src/glsl/lower_offset_array.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
  24 /**
  25  * \file lower_offset_array.cpp
  26  *
  27  * IR lower pass to decompose ir_texture ir_tg4 with an array of offsets
  28  * into four ir_tg4s with a single ivec2 offset, select the .w component of each,
  29  * and return those four values packed into a gvec4.
  30  *
  31  * \author Chris Forbes <chrisf@ijw.co.nz>
  32  */
  33
  34 #include "compiler/glsl_types.h"
  35 #include "ir.h"
  36 #include "ir_builder.h"
  37 #include "ir_optimization.h"
  38 #include "ir_rvalue_visitor.h"
  39
  40 using namespace ir_builder;
  41
  42 class lower_offset_array_visitor : public ir_rvalue_visitor {
  43 public:
  44    lower_offset_array_visitor()
  45    {
  46       progress = false;
  47    }
  48
  49    void handle_rvalue(ir_rvalue **rv);
  50
  51    bool progress;
  52 };
  53
  54 void
  55 lower_offset_array_visitor::handle_rvalue(ir_rvalue **rv)
  56 {
  57    if (*rv == NULL || (*rv)->ir_type != ir_type_texture)
  58       return;
  59
  60    ir_texture *ir = (ir_texture *) *rv;
  61    if (ir->op != ir_tg4 || !ir->offset || !ir->offset->type->is_array())
  62       return;
  63
  64    void *mem_ctx = ralloc_parent(ir);
  65
  66    ir_variable *var =
  67       new (mem_ctx) ir_variable(ir->type, "result", ir_var_temporary);
  68    base_ir->insert_before(var);
  69
  70    for (int i = 0; i < 4; i++) {
  71       ir_texture *tex = ir->clone(mem_ctx, NULL);
  72       tex->offset = new (mem_ctx) ir_dereference_array(tex->offset,
  73             new (mem_ctx) ir_constant(i));
  74
  75       base_ir->insert_before(assign(var, swizzle_w(tex), 1 << i));
  76    }
  77
  78    *rv = new (mem_ctx) ir_dereference_variable(var);
  79
  80    progress = true;
  81 }
  82
  83 bool
  84 lower_offset_arrays(exec_list *instructions)
  85 {
  86    lower_offset_array_visitor v;
  87
  88    visit_list_elements(&v, instructions);
  89
  90    return v.progress;
  91 }