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 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 }