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