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      1 /*
      2  * Copyright  2010 Intel Corporation
      3  *
      4  * Permission is hereby granted, free of charge, to any person obtaining a
      5  * copy of this software and associated documentation files (the "Software"),
      6  * to deal in the Software without restriction, including without limitation
      7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      8  * and/or sell copies of the Software, and to permit persons to whom the
      9  * Software is furnished to do so, subject to the following conditions:
     10  *
     11  * The above copyright notice and this permission notice (including the next
     12  * paragraph) shall be included in all copies or substantial portions of the
     13  * Software.
     14  *
     15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     21  * DEALINGS IN THE SOFTWARE.
     22  */
     23 
     24 /**
     25  * \file ir_mod_to_floor.cpp
     26  *
     27  * Breaks an ir_unop_mod expression down to (op1 * fract(op0 / op1))
     28  *
     29  * Many GPUs don't have a MOD instruction (945 and 965 included), and
     30  * if we have to break it down like this anyway, it gives an
     31  * opportunity to do things like constant fold the (1.0 / op1) easily.
     32  */
     33 
     34 #include "ir.h"
     35 
     36 class ir_mod_to_fract_visitor : public ir_hierarchical_visitor {
     37 public:
     38    ir_mod_to_fract_visitor()
     39    {
     40       this->made_progress = false;
     41    }
     42 
     43    ir_visitor_status visit_leave(ir_expression *);
     44 
     45    bool made_progress;
     46 };
     47 
     48 bool
     49 do_mod_to_fract(exec_list *instructions)
     50 {
     51    ir_mod_to_fract_visitor v;
     52 
     53    visit_list_elements(&v, instructions);
     54    return v.made_progress;
     55 }
     56 
     57 ir_visitor_status
     58 ir_mod_to_fract_visitor::visit_leave(ir_expression *ir)
     59 {
     60    if (ir->operation != ir_binop_mod)
     61       return visit_continue;
     62 
     63    ir_variable *temp = new(ir) ir_variable(ir->operands[1]->type, "mod_b",
     64 					   ir_var_temporary);
     65    this->base_ir->insert_before(temp);
     66 
     67    ir_assignment *assign;
     68    ir_rvalue *expr;
     69 
     70    assign = new(ir) ir_assignment(new(ir) ir_dereference_variable(temp),
     71 				  ir->operands[1], NULL);
     72    this->base_ir->insert_before(assign);
     73 
     74    expr = new(ir) ir_expression(ir_binop_div,
     75 				ir->operands[0]->type,
     76 				ir->operands[0],
     77 				new(ir) ir_dereference_variable(temp));
     78 
     79    expr = new(ir) ir_expression(ir_unop_fract,
     80 				ir->operands[0]->type,
     81 				expr,
     82 				NULL);
     83 
     84    ir->operation = ir_binop_mul;
     85    ir->operands[0] = new(ir) ir_dereference_variable(temp);
     86    ir->operands[1] = expr;
     87    this->made_progress = true;
     88 
     89    return visit_continue;
     90 }
     91