0,0 → 1,437 |
/* |
* Copyright © 2010 Intel Corporation |
* |
* Permission is hereby granted, free of charge, to any person obtaining a |
* constant of this software and associated documentation files (the "Software"), |
* to deal in the Software without restriction, including without limitation |
* the rights to use, constant, 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 constantright 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 CONSTANTRIGHT 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_constant_propagation.cpp |
* |
* Tracks assignments of constants to channels of variables, and |
* usage of those constant channels with direct usage of the constants. |
* |
* This can lead to constant folding and algebraic optimizations in |
* those later expressions, while causing no increase in instruction |
* count (due to constants being generally free to load from a |
* constant push buffer or as instruction immediate values) and |
* possibly reducing register pressure. |
*/ |
|
#include "ir.h" |
#include "ir_visitor.h" |
#include "ir_rvalue_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 *var, unsigned write_mask, ir_constant *constant) |
{ |
assert(var); |
assert(constant); |
this->var = var; |
this->write_mask = write_mask; |
this->constant = constant; |
} |
|
ir_variable *var; |
ir_constant *constant; |
unsigned write_mask; |
}; |
|
|
class kill_entry : public exec_node |
{ |
public: |
kill_entry(ir_variable *var, unsigned write_mask) |
{ |
assert(var); |
this->var = var; |
this->write_mask = write_mask; |
} |
|
ir_variable *var; |
unsigned write_mask; |
}; |
|
class ir_constant_propagation_visitor : public ir_rvalue_visitor { |
public: |
ir_constant_propagation_visitor() |
{ |
progress = false; |
mem_ctx = ralloc_context(0); |
this->acp = new(mem_ctx) exec_list; |
this->kills = new(mem_ctx) exec_list; |
} |
~ir_constant_propagation_visitor() |
{ |
ralloc_free(mem_ctx); |
} |
|
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_constant(ir_assignment *ir); |
void kill(ir_variable *ir, unsigned write_mask); |
void handle_if_block(exec_list *instructions); |
void handle_rvalue(ir_rvalue **rvalue); |
|
/** List of acp_entry: The available constants to propagate */ |
exec_list *acp; |
|
/** |
* List of kill_entry: The masks of variables whose values were |
* killed in this block. |
*/ |
exec_list *kills; |
|
bool progress; |
|
bool killed_all; |
|
void *mem_ctx; |
}; |
|
|
void |
ir_constant_propagation_visitor::handle_rvalue(ir_rvalue **rvalue) |
{ |
if (this->in_assignee || !*rvalue) |
return; |
|
const glsl_type *type = (*rvalue)->type; |
if (!type->is_scalar() && !type->is_vector()) |
return; |
|
ir_swizzle *swiz = NULL; |
ir_dereference_variable *deref = (*rvalue)->as_dereference_variable(); |
if (!deref) { |
swiz = (*rvalue)->as_swizzle(); |
if (!swiz) |
return; |
|
deref = swiz->val->as_dereference_variable(); |
if (!deref) |
return; |
} |
|
ir_constant_data data; |
memset(&data, 0, sizeof(data)); |
|
for (unsigned int i = 0; i < type->components(); i++) { |
int channel; |
acp_entry *found = NULL; |
|
if (swiz) { |
switch (i) { |
case 0: channel = swiz->mask.x; break; |
case 1: channel = swiz->mask.y; break; |
case 2: channel = swiz->mask.z; break; |
case 3: channel = swiz->mask.w; break; |
default: assert(!"shouldn't be reached"); channel = 0; break; |
} |
} else { |
channel = i; |
} |
|
foreach_iter(exec_list_iterator, iter, *this->acp) { |
acp_entry *entry = (acp_entry *)iter.get(); |
if (entry->var == deref->var && entry->write_mask & (1 << channel)) { |
found = entry; |
break; |
} |
} |
|
if (!found) |
return; |
|
int rhs_channel = 0; |
for (int j = 0; j < 4; j++) { |
if (j == channel) |
break; |
if (found->write_mask & (1 << j)) |
rhs_channel++; |
} |
|
switch (type->base_type) { |
case GLSL_TYPE_FLOAT: |
data.f[i] = found->constant->value.f[rhs_channel]; |
break; |
case GLSL_TYPE_INT: |
data.i[i] = found->constant->value.i[rhs_channel]; |
break; |
case GLSL_TYPE_UINT: |
data.u[i] = found->constant->value.u[rhs_channel]; |
break; |
case GLSL_TYPE_BOOL: |
data.b[i] = found->constant->value.b[rhs_channel]; |
break; |
default: |
assert(!"not reached"); |
break; |
} |
} |
|
*rvalue = new(ralloc_parent(deref)) ir_constant(type, &data); |
this->progress = true; |
} |
|
ir_visitor_status |
ir_constant_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); |
|
this->kills = orig_kills; |
this->acp = orig_acp; |
this->killed_all = orig_killed_all; |
|
return visit_continue_with_parent; |
} |
|
ir_visitor_status |
ir_constant_propagation_visitor::visit_leave(ir_assignment *ir) |
{ |
if (this->in_assignee) |
return visit_continue; |
|
kill(ir->lhs->variable_referenced(), ir->write_mask); |
|
add_constant(ir); |
|
return visit_continue; |
} |
|
ir_visitor_status |
ir_constant_propagation_visitor::visit_enter(ir_function *ir) |
{ |
(void) ir; |
return visit_continue; |
} |
|
ir_visitor_status |
ir_constant_propagation_visitor::visit_enter(ir_call *ir) |
{ |
/* Do constant propagation on call parameters, but skip any out params */ |
exec_list_iterator sig_param_iter = ir->get_callee()->parameters.iterator(); |
foreach_iter(exec_list_iterator, iter, ir->actual_parameters) { |
ir_variable *sig_param = (ir_variable *)sig_param_iter.get(); |
ir_rvalue *param = (ir_rvalue *)iter.get(); |
if (sig_param->mode != ir_var_out && sig_param->mode != ir_var_inout) { |
ir_rvalue *new_param = param; |
handle_rvalue(&new_param); |
if (new_param != param) |
param->replace_with(new_param); |
else |
param->accept(this); |
} |
sig_param_iter.next(); |
} |
|
/* Since we're unlinked, we don't (necssarily) 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_constant_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 constant 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->var, a->write_mask, |
a->constant)); |
} |
|
visit_list_elements(this, instructions); |
|
if (this->killed_all) { |
orig_acp->make_empty(); |
} |
|
exec_list *new_kills = this->kills; |
this->kills = orig_kills; |
this->acp = orig_acp; |
this->killed_all = this->killed_all || orig_killed_all; |
|
foreach_iter(exec_list_iterator, iter, *new_kills) { |
kill_entry *k = (kill_entry *)iter.get(); |
kill(k->var, k->write_mask); |
} |
} |
|
ir_visitor_status |
ir_constant_propagation_visitor::visit_enter(ir_if *ir) |
{ |
ir->condition->accept(this); |
handle_rvalue(&ir->condition); |
|
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_constant_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; |
this->acp = orig_acp; |
this->killed_all = this->killed_all || orig_killed_all; |
|
foreach_iter(exec_list_iterator, iter, *new_kills) { |
kill_entry *k = (kill_entry *)iter.get(); |
kill(k->var, k->write_mask); |
} |
|
/* already descended into the children. */ |
return visit_continue_with_parent; |
} |
|
void |
ir_constant_propagation_visitor::kill(ir_variable *var, unsigned write_mask) |
{ |
assert(var != NULL); |
|
/* We don't track non-vectors. */ |
if (!var->type->is_vector() && !var->type->is_scalar()) |
return; |
|
/* Remove any entries currently in the ACP for this kill. */ |
foreach_iter(exec_list_iterator, iter, *this->acp) { |
acp_entry *entry = (acp_entry *)iter.get(); |
|
if (entry->var == var) { |
entry->write_mask &= ~write_mask; |
if (entry->write_mask == 0) |
entry->remove(); |
} |
} |
|
/* Add this writemask of the variable to the list of killed |
* variables in this block. |
*/ |
foreach_iter(exec_list_iterator, iter, *this->kills) { |
kill_entry *entry = (kill_entry *)iter.get(); |
|
if (entry->var == var) { |
entry->write_mask |= write_mask; |
return; |
} |
} |
/* Not already in the list. Make new entry. */ |
this->kills->push_tail(new(this->mem_ctx) kill_entry(var, write_mask)); |
} |
|
/** |
* Adds an entry to the available constant list if it's a plain assignment |
* of a variable to a variable. |
*/ |
void |
ir_constant_propagation_visitor::add_constant(ir_assignment *ir) |
{ |
acp_entry *entry; |
|
if (ir->condition) { |
ir_constant *condition = ir->condition->as_constant(); |
if (!condition || !condition->value.b[0]) |
return; |
} |
|
if (!ir->write_mask) |
return; |
|
ir_dereference_variable *deref = ir->lhs->as_dereference_variable(); |
ir_constant *constant = ir->rhs->as_constant(); |
|
if (!deref || !constant) |
return; |
|
/* Only do constant propagation on vectors. Constant matrices, |
* arrays, or structures would require more work elsewhere. |
*/ |
if (!deref->var->type->is_vector() && !deref->var->type->is_scalar()) |
return; |
|
entry = new(this->mem_ctx) acp_entry(deref->var, ir->write_mask, constant); |
this->acp->push_tail(entry); |
} |
|
/** |
* Does a constant propagation pass on the code present in the instruction stream. |
*/ |
bool |
do_constant_propagation(exec_list *instructions) |
{ |
ir_constant_propagation_visitor v; |
|
visit_list_elements(&v, instructions); |
|
return v.progress; |
} |