* Add the LHS variable to the list of killed variables in this block. |
*/ |
this->kills->push_tail(new(this->mem_ctx) kill_entry(var)); |
} |
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/** |
* 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; |
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ir_variable *lhs_var = ir->whole_variable_written(); |
ir_variable *rhs_var = ir->rhs->whole_variable_referenced(); |
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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->mem_ctx) acp_entry(lhs_var, rhs_var); |
this->acp->push_tail(entry); |
} |
} |
} |
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/** |
* 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; |
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visit_list_elements(&v, instructions); |
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return v.progress; |
} |