src/compiler/glsl/lower_vector_insert.cpp

   1 /*
   2  * Copyright © 2013 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 #include "ir.h"
  24 #include "ir_builder.h"
  25 #include "ir_rvalue_visitor.h"
  26 #include "ir_optimization.h"
  27
  28 using namespace ir_builder;
  29
  30 namespace {
  31
  32 class vector_insert_visitor : public ir_rvalue_visitor {
  33 public:
  34    vector_insert_visitor(bool lower_nonconstant_index)
  35       : progress(false), lower_nonconstant_index(lower_nonconstant_index),
  36         remove_assignment(false)
  37    {
  38       factory.instructions = &factory_instructions;
  39    }
  40
  41    virtual ~vector_insert_visitor()
  42    {
  43       assert(factory_instructions.is_empty());
  44    }
  45
  46    virtual void handle_rvalue(ir_rvalue **rv);
  47    virtual ir_visitor_status visit_leave(ir_assignment *expr);
  48
  49    ir_factory factory;
  50    exec_list factory_instructions;
  51    bool progress;
  52    bool lower_nonconstant_index;
  53    bool remove_assignment;
  54 };
  55
  56 } /* anonymous namespace */
  57
  58 void
  59 vector_insert_visitor::handle_rvalue(ir_rvalue **rv)
  60 {
  61    if (*rv == NULL || (*rv)->ir_type != ir_type_expression)
  62       return;
  63
  64    ir_expression *const expr = (ir_expression *) *rv;
  65
  66    if (likely(expr->operation != ir_triop_vector_insert))
  67       return;
  68
  69    factory.mem_ctx = ralloc_parent(expr);
  70
  71    ir_constant *const idx =
  72       expr->operands[2]->constant_expression_value(factory.mem_ctx);
  73    if (idx != NULL) {
  74       unsigned index = idx->value.u[0];
  75
  76       if (index >= expr->operands[0]->type->vector_elements) {
  77          /* Section 5.11 (Out-of-Bounds Accesses) of the GLSL 4.60 spec says:
  78           *
  79           *  In the subsections described above for array, vector, matrix and
  80           *  structure accesses, any out-of-bounds access produced undefined
  81           *  behavior.... Out-of-bounds writes may be discarded or overwrite
  82           *  other variables of the active program.
  83           */
  84          this->remove_assignment = true;
  85          this->progress = true;
  86          return;
  87       }
  88
  89       /* Replace (vector_insert (vec) (scalar) (index)) with a dereference of
  90        * a new temporary.  The new temporary gets assigned as
  91        *
  92        *     t = vec
  93        *     t.mask = scalar
  94        *
  95        * where mask is the component selected by index.
  96        */
  97       ir_variable *const temp =
  98          factory.make_temp(expr->operands[0]->type, "vec_tmp");
  99
 100       const int mask = 1 << idx->value.i[0];
 101
 102       factory.emit(assign(temp, expr->operands[0]));
 103       factory.emit(assign(temp, expr->operands[1], mask));
 104
 105       this->progress = true;
 106       *rv = new(factory.mem_ctx) ir_dereference_variable(temp);
 107    } else if (this->lower_nonconstant_index) {
 108       /* Replace (vector_insert (vec) (scalar) (index)) with a dereference of
 109        * a new temporary.  The new temporary gets assigned as
 110        *
 111        *     t = vec
 112        *     if (index == 0)
 113        *         t.x = scalar
 114        *     if (index == 1)
 115        *         t.y = scalar
 116        *     if (index == 2)
 117        *         t.z = scalar
 118        *     if (index == 3)
 119        *         t.w = scalar
 120        */
 121       ir_variable *const temp =
 122          factory.make_temp(expr->operands[0]->type, "vec_tmp");
 123
 124       ir_variable *const src_temp =
 125          factory.make_temp(expr->operands[1]->type, "src_temp");
 126
 127       factory.emit(assign(temp, expr->operands[0]));
 128       factory.emit(assign(src_temp, expr->operands[1]));
 129
 130       assert(expr->operands[2]->type == glsl_type::int_type ||
 131              expr->operands[2]->type == glsl_type::uint_type);
 132
 133       for (unsigned i = 0; i < expr->type->vector_elements; i++) {
 134          ir_constant *const cmp_index =
 135             ir_constant::zero(factory.mem_ctx, expr->operands[2]->type);
 136          cmp_index->value.u[0] = i;
 137
 138          ir_variable *const cmp_result =
 139             factory.make_temp(glsl_type::bool_type, "index_condition");
 140
 141          factory.emit(assign(cmp_result,
 142                              equal(expr->operands[2]->clone(factory.mem_ctx,
 143                                                             NULL),
 144                                    cmp_index)));
 145
 146          factory.emit(if_tree(cmp_result,
 147                               assign(temp, src_temp, WRITEMASK_X << i)));
 148       }
 149
 150       this->progress = true;
 151       *rv = new(factory.mem_ctx) ir_dereference_variable(temp);
 152    }
 153
 154    base_ir->insert_before(factory.instructions);
 155 }
 156
 157 ir_visitor_status
 158 vector_insert_visitor::visit_leave(ir_assignment *ir)
 159 {
 160    ir_rvalue_visitor::visit_leave(ir);
 161
 162    if (this->remove_assignment) {
 163       ir->remove();
 164       this->remove_assignment = false;
 165    }
 166
 167    return visit_continue;
 168 }
 169
 170 bool
 171 lower_vector_insert(exec_list *instructions, bool lower_nonconstant_index)
 172 {
 173    vector_insert_visitor v(lower_nonconstant_index);
 174
 175    visit_list_elements(&v, instructions);
 176
 177    return v.progress;
 178 }