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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 "compiler/glsl_types.h"
     36 
     37 namespace {
     38 
     39 class ir_noop_swizzle_visitor : public ir_rvalue_visitor {
     40 public:
     41    ir_noop_swizzle_visitor()
     42    {
     43       this->progress = false;
     44    }
     45 
     46    void handle_rvalue(ir_rvalue **rvalue);
     47    bool progress;
     48 };
     49 
     50 } /* unnamed namespace */
     51 
     52 void
     53 ir_noop_swizzle_visitor::handle_rvalue(ir_rvalue **rvalue)
     54 {
     55    if (!*rvalue)
     56       return;
     57 
     58    ir_swizzle *swiz = (*rvalue)->as_swizzle();
     59    if (!swiz || swiz->type != swiz->val->type)
     60       return;
     61 
     62    int elems = swiz->val->type->vector_elements;
     63    if (swiz->mask.x != 0)
     64       return;
     65    if (elems >= 2 && swiz->mask.y != 1)
     66       return;
     67    if (elems >= 3 && swiz->mask.z != 2)
     68       return;
     69    if (elems >= 4 && swiz->mask.w != 3)
     70       return;
     71 
     72    this->progress = true;
     73    *rvalue = swiz->val;
     74 }
     75 
     76 bool
     77 do_noop_swizzle(exec_list *instructions)
     78 {
     79    ir_noop_swizzle_visitor v;
     80    visit_list_elements(&v, instructions);
     81 
     82    return v.progress;
     83 }
     84