src/glsl/lower_vec_index_to_swizzle.cpp

   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 lower_vec_index_to_swizzle.cpp
  26  *
  27  * Turns constant indexing into vector types to swizzles.  This will
  28  * let other swizzle-aware optimization passes catch these constructs,
  29  * and codegen backends not have to worry about this case.
  30  */
  31
  32 #include "ir.h"
  33 #include "ir_visitor.h"
  34 #include "ir_optimization.h"
  35 #include "glsl_types.h"
  36
  37 /**
  38  * Visitor class for replacing expressions with ir_constant values.
  39  */
  40
  41 class ir_vec_index_to_swizzle_visitor : public ir_hierarchical_visitor {
  42 public:
  43    ir_vec_index_to_swizzle_visitor()
  44    {
  45       progress = false;
  46    }
  47
  48    ir_rvalue *convert_vec_index_to_swizzle(ir_rvalue *val);
  49
  50    virtual ir_visitor_status visit_enter(ir_expression *);
  51    virtual ir_visitor_status visit_enter(ir_swizzle *);
  52    virtual ir_visitor_status visit_enter(ir_assignment *);
  53    virtual ir_visitor_status visit_enter(ir_return *);
  54    virtual ir_visitor_status visit_enter(ir_call *);
  55    virtual ir_visitor_status visit_enter(ir_if *);
  56
  57    bool progress;
  58 };
  59
  60 ir_rvalue *
  61 ir_vec_index_to_swizzle_visitor::convert_vec_index_to_swizzle(ir_rvalue *ir)
  62 {
  63    ir_dereference_array *deref = ir->as_dereference_array();
  64    ir_constant *ir_constant;
  65
  66    if (!deref)
  67       return ir;
  68
  69    if (deref->array->type->is_matrix() || deref->array->type->is_array())
  70       return ir;
  71
  72    assert(deref->array_index->type->base_type == GLSL_TYPE_INT);
  73    ir_constant = deref->array_index->constant_expression_value();
  74    if (!ir_constant)
  75       return ir;
  76
  77    void *ctx = talloc_parent(ir);
  78    this->progress = true;
  79    return new(ctx) ir_swizzle(deref->array,
  80                               ir_constant->value.i[0], 0, 0, 0, 1);
  81 }
  82
  83 ir_visitor_status
  84 ir_vec_index_to_swizzle_visitor::visit_enter(ir_expression *ir)
  85 {
  86    unsigned int i;
  87
  88    for (i = 0; i < ir->get_num_operands(); i++) {
  89       ir->operands[i] = convert_vec_index_to_swizzle(ir->operands[i]);
  90    }
  91
  92    return visit_continue;
  93 }
  94
  95 ir_visitor_status
  96 ir_vec_index_to_swizzle_visitor::visit_enter(ir_swizzle *ir)
  97 {
  98    /* Can't be hit from normal GLSL, since you can't swizzle a scalar (which
  99     * the result of indexing a vector is.  But maybe at some point we'll end up
 100     * using swizzling of scalars for vector construction.
 101     */
 102    ir->val = convert_vec_index_to_swizzle(ir->val);
 103
 104    return visit_continue;
 105 }
 106
 107 ir_visitor_status
 108 ir_vec_index_to_swizzle_visitor::visit_enter(ir_assignment *ir)
 109 {
 110    ir->set_lhs(convert_vec_index_to_swizzle(ir->lhs));
 111    ir->rhs = convert_vec_index_to_swizzle(ir->rhs);
 112
 113    return visit_continue;
 114 }
 115
 116 ir_visitor_status
 117 ir_vec_index_to_swizzle_visitor::visit_enter(ir_call *ir)
 118 {
 119    foreach_iter(exec_list_iterator, iter, *ir) {
 120       ir_rvalue *param = (ir_rvalue *)iter.get();
 121       ir_rvalue *new_param = convert_vec_index_to_swizzle(param);
 122
 123       if (new_param != param) {
 124          param->replace_with(new_param);
 125       }
 126    }
 127
 128    return visit_continue;
 129 }
 130
 131 ir_visitor_status
 132 ir_vec_index_to_swizzle_visitor::visit_enter(ir_return *ir)
 133 {
 134    if (ir->value) {
 135       ir->value = convert_vec_index_to_swizzle(ir->value);
 136    }
 137
 138    return visit_continue;
 139 }
 140
 141 ir_visitor_status
 142 ir_vec_index_to_swizzle_visitor::visit_enter(ir_if *ir)
 143 {
 144    ir->condition = convert_vec_index_to_swizzle(ir->condition);
 145
 146    return visit_continue;
 147 }
 148
 149 bool
 150 do_vec_index_to_swizzle(exec_list *instructions)
 151 {
 152    ir_vec_index_to_swizzle_visitor v;
 153
 154    v.run(instructions);
 155
 156    return v.progress;
 157 }