src/glsl/opt_dead_functions.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 opt_dead_functions.cpp
  26   *
  27   * Eliminates unused functions from the linked program.
  28   */
  29
  30  #include "ir.h"
  31  #include "ir_visitor.h"
  32  #include "ir_expression_flattening.h"
  33  #include "glsl_types.h"
  34
  35  using std::strcmp;
  36
  37  class signature_entry : public exec_node
  38  {
  39  public:
  40     signature_entry(ir_function_signature *sig)
  41     {
  42        this->signature = sig;
  43        this->used = false;
  44     }
  45
  46     ir_function_signature *signature;
  47     bool used;
  48  };
  49
  50  class ir_dead_functions_visitor : public ir_hierarchical_visitor {
  51  public:
  52     ir_dead_functions_visitor()
  53     {
  54        this->mem_ctx = ralloc_context(NULL);
  55     }
  56
  57     ~ir_dead_functions_visitor()
  58     {
  59        ralloc_free(this->mem_ctx);
  60     }
  61
  62     virtual ir_visitor_status visit_enter(ir_function_signature *);
  63     virtual ir_visitor_status visit_enter(ir_call *);
  64
  65     signature_entry *get_signature_entry(ir_function_signature *var);
  66
  67     bool (*predicate)(ir_instruction *ir);
  68
  69     /* List of signature_entry */
  70     exec_list signature_list;
  71     void *mem_ctx;
  72  };
  73
  74
  75  signature_entry *
  76  ir_dead_functions_visitor::get_signature_entry(ir_function_signature *sig)
  77  {
  78     foreach_iter(exec_list_iterator, iter, this->signature_list) {
  79        signature_entry *entry = (signature_entry *)iter.get();
  80        if (entry->signature == sig)
  81           return entry;
  82     }
  83
  84     signature_entry *entry = new(mem_ctx) signature_entry(sig);
  85     this->signature_list.push_tail(entry);
  86     return entry;
  87  }
  88
  89
  90  ir_visitor_status
  91  ir_dead_functions_visitor::visit_enter(ir_function_signature *ir)
  92  {
  93     signature_entry *entry = this->get_signature_entry(ir);
  94
  95     if (strcmp(ir->function_name(), "main") == 0) {
  96        entry->used = true;
  97     }
  98
  99     return visit_continue;
 100  }
 101
 102
 103  ir_visitor_status
 104  ir_dead_functions_visitor::visit_enter(ir_call *ir)
 105  {
 106     signature_entry *entry = this->get_signature_entry(ir->get_callee());
 107
 108     entry->used = true;
 109
 110    return visit_continue;
 111 }
 112
 113 bool
 114 do_dead_functions(exec_list *instructions)
 115 {
 116    ir_dead_functions_visitor v;
 117    bool progress = false;
 118
 119    visit_list_elements(&v, instructions);
 120
 121    /* Now that we've figured out which function signatures are used, remove
 122     * the unused ones, and remove function definitions that have no more
 123     * signatures.
 124     */
 125     foreach_iter(exec_list_iterator, iter, v.signature_list) {
 126       signature_entry *entry = (signature_entry *)iter.get();
 127
 128       if (!entry->used) {
 129          entry->signature->remove();
 130          delete entry->signature;
 131          progress = true;
 132       }
 133       delete(entry);
 134    }
 135
 136    /* We don't just do this above when we nuked a signature because of
 137     * const pointers.
 138     */
 139    foreach_iter(exec_list_iterator, iter, *instructions) {
 140       ir_instruction *ir = (ir_instruction *)iter.get();
 141       ir_function *func = ir->as_function();
 142
 143       if (func && func->signatures.is_empty()) {
 144          /* At this point (post-linking), the symbol table is no
 145           * longer in use, so not removing the function from the
 146           * symbol table should be OK.
 147           */
 148          func->remove();
 149          delete func;
 150          progress = true;
 151       }
 152    }
 153
 154    return progress;
 155 }