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1 /*
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337
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2 * Copyright 1997-2008 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 // Optimization - Graph Style
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26
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27 #include "incls/_precompiled.incl"
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28 #include "incls/_block.cpp.incl"
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29
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30
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31 //-----------------------------------------------------------------------------
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32 void Block_Array::grow( uint i ) {
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33 assert(i >= Max(), "must be an overflow");
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34 debug_only(_limit = i+1);
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35 if( i < _size ) return;
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36 if( !_size ) {
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37 _size = 1;
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38 _blocks = (Block**)_arena->Amalloc( _size * sizeof(Block*) );
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39 _blocks[0] = NULL;
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40 }
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41 uint old = _size;
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42 while( i >= _size ) _size <<= 1; // Double to fit
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43 _blocks = (Block**)_arena->Arealloc( _blocks, old*sizeof(Block*),_size*sizeof(Block*));
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44 Copy::zero_to_bytes( &_blocks[old], (_size-old)*sizeof(Block*) );
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45 }
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46
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47 //=============================================================================
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48 void Block_List::remove(uint i) {
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49 assert(i < _cnt, "index out of bounds");
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50 Copy::conjoint_words_to_lower((HeapWord*)&_blocks[i+1], (HeapWord*)&_blocks[i], ((_cnt-i-1)*sizeof(Block*)));
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51 pop(); // shrink list by one block
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52 }
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53
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54 void Block_List::insert(uint i, Block *b) {
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55 push(b); // grow list by one block
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56 Copy::conjoint_words_to_higher((HeapWord*)&_blocks[i], (HeapWord*)&_blocks[i+1], ((_cnt-i-1)*sizeof(Block*)));
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57 _blocks[i] = b;
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58 }
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59
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418
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60 #ifndef PRODUCT
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61 void Block_List::print() {
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62 for (uint i=0; i < size(); i++) {
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63 tty->print("B%d ", _blocks[i]->_pre_order);
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64 }
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65 tty->print("size = %d\n", size());
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66 }
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67 #endif
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68
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69 //=============================================================================
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70
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71 uint Block::code_alignment() {
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72 // Check for Root block
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73 if( _pre_order == 0 ) return CodeEntryAlignment;
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74 // Check for Start block
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75 if( _pre_order == 1 ) return InteriorEntryAlignment;
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76 // Check for loop alignment
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418
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77 if (has_loop_alignment()) return loop_alignment();
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78
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79 return 1; // no particular alignment
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80 }
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81
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82 uint Block::compute_loop_alignment() {
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83 Node *h = head();
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84 if( h->is_Loop() && h->as_Loop()->is_inner_loop() ) {
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85 // Pre- and post-loops have low trip count so do not bother with
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86 // NOPs for align loop head. The constants are hidden from tuning
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87 // but only because my "divide by 4" heuristic surely gets nearly
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88 // all possible gain (a "do not align at all" heuristic has a
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89 // chance of getting a really tiny gain).
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90 if( h->is_CountedLoop() && (h->as_CountedLoop()->is_pre_loop() ||
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91 h->as_CountedLoop()->is_post_loop()) )
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92 return (OptoLoopAlignment > 4) ? (OptoLoopAlignment>>2) : 1;
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93 // Loops with low backedge frequency should not be aligned.
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94 Node *n = h->in(LoopNode::LoopBackControl)->in(0);
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95 if( n->is_MachIf() && n->as_MachIf()->_prob < 0.01 ) {
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96 return 1; // Loop does not loop, more often than not!
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97 }
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98 return OptoLoopAlignment; // Otherwise align loop head
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99 }
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418
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100
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101 return 1; // no particular alignment
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102 }
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103
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104 //-----------------------------------------------------------------------------
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105 // Compute the size of first 'inst_cnt' instructions in this block.
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106 // Return the number of instructions left to compute if the block has
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418
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107 // less then 'inst_cnt' instructions. Stop, and return 0 if sum_size
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108 // exceeds OptoLoopAlignment.
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109 uint Block::compute_first_inst_size(uint& sum_size, uint inst_cnt,
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110 PhaseRegAlloc* ra) {
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111 uint last_inst = _nodes.size();
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112 for( uint j = 0; j < last_inst && inst_cnt > 0; j++ ) {
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113 uint inst_size = _nodes[j]->size(ra);
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114 if( inst_size > 0 ) {
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115 inst_cnt--;
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116 uint sz = sum_size + inst_size;
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117 if( sz <= (uint)OptoLoopAlignment ) {
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118 // Compute size of instructions which fit into fetch buffer only
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119 // since all inst_cnt instructions will not fit even if we align them.
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120 sum_size = sz;
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121 } else {
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122 return 0;
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123 }
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124 }
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125 }
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126 return inst_cnt;
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127 }
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128
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129 //-----------------------------------------------------------------------------
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130 uint Block::find_node( const Node *n ) const {
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131 for( uint i = 0; i < _nodes.size(); i++ ) {
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132 if( _nodes[i] == n )
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133 return i;
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134 }
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135 ShouldNotReachHere();
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136 return 0;
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137 }
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138
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139 // Find and remove n from block list
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140 void Block::find_remove( const Node *n ) {
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141 _nodes.remove(find_node(n));
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142 }
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143
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144 //------------------------------is_Empty---------------------------------------
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145 // Return empty status of a block. Empty blocks contain only the head, other
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146 // ideal nodes, and an optional trailing goto.
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147 int Block::is_Empty() const {
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148
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149 // Root or start block is not considered empty
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150 if (head()->is_Root() || head()->is_Start()) {
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151 return not_empty;
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152 }
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153
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154 int success_result = completely_empty;
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155 int end_idx = _nodes.size()-1;
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156
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157 // Check for ending goto
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158 if ((end_idx > 0) && (_nodes[end_idx]->is_Goto())) {
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159 success_result = empty_with_goto;
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160 end_idx--;
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161 }
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162
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163 // Unreachable blocks are considered empty
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164 if (num_preds() <= 1) {
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165 return success_result;
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166 }
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167
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168 // Ideal nodes are allowable in empty blocks: skip them Only MachNodes
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169 // turn directly into code, because only MachNodes have non-trivial
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170 // emit() functions.
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171 while ((end_idx > 0) && !_nodes[end_idx]->is_Mach()) {
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172 end_idx--;
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173 }
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174
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175 // No room for any interesting instructions?
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176 if (end_idx == 0) {
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177 return success_result;
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178 }
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179
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180 return not_empty;
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181 }
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182
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183 //------------------------------has_uncommon_code------------------------------
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184 // Return true if the block's code implies that it is not likely to be
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185 // executed infrequently. Check to see if the block ends in a Halt or
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186 // a low probability call.
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187 bool Block::has_uncommon_code() const {
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188 Node* en = end();
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189
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190 if (en->is_Goto())
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191 en = en->in(0);
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192 if (en->is_Catch())
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193 en = en->in(0);
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194 if (en->is_Proj() && en->in(0)->is_MachCall()) {
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195 MachCallNode* call = en->in(0)->as_MachCall();
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196 if (call->cnt() != COUNT_UNKNOWN && call->cnt() <= PROB_UNLIKELY_MAG(4)) {
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197 // This is true for slow-path stubs like new_{instance,array},
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198 // slow_arraycopy, complete_monitor_locking, uncommon_trap.
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199 // The magic number corresponds to the probability of an uncommon_trap,
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200 // even though it is a count not a probability.
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201 return true;
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202 }
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203 }
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204
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205 int op = en->is_Mach() ? en->as_Mach()->ideal_Opcode() : en->Opcode();
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206 return op == Op_Halt;
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207 }
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208
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209 //------------------------------is_uncommon------------------------------------
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210 // True if block is low enough frequency or guarded by a test which
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211 // mostly does not go here.
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212 bool Block::is_uncommon( Block_Array &bbs ) const {
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213 // Initial blocks must never be moved, so are never uncommon.
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214 if (head()->is_Root() || head()->is_Start()) return false;
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215
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216 // Check for way-low freq
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217 if( _freq < BLOCK_FREQUENCY(0.00001f) ) return true;
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218
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219 // Look for code shape indicating uncommon_trap or slow path
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220 if (has_uncommon_code()) return true;
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221
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222 const float epsilon = 0.05f;
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223 const float guard_factor = PROB_UNLIKELY_MAG(4) / (1.f - epsilon);
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224 uint uncommon_preds = 0;
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225 uint freq_preds = 0;
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226 uint uncommon_for_freq_preds = 0;
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227
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228 for( uint i=1; i<num_preds(); i++ ) {
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229 Block* guard = bbs[pred(i)->_idx];
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230 // Check to see if this block follows its guard 1 time out of 10000
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231 // or less.
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232 //
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233 // See list of magnitude-4 unlikely probabilities in cfgnode.hpp which
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234 // we intend to be "uncommon", such as slow-path TLE allocation,
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235 // predicted call failure, and uncommon trap triggers.
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236 //
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237 // Use an epsilon value of 5% to allow for variability in frequency
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238 // predictions and floating point calculations. The net effect is
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239 // that guard_factor is set to 9500.
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240 //
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241 // Ignore low-frequency blocks.
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242 // The next check is (guard->_freq < 1.e-5 * 9500.).
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243 if(guard->_freq*BLOCK_FREQUENCY(guard_factor) < BLOCK_FREQUENCY(0.00001f)) {
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244 uncommon_preds++;
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245 } else {
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246 freq_preds++;
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247 if( _freq < guard->_freq * guard_factor ) {
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248 uncommon_for_freq_preds++;
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249 }
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250 }
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251 }
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252 if( num_preds() > 1 &&
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253 // The block is uncommon if all preds are uncommon or
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254 (uncommon_preds == (num_preds()-1) ||
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255 // it is uncommon for all frequent preds.
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256 uncommon_for_freq_preds == freq_preds) ) {
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257 return true;
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258 }
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259 return false;
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260 }
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261
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262 //------------------------------dump-------------------------------------------
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263 #ifndef PRODUCT
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264 void Block::dump_bidx(const Block* orig) const {
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265 if (_pre_order) tty->print("B%d",_pre_order);
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266 else tty->print("N%d", head()->_idx);
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267
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268 if (Verbose && orig != this) {
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269 // Dump the original block's idx
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270 tty->print(" (");
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271 orig->dump_bidx(orig);
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272 tty->print(")");
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273 }
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274 }
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275
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276 void Block::dump_pred(const Block_Array *bbs, Block* orig) const {
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277 if (is_connector()) {
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278 for (uint i=1; i<num_preds(); i++) {
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279 Block *p = ((*bbs)[pred(i)->_idx]);
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280 p->dump_pred(bbs, orig);
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281 }
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282 } else {
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283 dump_bidx(orig);
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284 tty->print(" ");
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285 }
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286 }
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287
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288 void Block::dump_head( const Block_Array *bbs ) const {
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289 // Print the basic block
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290 dump_bidx(this);
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291 tty->print(": #\t");
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292
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293 // Print the incoming CFG edges and the outgoing CFG edges
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294 for( uint i=0; i<_num_succs; i++ ) {
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295 non_connector_successor(i)->dump_bidx(_succs[i]);
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296 tty->print(" ");
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297 }
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298 tty->print("<- ");
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299 if( head()->is_block_start() ) {
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300 for (uint i=1; i<num_preds(); i++) {
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301 Node *s = pred(i);
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302 if (bbs) {
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303 Block *p = (*bbs)[s->_idx];
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304 p->dump_pred(bbs, p);
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305 } else {
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306 while (!s->is_block_start())
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307 s = s->in(0);
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308 tty->print("N%d ", s->_idx );
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309 }
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310 }
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311 } else
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312 tty->print("BLOCK HEAD IS JUNK ");
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313
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314 // Print loop, if any
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315 const Block *bhead = this; // Head of self-loop
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316 Node *bh = bhead->head();
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317 if( bbs && bh->is_Loop() && !head()->is_Root() ) {
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318 LoopNode *loop = bh->as_Loop();
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319 const Block *bx = (*bbs)[loop->in(LoopNode::LoopBackControl)->_idx];
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320 while (bx->is_connector()) {
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321 bx = (*bbs)[bx->pred(1)->_idx];
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322 }
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323 tty->print("\tLoop: B%d-B%d ", bhead->_pre_order, bx->_pre_order);
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324 // Dump any loop-specific bits, especially for CountedLoops.
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325 loop->dump_spec(tty);
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418
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326 } else if (has_loop_alignment()) {
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327 tty->print(" top-of-loop");
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328 }
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329 tty->print(" Freq: %g",_freq);
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330 if( Verbose || WizardMode ) {
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331 tty->print(" IDom: %d/#%d", _idom ? _idom->_pre_order : 0, _dom_depth);
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332 tty->print(" RegPressure: %d",_reg_pressure);
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333 tty->print(" IHRP Index: %d",_ihrp_index);
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334 tty->print(" FRegPressure: %d",_freg_pressure);
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335 tty->print(" FHRP Index: %d",_fhrp_index);
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336 }
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337 tty->print_cr("");
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338 }
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339
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340 void Block::dump() const { dump(0); }
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341
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342 void Block::dump( const Block_Array *bbs ) const {
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343 dump_head(bbs);
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344 uint cnt = _nodes.size();
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345 for( uint i=0; i<cnt; i++ )
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346 _nodes[i]->dump();
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347 tty->print("\n");
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348 }
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349 #endif
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350
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351 //=============================================================================
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352 //------------------------------PhaseCFG---------------------------------------
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353 PhaseCFG::PhaseCFG( Arena *a, RootNode *r, Matcher &m ) :
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354 Phase(CFG),
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355 _bbs(a),
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356 _root(r)
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357 #ifndef PRODUCT
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358 , _trace_opto_pipelining(TraceOptoPipelining || C->method_has_option("TraceOptoPipelining"))
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359 #endif
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360 {
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361 ResourceMark rm;
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362 // I'll need a few machine-specific GotoNodes. Make an Ideal GotoNode,
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363 // then Match it into a machine-specific Node. Then clone the machine
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364 // Node on demand.
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365 Node *x = new (C, 1) GotoNode(NULL);
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366 x->init_req(0, x);
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367 _goto = m.match_tree(x);
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368 assert(_goto != NULL, "");
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369 _goto->set_req(0,_goto);
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370
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371 // Build the CFG in Reverse Post Order
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372 _num_blocks = build_cfg();
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373 _broot = _bbs[_root->_idx];
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374 }
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375
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376 //------------------------------build_cfg--------------------------------------
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377 // Build a proper looking CFG. Make every block begin with either a StartNode
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378 // or a RegionNode. Make every block end with either a Goto, If or Return.
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379 // The RootNode both starts and ends it's own block. Do this with a recursive
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380 // backwards walk over the control edges.
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381 uint PhaseCFG::build_cfg() {
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382 Arena *a = Thread::current()->resource_area();
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383 VectorSet visited(a);
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384
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385 // Allocate stack with enough space to avoid frequent realloc
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386 Node_Stack nstack(a, C->unique() >> 1);
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387 nstack.push(_root, 0);
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388 uint sum = 0; // Counter for blocks
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389
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390 while (nstack.is_nonempty()) {
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391 // node and in's index from stack's top
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392 // 'np' is _root (see above) or RegionNode, StartNode: we push on stack
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393 // only nodes which point to the start of basic block (see below).
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394 Node *np = nstack.node();
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395 // idx > 0, except for the first node (_root) pushed on stack
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396 // at the beginning when idx == 0.
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397 // We will use the condition (idx == 0) later to end the build.
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398 uint idx = nstack.index();
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399 Node *proj = np->in(idx);
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400 const Node *x = proj->is_block_proj();
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401 // Does the block end with a proper block-ending Node? One of Return,
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402 // If or Goto? (This check should be done for visited nodes also).
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403 if (x == NULL) { // Does not end right...
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404 Node *g = _goto->clone(); // Force it to end in a Goto
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405 g->set_req(0, proj);
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406 np->set_req(idx, g);
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407 x = proj = g;
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408 }
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409 if (!visited.test_set(x->_idx)) { // Visit this block once
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410 // Skip any control-pinned middle'in stuff
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411 Node *p = proj;
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412 do {
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413 proj = p; // Update pointer to last Control
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414 p = p->in(0); // Move control forward
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415 } while( !p->is_block_proj() &&
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416 !p->is_block_start() );
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417 // Make the block begin with one of Region or StartNode.
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418 if( !p->is_block_start() ) {
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419 RegionNode *r = new (C, 2) RegionNode( 2 );
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420 r->init_req(1, p); // Insert RegionNode in the way
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421 proj->set_req(0, r); // Insert RegionNode in the way
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422 p = r;
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423 }
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424 // 'p' now points to the start of this basic block
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425
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426 // Put self in array of basic blocks
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427 Block *bb = new (_bbs._arena) Block(_bbs._arena,p);
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428 _bbs.map(p->_idx,bb);
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429 _bbs.map(x->_idx,bb);
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430 if( x != p ) // Only for root is x == p
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431 bb->_nodes.push((Node*)x);
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432
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433 // Now handle predecessors
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434 ++sum; // Count 1 for self block
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435 uint cnt = bb->num_preds();
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436 for (int i = (cnt - 1); i > 0; i-- ) { // For all predecessors
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437 Node *prevproj = p->in(i); // Get prior input
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438 assert( !prevproj->is_Con(), "dead input not removed" );
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439 // Check to see if p->in(i) is a "control-dependent" CFG edge -
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440 // i.e., it splits at the source (via an IF or SWITCH) and merges
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441 // at the destination (via a many-input Region).
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442 // This breaks critical edges. The RegionNode to start the block
|
|
443 // will be added when <p,i> is pulled off the node stack
|
|
444 if ( cnt > 2 ) { // Merging many things?
|
|
445 assert( prevproj== bb->pred(i),"");
|
|
446 if(prevproj->is_block_proj() != prevproj) { // Control-dependent edge?
|
|
447 // Force a block on the control-dependent edge
|
|
448 Node *g = _goto->clone(); // Force it to end in a Goto
|
|
449 g->set_req(0,prevproj);
|
|
450 p->set_req(i,g);
|
|
451 }
|
|
452 }
|
|
453 nstack.push(p, i); // 'p' is RegionNode or StartNode
|
|
454 }
|
|
455 } else { // Post-processing visited nodes
|
|
456 nstack.pop(); // remove node from stack
|
|
457 // Check if it the fist node pushed on stack at the beginning.
|
|
458 if (idx == 0) break; // end of the build
|
|
459 // Find predecessor basic block
|
|
460 Block *pb = _bbs[x->_idx];
|
|
461 // Insert into nodes array, if not already there
|
|
462 if( !_bbs.lookup(proj->_idx) ) {
|
|
463 assert( x != proj, "" );
|
|
464 // Map basic block of projection
|
|
465 _bbs.map(proj->_idx,pb);
|
|
466 pb->_nodes.push(proj);
|
|
467 }
|
|
468 // Insert self as a child of my predecessor block
|
|
469 pb->_succs.map(pb->_num_succs++, _bbs[np->_idx]);
|
|
470 assert( pb->_nodes[ pb->_nodes.size() - pb->_num_succs ]->is_block_proj(),
|
|
471 "too many control users, not a CFG?" );
|
|
472 }
|
|
473 }
|
|
474 // Return number of basic blocks for all children and self
|
|
475 return sum;
|
|
476 }
|
|
477
|
|
478 //------------------------------insert_goto_at---------------------------------
|
|
479 // Inserts a goto & corresponding basic block between
|
|
480 // block[block_no] and its succ_no'th successor block
|
|
481 void PhaseCFG::insert_goto_at(uint block_no, uint succ_no) {
|
|
482 // get block with block_no
|
|
483 assert(block_no < _num_blocks, "illegal block number");
|
|
484 Block* in = _blocks[block_no];
|
|
485 // get successor block succ_no
|
|
486 assert(succ_no < in->_num_succs, "illegal successor number");
|
|
487 Block* out = in->_succs[succ_no];
|
308
|
488 // Compute frequency of the new block. Do this before inserting
|
|
489 // new block in case succ_prob() needs to infer the probability from
|
|
490 // surrounding blocks.
|
|
491 float freq = in->_freq * in->succ_prob(succ_no);
|
0
|
492 // get ProjNode corresponding to the succ_no'th successor of the in block
|
|
493 ProjNode* proj = in->_nodes[in->_nodes.size() - in->_num_succs + succ_no]->as_Proj();
|
|
494 // create region for basic block
|
|
495 RegionNode* region = new (C, 2) RegionNode(2);
|
|
496 region->init_req(1, proj);
|
|
497 // setup corresponding basic block
|
|
498 Block* block = new (_bbs._arena) Block(_bbs._arena, region);
|
|
499 _bbs.map(region->_idx, block);
|
|
500 C->regalloc()->set_bad(region->_idx);
|
|
501 // add a goto node
|
|
502 Node* gto = _goto->clone(); // get a new goto node
|
|
503 gto->set_req(0, region);
|
|
504 // add it to the basic block
|
|
505 block->_nodes.push(gto);
|
|
506 _bbs.map(gto->_idx, block);
|
|
507 C->regalloc()->set_bad(gto->_idx);
|
|
508 // hook up successor block
|
|
509 block->_succs.map(block->_num_succs++, out);
|
|
510 // remap successor's predecessors if necessary
|
|
511 for (uint i = 1; i < out->num_preds(); i++) {
|
|
512 if (out->pred(i) == proj) out->head()->set_req(i, gto);
|
|
513 }
|
|
514 // remap predecessor's successor to new block
|
|
515 in->_succs.map(succ_no, block);
|
308
|
516 // Set the frequency of the new block
|
|
517 block->_freq = freq;
|
0
|
518 // add new basic block to basic block list
|
|
519 _blocks.insert(block_no + 1, block);
|
|
520 _num_blocks++;
|
|
521 }
|
|
522
|
|
523 //------------------------------no_flip_branch---------------------------------
|
|
524 // Does this block end in a multiway branch that cannot have the default case
|
|
525 // flipped for another case?
|
|
526 static bool no_flip_branch( Block *b ) {
|
|
527 int branch_idx = b->_nodes.size() - b->_num_succs-1;
|
|
528 if( branch_idx < 1 ) return false;
|
|
529 Node *bra = b->_nodes[branch_idx];
|
418
|
530 if( bra->is_Catch() )
|
|
531 return true;
|
0
|
532 if( bra->is_Mach() ) {
|
418
|
533 if( bra->is_MachNullCheck() )
|
|
534 return true;
|
0
|
535 int iop = bra->as_Mach()->ideal_Opcode();
|
|
536 if( iop == Op_FastLock || iop == Op_FastUnlock )
|
|
537 return true;
|
|
538 }
|
|
539 return false;
|
|
540 }
|
|
541
|
|
542 //------------------------------convert_NeverBranch_to_Goto--------------------
|
|
543 // Check for NeverBranch at block end. This needs to become a GOTO to the
|
|
544 // true target. NeverBranch are treated as a conditional branch that always
|
|
545 // goes the same direction for most of the optimizer and are used to give a
|
|
546 // fake exit path to infinite loops. At this late stage they need to turn
|
|
547 // into Goto's so that when you enter the infinite loop you indeed hang.
|
|
548 void PhaseCFG::convert_NeverBranch_to_Goto(Block *b) {
|
|
549 // Find true target
|
|
550 int end_idx = b->end_idx();
|
|
551 int idx = b->_nodes[end_idx+1]->as_Proj()->_con;
|
|
552 Block *succ = b->_succs[idx];
|
|
553 Node* gto = _goto->clone(); // get a new goto node
|
|
554 gto->set_req(0, b->head());
|
|
555 Node *bp = b->_nodes[end_idx];
|
|
556 b->_nodes.map(end_idx,gto); // Slam over NeverBranch
|
|
557 _bbs.map(gto->_idx, b);
|
|
558 C->regalloc()->set_bad(gto->_idx);
|
|
559 b->_nodes.pop(); // Yank projections
|
|
560 b->_nodes.pop(); // Yank projections
|
|
561 b->_succs.map(0,succ); // Map only successor
|
|
562 b->_num_succs = 1;
|
|
563 // remap successor's predecessors if necessary
|
|
564 uint j;
|
|
565 for( j = 1; j < succ->num_preds(); j++)
|
|
566 if( succ->pred(j)->in(0) == bp )
|
|
567 succ->head()->set_req(j, gto);
|
|
568 // Kill alternate exit path
|
|
569 Block *dead = b->_succs[1-idx];
|
|
570 for( j = 1; j < dead->num_preds(); j++)
|
|
571 if( dead->pred(j)->in(0) == bp )
|
|
572 break;
|
|
573 // Scan through block, yanking dead path from
|
|
574 // all regions and phis.
|
|
575 dead->head()->del_req(j);
|
|
576 for( int k = 1; dead->_nodes[k]->is_Phi(); k++ )
|
|
577 dead->_nodes[k]->del_req(j);
|
|
578 }
|
|
579
|
418
|
580 //------------------------------move_to_next-----------------------------------
|
0
|
581 // Helper function to move block bx to the slot following b_index. Return
|
|
582 // true if the move is successful, otherwise false
|
418
|
583 bool PhaseCFG::move_to_next(Block* bx, uint b_index) {
|
0
|
584 if (bx == NULL) return false;
|
|
585
|
|
586 // Return false if bx is already scheduled.
|
|
587 uint bx_index = bx->_pre_order;
|
|
588 if ((bx_index <= b_index) && (_blocks[bx_index] == bx)) {
|
|
589 return false;
|
|
590 }
|
|
591
|
|
592 // Find the current index of block bx on the block list
|
|
593 bx_index = b_index + 1;
|
|
594 while( bx_index < _num_blocks && _blocks[bx_index] != bx ) bx_index++;
|
|
595 assert(_blocks[bx_index] == bx, "block not found");
|
|
596
|
|
597 // If the previous block conditionally falls into bx, return false,
|
|
598 // because moving bx will create an extra jump.
|
|
599 for(uint k = 1; k < bx->num_preds(); k++ ) {
|
|
600 Block* pred = _bbs[bx->pred(k)->_idx];
|
|
601 if (pred == _blocks[bx_index-1]) {
|
|
602 if (pred->_num_succs != 1) {
|
|
603 return false;
|
|
604 }
|
|
605 }
|
|
606 }
|
|
607
|
|
608 // Reinsert bx just past block 'b'
|
|
609 _blocks.remove(bx_index);
|
|
610 _blocks.insert(b_index + 1, bx);
|
|
611 return true;
|
|
612 }
|
|
613
|
418
|
614 //------------------------------move_to_end------------------------------------
|
0
|
615 // Move empty and uncommon blocks to the end.
|
418
|
616 void PhaseCFG::move_to_end(Block *b, uint i) {
|
0
|
617 int e = b->is_Empty();
|
|
618 if (e != Block::not_empty) {
|
|
619 if (e == Block::empty_with_goto) {
|
|
620 // Remove the goto, but leave the block.
|
|
621 b->_nodes.pop();
|
|
622 }
|
|
623 // Mark this block as a connector block, which will cause it to be
|
|
624 // ignored in certain functions such as non_connector_successor().
|
|
625 b->set_connector();
|
|
626 }
|
|
627 // Move the empty block to the end, and don't recheck.
|
|
628 _blocks.remove(i);
|
|
629 _blocks.push(b);
|
|
630 }
|
|
631
|
418
|
632 //---------------------------set_loop_alignment--------------------------------
|
|
633 // Set loop alignment for every block
|
|
634 void PhaseCFG::set_loop_alignment() {
|
|
635 uint last = _num_blocks;
|
|
636 assert( _blocks[0] == _broot, "" );
|
|
637
|
|
638 for (uint i = 1; i < last; i++ ) {
|
|
639 Block *b = _blocks[i];
|
|
640 if (b->head()->is_Loop()) {
|
|
641 b->set_loop_alignment(b);
|
|
642 }
|
|
643 }
|
|
644 }
|
|
645
|
|
646 //-----------------------------remove_empty------------------------------------
|
|
647 // Make empty basic blocks to be "connector" blocks, Move uncommon blocks
|
|
648 // to the end.
|
|
649 void PhaseCFG::remove_empty() {
|
0
|
650 // Move uncommon blocks to the end
|
|
651 uint last = _num_blocks;
|
|
652 assert( _blocks[0] == _broot, "" );
|
418
|
653
|
|
654 for (uint i = 1; i < last; i++) {
|
0
|
655 Block *b = _blocks[i];
|
418
|
656 if (b->is_connector()) break;
|
0
|
657
|
|
658 // Check for NeverBranch at block end. This needs to become a GOTO to the
|
|
659 // true target. NeverBranch are treated as a conditional branch that
|
|
660 // always goes the same direction for most of the optimizer and are used
|
|
661 // to give a fake exit path to infinite loops. At this late stage they
|
|
662 // need to turn into Goto's so that when you enter the infinite loop you
|
|
663 // indeed hang.
|
|
664 if( b->_nodes[b->end_idx()]->Opcode() == Op_NeverBranch )
|
|
665 convert_NeverBranch_to_Goto(b);
|
|
666
|
|
667 // Look for uncommon blocks and move to end.
|
418
|
668 if (!C->do_freq_based_layout()) {
|
|
669 if( b->is_uncommon(_bbs) ) {
|
|
670 move_to_end(b, i);
|
|
671 last--; // No longer check for being uncommon!
|
|
672 if( no_flip_branch(b) ) { // Fall-thru case must follow?
|
|
673 b = _blocks[i]; // Find the fall-thru block
|
|
674 move_to_end(b, i);
|
|
675 last--;
|
|
676 }
|
|
677 i--; // backup block counter post-increment
|
0
|
678 }
|
|
679 }
|
|
680 }
|
|
681
|
418
|
682 // Move empty blocks to the end
|
0
|
683 last = _num_blocks;
|
418
|
684 for (uint i = 1; i < last; i++) {
|
0
|
685 Block *b = _blocks[i];
|
418
|
686 if (b->is_Empty() != Block::not_empty) {
|
|
687 move_to_end(b, i);
|
|
688 last--;
|
|
689 i--;
|
0
|
690 }
|
|
691 } // End of for all blocks
|
418
|
692 }
|
0
|
693
|
418
|
694 //-----------------------------fixup_flow--------------------------------------
|
|
695 // Fix up the final control flow for basic blocks.
|
|
696 void PhaseCFG::fixup_flow() {
|
0
|
697 // Fixup final control flow for the blocks. Remove jump-to-next
|
|
698 // block. If neither arm of a IF follows the conditional branch, we
|
|
699 // have to add a second jump after the conditional. We place the
|
|
700 // TRUE branch target in succs[0] for both GOTOs and IFs.
|
418
|
701 for (uint i=0; i < _num_blocks; i++) {
|
0
|
702 Block *b = _blocks[i];
|
|
703 b->_pre_order = i; // turn pre-order into block-index
|
|
704
|
|
705 // Connector blocks need no further processing.
|
|
706 if (b->is_connector()) {
|
|
707 assert((i+1) == _num_blocks || _blocks[i+1]->is_connector(),
|
|
708 "All connector blocks should sink to the end");
|
|
709 continue;
|
|
710 }
|
|
711 assert(b->is_Empty() != Block::completely_empty,
|
|
712 "Empty blocks should be connectors");
|
|
713
|
|
714 Block *bnext = (i < _num_blocks-1) ? _blocks[i+1] : NULL;
|
|
715 Block *bs0 = b->non_connector_successor(0);
|
|
716
|
|
717 // Check for multi-way branches where I cannot negate the test to
|
|
718 // exchange the true and false targets.
|
|
719 if( no_flip_branch( b ) ) {
|
|
720 // Find fall through case - if must fall into its target
|
|
721 int branch_idx = b->_nodes.size() - b->_num_succs;
|
|
722 for (uint j2 = 0; j2 < b->_num_succs; j2++) {
|
|
723 const ProjNode* p = b->_nodes[branch_idx + j2]->as_Proj();
|
|
724 if (p->_con == 0) {
|
|
725 // successor j2 is fall through case
|
|
726 if (b->non_connector_successor(j2) != bnext) {
|
|
727 // but it is not the next block => insert a goto
|
|
728 insert_goto_at(i, j2);
|
|
729 }
|
|
730 // Put taken branch in slot 0
|
|
731 if( j2 == 0 && b->_num_succs == 2) {
|
|
732 // Flip targets in succs map
|
|
733 Block *tbs0 = b->_succs[0];
|
|
734 Block *tbs1 = b->_succs[1];
|
|
735 b->_succs.map( 0, tbs1 );
|
|
736 b->_succs.map( 1, tbs0 );
|
|
737 }
|
|
738 break;
|
|
739 }
|
|
740 }
|
|
741 // Remove all CatchProjs
|
418
|
742 for (uint j1 = 0; j1 < b->_num_succs; j1++) b->_nodes.pop();
|
0
|
743
|
|
744 } else if (b->_num_succs == 1) {
|
|
745 // Block ends in a Goto?
|
|
746 if (bnext == bs0) {
|
|
747 // We fall into next block; remove the Goto
|
|
748 b->_nodes.pop();
|
|
749 }
|
|
750
|
|
751 } else if( b->_num_succs == 2 ) { // Block ends in a If?
|
|
752 // Get opcode of 1st projection (matches _succs[0])
|
|
753 // Note: Since this basic block has 2 exits, the last 2 nodes must
|
|
754 // be projections (in any order), the 3rd last node must be
|
|
755 // the IfNode (we have excluded other 2-way exits such as
|
|
756 // CatchNodes already).
|
|
757 MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach();
|
|
758 ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj();
|
|
759 ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj();
|
|
760
|
|
761 // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1].
|
|
762 assert(proj0->raw_out(0) == b->_succs[0]->head(), "Mismatch successor 0");
|
|
763 assert(proj1->raw_out(0) == b->_succs[1]->head(), "Mismatch successor 1");
|
|
764
|
|
765 Block *bs1 = b->non_connector_successor(1);
|
|
766
|
|
767 // Check for neither successor block following the current
|
|
768 // block ending in a conditional. If so, move one of the
|
|
769 // successors after the current one, provided that the
|
|
770 // successor was previously unscheduled, but moveable
|
|
771 // (i.e., all paths to it involve a branch).
|
418
|
772 if( !C->do_freq_based_layout() && bnext != bs0 && bnext != bs1 ) {
|
0
|
773 // Choose the more common successor based on the probability
|
|
774 // of the conditional branch.
|
|
775 Block *bx = bs0;
|
|
776 Block *by = bs1;
|
|
777
|
|
778 // _prob is the probability of taking the true path. Make
|
|
779 // p the probability of taking successor #1.
|
|
780 float p = iff->as_MachIf()->_prob;
|
|
781 if( proj0->Opcode() == Op_IfTrue ) {
|
|
782 p = 1.0 - p;
|
|
783 }
|
|
784
|
|
785 // Prefer successor #1 if p > 0.5
|
|
786 if (p > PROB_FAIR) {
|
|
787 bx = bs1;
|
|
788 by = bs0;
|
|
789 }
|
|
790
|
|
791 // Attempt the more common successor first
|
418
|
792 if (move_to_next(bx, i)) {
|
0
|
793 bnext = bx;
|
418
|
794 } else if (move_to_next(by, i)) {
|
0
|
795 bnext = by;
|
|
796 }
|
|
797 }
|
|
798
|
|
799 // Check for conditional branching the wrong way. Negate
|
|
800 // conditional, if needed, so it falls into the following block
|
|
801 // and branches to the not-following block.
|
|
802
|
|
803 // Check for the next block being in succs[0]. We are going to branch
|
|
804 // to succs[0], so we want the fall-thru case as the next block in
|
|
805 // succs[1].
|
|
806 if (bnext == bs0) {
|
|
807 // Fall-thru case in succs[0], so flip targets in succs map
|
|
808 Block *tbs0 = b->_succs[0];
|
|
809 Block *tbs1 = b->_succs[1];
|
|
810 b->_succs.map( 0, tbs1 );
|
|
811 b->_succs.map( 1, tbs0 );
|
|
812 // Flip projection for each target
|
|
813 { ProjNode *tmp = proj0; proj0 = proj1; proj1 = tmp; }
|
|
814
|
418
|
815 } else if( bnext != bs1 ) {
|
|
816 // Need a double-branch
|
0
|
817 // The existing conditional branch need not change.
|
|
818 // Add a unconditional branch to the false target.
|
|
819 // Alas, it must appear in its own block and adding a
|
|
820 // block this late in the game is complicated. Sigh.
|
|
821 insert_goto_at(i, 1);
|
|
822 }
|
|
823
|
|
824 // Make sure we TRUE branch to the target
|
418
|
825 if( proj0->Opcode() == Op_IfFalse ) {
|
0
|
826 iff->negate();
|
418
|
827 }
|
0
|
828
|
|
829 b->_nodes.pop(); // Remove IfFalse & IfTrue projections
|
|
830 b->_nodes.pop();
|
|
831
|
|
832 } else {
|
|
833 // Multi-exit block, e.g. a switch statement
|
|
834 // But we don't need to do anything here
|
|
835 }
|
|
836 } // End of for all blocks
|
|
837 }
|
|
838
|
|
839
|
|
840 //------------------------------dump-------------------------------------------
|
|
841 #ifndef PRODUCT
|
|
842 void PhaseCFG::_dump_cfg( const Node *end, VectorSet &visited ) const {
|
|
843 const Node *x = end->is_block_proj();
|
|
844 assert( x, "not a CFG" );
|
|
845
|
|
846 // Do not visit this block again
|
|
847 if( visited.test_set(x->_idx) ) return;
|
|
848
|
|
849 // Skip through this block
|
|
850 const Node *p = x;
|
|
851 do {
|
|
852 p = p->in(0); // Move control forward
|
|
853 assert( !p->is_block_proj() || p->is_Root(), "not a CFG" );
|
|
854 } while( !p->is_block_start() );
|
|
855
|
|
856 // Recursively visit
|
|
857 for( uint i=1; i<p->req(); i++ )
|
|
858 _dump_cfg(p->in(i),visited);
|
|
859
|
|
860 // Dump the block
|
|
861 _bbs[p->_idx]->dump(&_bbs);
|
|
862 }
|
|
863
|
|
864 void PhaseCFG::dump( ) const {
|
|
865 tty->print("\n--- CFG --- %d BBs\n",_num_blocks);
|
|
866 if( _blocks.size() ) { // Did we do basic-block layout?
|
|
867 for( uint i=0; i<_num_blocks; i++ )
|
|
868 _blocks[i]->dump(&_bbs);
|
|
869 } else { // Else do it with a DFS
|
|
870 VectorSet visited(_bbs._arena);
|
|
871 _dump_cfg(_root,visited);
|
|
872 }
|
|
873 }
|
|
874
|
|
875 void PhaseCFG::dump_headers() {
|
|
876 for( uint i = 0; i < _num_blocks; i++ ) {
|
|
877 if( _blocks[i] == NULL ) continue;
|
|
878 _blocks[i]->dump_head(&_bbs);
|
|
879 }
|
|
880 }
|
|
881
|
|
882 void PhaseCFG::verify( ) const {
|
|
883 // Verify sane CFG
|
|
884 for( uint i = 0; i < _num_blocks; i++ ) {
|
|
885 Block *b = _blocks[i];
|
|
886 uint cnt = b->_nodes.size();
|
|
887 uint j;
|
|
888 for( j = 0; j < cnt; j++ ) {
|
|
889 Node *n = b->_nodes[j];
|
|
890 assert( _bbs[n->_idx] == b, "" );
|
|
891 if( j >= 1 && n->is_Mach() &&
|
|
892 n->as_Mach()->ideal_Opcode() == Op_CreateEx ) {
|
|
893 assert( j == 1 || b->_nodes[j-1]->is_Phi(),
|
|
894 "CreateEx must be first instruction in block" );
|
|
895 }
|
|
896 for( uint k = 0; k < n->req(); k++ ) {
|
|
897 Node *use = n->in(k);
|
|
898 if( use && use != n ) {
|
|
899 assert( _bbs[use->_idx] || use->is_Con(),
|
|
900 "must have block; constants for debug info ok" );
|
|
901 }
|
|
902 }
|
|
903 }
|
|
904
|
|
905 j = b->end_idx();
|
|
906 Node *bp = (Node*)b->_nodes[b->_nodes.size()-1]->is_block_proj();
|
|
907 assert( bp, "last instruction must be a block proj" );
|
|
908 assert( bp == b->_nodes[j], "wrong number of successors for this block" );
|
|
909 if( bp->is_Catch() ) {
|
|
910 while( b->_nodes[--j]->Opcode() == Op_MachProj ) ;
|
|
911 assert( b->_nodes[j]->is_Call(), "CatchProj must follow call" );
|
|
912 }
|
|
913 else if( bp->is_Mach() && bp->as_Mach()->ideal_Opcode() == Op_If ) {
|
|
914 assert( b->_num_succs == 2, "Conditional branch must have two targets");
|
|
915 }
|
|
916 }
|
|
917 }
|
|
918 #endif
|
|
919
|
|
920 //=============================================================================
|
|
921 //------------------------------UnionFind--------------------------------------
|
|
922 UnionFind::UnionFind( uint max ) : _cnt(max), _max(max), _indices(NEW_RESOURCE_ARRAY(uint,max)) {
|
|
923 Copy::zero_to_bytes( _indices, sizeof(uint)*max );
|
|
924 }
|
|
925
|
|
926 void UnionFind::extend( uint from_idx, uint to_idx ) {
|
|
927 _nesting.check();
|
|
928 if( from_idx >= _max ) {
|
|
929 uint size = 16;
|
|
930 while( size <= from_idx ) size <<=1;
|
|
931 _indices = REALLOC_RESOURCE_ARRAY( uint, _indices, _max, size );
|
|
932 _max = size;
|
|
933 }
|
|
934 while( _cnt <= from_idx ) _indices[_cnt++] = 0;
|
|
935 _indices[from_idx] = to_idx;
|
|
936 }
|
|
937
|
|
938 void UnionFind::reset( uint max ) {
|
|
939 assert( max <= max_uint, "Must fit within uint" );
|
|
940 // Force the Union-Find mapping to be at least this large
|
|
941 extend(max,0);
|
|
942 // Initialize to be the ID mapping.
|
418
|
943 for( uint i=0; i<max; i++ ) map(i,i);
|
0
|
944 }
|
|
945
|
|
946 //------------------------------Find_compress----------------------------------
|
|
947 // Straight out of Tarjan's union-find algorithm
|
|
948 uint UnionFind::Find_compress( uint idx ) {
|
|
949 uint cur = idx;
|
|
950 uint next = lookup(cur);
|
|
951 while( next != cur ) { // Scan chain of equivalences
|
|
952 assert( next < cur, "always union smaller" );
|
|
953 cur = next; // until find a fixed-point
|
|
954 next = lookup(cur);
|
|
955 }
|
|
956 // Core of union-find algorithm: update chain of
|
|
957 // equivalences to be equal to the root.
|
|
958 while( idx != next ) {
|
|
959 uint tmp = lookup(idx);
|
|
960 map(idx, next);
|
|
961 idx = tmp;
|
|
962 }
|
|
963 return idx;
|
|
964 }
|
|
965
|
|
966 //------------------------------Find_const-------------------------------------
|
|
967 // Like Find above, but no path compress, so bad asymptotic behavior
|
|
968 uint UnionFind::Find_const( uint idx ) const {
|
|
969 if( idx == 0 ) return idx; // Ignore the zero idx
|
|
970 // Off the end? This can happen during debugging dumps
|
|
971 // when data structures have not finished being updated.
|
|
972 if( idx >= _max ) return idx;
|
|
973 uint next = lookup(idx);
|
|
974 while( next != idx ) { // Scan chain of equivalences
|
|
975 idx = next; // until find a fixed-point
|
|
976 next = lookup(idx);
|
|
977 }
|
|
978 return next;
|
|
979 }
|
|
980
|
|
981 //------------------------------Union------------------------------------------
|
|
982 // union 2 sets together.
|
|
983 void UnionFind::Union( uint idx1, uint idx2 ) {
|
|
984 uint src = Find(idx1);
|
|
985 uint dst = Find(idx2);
|
|
986 assert( src, "" );
|
|
987 assert( dst, "" );
|
|
988 assert( src < _max, "oob" );
|
|
989 assert( dst < _max, "oob" );
|
|
990 assert( src < dst, "always union smaller" );
|
|
991 map(dst,src);
|
|
992 }
|
418
|
993
|
|
994 #ifndef PRODUCT
|
|
995 static void edge_dump(GrowableArray<CFGEdge *> *edges) {
|
|
996 tty->print_cr("---- Edges ----");
|
|
997 for (int i = 0; i < edges->length(); i++) {
|
|
998 CFGEdge *e = edges->at(i);
|
|
999 if (e != NULL) {
|
|
1000 edges->at(i)->dump();
|
|
1001 }
|
|
1002 }
|
|
1003 }
|
|
1004
|
|
1005 static void trace_dump(Trace *traces[], int count) {
|
|
1006 tty->print_cr("---- Traces ----");
|
|
1007 for (int i = 0; i < count; i++) {
|
|
1008 Trace *tr = traces[i];
|
|
1009 if (tr != NULL) {
|
|
1010 tr->dump();
|
|
1011 }
|
|
1012 }
|
|
1013 }
|
|
1014
|
|
1015 void Trace::dump( ) const {
|
|
1016 tty->print_cr("Trace (freq %f)", first_block()->_freq);
|
|
1017 for (Block *b = first_block(); b != NULL; b = next(b)) {
|
|
1018 tty->print(" B%d", b->_pre_order);
|
|
1019 if (b->head()->is_Loop()) {
|
|
1020 tty->print(" (L%d)", b->compute_loop_alignment());
|
|
1021 }
|
|
1022 if (b->has_loop_alignment()) {
|
|
1023 tty->print(" (T%d)", b->code_alignment());
|
|
1024 }
|
|
1025 }
|
|
1026 tty->cr();
|
|
1027 }
|
|
1028
|
|
1029 void CFGEdge::dump( ) const {
|
|
1030 tty->print(" B%d --> B%d Freq: %f out:%3d%% in:%3d%% State: ",
|
|
1031 from()->_pre_order, to()->_pre_order, freq(), _from_pct, _to_pct);
|
|
1032 switch(state()) {
|
|
1033 case connected:
|
|
1034 tty->print("connected");
|
|
1035 break;
|
|
1036 case open:
|
|
1037 tty->print("open");
|
|
1038 break;
|
|
1039 case interior:
|
|
1040 tty->print("interior");
|
|
1041 break;
|
|
1042 }
|
|
1043 if (infrequent()) {
|
|
1044 tty->print(" infrequent");
|
|
1045 }
|
|
1046 tty->cr();
|
|
1047 }
|
|
1048 #endif
|
|
1049
|
|
1050 //=============================================================================
|
|
1051
|
|
1052 //------------------------------edge_order-------------------------------------
|
|
1053 // Comparison function for edges
|
|
1054 static int edge_order(CFGEdge **e0, CFGEdge **e1) {
|
|
1055 float freq0 = (*e0)->freq();
|
|
1056 float freq1 = (*e1)->freq();
|
|
1057 if (freq0 != freq1) {
|
|
1058 return freq0 > freq1 ? -1 : 1;
|
|
1059 }
|
|
1060
|
|
1061 int dist0 = (*e0)->to()->_rpo - (*e0)->from()->_rpo;
|
|
1062 int dist1 = (*e1)->to()->_rpo - (*e1)->from()->_rpo;
|
|
1063
|
|
1064 return dist1 - dist0;
|
|
1065 }
|
|
1066
|
|
1067 //------------------------------trace_frequency_order--------------------------
|
|
1068 // Comparison function for edges
|
|
1069 static int trace_frequency_order(const void *p0, const void *p1) {
|
|
1070 Trace *tr0 = *(Trace **) p0;
|
|
1071 Trace *tr1 = *(Trace **) p1;
|
|
1072 Block *b0 = tr0->first_block();
|
|
1073 Block *b1 = tr1->first_block();
|
|
1074
|
|
1075 // The trace of connector blocks goes at the end;
|
|
1076 // we only expect one such trace
|
|
1077 if (b0->is_connector() != b1->is_connector()) {
|
|
1078 return b1->is_connector() ? -1 : 1;
|
|
1079 }
|
|
1080
|
|
1081 // Pull more frequently executed blocks to the beginning
|
|
1082 float freq0 = b0->_freq;
|
|
1083 float freq1 = b1->_freq;
|
|
1084 if (freq0 != freq1) {
|
|
1085 return freq0 > freq1 ? -1 : 1;
|
|
1086 }
|
|
1087
|
|
1088 int diff = tr0->first_block()->_rpo - tr1->first_block()->_rpo;
|
|
1089
|
|
1090 return diff;
|
|
1091 }
|
|
1092
|
|
1093 //------------------------------find_edges-------------------------------------
|
|
1094 // Find edges of interest, i.e, those which can fall through. Presumes that
|
|
1095 // edges which don't fall through are of low frequency and can be generally
|
|
1096 // ignored. Initialize the list of traces.
|
|
1097 void PhaseBlockLayout::find_edges()
|
|
1098 {
|
|
1099 // Walk the blocks, creating edges and Traces
|
|
1100 uint i;
|
|
1101 Trace *tr = NULL;
|
|
1102 for (i = 0; i < _cfg._num_blocks; i++) {
|
|
1103 Block *b = _cfg._blocks[i];
|
|
1104 tr = new Trace(b, next, prev);
|
|
1105 traces[tr->id()] = tr;
|
|
1106
|
|
1107 // All connector blocks should be at the end of the list
|
|
1108 if (b->is_connector()) break;
|
|
1109
|
|
1110 // If this block and the next one have a one-to-one successor
|
|
1111 // predecessor relationship, simply append the next block
|
|
1112 int nfallthru = b->num_fall_throughs();
|
|
1113 while (nfallthru == 1 &&
|
|
1114 b->succ_fall_through(0)) {
|
|
1115 Block *n = b->_succs[0];
|
|
1116
|
|
1117 // Skip over single-entry connector blocks, we don't want to
|
|
1118 // add them to the trace.
|
|
1119 while (n->is_connector() && n->num_preds() == 1) {
|
|
1120 n = n->_succs[0];
|
|
1121 }
|
|
1122
|
|
1123 // We see a merge point, so stop search for the next block
|
|
1124 if (n->num_preds() != 1) break;
|
|
1125
|
|
1126 i++;
|
|
1127 assert(n = _cfg._blocks[i], "expecting next block");
|
|
1128 tr->append(n);
|
|
1129 uf->map(n->_pre_order, tr->id());
|
|
1130 traces[n->_pre_order] = NULL;
|
|
1131 nfallthru = b->num_fall_throughs();
|
|
1132 b = n;
|
|
1133 }
|
|
1134
|
|
1135 if (nfallthru > 0) {
|
|
1136 // Create a CFGEdge for each outgoing
|
|
1137 // edge that could be a fall-through.
|
|
1138 for (uint j = 0; j < b->_num_succs; j++ ) {
|
|
1139 if (b->succ_fall_through(j)) {
|
|
1140 Block *target = b->non_connector_successor(j);
|
|
1141 float freq = b->_freq * b->succ_prob(j);
|
|
1142 int from_pct = (int) ((100 * freq) / b->_freq);
|
|
1143 int to_pct = (int) ((100 * freq) / target->_freq);
|
|
1144 edges->append(new CFGEdge(b, target, freq, from_pct, to_pct));
|
|
1145 }
|
|
1146 }
|
|
1147 }
|
|
1148 }
|
|
1149
|
|
1150 // Group connector blocks into one trace
|
|
1151 for (i++; i < _cfg._num_blocks; i++) {
|
|
1152 Block *b = _cfg._blocks[i];
|
|
1153 assert(b->is_connector(), "connector blocks at the end");
|
|
1154 tr->append(b);
|
|
1155 uf->map(b->_pre_order, tr->id());
|
|
1156 traces[b->_pre_order] = NULL;
|
|
1157 }
|
|
1158 }
|
|
1159
|
|
1160 //------------------------------union_traces----------------------------------
|
|
1161 // Union two traces together in uf, and null out the trace in the list
|
|
1162 void PhaseBlockLayout::union_traces(Trace* updated_trace, Trace* old_trace)
|
|
1163 {
|
|
1164 uint old_id = old_trace->id();
|
|
1165 uint updated_id = updated_trace->id();
|
|
1166
|
|
1167 uint lo_id = updated_id;
|
|
1168 uint hi_id = old_id;
|
|
1169
|
|
1170 // If from is greater than to, swap values to meet
|
|
1171 // UnionFind guarantee.
|
|
1172 if (updated_id > old_id) {
|
|
1173 lo_id = old_id;
|
|
1174 hi_id = updated_id;
|
|
1175
|
|
1176 // Fix up the trace ids
|
|
1177 traces[lo_id] = traces[updated_id];
|
|
1178 updated_trace->set_id(lo_id);
|
|
1179 }
|
|
1180
|
|
1181 // Union the lower with the higher and remove the pointer
|
|
1182 // to the higher.
|
|
1183 uf->Union(lo_id, hi_id);
|
|
1184 traces[hi_id] = NULL;
|
|
1185 }
|
|
1186
|
|
1187 //------------------------------grow_traces-------------------------------------
|
|
1188 // Append traces together via the most frequently executed edges
|
|
1189 void PhaseBlockLayout::grow_traces()
|
|
1190 {
|
|
1191 // Order the edges, and drive the growth of Traces via the most
|
|
1192 // frequently executed edges.
|
|
1193 edges->sort(edge_order);
|
|
1194 for (int i = 0; i < edges->length(); i++) {
|
|
1195 CFGEdge *e = edges->at(i);
|
|
1196
|
|
1197 if (e->state() != CFGEdge::open) continue;
|
|
1198
|
|
1199 Block *src_block = e->from();
|
|
1200 Block *targ_block = e->to();
|
|
1201
|
|
1202 // Don't grow traces along backedges?
|
|
1203 if (!BlockLayoutRotateLoops) {
|
|
1204 if (targ_block->_rpo <= src_block->_rpo) {
|
|
1205 targ_block->set_loop_alignment(targ_block);
|
|
1206 continue;
|
|
1207 }
|
|
1208 }
|
|
1209
|
|
1210 Trace *src_trace = trace(src_block);
|
|
1211 Trace *targ_trace = trace(targ_block);
|
|
1212
|
|
1213 // If the edge in question can join two traces at their ends,
|
|
1214 // append one trace to the other.
|
|
1215 if (src_trace->last_block() == src_block) {
|
|
1216 if (src_trace == targ_trace) {
|
|
1217 e->set_state(CFGEdge::interior);
|
|
1218 if (targ_trace->backedge(e)) {
|
|
1219 // Reset i to catch any newly eligible edge
|
|
1220 // (Or we could remember the first "open" edge, and reset there)
|
|
1221 i = 0;
|
|
1222 }
|
|
1223 } else if (targ_trace->first_block() == targ_block) {
|
|
1224 e->set_state(CFGEdge::connected);
|
|
1225 src_trace->append(targ_trace);
|
|
1226 union_traces(src_trace, targ_trace);
|
|
1227 }
|
|
1228 }
|
|
1229 }
|
|
1230 }
|
|
1231
|
|
1232 //------------------------------merge_traces-----------------------------------
|
|
1233 // Embed one trace into another, if the fork or join points are sufficiently
|
|
1234 // balanced.
|
|
1235 void PhaseBlockLayout::merge_traces(bool fall_thru_only)
|
|
1236 {
|
|
1237 // Walk the edge list a another time, looking at unprocessed edges.
|
|
1238 // Fold in diamonds
|
|
1239 for (int i = 0; i < edges->length(); i++) {
|
|
1240 CFGEdge *e = edges->at(i);
|
|
1241
|
|
1242 if (e->state() != CFGEdge::open) continue;
|
|
1243 if (fall_thru_only) {
|
|
1244 if (e->infrequent()) continue;
|
|
1245 }
|
|
1246
|
|
1247 Block *src_block = e->from();
|
|
1248 Trace *src_trace = trace(src_block);
|
|
1249 bool src_at_tail = src_trace->last_block() == src_block;
|
|
1250
|
|
1251 Block *targ_block = e->to();
|
|
1252 Trace *targ_trace = trace(targ_block);
|
|
1253 bool targ_at_start = targ_trace->first_block() == targ_block;
|
|
1254
|
|
1255 if (src_trace == targ_trace) {
|
|
1256 // This may be a loop, but we can't do much about it.
|
|
1257 e->set_state(CFGEdge::interior);
|
|
1258 continue;
|
|
1259 }
|
|
1260
|
|
1261 if (fall_thru_only) {
|
|
1262 // If the edge links the middle of two traces, we can't do anything.
|
|
1263 // Mark the edge and continue.
|
|
1264 if (!src_at_tail & !targ_at_start) {
|
|
1265 continue;
|
|
1266 }
|
|
1267
|
|
1268 // Don't grow traces along backedges?
|
|
1269 if (!BlockLayoutRotateLoops && (targ_block->_rpo <= src_block->_rpo)) {
|
|
1270 continue;
|
|
1271 }
|
|
1272
|
|
1273 // If both ends of the edge are available, why didn't we handle it earlier?
|
|
1274 assert(src_at_tail ^ targ_at_start, "Should have caught this edge earlier.");
|
|
1275
|
|
1276 if (targ_at_start) {
|
|
1277 // Insert the "targ" trace in the "src" trace if the insertion point
|
|
1278 // is a two way branch.
|
|
1279 // Better profitability check possible, but may not be worth it.
|
|
1280 // Someday, see if the this "fork" has an associated "join";
|
|
1281 // then make a policy on merging this trace at the fork or join.
|
|
1282 // For example, other things being equal, it may be better to place this
|
|
1283 // trace at the join point if the "src" trace ends in a two-way, but
|
|
1284 // the insertion point is one-way.
|
|
1285 assert(src_block->num_fall_throughs() == 2, "unexpected diamond");
|
|
1286 e->set_state(CFGEdge::connected);
|
|
1287 src_trace->insert_after(src_block, targ_trace);
|
|
1288 union_traces(src_trace, targ_trace);
|
|
1289 } else if (src_at_tail) {
|
|
1290 if (src_trace != trace(_cfg._broot)) {
|
|
1291 e->set_state(CFGEdge::connected);
|
|
1292 targ_trace->insert_before(targ_block, src_trace);
|
|
1293 union_traces(targ_trace, src_trace);
|
|
1294 }
|
|
1295 }
|
|
1296 } else if (e->state() == CFGEdge::open) {
|
|
1297 // Append traces, even without a fall-thru connection.
|
|
1298 // But leave root entry at the begining of the block list.
|
|
1299 if (targ_trace != trace(_cfg._broot)) {
|
|
1300 e->set_state(CFGEdge::connected);
|
|
1301 src_trace->append(targ_trace);
|
|
1302 union_traces(src_trace, targ_trace);
|
|
1303 }
|
|
1304 }
|
|
1305 }
|
|
1306 }
|
|
1307
|
|
1308 //----------------------------reorder_traces-----------------------------------
|
|
1309 // Order the sequence of the traces in some desirable way, and fixup the
|
|
1310 // jumps at the end of each block.
|
|
1311 void PhaseBlockLayout::reorder_traces(int count)
|
|
1312 {
|
|
1313 ResourceArea *area = Thread::current()->resource_area();
|
|
1314 Trace ** new_traces = NEW_ARENA_ARRAY(area, Trace *, count);
|
|
1315 Block_List worklist;
|
|
1316 int new_count = 0;
|
|
1317
|
|
1318 // Compact the traces.
|
|
1319 for (int i = 0; i < count; i++) {
|
|
1320 Trace *tr = traces[i];
|
|
1321 if (tr != NULL) {
|
|
1322 new_traces[new_count++] = tr;
|
|
1323 }
|
|
1324 }
|
|
1325
|
|
1326 // The entry block should be first on the new trace list.
|
|
1327 Trace *tr = trace(_cfg._broot);
|
|
1328 assert(tr == new_traces[0], "entry trace misplaced");
|
|
1329
|
|
1330 // Sort the new trace list by frequency
|
|
1331 qsort(new_traces + 1, new_count - 1, sizeof(new_traces[0]), trace_frequency_order);
|
|
1332
|
|
1333 // Patch up the successor blocks
|
|
1334 _cfg._blocks.reset();
|
|
1335 _cfg._num_blocks = 0;
|
|
1336 for (int i = 0; i < new_count; i++) {
|
|
1337 Trace *tr = new_traces[i];
|
|
1338 if (tr != NULL) {
|
|
1339 tr->fixup_blocks(_cfg);
|
|
1340 }
|
|
1341 }
|
|
1342 }
|
|
1343
|
|
1344 //------------------------------PhaseBlockLayout-------------------------------
|
|
1345 // Order basic blocks based on frequency
|
|
1346 PhaseBlockLayout::PhaseBlockLayout(PhaseCFG &cfg) :
|
|
1347 Phase(BlockLayout),
|
|
1348 _cfg(cfg)
|
|
1349 {
|
|
1350 ResourceMark rm;
|
|
1351 ResourceArea *area = Thread::current()->resource_area();
|
|
1352
|
|
1353 // List of traces
|
|
1354 int size = _cfg._num_blocks + 1;
|
|
1355 traces = NEW_ARENA_ARRAY(area, Trace *, size);
|
|
1356 memset(traces, 0, size*sizeof(Trace*));
|
|
1357 next = NEW_ARENA_ARRAY(area, Block *, size);
|
|
1358 memset(next, 0, size*sizeof(Block *));
|
|
1359 prev = NEW_ARENA_ARRAY(area, Block *, size);
|
|
1360 memset(prev , 0, size*sizeof(Block *));
|
|
1361
|
|
1362 // List of edges
|
|
1363 edges = new GrowableArray<CFGEdge*>;
|
|
1364
|
|
1365 // Mapping block index --> block_trace
|
|
1366 uf = new UnionFind(size);
|
|
1367 uf->reset(size);
|
|
1368
|
|
1369 // Find edges and create traces.
|
|
1370 find_edges();
|
|
1371
|
|
1372 // Grow traces at their ends via most frequent edges.
|
|
1373 grow_traces();
|
|
1374
|
|
1375 // Merge one trace into another, but only at fall-through points.
|
|
1376 // This may make diamonds and other related shapes in a trace.
|
|
1377 merge_traces(true);
|
|
1378
|
|
1379 // Run merge again, allowing two traces to be catenated, even if
|
|
1380 // one does not fall through into the other. This appends loosely
|
|
1381 // related traces to be near each other.
|
|
1382 merge_traces(false);
|
|
1383
|
|
1384 // Re-order all the remaining traces by frequency
|
|
1385 reorder_traces(size);
|
|
1386
|
|
1387 assert(_cfg._num_blocks >= (uint) (size - 1), "number of blocks can not shrink");
|
|
1388 }
|
|
1389
|
|
1390
|
|
1391 //------------------------------backedge---------------------------------------
|
|
1392 // Edge e completes a loop in a trace. If the target block is head of the
|
|
1393 // loop, rotate the loop block so that the loop ends in a conditional branch.
|
|
1394 bool Trace::backedge(CFGEdge *e) {
|
|
1395 bool loop_rotated = false;
|
|
1396 Block *src_block = e->from();
|
|
1397 Block *targ_block = e->to();
|
|
1398
|
|
1399 assert(last_block() == src_block, "loop discovery at back branch");
|
|
1400 if (first_block() == targ_block) {
|
|
1401 if (BlockLayoutRotateLoops && last_block()->num_fall_throughs() < 2) {
|
|
1402 // Find the last block in the trace that has a conditional
|
|
1403 // branch.
|
|
1404 Block *b;
|
|
1405 for (b = last_block(); b != NULL; b = prev(b)) {
|
|
1406 if (b->num_fall_throughs() == 2) {
|
|
1407 break;
|
|
1408 }
|
|
1409 }
|
|
1410
|
|
1411 if (b != last_block() && b != NULL) {
|
|
1412 loop_rotated = true;
|
|
1413
|
|
1414 // Rotate the loop by doing two-part linked-list surgery.
|
|
1415 append(first_block());
|
|
1416 break_loop_after(b);
|
|
1417 }
|
|
1418 }
|
|
1419
|
|
1420 // Backbranch to the top of a trace
|
|
1421 // Scroll foward through the trace from the targ_block. If we find
|
|
1422 // a loop head before another loop top, use the the loop head alignment.
|
|
1423 for (Block *b = targ_block; b != NULL; b = next(b)) {
|
|
1424 if (b->has_loop_alignment()) {
|
|
1425 break;
|
|
1426 }
|
|
1427 if (b->head()->is_Loop()) {
|
|
1428 targ_block = b;
|
|
1429 break;
|
|
1430 }
|
|
1431 }
|
|
1432
|
|
1433 first_block()->set_loop_alignment(targ_block);
|
|
1434
|
|
1435 } else {
|
|
1436 // Backbranch into the middle of a trace
|
|
1437 targ_block->set_loop_alignment(targ_block);
|
|
1438 }
|
|
1439
|
|
1440 return loop_rotated;
|
|
1441 }
|
|
1442
|
|
1443 //------------------------------fixup_blocks-----------------------------------
|
|
1444 // push blocks onto the CFG list
|
|
1445 // ensure that blocks have the correct two-way branch sense
|
|
1446 void Trace::fixup_blocks(PhaseCFG &cfg) {
|
|
1447 Block *last = last_block();
|
|
1448 for (Block *b = first_block(); b != NULL; b = next(b)) {
|
|
1449 cfg._blocks.push(b);
|
|
1450 cfg._num_blocks++;
|
|
1451 if (!b->is_connector()) {
|
|
1452 int nfallthru = b->num_fall_throughs();
|
|
1453 if (b != last) {
|
|
1454 if (nfallthru == 2) {
|
|
1455 // Ensure that the sense of the branch is correct
|
|
1456 Block *bnext = next(b);
|
|
1457 Block *bs0 = b->non_connector_successor(0);
|
|
1458
|
|
1459 MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach();
|
|
1460 ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj();
|
|
1461 ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj();
|
|
1462
|
|
1463 if (bnext == bs0) {
|
|
1464 // Fall-thru case in succs[0], should be in succs[1]
|
|
1465
|
|
1466 // Flip targets in _succs map
|
|
1467 Block *tbs0 = b->_succs[0];
|
|
1468 Block *tbs1 = b->_succs[1];
|
|
1469 b->_succs.map( 0, tbs1 );
|
|
1470 b->_succs.map( 1, tbs0 );
|
|
1471
|
|
1472 // Flip projections to match targets
|
|
1473 b->_nodes.map(b->_nodes.size()-2, proj1);
|
|
1474 b->_nodes.map(b->_nodes.size()-1, proj0);
|
|
1475 }
|
|
1476 }
|
|
1477 }
|
|
1478 }
|
|
1479 }
|
|
1480 }
|