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/*
* 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_div_to_mul_rcp.cpp
*
* Breaks an ir_unop_div expression down to op0 * (rcp(op1)).
*
* Many GPUs don't have a divide instruction (945 and 965 included),
* but they do have an RCP instruction to compute an approximate
* reciprocal. By breaking the operation down, constant reciprocals
* can get constant folded.
*/
#include "ir.h"
#include "glsl_types.h"
class ir_div_to_mul_rcp_visitor : public ir_hierarchical_visitor {
public:
ir_div_to_mul_rcp_visitor()
{
this->made_progress = false;
}
ir_visitor_status visit_leave(ir_expression *);
bool made_progress;
};
bool
do_div_to_mul_rcp(exec_list *instructions)
{
ir_div_to_mul_rcp_visitor v;
visit_list_elements(&v, instructions);
return v.made_progress;
}
ir_visitor_status
ir_div_to_mul_rcp_visitor::visit_leave(ir_expression *ir)
{
if (ir->operation != ir_binop_div)
return visit_continue;
if (ir->operands[1]->type->base_type != GLSL_TYPE_INT &&
ir->operands[1]->type->base_type != GLSL_TYPE_UINT) {
/* New expression for the 1.0 / op1 */
ir_rvalue *expr;
expr = new(ir) ir_expression(ir_unop_rcp,
ir->operands[1]->type,
ir->operands[1],
NULL);
/* op0 / op1 -> op0 * (1.0 / op1) */
ir->operation = ir_binop_mul;
ir->operands[1] = expr;
} else {
/* Be careful with integer division -- we need to do it as a
* float and re-truncate, since rcp(n > 1) of an integer would
* just be 0.
*/
ir_rvalue *op0, *op1;
const struct glsl_type *vec_type;
vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,
ir->operands[1]->type->vector_elements,
ir->operands[1]->type->matrix_columns);
if (ir->operands[1]->type->base_type == GLSL_TYPE_INT)
op1 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[1], NULL);
else
op1 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[1], NULL);
op1 = new(ir) ir_expression(ir_unop_rcp, op1->type, op1, NULL);
vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,
ir->operands[0]->type->vector_elements,
ir->operands[0]->type->matrix_columns);
if (ir->operands[0]->type->base_type == GLSL_TYPE_INT)
op0 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[0], NULL);
else
op0 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[0], NULL);
op0 = new(ir) ir_expression(ir_binop_mul, vec_type, op0, op1);
ir->operation = ir_unop_f2i;
ir->operands[0] = op0;
ir->operands[1] = NULL;
}
this->made_progress = true;
return visit_continue;
}
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