workbench/libs/mesa/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 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 = ralloc_context(NULL);
  53       this->seen_another_function_signature = false;
  54    }
  55
  56    ~ir_dead_functions_visitor()
  57    {
  58       ralloc_free(this->mem_ctx);
  59    }
  60
  61    virtual ir_visitor_status visit_enter(ir_function_signature *);
  62    virtual ir_visitor_status visit_enter(ir_call *);
  63
  64    signature_entry *get_signature_entry(ir_function_signature *var);
  65
  66    bool (*predicate)(ir_instruction *ir);
  67
  68    bool seen_another_function_signature;
  69
  70    /* List of signature_entry */
  71    exec_list signature_list;
  72    void *mem_ctx;
  73 };
  74
  75
  76 signature_entry *
  77 ir_dead_functions_visitor::get_signature_entry(ir_function_signature *sig)
  78 {
  79    foreach_iter(exec_list_iterator, iter, this->signature_list) {
  80       signature_entry *entry = (signature_entry *)iter.get();
  81       if (entry->signature == sig)
  82          return entry;
  83    }
  84
  85    signature_entry *entry = new(mem_ctx) signature_entry(sig);
  86    this->signature_list.push_tail(entry);
  87    return entry;
  88 }
  89
  90
  91 ir_visitor_status
  92 ir_dead_functions_visitor::visit_enter(ir_function_signature *ir)
  93 {
  94    signature_entry *entry = this->get_signature_entry(ir);
  95
  96    if (strcmp(ir->function_name(), "main") == 0) {
  97       entry->used = true;
  98    }
  99
 100    /* If this is the first signature to look at, no need to descend to see
 101     * if it has calls to another function signature.
 102     */
 103    if (!this->seen_another_function_signature) {
 104       this->seen_another_function_signature = true;
 105       return visit_continue_with_parent;
 106    }
 107
 108    return visit_continue;
 109 }
 110
 111
 112 ir_visitor_status
 113 ir_dead_functions_visitor::visit_enter(ir_call *ir)
 114 {
 115    signature_entry *entry = this->get_signature_entry(ir->get_callee());
 116
 117    entry->used = true;
 118
 119    return visit_continue;
 120 }
 121
 122 bool
 123 do_dead_functions(exec_list *instructions)
 124 {
 125    ir_dead_functions_visitor v;
 126    bool progress = false;
 127
 128    visit_list_elements(&v, instructions);
 129
 130    /* Now that we've figured out which function signatures are used, remove
 131     * the unused ones, and remove function definitions that have no more
 132     * signatures.
 133     */
 134     foreach_iter(exec_list_iterator, iter, v.signature_list) {
 135       signature_entry *entry = (signature_entry *)iter.get();
 136
 137       if (!entry->used) {
 138          entry->signature->remove();
 139          delete entry->signature;
 140          progress = true;
 141       }
 142       delete(entry);
 143    }
 144
 145    /* We don't just do this above when we nuked a signature because of
 146     * const pointers.
 147     */
 148    foreach_iter(exec_list_iterator, iter, *instructions) {
 149       ir_instruction *ir = (ir_instruction *)iter.get();
 150       ir_function *func = ir->as_function();
 151
 152       if (func && func->signatures.is_empty()) {
 153          /* At this point (post-linking), the symbol table is no
 154           * longer in use, so not removing the function from the
 155           * symbol table should be OK.
 156           */
 157          func->remove();
 158          delete func;
 159          progress = true;
 160       }
 161    }
 162
 163    return progress;
 164 }