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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 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. namespace {
  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.    /* List of signature_entry */
  68.    exec_list signature_list;
  69.    void *mem_ctx;
  70. };
  71.  
  72. } /* unnamed namespace */
  73.  
  74. signature_entry *
  75. ir_dead_functions_visitor::get_signature_entry(ir_function_signature *sig)
  76. {
  77.    foreach_iter(exec_list_iterator, iter, this->signature_list) {
  78.       signature_entry *entry = (signature_entry *)iter.get();
  79.       if (entry->signature == sig)
  80.          return entry;
  81.    }
  82.  
  83.    signature_entry *entry = new(mem_ctx) signature_entry(sig);
  84.    this->signature_list.push_tail(entry);
  85.    return entry;
  86. }
  87.  
  88.  
  89. ir_visitor_status
  90. ir_dead_functions_visitor::visit_enter(ir_function_signature *ir)
  91. {
  92.    signature_entry *entry = this->get_signature_entry(ir);
  93.  
  94.    if (strcmp(ir->function_name(), "main") == 0) {
  95.       entry->used = true;
  96.    }
  97.  
  98.  
  99.  
  100.    return visit_continue;
  101. }
  102.  
  103.  
  104. ir_visitor_status
  105. ir_dead_functions_visitor::visit_enter(ir_call *ir)
  106. {
  107.    signature_entry *entry = this->get_signature_entry(ir->callee);
  108.  
  109.    entry->used = true;
  110.  
  111.    return visit_continue;
  112. }
  113.  
  114. bool
  115. do_dead_functions(exec_list *instructions)
  116. {
  117.    ir_dead_functions_visitor v;
  118.    bool progress = false;
  119.  
  120.    visit_list_elements(&v, instructions);
  121.  
  122.    /* Now that we've figured out which function signatures are used, remove
  123.     * the unused ones, and remove function definitions that have no more
  124.     * signatures.
  125.     */
  126.     foreach_iter(exec_list_iterator, iter, v.signature_list) {
  127.       signature_entry *entry = (signature_entry *)iter.get();
  128.  
  129.       if (!entry->used) {
  130.          entry->signature->remove();
  131.          delete entry->signature;
  132.          progress = true;
  133.       }
  134.       delete(entry);
  135.    }
  136.  
  137.    /* We don't just do this above when we nuked a signature because of
  138.     * const pointers.
  139.     */
  140.    foreach_iter(exec_list_iterator, iter, *instructions) {
  141.       ir_instruction *ir = (ir_instruction *)iter.get();
  142.       ir_function *func = ir->as_function();
  143.  
  144.       if (func && func->signatures.is_empty()) {
  145.          /* At this point (post-linking), the symbol table is no
  146.           * longer in use, so not removing the function from the
  147.           * symbol table should be OK.
  148.           */
  149.          func->remove();
  150.          delete func;
  151.          progress = true;
  152.       }
  153.    }
  154.  
  155.    return progress;
  156. }
  157.