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0
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1 /*
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2 * Copyright 1999-2005 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 #include "incls/_precompiled.incl"
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26 #include "incls/_c1_ValueMap.cpp.incl"
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27
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28
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29 #ifndef PRODUCT
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30
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31 int ValueMap::_number_of_finds = 0;
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32 int ValueMap::_number_of_hits = 0;
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33 int ValueMap::_number_of_kills = 0;
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34
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35 #define TRACE_VALUE_NUMBERING(code) if (PrintValueNumbering) { code; }
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36
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37 #else
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38
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39 #define TRACE_VALUE_NUMBERING(code)
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40
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41 #endif
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42
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43
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44 ValueMap::ValueMap()
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45 : _nesting(0)
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46 , _entries(ValueMapInitialSize, NULL)
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47 , _killed_values()
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48 , _entry_count(0)
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49 {
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50 NOT_PRODUCT(reset_statistics());
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51 }
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52
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53
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54 ValueMap::ValueMap(ValueMap* old)
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55 : _nesting(old->_nesting + 1)
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56 , _entries(old->_entries.length())
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57 , _killed_values()
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58 , _entry_count(old->_entry_count)
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59 {
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60 for (int i = size() - 1; i >= 0; i--) {
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61 _entries.at_put(i, old->entry_at(i));
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62 }
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63 _killed_values.set_from(&old->_killed_values);
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64 }
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65
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66
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67 void ValueMap::increase_table_size() {
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68 int old_size = size();
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69 int new_size = old_size * 2 + 1;
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70
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71 ValueMapEntryList worklist(8);
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72 ValueMapEntryArray new_entries(new_size, NULL);
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73 int new_entry_count = 0;
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74
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75 TRACE_VALUE_NUMBERING(tty->print_cr("increasing table size from %d to %d", old_size, new_size));
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76
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77 for (int i = old_size - 1; i >= 0; i--) {
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78 ValueMapEntry* entry;
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79 for (entry = entry_at(i); entry != NULL; entry = entry->next()) {
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80 if (!is_killed(entry->value())) {
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81 worklist.push(entry);
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82 }
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83 }
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84
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85 while (!worklist.is_empty()) {
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86 entry = worklist.pop();
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87 int new_index = entry_index(entry->hash(), new_size);
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88
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89 if (entry->nesting() != nesting() && new_entries.at(new_index) != entry->next()) {
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90 // changing entries with a lower nesting than the current nesting of the table
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91 // is not allowed because then the same entry is contained in multiple value maps.
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92 // clone entry when next-pointer must be changed
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93 entry = new ValueMapEntry(entry->hash(), entry->value(), entry->nesting(), NULL);
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94 }
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95 entry->set_next(new_entries.at(new_index));
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96 new_entries.at_put(new_index, entry);
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97 new_entry_count++;
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98 }
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99 }
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100
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101 _entries = new_entries;
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102 _entry_count = new_entry_count;
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103 }
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104
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105
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106 Value ValueMap::find_insert(Value x) {
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107 const intx hash = x->hash();
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108 if (hash != 0) {
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109 // 0 hash means: exclude from value numbering
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110 NOT_PRODUCT(_number_of_finds++);
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111
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112 for (ValueMapEntry* entry = entry_at(entry_index(hash, size())); entry != NULL; entry = entry->next()) {
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113 if (entry->hash() == hash) {
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114 Value f = entry->value();
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115
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116 if (!is_killed(f) && f->is_equal(x)) {
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117 NOT_PRODUCT(_number_of_hits++);
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118 TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: %s %c%d equal to %c%d (size %d, entries %d, nesting-diff %d)", x->name(), x->type()->tchar(), x->id(), f->type()->tchar(), f->id(), size(), entry_count(), nesting() - entry->nesting()));
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119
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120 if (entry->nesting() != nesting() && f->as_Constant() == NULL) {
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121 // non-constant values of of another block must be pinned,
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122 // otherwise it is possible that they are not evaluated
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123 f->pin(Instruction::PinGlobalValueNumbering);
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124 }
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125
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126 return f;
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127
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128 }
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129 }
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130 }
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131
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132 // x not found, so insert it
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133 if (entry_count() >= size_threshold()) {
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134 increase_table_size();
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135 }
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136 int idx = entry_index(hash, size());
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137 _entries.at_put(idx, new ValueMapEntry(hash, x, nesting(), entry_at(idx)));
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138 _entry_count++;
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139
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140 TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: insert %s %c%d (size %d, entries %d, nesting %d)", x->name(), x->type()->tchar(), x->id(), size(), entry_count(), nesting()));
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141 }
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142
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143 return x;
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144 }
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145
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146
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147 #define GENERIC_KILL_VALUE(must_kill_implementation) \
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148 NOT_PRODUCT(_number_of_kills++); \
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149 \
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150 for (int i = size() - 1; i >= 0; i--) { \
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151 ValueMapEntry* prev_entry = NULL; \
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152 for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) { \
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153 Value value = entry->value(); \
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154 \
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155 must_kill_implementation(must_kill, entry, value) \
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156 \
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157 if (must_kill) { \
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158 kill_value(value); \
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159 \
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160 if (prev_entry == NULL) { \
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161 _entries.at_put(i, entry->next()); \
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162 _entry_count--; \
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163 } else if (prev_entry->nesting() == nesting()) { \
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164 prev_entry->set_next(entry->next()); \
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165 _entry_count--; \
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166 } else { \
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167 prev_entry = entry; \
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168 } \
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169 \
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170 TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: killed %s %c%d (size %d, entries %d, nesting-diff %d)", value->name(), value->type()->tchar(), value->id(), size(), entry_count(), nesting() - entry->nesting())); \
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171 } else { \
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172 prev_entry = entry; \
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173 } \
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174 } \
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175 } \
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176
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177 #define MUST_KILL_MEMORY(must_kill, entry, value) \
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178 bool must_kill = value->as_LoadField() != NULL || value->as_LoadIndexed() != NULL;
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179
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180 #define MUST_KILL_ARRAY(must_kill, entry, value) \
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181 bool must_kill = value->as_LoadIndexed() != NULL \
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182 && value->type()->tag() == type->tag();
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183
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184 #define MUST_KILL_FIELD(must_kill, entry, value) \
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185 /* ciField's are not unique; must compare their contents */ \
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186 LoadField* lf = value->as_LoadField(); \
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187 bool must_kill = lf != NULL \
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188 && lf->field()->holder() == field->holder() \
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189 && lf->field()->offset() == field->offset();
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190
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191 #define MUST_KILL_EXCEPTION(must_kill, entry, value) \
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192 assert(entry->nesting() < nesting(), "must not find bigger nesting than current"); \
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193 bool must_kill = (entry->nesting() == nesting() - 1);
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194
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195
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196 void ValueMap::kill_memory() {
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197 GENERIC_KILL_VALUE(MUST_KILL_MEMORY);
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198 }
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199
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200 void ValueMap::kill_array(ValueType* type) {
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201 GENERIC_KILL_VALUE(MUST_KILL_ARRAY);
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202 }
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203
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204 void ValueMap::kill_field(ciField* field) {
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205 GENERIC_KILL_VALUE(MUST_KILL_FIELD);
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206 }
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207
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208 void ValueMap::kill_exception() {
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209 GENERIC_KILL_VALUE(MUST_KILL_EXCEPTION);
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210 }
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211
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212
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213 void ValueMap::kill_map(ValueMap* map) {
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214 assert(is_global_value_numbering(), "only for global value numbering");
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215 _killed_values.set_union(&map->_killed_values);
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216 }
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217
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218 void ValueMap::kill_all() {
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219 assert(is_local_value_numbering(), "only for local value numbering");
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220 for (int i = size() - 1; i >= 0; i--) {
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221 _entries.at_put(i, NULL);
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222 }
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223 _entry_count = 0;
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224 }
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225
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226
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227 #ifndef PRODUCT
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228
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229 void ValueMap::print() {
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230 tty->print_cr("(size %d, entries %d, nesting %d)", size(), entry_count(), nesting());
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231
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232 int entries = 0;
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233 for (int i = 0; i < size(); i++) {
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234 if (entry_at(i) != NULL) {
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235 tty->print(" %2d: ", i);
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236 for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) {
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237 Value value = entry->value();
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238 tty->print("%s %c%d (%s%d) -> ", value->name(), value->type()->tchar(), value->id(), is_killed(value) ? "x" : "", entry->nesting());
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239 entries++;
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240 }
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241 tty->print_cr("NULL");
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242 }
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243 }
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244
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245 _killed_values.print();
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246 assert(entry_count() == entries, "entry_count incorrect");
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247 }
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248
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249 void ValueMap::reset_statistics() {
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250 _number_of_finds = 0;
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251 _number_of_hits = 0;
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252 _number_of_kills = 0;
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253 }
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254
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255 void ValueMap::print_statistics() {
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256 float hit_rate = 0;
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257 if (_number_of_finds != 0) {
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258 hit_rate = (float)_number_of_hits / _number_of_finds;
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259 }
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260
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261 tty->print_cr("finds:%3d hits:%3d kills:%3d hit rate: %1.4f", _number_of_finds, _number_of_hits, _number_of_kills, hit_rate);
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262 }
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263
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264 #endif
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265
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266
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267
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268 class ShortLoopOptimizer : public ValueNumberingVisitor {
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269 private:
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270 GlobalValueNumbering* _gvn;
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271 BlockList _loop_blocks;
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272 bool _too_complicated_loop;
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273
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274 // simplified access to methods of GlobalValueNumbering
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275 ValueMap* current_map() { return _gvn->current_map(); }
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276 ValueMap* value_map_of(BlockBegin* block) { return _gvn->value_map_of(block); }
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277
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278 // implementation for abstract methods of ValueNumberingVisitor
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279 void kill_memory() { _too_complicated_loop = true; }
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280 void kill_field(ciField* field) { current_map()->kill_field(field); };
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281 void kill_array(ValueType* type) { current_map()->kill_array(type); };
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282
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283 public:
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284 ShortLoopOptimizer(GlobalValueNumbering* gvn)
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285 : _gvn(gvn)
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286 , _loop_blocks(ValueMapMaxLoopSize)
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287 , _too_complicated_loop(false)
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288 {
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289 }
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290
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291 bool process(BlockBegin* loop_header);
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292 };
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293
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294
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295 bool ShortLoopOptimizer::process(BlockBegin* loop_header) {
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296 TRACE_VALUE_NUMBERING(tty->print_cr("** loop header block"));
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297
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298 _too_complicated_loop = false;
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299 _loop_blocks.clear();
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300 _loop_blocks.append(loop_header);
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301
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302 for (int i = 0; i < _loop_blocks.length(); i++) {
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303 BlockBegin* block = _loop_blocks.at(i);
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304 TRACE_VALUE_NUMBERING(tty->print_cr("processing loop block B%d", block->block_id()));
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305
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306 if (block->is_set(BlockBegin::exception_entry_flag)) {
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307 // this would be too complicated
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308 return false;
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309 }
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310
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311 // add predecessors to worklist
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312 for (int j = block->number_of_preds() - 1; j >= 0; j--) {
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313 BlockBegin* pred = block->pred_at(j);
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314
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315 ValueMap* pred_map = value_map_of(pred);
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316 if (pred_map != NULL) {
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317 current_map()->kill_map(pred_map);
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318 } else if (!_loop_blocks.contains(pred)) {
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319 if (_loop_blocks.length() >= ValueMapMaxLoopSize) {
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320 return false;
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321 }
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322 _loop_blocks.append(pred);
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323 }
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324 }
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325
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326 // use the instruction visitor for killing values
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327 for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
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328 instr->visit(this);
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329 if (_too_complicated_loop) {
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330 return false;
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331 }
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332 }
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333 }
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334
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335 TRACE_VALUE_NUMBERING(tty->print_cr("** loop successfully optimized"));
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336 return true;
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337 }
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338
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339
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340 GlobalValueNumbering::GlobalValueNumbering(IR* ir)
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341 : _current_map(NULL)
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342 , _value_maps(ir->linear_scan_order()->length(), NULL)
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343 {
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344 TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering"));
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345
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346 ShortLoopOptimizer short_loop_optimizer(this);
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347 int subst_count = 0;
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348
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349 BlockList* blocks = ir->linear_scan_order();
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350 int num_blocks = blocks->length();
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351
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352 BlockBegin* start_block = blocks->at(0);
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353 assert(start_block == ir->start() && start_block->number_of_preds() == 0 && start_block->dominator() == NULL, "must be start block");
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354 assert(start_block->next()->as_Base() != NULL && start_block->next()->next() == NULL, "start block must not have instructions");
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355
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356 // initial, empty value map with nesting 0
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357 set_value_map_of(start_block, new ValueMap());
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358
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359 for (int i = 1; i < num_blocks; i++) {
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360 BlockBegin* block = blocks->at(i);
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361 TRACE_VALUE_NUMBERING(tty->print_cr("**** processing block B%d", block->block_id()));
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362
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363 int num_preds = block->number_of_preds();
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364 assert(num_preds > 0, "block must have predecessors");
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365
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366 BlockBegin* dominator = block->dominator();
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367 assert(dominator != NULL, "dominator must exist");
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368 assert(value_map_of(dominator) != NULL, "value map of dominator must exist");
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369
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370 // create new value map with increased nesting
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371 _current_map = new ValueMap(value_map_of(dominator));
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372
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373 if (num_preds == 1) {
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374 assert(dominator == block->pred_at(0), "dominator must be equal to predecessor");
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375 // nothing to do here
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376
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377 } else if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) {
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378 // block has incoming backward branches -> try to optimize short loops
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379 if (!short_loop_optimizer.process(block)) {
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380 // loop is too complicated, so kill all memory loads because there might be
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381 // stores to them in the loop
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382 current_map()->kill_memory();
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383 }
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384
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385 } else {
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386 // only incoming forward branches that are already processed
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387 for (int j = 0; j < num_preds; j++) {
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388 BlockBegin* pred = block->pred_at(j);
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389 ValueMap* pred_map = value_map_of(pred);
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390
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391 if (pred_map != NULL) {
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392 // propagate killed values of the predecessor to this block
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393 current_map()->kill_map(value_map_of(pred));
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394 } else {
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395 // kill all memory loads because predecessor not yet processed
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396 // (this can happen with non-natural loops and OSR-compiles)
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397 current_map()->kill_memory();
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398 }
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399 }
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400 }
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401
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402 if (block->is_set(BlockBegin::exception_entry_flag)) {
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403 current_map()->kill_exception();
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404 }
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405
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406 TRACE_VALUE_NUMBERING(tty->print("value map before processing block: "); current_map()->print());
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407
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408 // visit all instructions of this block
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409 for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
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410 assert(!instr->has_subst(), "substitution already set");
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411
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412 // check if instruction kills any values
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413 instr->visit(this);
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414
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415 if (instr->hash() != 0) {
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416 Value f = current_map()->find_insert(instr);
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417 if (f != instr) {
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418 assert(!f->has_subst(), "can't have a substitution");
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419 instr->set_subst(f);
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420 subst_count++;
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421 }
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422 }
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423 }
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424
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425 // remember value map for successors
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426 set_value_map_of(block, current_map());
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427 }
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428
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429 if (subst_count != 0) {
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430 SubstitutionResolver resolver(ir);
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431 }
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432
|
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433 TRACE_VALUE_NUMBERING(tty->print("****** end of global value numbering. "); ValueMap::print_statistics());
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|
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434 }
|
