0,0 → 1,198 |
/* |
* 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 lower_discard.cpp |
* |
* This pass moves discards out of if-statements. |
* |
* Case 1: The "then" branch contains a conditional discard: |
* --------------------------------------------------------- |
* |
* if (cond1) { |
* s1; |
* discard cond2; |
* s2; |
* } else { |
* s3; |
* } |
* |
* becomes: |
* |
* temp = false; |
* if (cond1) { |
* s1; |
* temp = cond2; |
* s2; |
* } else { |
* s3; |
* } |
* discard temp; |
* |
* Case 2: The "else" branch contains a conditional discard: |
* --------------------------------------------------------- |
* |
* if (cond1) { |
* s1; |
* } else { |
* s2; |
* discard cond2; |
* s3; |
* } |
* |
* becomes: |
* |
* temp = false; |
* if (cond1) { |
* s1; |
* } else { |
* s2; |
* temp = cond2; |
* s3; |
* } |
* discard temp; |
* |
* Case 3: Both branches contain a conditional discard: |
* ---------------------------------------------------- |
* |
* if (cond1) { |
* s1; |
* discard cond2; |
* s2; |
* } else { |
* s3; |
* discard cond3; |
* s4; |
* } |
* |
* becomes: |
* |
* temp = false; |
* if (cond1) { |
* s1; |
* temp = cond2; |
* s2; |
* } else { |
* s3; |
* temp = cond3; |
* s4; |
* } |
* discard temp; |
* |
* If there are multiple conditional discards, we need only deal with one of |
* them. Repeatedly applying this pass will take care of the others. |
* |
* Unconditional discards are treated as having a condition of "true". |
*/ |
|
#include "glsl_types.h" |
#include "ir.h" |
|
class lower_discard_visitor : public ir_hierarchical_visitor { |
public: |
lower_discard_visitor() |
{ |
this->progress = false; |
} |
|
ir_visitor_status visit_leave(ir_if *); |
|
bool progress; |
}; |
|
|
bool |
lower_discard(exec_list *instructions) |
{ |
lower_discard_visitor v; |
|
visit_list_elements(&v, instructions); |
|
return v.progress; |
} |
|
|
static ir_discard * |
find_discard(exec_list &instructions) |
{ |
foreach_list(n, &instructions) { |
ir_discard *ir = ((ir_instruction *) n)->as_discard(); |
if (ir != NULL) |
return ir; |
} |
return NULL; |
} |
|
|
static void |
replace_discard(void *mem_ctx, ir_variable *var, ir_discard *ir) |
{ |
ir_rvalue *condition = ir->condition; |
|
/* For unconditional discards, use "true" as the condition. */ |
if (condition == NULL) |
condition = new(mem_ctx) ir_constant(true); |
|
ir_assignment *assignment = |
new(mem_ctx) ir_assignment(new(mem_ctx) ir_dereference_variable(var), |
condition, NULL); |
|
ir->replace_with(assignment); |
} |
|
|
ir_visitor_status |
lower_discard_visitor::visit_leave(ir_if *ir) |
{ |
ir_discard *then_discard = find_discard(ir->then_instructions); |
ir_discard *else_discard = find_discard(ir->else_instructions); |
|
if (then_discard == NULL && else_discard == NULL) |
return visit_continue; |
|
void *mem_ctx = ralloc_parent(ir); |
|
ir_variable *temp = new(mem_ctx) ir_variable(glsl_type::bool_type, |
"discard_cond_temp", |
ir_var_temporary); |
ir_assignment *temp_initializer = |
new(mem_ctx) ir_assignment(new(mem_ctx) ir_dereference_variable(temp), |
new(mem_ctx) ir_constant(false), NULL); |
|
ir->insert_before(temp); |
ir->insert_before(temp_initializer); |
|
if (then_discard != NULL) |
replace_discard(mem_ctx, temp, then_discard); |
|
if (else_discard != NULL) |
replace_discard(mem_ctx, temp, else_discard); |
|
ir_discard *discard = then_discard != NULL ? then_discard : else_discard; |
discard->condition = new(mem_ctx) ir_dereference_variable(temp); |
ir->insert_after(discard); |
|
this->progress = true; |
|
return visit_continue; |
} |