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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 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 = hieralloc_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 }
    158