src/glsl/loop_unroll.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 #include "glsl_types.h"
  25 #include "loop_analysis.h"
  26 #include "ir_hierarchical_visitor.h"
  27
  28 class loop_unroll_visitor : public ir_hierarchical_visitor {
  29 public:
  30    loop_unroll_visitor(loop_state *state)
  31    {
  32       this->state = state;
  33       this->progress = false;
  34    }
  35
  36    virtual ir_visitor_status visit_leave(ir_loop *ir);
  37
  38    loop_state *state;
  39
  40    bool progress;
  41 };
  42
  43
  44 ir_visitor_status
  45 loop_unroll_visitor::visit_leave(ir_loop *ir)
  46 {
  47    loop_variable_state *const ls = this->state->get(ir);
  48
  49    /* If we've entered a loop that hasn't been analyzed, something really,
  50     * really bad has happened.
  51     */
  52    if (ls == NULL) {
  53       assert(ls != NULL);
  54       return visit_continue;
  55    }
  56
  57    /* Don't try to unroll loops where the number of iterations is not known
  58     * at compile-time.
  59     */
  60    if (ls->max_iterations < 0)
  61       return visit_continue;
  62
  63    /* Don't try to unroll loops that have zillions of iterations either.
  64     */
  65    if (ls->max_iterations > 32)
  66       return visit_continue;
  67
  68    if (ls->num_loop_jumps > 0)
  69       return visit_continue;
  70
  71    void *const mem_ctx = talloc_parent(ir);
  72
  73    for (int i = 0; i < ls->max_iterations; i++) {
  74       exec_list copy_list;
  75
  76       copy_list.make_empty();
  77       clone_ir_list(mem_ctx, &copy_list, &ir->body_instructions);
  78
  79       ir->insert_before(&copy_list);
  80    }
  81
  82    /* The loop has been replaced by the unrolled copies.  Remove the original
  83     * loop from the IR sequence.
  84     */
  85    ir->remove();
  86
  87    this->progress = true;
  88    return visit_continue;
  89 }
  90
  91
  92 bool
  93 unroll_loops(exec_list *instructions, loop_state *ls)
  94 {
  95    loop_unroll_visitor v(ls);
  96
  97    v.run(instructions);
  98
  99    return v.progress;
 100 }