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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 opt_noop_swizzle.cpp
     26  *
     27  * If a swizzle doesn't change the order or count of components, then
     28  * remove the swizzle so that other optimization passes see the value
     29  * behind it.
     30  */
     31 
     32 #include "ir.h"
     33 #include "ir_visitor.h"
     34 #include "ir_rvalue_visitor.h"
     35 #include "ir_print_visitor.h"
     36 #include "glsl_types.h"
     37 
     38 class ir_noop_swizzle_visitor : public ir_rvalue_visitor {
     39 public:
     40    ir_noop_swizzle_visitor()
     41    {
     42       this->progress = false;
     43    }
     44 
     45    void handle_rvalue(ir_rvalue **rvalue);
     46    bool progress;
     47 };
     48 
     49 void
     50 ir_noop_swizzle_visitor::handle_rvalue(ir_rvalue **rvalue)
     51 {
     52    if (!*rvalue)
     53       return;
     54 
     55    ir_swizzle *swiz = (*rvalue)->as_swizzle();
     56    if (!swiz || swiz->type != swiz->val->type)
     57       return;
     58 
     59    int elems = swiz->val->type->vector_elements;
     60    if (swiz->mask.x != 0)
     61       return;
     62    if (elems >= 2 && swiz->mask.y != 1)
     63       return;
     64    if (elems >= 3 && swiz->mask.z != 2)
     65       return;
     66    if (elems >= 4 && swiz->mask.w != 3)
     67       return;
     68 
     69    this->progress = true;
     70    *rvalue = swiz->val;
     71 }
     72 
     73 bool
     74 do_noop_swizzle(exec_list *instructions)
     75 {
     76    ir_noop_swizzle_visitor v;
     77    visit_list_elements(&v, instructions);
     78 
     79    return v.progress;
     80 }
     81