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1 /* |
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2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #include "precompiled.hpp" |
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26 #include "libadt/vectset.hpp" |
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27 #include "memory/allocation.inline.hpp" |
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28 #include "opto/block.hpp" |
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29 #include "opto/cfgnode.hpp" |
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30 #include "opto/chaitin.hpp" |
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31 #include "opto/loopnode.hpp" |
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32 #include "opto/machnode.hpp" |
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33 #include "opto/matcher.hpp" |
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34 #include "opto/opcodes.hpp" |
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35 #include "opto/rootnode.hpp" |
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36 #include "utilities/copy.hpp" |
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37 |
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38 void Block_Array::grow( uint i ) { |
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39 assert(i >= Max(), "must be an overflow"); |
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40 debug_only(_limit = i+1); |
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41 if( i < _size ) return; |
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42 if( !_size ) { |
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43 _size = 1; |
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44 _blocks = (Block**)_arena->Amalloc( _size * sizeof(Block*) ); |
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45 _blocks[0] = NULL; |
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46 } |
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47 uint old = _size; |
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48 while( i >= _size ) _size <<= 1; // Double to fit |
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49 _blocks = (Block**)_arena->Arealloc( _blocks, old*sizeof(Block*),_size*sizeof(Block*)); |
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50 Copy::zero_to_bytes( &_blocks[old], (_size-old)*sizeof(Block*) ); |
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51 } |
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52 |
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53 void Block_List::remove(uint i) { |
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54 assert(i < _cnt, "index out of bounds"); |
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55 Copy::conjoint_words_to_lower((HeapWord*)&_blocks[i+1], (HeapWord*)&_blocks[i], ((_cnt-i-1)*sizeof(Block*))); |
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56 pop(); // shrink list by one block |
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57 } |
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58 |
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59 void Block_List::insert(uint i, Block *b) { |
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60 push(b); // grow list by one block |
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61 Copy::conjoint_words_to_higher((HeapWord*)&_blocks[i], (HeapWord*)&_blocks[i+1], ((_cnt-i-1)*sizeof(Block*))); |
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62 _blocks[i] = b; |
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63 } |
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64 |
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65 #ifndef PRODUCT |
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66 void Block_List::print() { |
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67 for (uint i=0; i < size(); i++) { |
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68 tty->print("B%d ", _blocks[i]->_pre_order); |
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69 } |
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70 tty->print("size = %d\n", size()); |
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71 } |
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72 #endif |
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73 |
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74 uint Block::code_alignment() { |
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75 // Check for Root block |
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76 if (_pre_order == 0) return CodeEntryAlignment; |
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77 // Check for Start block |
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78 if (_pre_order == 1) return InteriorEntryAlignment; |
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79 // Check for loop alignment |
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80 if (has_loop_alignment()) return loop_alignment(); |
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81 |
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82 return relocInfo::addr_unit(); // no particular alignment |
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83 } |
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84 |
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85 uint Block::compute_loop_alignment() { |
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86 Node *h = head(); |
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87 int unit_sz = relocInfo::addr_unit(); |
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88 if (h->is_Loop() && h->as_Loop()->is_inner_loop()) { |
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89 // Pre- and post-loops have low trip count so do not bother with |
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90 // NOPs for align loop head. The constants are hidden from tuning |
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91 // but only because my "divide by 4" heuristic surely gets nearly |
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92 // all possible gain (a "do not align at all" heuristic has a |
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93 // chance of getting a really tiny gain). |
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94 if (h->is_CountedLoop() && (h->as_CountedLoop()->is_pre_loop() || |
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95 h->as_CountedLoop()->is_post_loop())) { |
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96 return (OptoLoopAlignment > 4*unit_sz) ? (OptoLoopAlignment>>2) : unit_sz; |
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97 } |
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98 // Loops with low backedge frequency should not be aligned. |
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99 Node *n = h->in(LoopNode::LoopBackControl)->in(0); |
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100 if (n->is_MachIf() && n->as_MachIf()->_prob < 0.01) { |
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101 return unit_sz; // Loop does not loop, more often than not! |
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102 } |
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103 return OptoLoopAlignment; // Otherwise align loop head |
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104 } |
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105 |
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106 return unit_sz; // no particular alignment |
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107 } |
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108 |
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109 // Compute the size of first 'inst_cnt' instructions in this block. |
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110 // Return the number of instructions left to compute if the block has |
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111 // less then 'inst_cnt' instructions. Stop, and return 0 if sum_size |
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112 // exceeds OptoLoopAlignment. |
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113 uint Block::compute_first_inst_size(uint& sum_size, uint inst_cnt, |
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114 PhaseRegAlloc* ra) { |
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115 uint last_inst = number_of_nodes(); |
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116 for( uint j = 0; j < last_inst && inst_cnt > 0; j++ ) { |
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117 uint inst_size = get_node(j)->size(ra); |
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118 if( inst_size > 0 ) { |
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119 inst_cnt--; |
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120 uint sz = sum_size + inst_size; |
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121 if( sz <= (uint)OptoLoopAlignment ) { |
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122 // Compute size of instructions which fit into fetch buffer only |
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123 // since all inst_cnt instructions will not fit even if we align them. |
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124 sum_size = sz; |
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125 } else { |
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126 return 0; |
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127 } |
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128 } |
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129 } |
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130 return inst_cnt; |
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131 } |
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132 |
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133 uint Block::find_node( const Node *n ) const { |
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134 for( uint i = 0; i < number_of_nodes(); i++ ) { |
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135 if( get_node(i) == n ) |
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136 return i; |
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137 } |
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138 ShouldNotReachHere(); |
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139 return 0; |
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140 } |
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141 |
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142 // Find and remove n from block list |
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143 void Block::find_remove( const Node *n ) { |
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144 remove_node(find_node(n)); |
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145 } |
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146 |
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147 bool Block::contains(const Node *n) const { |
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148 return _nodes.contains(n); |
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149 } |
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150 |
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151 // Return empty status of a block. Empty blocks contain only the head, other |
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152 // ideal nodes, and an optional trailing goto. |
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153 int Block::is_Empty() const { |
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154 |
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155 // Root or start block is not considered empty |
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156 if (head()->is_Root() || head()->is_Start()) { |
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157 return not_empty; |
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158 } |
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159 |
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160 int success_result = completely_empty; |
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161 int end_idx = number_of_nodes() - 1; |
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162 |
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163 // Check for ending goto |
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164 if ((end_idx > 0) && (get_node(end_idx)->is_MachGoto())) { |
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165 success_result = empty_with_goto; |
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166 end_idx--; |
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167 } |
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168 |
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169 // Unreachable blocks are considered empty |
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170 if (num_preds() <= 1) { |
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171 return success_result; |
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172 } |
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173 |
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174 // Ideal nodes are allowable in empty blocks: skip them Only MachNodes |
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175 // turn directly into code, because only MachNodes have non-trivial |
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176 // emit() functions. |
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177 while ((end_idx > 0) && !get_node(end_idx)->is_Mach()) { |
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178 end_idx--; |
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179 } |
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180 |
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181 // No room for any interesting instructions? |
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182 if (end_idx == 0) { |
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183 return success_result; |
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184 } |
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185 |
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186 return not_empty; |
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187 } |
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188 |
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189 // Return true if the block's code implies that it is likely to be |
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190 // executed infrequently. Check to see if the block ends in a Halt or |
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191 // a low probability call. |
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192 bool Block::has_uncommon_code() const { |
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193 Node* en = end(); |
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194 |
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195 if (en->is_MachGoto()) |
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196 en = en->in(0); |
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197 if (en->is_Catch()) |
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198 en = en->in(0); |
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199 if (en->is_MachProj() && en->in(0)->is_MachCall()) { |
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200 MachCallNode* call = en->in(0)->as_MachCall(); |
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201 if (call->cnt() != COUNT_UNKNOWN && call->cnt() <= PROB_UNLIKELY_MAG(4)) { |
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202 // This is true for slow-path stubs like new_{instance,array}, |
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203 // slow_arraycopy, complete_monitor_locking, uncommon_trap. |
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204 // The magic number corresponds to the probability of an uncommon_trap, |
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205 // even though it is a count not a probability. |
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206 return true; |
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207 } |
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208 } |
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209 |
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210 int op = en->is_Mach() ? en->as_Mach()->ideal_Opcode() : en->Opcode(); |
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211 return op == Op_Halt; |
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212 } |
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213 |
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214 // True if block is low enough frequency or guarded by a test which |
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215 // mostly does not go here. |
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216 bool PhaseCFG::is_uncommon(const Block* block) { |
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217 // Initial blocks must never be moved, so are never uncommon. |
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218 if (block->head()->is_Root() || block->head()->is_Start()) return false; |
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219 |
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220 // Check for way-low freq |
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221 if(block->_freq < BLOCK_FREQUENCY(0.00001f) ) return true; |
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222 |
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223 // Look for code shape indicating uncommon_trap or slow path |
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224 if (block->has_uncommon_code()) return true; |
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225 |
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226 const float epsilon = 0.05f; |
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227 const float guard_factor = PROB_UNLIKELY_MAG(4) / (1.f - epsilon); |
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228 uint uncommon_preds = 0; |
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229 uint freq_preds = 0; |
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230 uint uncommon_for_freq_preds = 0; |
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231 |
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232 for( uint i=1; i< block->num_preds(); i++ ) { |
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233 Block* guard = get_block_for_node(block->pred(i)); |
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234 // Check to see if this block follows its guard 1 time out of 10000 |
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235 // or less. |
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236 // |
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237 // See list of magnitude-4 unlikely probabilities in cfgnode.hpp which |
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238 // we intend to be "uncommon", such as slow-path TLE allocation, |
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239 // predicted call failure, and uncommon trap triggers. |
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240 // |
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241 // Use an epsilon value of 5% to allow for variability in frequency |
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242 // predictions and floating point calculations. The net effect is |
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243 // that guard_factor is set to 9500. |
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244 // |
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245 // Ignore low-frequency blocks. |
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246 // The next check is (guard->_freq < 1.e-5 * 9500.). |
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247 if(guard->_freq*BLOCK_FREQUENCY(guard_factor) < BLOCK_FREQUENCY(0.00001f)) { |
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248 uncommon_preds++; |
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249 } else { |
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250 freq_preds++; |
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251 if(block->_freq < guard->_freq * guard_factor ) { |
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252 uncommon_for_freq_preds++; |
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253 } |
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254 } |
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255 } |
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256 if( block->num_preds() > 1 && |
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257 // The block is uncommon if all preds are uncommon or |
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258 (uncommon_preds == (block->num_preds()-1) || |
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259 // it is uncommon for all frequent preds. |
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260 uncommon_for_freq_preds == freq_preds) ) { |
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261 return true; |
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262 } |
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263 return false; |
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264 } |
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265 |
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266 #ifndef PRODUCT |
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267 void Block::dump_bidx(const Block* orig, outputStream* st) const { |
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268 if (_pre_order) st->print("B%d",_pre_order); |
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269 else st->print("N%d", head()->_idx); |
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270 |
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271 if (Verbose && orig != this) { |
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272 // Dump the original block's idx |
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273 st->print(" ("); |
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274 orig->dump_bidx(orig, st); |
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275 st->print(")"); |
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276 } |
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277 } |
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278 |
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279 void Block::dump_pred(const PhaseCFG* cfg, Block* orig, outputStream* st) const { |
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280 if (is_connector()) { |
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281 for (uint i=1; i<num_preds(); i++) { |
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282 Block *p = cfg->get_block_for_node(pred(i)); |
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283 p->dump_pred(cfg, orig, st); |
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284 } |
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285 } else { |
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286 dump_bidx(orig, st); |
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287 st->print(" "); |
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288 } |
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289 } |
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290 |
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291 void Block::dump_head(const PhaseCFG* cfg, outputStream* st) const { |
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292 // Print the basic block |
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293 dump_bidx(this, st); |
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294 st->print(": #\t"); |
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295 |
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296 // Print the incoming CFG edges and the outgoing CFG edges |
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297 for( uint i=0; i<_num_succs; i++ ) { |
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298 non_connector_successor(i)->dump_bidx(_succs[i], st); |
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299 st->print(" "); |
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300 } |
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301 st->print("<- "); |
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302 if( head()->is_block_start() ) { |
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303 for (uint i=1; i<num_preds(); i++) { |
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304 Node *s = pred(i); |
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305 if (cfg != NULL) { |
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306 Block *p = cfg->get_block_for_node(s); |
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307 p->dump_pred(cfg, p, st); |
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308 } else { |
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309 while (!s->is_block_start()) |
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310 s = s->in(0); |
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311 st->print("N%d ", s->_idx ); |
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312 } |
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313 } |
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314 } else { |
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315 st->print("BLOCK HEAD IS JUNK "); |
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316 } |
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317 |
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318 // Print loop, if any |
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319 const Block *bhead = this; // Head of self-loop |
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320 Node *bh = bhead->head(); |
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321 |
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322 if ((cfg != NULL) && bh->is_Loop() && !head()->is_Root()) { |
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323 LoopNode *loop = bh->as_Loop(); |
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324 const Block *bx = cfg->get_block_for_node(loop->in(LoopNode::LoopBackControl)); |
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325 while (bx->is_connector()) { |
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326 bx = cfg->get_block_for_node(bx->pred(1)); |
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327 } |
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328 st->print("\tLoop: B%d-B%d ", bhead->_pre_order, bx->_pre_order); |
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329 // Dump any loop-specific bits, especially for CountedLoops. |
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330 loop->dump_spec(st); |
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331 } else if (has_loop_alignment()) { |
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332 st->print(" top-of-loop"); |
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333 } |
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334 st->print(" Freq: %g",_freq); |
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335 if( Verbose || WizardMode ) { |
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336 st->print(" IDom: %d/#%d", _idom ? _idom->_pre_order : 0, _dom_depth); |
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337 st->print(" RegPressure: %d",_reg_pressure); |
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338 st->print(" IHRP Index: %d",_ihrp_index); |
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339 st->print(" FRegPressure: %d",_freg_pressure); |
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340 st->print(" FHRP Index: %d",_fhrp_index); |
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341 } |
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342 st->cr(); |
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343 } |
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344 |
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345 void Block::dump() const { |
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346 dump(NULL); |
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347 } |
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348 |
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349 void Block::dump(const PhaseCFG* cfg) const { |
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350 dump_head(cfg); |
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351 for (uint i=0; i< number_of_nodes(); i++) { |
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352 get_node(i)->dump(); |
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353 } |
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354 tty->print("\n"); |
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355 } |
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356 #endif |
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357 |
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358 PhaseCFG::PhaseCFG(Arena* arena, RootNode* root, Matcher& matcher) |
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359 : Phase(CFG) |
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360 , _block_arena(arena) |
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361 , _root(root) |
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362 , _matcher(matcher) |
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363 , _node_to_block_mapping(arena) |
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364 , _node_latency(NULL) |
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365 #ifndef PRODUCT |
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366 , _trace_opto_pipelining(TraceOptoPipelining || C->method_has_option("TraceOptoPipelining")) |
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367 #endif |
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368 #ifdef ASSERT |
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369 , _raw_oops(arena) |
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370 #endif |
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371 { |
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372 ResourceMark rm; |
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373 // I'll need a few machine-specific GotoNodes. Make an Ideal GotoNode, |
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374 // then Match it into a machine-specific Node. Then clone the machine |
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375 // Node on demand. |
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376 Node *x = new (C) GotoNode(NULL); |
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377 x->init_req(0, x); |
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378 _goto = matcher.match_tree(x); |
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379 assert(_goto != NULL, ""); |
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380 _goto->set_req(0,_goto); |
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381 |
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382 // Build the CFG in Reverse Post Order |
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383 _number_of_blocks = build_cfg(); |
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384 _root_block = get_block_for_node(_root); |
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385 } |
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386 |
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387 // Build a proper looking CFG. Make every block begin with either a StartNode |
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388 // or a RegionNode. Make every block end with either a Goto, If or Return. |
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389 // The RootNode both starts and ends it's own block. Do this with a recursive |
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390 // backwards walk over the control edges. |
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391 uint PhaseCFG::build_cfg() { |
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392 Arena *a = Thread::current()->resource_area(); |
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393 VectorSet visited(a); |
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394 |
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395 // Allocate stack with enough space to avoid frequent realloc |
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396 Node_Stack nstack(a, C->unique() >> 1); |
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397 nstack.push(_root, 0); |
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398 uint sum = 0; // Counter for blocks |
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399 |
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400 while (nstack.is_nonempty()) { |
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401 // node and in's index from stack's top |
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402 // 'np' is _root (see above) or RegionNode, StartNode: we push on stack |
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403 // only nodes which point to the start of basic block (see below). |
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404 Node *np = nstack.node(); |
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405 // idx > 0, except for the first node (_root) pushed on stack |
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406 // at the beginning when idx == 0. |
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407 // We will use the condition (idx == 0) later to end the build. |
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408 uint idx = nstack.index(); |
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409 Node *proj = np->in(idx); |
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410 const Node *x = proj->is_block_proj(); |
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411 // Does the block end with a proper block-ending Node? One of Return, |
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412 // If or Goto? (This check should be done for visited nodes also). |
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413 if (x == NULL) { // Does not end right... |
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414 Node *g = _goto->clone(); // Force it to end in a Goto |
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415 g->set_req(0, proj); |
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416 np->set_req(idx, g); |
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417 x = proj = g; |
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418 } |
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419 if (!visited.test_set(x->_idx)) { // Visit this block once |
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420 // Skip any control-pinned middle'in stuff |
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421 Node *p = proj; |
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422 do { |
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423 proj = p; // Update pointer to last Control |
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424 p = p->in(0); // Move control forward |
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425 } while( !p->is_block_proj() && |
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426 !p->is_block_start() ); |
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427 // Make the block begin with one of Region or StartNode. |
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428 if( !p->is_block_start() ) { |
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429 RegionNode *r = new (C) RegionNode( 2 ); |
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430 r->init_req(1, p); // Insert RegionNode in the way |
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431 proj->set_req(0, r); // Insert RegionNode in the way |
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432 p = r; |
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433 } |
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434 // 'p' now points to the start of this basic block |
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435 |
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436 // Put self in array of basic blocks |
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437 Block *bb = new (_block_arena) Block(_block_arena, p); |
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438 map_node_to_block(p, bb); |
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439 map_node_to_block(x, bb); |
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440 if( x != p ) { // Only for root is x == p |
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441 bb->push_node((Node*)x); |
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442 } |
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443 // Now handle predecessors |
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444 ++sum; // Count 1 for self block |
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445 uint cnt = bb->num_preds(); |
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446 for (int i = (cnt - 1); i > 0; i-- ) { // For all predecessors |
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447 Node *prevproj = p->in(i); // Get prior input |
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448 assert( !prevproj->is_Con(), "dead input not removed" ); |
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449 // Check to see if p->in(i) is a "control-dependent" CFG edge - |
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450 // i.e., it splits at the source (via an IF or SWITCH) and merges |
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451 // at the destination (via a many-input Region). |
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452 // This breaks critical edges. The RegionNode to start the block |
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453 // will be added when <p,i> is pulled off the node stack |
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454 if ( cnt > 2 ) { // Merging many things? |
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455 assert( prevproj== bb->pred(i),""); |
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456 if(prevproj->is_block_proj() != prevproj) { // Control-dependent edge? |
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457 // Force a block on the control-dependent edge |
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458 Node *g = _goto->clone(); // Force it to end in a Goto |
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459 g->set_req(0,prevproj); |
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460 p->set_req(i,g); |
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461 } |
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462 } |
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463 nstack.push(p, i); // 'p' is RegionNode or StartNode |
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464 } |
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465 } else { // Post-processing visited nodes |
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466 nstack.pop(); // remove node from stack |
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467 // Check if it the fist node pushed on stack at the beginning. |
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468 if (idx == 0) break; // end of the build |
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469 // Find predecessor basic block |
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470 Block *pb = get_block_for_node(x); |
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471 // Insert into nodes array, if not already there |
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472 if (!has_block(proj)) { |
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473 assert( x != proj, "" ); |
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474 // Map basic block of projection |
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475 map_node_to_block(proj, pb); |
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476 pb->push_node(proj); |
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477 } |
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478 // Insert self as a child of my predecessor block |
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479 pb->_succs.map(pb->_num_succs++, get_block_for_node(np)); |
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480 assert( pb->get_node(pb->number_of_nodes() - pb->_num_succs)->is_block_proj(), |
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481 "too many control users, not a CFG?" ); |
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482 } |
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483 } |
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484 // Return number of basic blocks for all children and self |
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485 return sum; |
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486 } |
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487 |
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488 // Inserts a goto & corresponding basic block between |
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489 // block[block_no] and its succ_no'th successor block |
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490 void PhaseCFG::insert_goto_at(uint block_no, uint succ_no) { |
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491 // get block with block_no |
|
492 assert(block_no < number_of_blocks(), "illegal block number"); |
|
493 Block* in = get_block(block_no); |
|
494 // get successor block succ_no |
|
495 assert(succ_no < in->_num_succs, "illegal successor number"); |
|
496 Block* out = in->_succs[succ_no]; |
|
497 // Compute frequency of the new block. Do this before inserting |
|
498 // new block in case succ_prob() needs to infer the probability from |
|
499 // surrounding blocks. |
|
500 float freq = in->_freq * in->succ_prob(succ_no); |
|
501 // get ProjNode corresponding to the succ_no'th successor of the in block |
|
502 ProjNode* proj = in->get_node(in->number_of_nodes() - in->_num_succs + succ_no)->as_Proj(); |
|
503 // create region for basic block |
|
504 RegionNode* region = new (C) RegionNode(2); |
|
505 region->init_req(1, proj); |
|
506 // setup corresponding basic block |
|
507 Block* block = new (_block_arena) Block(_block_arena, region); |
|
508 map_node_to_block(region, block); |
|
509 C->regalloc()->set_bad(region->_idx); |
|
510 // add a goto node |
|
511 Node* gto = _goto->clone(); // get a new goto node |
|
512 gto->set_req(0, region); |
|
513 // add it to the basic block |
|
514 block->push_node(gto); |
|
515 map_node_to_block(gto, block); |
|
516 C->regalloc()->set_bad(gto->_idx); |
|
517 // hook up successor block |
|
518 block->_succs.map(block->_num_succs++, out); |
|
519 // remap successor's predecessors if necessary |
|
520 for (uint i = 1; i < out->num_preds(); i++) { |
|
521 if (out->pred(i) == proj) out->head()->set_req(i, gto); |
|
522 } |
|
523 // remap predecessor's successor to new block |
|
524 in->_succs.map(succ_no, block); |
|
525 // Set the frequency of the new block |
|
526 block->_freq = freq; |
|
527 // add new basic block to basic block list |
|
528 add_block_at(block_no + 1, block); |
|
529 } |
|
530 |
|
531 // Does this block end in a multiway branch that cannot have the default case |
|
532 // flipped for another case? |
|
533 static bool no_flip_branch(Block *b) { |
|
534 int branch_idx = b->number_of_nodes() - b->_num_succs-1; |
|
535 if (branch_idx < 1) { |
|
536 return false; |
|
537 } |
|
538 Node *branch = b->get_node(branch_idx); |
|
539 if (branch->is_Catch()) { |
|
540 return true; |
|
541 } |
|
542 if (branch->is_Mach()) { |
|
543 if (branch->is_MachNullCheck()) { |
|
544 return true; |
|
545 } |
|
546 int iop = branch->as_Mach()->ideal_Opcode(); |
|
547 if (iop == Op_FastLock || iop == Op_FastUnlock) { |
|
548 return true; |
|
549 } |
|
550 // Don't flip if branch has an implicit check. |
|
551 if (branch->as_Mach()->is_TrapBasedCheckNode()) { |
|
552 return true; |
|
553 } |
|
554 } |
|
555 return false; |
|
556 } |
|
557 |
|
558 // Check for NeverBranch at block end. This needs to become a GOTO to the |
|
559 // true target. NeverBranch are treated as a conditional branch that always |
|
560 // goes the same direction for most of the optimizer and are used to give a |
|
561 // fake exit path to infinite loops. At this late stage they need to turn |
|
562 // into Goto's so that when you enter the infinite loop you indeed hang. |
|
563 void PhaseCFG::convert_NeverBranch_to_Goto(Block *b) { |
|
564 // Find true target |
|
565 int end_idx = b->end_idx(); |
|
566 int idx = b->get_node(end_idx+1)->as_Proj()->_con; |
|
567 Block *succ = b->_succs[idx]; |
|
568 Node* gto = _goto->clone(); // get a new goto node |
|
569 gto->set_req(0, b->head()); |
|
570 Node *bp = b->get_node(end_idx); |
|
571 b->map_node(gto, end_idx); // Slam over NeverBranch |
|
572 map_node_to_block(gto, b); |
|
573 C->regalloc()->set_bad(gto->_idx); |
|
574 b->pop_node(); // Yank projections |
|
575 b->pop_node(); // Yank projections |
|
576 b->_succs.map(0,succ); // Map only successor |
|
577 b->_num_succs = 1; |
|
578 // remap successor's predecessors if necessary |
|
579 uint j; |
|
580 for( j = 1; j < succ->num_preds(); j++) |
|
581 if( succ->pred(j)->in(0) == bp ) |
|
582 succ->head()->set_req(j, gto); |
|
583 // Kill alternate exit path |
|
584 Block *dead = b->_succs[1-idx]; |
|
585 for( j = 1; j < dead->num_preds(); j++) |
|
586 if( dead->pred(j)->in(0) == bp ) |
|
587 break; |
|
588 // Scan through block, yanking dead path from |
|
589 // all regions and phis. |
|
590 dead->head()->del_req(j); |
|
591 for( int k = 1; dead->get_node(k)->is_Phi(); k++ ) |
|
592 dead->get_node(k)->del_req(j); |
|
593 } |
|
594 |
|
595 // Helper function to move block bx to the slot following b_index. Return |
|
596 // true if the move is successful, otherwise false |
|
597 bool PhaseCFG::move_to_next(Block* bx, uint b_index) { |
|
598 if (bx == NULL) return false; |
|
599 |
|
600 // Return false if bx is already scheduled. |
|
601 uint bx_index = bx->_pre_order; |
|
602 if ((bx_index <= b_index) && (get_block(bx_index) == bx)) { |
|
603 return false; |
|
604 } |
|
605 |
|
606 // Find the current index of block bx on the block list |
|
607 bx_index = b_index + 1; |
|
608 while (bx_index < number_of_blocks() && get_block(bx_index) != bx) { |
|
609 bx_index++; |
|
610 } |
|
611 assert(get_block(bx_index) == bx, "block not found"); |
|
612 |
|
613 // If the previous block conditionally falls into bx, return false, |
|
614 // because moving bx will create an extra jump. |
|
615 for(uint k = 1; k < bx->num_preds(); k++ ) { |
|
616 Block* pred = get_block_for_node(bx->pred(k)); |
|
617 if (pred == get_block(bx_index - 1)) { |
|
618 if (pred->_num_succs != 1) { |
|
619 return false; |
|
620 } |
|
621 } |
|
622 } |
|
623 |
|
624 // Reinsert bx just past block 'b' |
|
625 _blocks.remove(bx_index); |
|
626 _blocks.insert(b_index + 1, bx); |
|
627 return true; |
|
628 } |
|
629 |
|
630 // Move empty and uncommon blocks to the end. |
|
631 void PhaseCFG::move_to_end(Block *b, uint i) { |
|
632 int e = b->is_Empty(); |
|
633 if (e != Block::not_empty) { |
|
634 if (e == Block::empty_with_goto) { |
|
635 // Remove the goto, but leave the block. |
|
636 b->pop_node(); |
|
637 } |
|
638 // Mark this block as a connector block, which will cause it to be |
|
639 // ignored in certain functions such as non_connector_successor(). |
|
640 b->set_connector(); |
|
641 } |
|
642 // Move the empty block to the end, and don't recheck. |
|
643 _blocks.remove(i); |
|
644 _blocks.push(b); |
|
645 } |
|
646 |
|
647 // Set loop alignment for every block |
|
648 void PhaseCFG::set_loop_alignment() { |
|
649 uint last = number_of_blocks(); |
|
650 assert(get_block(0) == get_root_block(), ""); |
|
651 |
|
652 for (uint i = 1; i < last; i++) { |
|
653 Block* block = get_block(i); |
|
654 if (block->head()->is_Loop()) { |
|
655 block->set_loop_alignment(block); |
|
656 } |
|
657 } |
|
658 } |
|
659 |
|
660 // Make empty basic blocks to be "connector" blocks, Move uncommon blocks |
|
661 // to the end. |
|
662 void PhaseCFG::remove_empty_blocks() { |
|
663 // Move uncommon blocks to the end |
|
664 uint last = number_of_blocks(); |
|
665 assert(get_block(0) == get_root_block(), ""); |
|
666 |
|
667 for (uint i = 1; i < last; i++) { |
|
668 Block* block = get_block(i); |
|
669 if (block->is_connector()) { |
|
670 break; |
|
671 } |
|
672 |
|
673 // Check for NeverBranch at block end. This needs to become a GOTO to the |
|
674 // true target. NeverBranch are treated as a conditional branch that |
|
675 // always goes the same direction for most of the optimizer and are used |
|
676 // to give a fake exit path to infinite loops. At this late stage they |
|
677 // need to turn into Goto's so that when you enter the infinite loop you |
|
678 // indeed hang. |
|
679 if (block->get_node(block->end_idx())->Opcode() == Op_NeverBranch) { |
|
680 convert_NeverBranch_to_Goto(block); |
|
681 } |
|
682 |
|
683 // Look for uncommon blocks and move to end. |
|
684 if (!C->do_freq_based_layout()) { |
|
685 if (is_uncommon(block)) { |
|
686 move_to_end(block, i); |
|
687 last--; // No longer check for being uncommon! |
|
688 if (no_flip_branch(block)) { // Fall-thru case must follow? |
|
689 // Find the fall-thru block |
|
690 block = get_block(i); |
|
691 move_to_end(block, i); |
|
692 last--; |
|
693 } |
|
694 // backup block counter post-increment |
|
695 i--; |
|
696 } |
|
697 } |
|
698 } |
|
699 |
|
700 // Move empty blocks to the end |
|
701 last = number_of_blocks(); |
|
702 for (uint i = 1; i < last; i++) { |
|
703 Block* block = get_block(i); |
|
704 if (block->is_Empty() != Block::not_empty) { |
|
705 move_to_end(block, i); |
|
706 last--; |
|
707 i--; |
|
708 } |
|
709 } // End of for all blocks |
|
710 } |
|
711 |
|
712 Block *PhaseCFG::fixup_trap_based_check(Node *branch, Block *block, int block_pos, Block *bnext) { |
|
713 // Trap based checks must fall through to the successor with |
|
714 // PROB_ALWAYS. |
|
715 // They should be an If with 2 successors. |
|
716 assert(branch->is_MachIf(), "must be If"); |
|
717 assert(block->_num_succs == 2, "must have 2 successors"); |
|
718 |
|
719 // Get the If node and the projection for the first successor. |
|
720 MachIfNode *iff = block->get_node(block->number_of_nodes()-3)->as_MachIf(); |
|
721 ProjNode *proj0 = block->get_node(block->number_of_nodes()-2)->as_Proj(); |
|
722 ProjNode *proj1 = block->get_node(block->number_of_nodes()-1)->as_Proj(); |
|
723 ProjNode *projt = (proj0->Opcode() == Op_IfTrue) ? proj0 : proj1; |
|
724 ProjNode *projf = (proj0->Opcode() == Op_IfFalse) ? proj0 : proj1; |
|
725 |
|
726 // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1]. |
|
727 assert(proj0->raw_out(0) == block->_succs[0]->head(), "Mismatch successor 0"); |
|
728 assert(proj1->raw_out(0) == block->_succs[1]->head(), "Mismatch successor 1"); |
|
729 |
|
730 ProjNode *proj_always; |
|
731 ProjNode *proj_never; |
|
732 // We must negate the branch if the implicit check doesn't follow |
|
733 // the branch's TRUE path. Then, the new TRUE branch target will |
|
734 // be the old FALSE branch target. |
|
735 if (iff->_prob <= 2*PROB_NEVER) { // There are small rounding errors. |
|
736 proj_never = projt; |
|
737 proj_always = projf; |
|
738 } else { |
|
739 // We must negate the branch if the trap doesn't follow the |
|
740 // branch's TRUE path. Then, the new TRUE branch target will |
|
741 // be the old FALSE branch target. |
|
742 proj_never = projf; |
|
743 proj_always = projt; |
|
744 iff->negate(); |
|
745 } |
|
746 assert(iff->_prob <= 2*PROB_NEVER, "Trap based checks are expected to trap never!"); |
|
747 // Map the successors properly |
|
748 block->_succs.map(0, get_block_for_node(proj_never ->raw_out(0))); // The target of the trap. |
|
749 block->_succs.map(1, get_block_for_node(proj_always->raw_out(0))); // The fall through target. |
|
750 |
|
751 if (block->get_node(block->number_of_nodes() - block->_num_succs + 1) != proj_always) { |
|
752 block->map_node(proj_never, block->number_of_nodes() - block->_num_succs + 0); |
|
753 block->map_node(proj_always, block->number_of_nodes() - block->_num_succs + 1); |
|
754 } |
|
755 |
|
756 // Place the fall through block after this block. |
|
757 Block *bs1 = block->non_connector_successor(1); |
|
758 if (bs1 != bnext && move_to_next(bs1, block_pos)) { |
|
759 bnext = bs1; |
|
760 } |
|
761 // If the fall through block still is not the next block, insert a goto. |
|
762 if (bs1 != bnext) { |
|
763 insert_goto_at(block_pos, 1); |
|
764 } |
|
765 return bnext; |
|
766 } |
|
767 |
|
768 // Fix up the final control flow for basic blocks. |
|
769 void PhaseCFG::fixup_flow() { |
|
770 // Fixup final control flow for the blocks. Remove jump-to-next |
|
771 // block. If neither arm of an IF follows the conditional branch, we |
|
772 // have to add a second jump after the conditional. We place the |
|
773 // TRUE branch target in succs[0] for both GOTOs and IFs. |
|
774 for (uint i = 0; i < number_of_blocks(); i++) { |
|
775 Block* block = get_block(i); |
|
776 block->_pre_order = i; // turn pre-order into block-index |
|
777 |
|
778 // Connector blocks need no further processing. |
|
779 if (block->is_connector()) { |
|
780 assert((i+1) == number_of_blocks() || get_block(i + 1)->is_connector(), "All connector blocks should sink to the end"); |
|
781 continue; |
|
782 } |
|
783 assert(block->is_Empty() != Block::completely_empty, "Empty blocks should be connectors"); |
|
784 |
|
785 Block* bnext = (i < number_of_blocks() - 1) ? get_block(i + 1) : NULL; |
|
786 Block* bs0 = block->non_connector_successor(0); |
|
787 |
|
788 // Check for multi-way branches where I cannot negate the test to |
|
789 // exchange the true and false targets. |
|
790 if (no_flip_branch(block)) { |
|
791 // Find fall through case - if must fall into its target. |
|
792 // Get the index of the branch's first successor. |
|
793 int branch_idx = block->number_of_nodes() - block->_num_succs; |
|
794 |
|
795 // The branch is 1 before the branch's first successor. |
|
796 Node *branch = block->get_node(branch_idx-1); |
|
797 |
|
798 // Handle no-flip branches which have implicit checks and which require |
|
799 // special block ordering and individual semantics of the 'fall through |
|
800 // case'. |
|
801 if ((TrapBasedNullChecks || TrapBasedRangeChecks) && |
|
802 branch->is_Mach() && branch->as_Mach()->is_TrapBasedCheckNode()) { |
|
803 bnext = fixup_trap_based_check(branch, block, i, bnext); |
|
804 } else { |
|
805 // Else, default handling for no-flip branches |
|
806 for (uint j2 = 0; j2 < block->_num_succs; j2++) { |
|
807 const ProjNode* p = block->get_node(branch_idx + j2)->as_Proj(); |
|
808 if (p->_con == 0) { |
|
809 // successor j2 is fall through case |
|
810 if (block->non_connector_successor(j2) != bnext) { |
|
811 // but it is not the next block => insert a goto |
|
812 insert_goto_at(i, j2); |
|
813 } |
|
814 // Put taken branch in slot 0 |
|
815 if (j2 == 0 && block->_num_succs == 2) { |
|
816 // Flip targets in succs map |
|
817 Block *tbs0 = block->_succs[0]; |
|
818 Block *tbs1 = block->_succs[1]; |
|
819 block->_succs.map(0, tbs1); |
|
820 block->_succs.map(1, tbs0); |
|
821 } |
|
822 break; |
|
823 } |
|
824 } |
|
825 } |
|
826 |
|
827 // Remove all CatchProjs |
|
828 for (uint j = 0; j < block->_num_succs; j++) { |
|
829 block->pop_node(); |
|
830 } |
|
831 |
|
832 } else if (block->_num_succs == 1) { |
|
833 // Block ends in a Goto? |
|
834 if (bnext == bs0) { |
|
835 // We fall into next block; remove the Goto |
|
836 block->pop_node(); |
|
837 } |
|
838 |
|
839 } else if(block->_num_succs == 2) { // Block ends in a If? |
|
840 // Get opcode of 1st projection (matches _succs[0]) |
|
841 // Note: Since this basic block has 2 exits, the last 2 nodes must |
|
842 // be projections (in any order), the 3rd last node must be |
|
843 // the IfNode (we have excluded other 2-way exits such as |
|
844 // CatchNodes already). |
|
845 MachNode* iff = block->get_node(block->number_of_nodes() - 3)->as_Mach(); |
|
846 ProjNode* proj0 = block->get_node(block->number_of_nodes() - 2)->as_Proj(); |
|
847 ProjNode* proj1 = block->get_node(block->number_of_nodes() - 1)->as_Proj(); |
|
848 |
|
849 // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1]. |
|
850 assert(proj0->raw_out(0) == block->_succs[0]->head(), "Mismatch successor 0"); |
|
851 assert(proj1->raw_out(0) == block->_succs[1]->head(), "Mismatch successor 1"); |
|
852 |
|
853 Block* bs1 = block->non_connector_successor(1); |
|
854 |
|
855 // Check for neither successor block following the current |
|
856 // block ending in a conditional. If so, move one of the |
|
857 // successors after the current one, provided that the |
|
858 // successor was previously unscheduled, but moveable |
|
859 // (i.e., all paths to it involve a branch). |
|
860 if (!C->do_freq_based_layout() && bnext != bs0 && bnext != bs1) { |
|
861 // Choose the more common successor based on the probability |
|
862 // of the conditional branch. |
|
863 Block* bx = bs0; |
|
864 Block* by = bs1; |
|
865 |
|
866 // _prob is the probability of taking the true path. Make |
|
867 // p the probability of taking successor #1. |
|
868 float p = iff->as_MachIf()->_prob; |
|
869 if (proj0->Opcode() == Op_IfTrue) { |
|
870 p = 1.0 - p; |
|
871 } |
|
872 |
|
873 // Prefer successor #1 if p > 0.5 |
|
874 if (p > PROB_FAIR) { |
|
875 bx = bs1; |
|
876 by = bs0; |
|
877 } |
|
878 |
|
879 // Attempt the more common successor first |
|
880 if (move_to_next(bx, i)) { |
|
881 bnext = bx; |
|
882 } else if (move_to_next(by, i)) { |
|
883 bnext = by; |
|
884 } |
|
885 } |
|
886 |
|
887 // Check for conditional branching the wrong way. Negate |
|
888 // conditional, if needed, so it falls into the following block |
|
889 // and branches to the not-following block. |
|
890 |
|
891 // Check for the next block being in succs[0]. We are going to branch |
|
892 // to succs[0], so we want the fall-thru case as the next block in |
|
893 // succs[1]. |
|
894 if (bnext == bs0) { |
|
895 // Fall-thru case in succs[0], so flip targets in succs map |
|
896 Block* tbs0 = block->_succs[0]; |
|
897 Block* tbs1 = block->_succs[1]; |
|
898 block->_succs.map(0, tbs1); |
|
899 block->_succs.map(1, tbs0); |
|
900 // Flip projection for each target |
|
901 ProjNode* tmp = proj0; |
|
902 proj0 = proj1; |
|
903 proj1 = tmp; |
|
904 |
|
905 } else if(bnext != bs1) { |
|
906 // Need a double-branch |
|
907 // The existing conditional branch need not change. |
|
908 // Add a unconditional branch to the false target. |
|
909 // Alas, it must appear in its own block and adding a |
|
910 // block this late in the game is complicated. Sigh. |
|
911 insert_goto_at(i, 1); |
|
912 } |
|
913 |
|
914 // Make sure we TRUE branch to the target |
|
915 if (proj0->Opcode() == Op_IfFalse) { |
|
916 iff->as_MachIf()->negate(); |
|
917 } |
|
918 |
|
919 block->pop_node(); // Remove IfFalse & IfTrue projections |
|
920 block->pop_node(); |
|
921 |
|
922 } else { |
|
923 // Multi-exit block, e.g. a switch statement |
|
924 // But we don't need to do anything here |
|
925 } |
|
926 } // End of for all blocks |
|
927 } |
|
928 |
|
929 |
|
930 // postalloc_expand: Expand nodes after register allocation. |
|
931 // |
|
932 // postalloc_expand has to be called after register allocation, just |
|
933 // before output (i.e. scheduling). It only gets called if |
|
934 // Matcher::require_postalloc_expand is true. |
|
935 // |
|
936 // Background: |
|
937 // |
|
938 // Nodes that are expandend (one compound node requiring several |
|
939 // assembler instructions to be implemented split into two or more |
|
940 // non-compound nodes) after register allocation are not as nice as |
|
941 // the ones expanded before register allocation - they don't |
|
942 // participate in optimizations as global code motion. But after |
|
943 // register allocation we can expand nodes that use registers which |
|
944 // are not spillable or registers that are not allocated, because the |
|
945 // old compound node is simply replaced (in its location in the basic |
|
946 // block) by a new subgraph which does not contain compound nodes any |
|
947 // more. The scheduler called during output can later on process these |
|
948 // non-compound nodes. |
|
949 // |
|
950 // Implementation: |
|
951 // |
|
952 // Nodes requiring postalloc expand are specified in the ad file by using |
|
953 // a postalloc_expand statement instead of ins_encode. A postalloc_expand |
|
954 // contains a single call to an encoding, as does an ins_encode |
|
955 // statement. Instead of an emit() function a postalloc_expand() function |
|
956 // is generated that doesn't emit assembler but creates a new |
|
957 // subgraph. The code below calls this postalloc_expand function for each |
|
958 // node with the appropriate attribute. This function returns the new |
|
959 // nodes generated in an array passed in the call. The old node, |
|
960 // potential MachTemps before and potential Projs after it then get |
|
961 // disconnected and replaced by the new nodes. The instruction |
|
962 // generating the result has to be the last one in the array. In |
|
963 // general it is assumed that Projs after the node expanded are |
|
964 // kills. These kills are not required any more after expanding as |
|
965 // there are now explicitly visible def-use chains and the Projs are |
|
966 // removed. This does not hold for calls: They do not only have |
|
967 // kill-Projs but also Projs defining values. Therefore Projs after |
|
968 // the node expanded are removed for all but for calls. If a node is |
|
969 // to be reused, it must be added to the nodes list returned, and it |
|
970 // will be added again. |
|
971 // |
|
972 // Implementing the postalloc_expand function for a node in an enc_class |
|
973 // is rather tedious. It requires knowledge about many node details, as |
|
974 // the nodes and the subgraph must be hand crafted. To simplify this, |
|
975 // adlc generates some utility variables into the postalloc_expand function, |
|
976 // e.g., holding the operands as specified by the postalloc_expand encoding |
|
977 // specification, e.g.: |
|
978 // * unsigned idx_<par_name> holding the index of the node in the ins |
|
979 // * Node *n_<par_name> holding the node loaded from the ins |
|
980 // * MachOpnd *op_<par_name> holding the corresponding operand |
|
981 // |
|
982 // The ordering of operands can not be determined by looking at a |
|
983 // rule. Especially if a match rule matches several different trees, |
|
984 // several nodes are generated from one instruct specification with |
|
985 // different operand orderings. In this case the adlc generated |
|
986 // variables are the only way to access the ins and operands |
|
987 // deterministically. |
|
988 // |
|
989 // If assigning a register to a node that contains an oop, don't |
|
990 // forget to call ra_->set_oop() for the node. |
|
991 void PhaseCFG::postalloc_expand(PhaseRegAlloc* _ra) { |
|
992 GrowableArray <Node *> new_nodes(32); // Array with new nodes filled by postalloc_expand function of node. |
|
993 GrowableArray <Node *> remove(32); |
|
994 GrowableArray <Node *> succs(32); |
|
995 unsigned int max_idx = C->unique(); // Remember to distinguish new from old nodes. |
|
996 DEBUG_ONLY(bool foundNode = false); |
|
997 |
|
998 // for all blocks |
|
999 for (uint i = 0; i < number_of_blocks(); i++) { |
|
1000 Block *b = _blocks[i]; |
|
1001 // For all instructions in the current block. |
|
1002 for (uint j = 0; j < b->number_of_nodes(); j++) { |
|
1003 Node *n = b->get_node(j); |
|
1004 if (n->is_Mach() && n->as_Mach()->requires_postalloc_expand()) { |
|
1005 #ifdef ASSERT |
|
1006 if (TracePostallocExpand) { |
|
1007 if (!foundNode) { |
|
1008 foundNode = true; |
|
1009 tty->print("POSTALLOC EXPANDING %d %s\n", C->compile_id(), |
|
1010 C->method() ? C->method()->name()->as_utf8() : C->stub_name()); |
|
1011 } |
|
1012 tty->print(" postalloc expanding "); n->dump(); |
|
1013 if (Verbose) { |
|
1014 tty->print(" with ins:\n"); |
|
1015 for (uint k = 0; k < n->len(); ++k) { |
|
1016 if (n->in(k)) { tty->print(" "); n->in(k)->dump(); } |
|
1017 } |
|
1018 } |
|
1019 } |
|
1020 #endif |
|
1021 new_nodes.clear(); |
|
1022 // Collect nodes that have to be removed from the block later on. |
|
1023 uint req = n->req(); |
|
1024 remove.clear(); |
|
1025 for (uint k = 0; k < req; ++k) { |
|
1026 if (n->in(k) && n->in(k)->is_MachTemp()) { |
|
1027 remove.push(n->in(k)); // MachTemps which are inputs to the old node have to be removed. |
|
1028 n->in(k)->del_req(0); |
|
1029 j--; |
|
1030 } |
|
1031 } |
|
1032 |
|
1033 // Check whether we can allocate enough nodes. We set a fix limit for |
|
1034 // the size of postalloc expands with this. |
|
1035 uint unique_limit = C->unique() + 40; |
|
1036 if (unique_limit >= _ra->node_regs_max_index()) { |
|
1037 Compile::current()->record_failure("out of nodes in postalloc expand"); |
|
1038 return; |
|
1039 } |
|
1040 |
|
1041 // Emit (i.e. generate new nodes). |
|
1042 n->as_Mach()->postalloc_expand(&new_nodes, _ra); |
|
1043 |
|
1044 assert(C->unique() < unique_limit, "You allocated too many nodes in your postalloc expand."); |
|
1045 |
|
1046 // Disconnect the inputs of the old node. |
|
1047 // |
|
1048 // We reuse MachSpillCopy nodes. If we need to expand them, there |
|
1049 // are many, so reusing pays off. If reused, the node already |
|
1050 // has the new ins. n must be the last node on new_nodes list. |
|
1051 if (!n->is_MachSpillCopy()) { |
|
1052 for (int k = req - 1; k >= 0; --k) { |
|
1053 n->del_req(k); |
|
1054 } |
|
1055 } |
|
1056 |
|
1057 #ifdef ASSERT |
|
1058 // Check that all nodes have proper operands. |
|
1059 for (int k = 0; k < new_nodes.length(); ++k) { |
|
1060 if (new_nodes.at(k)->_idx < max_idx || !new_nodes.at(k)->is_Mach()) continue; // old node, Proj ... |
|
1061 MachNode *m = new_nodes.at(k)->as_Mach(); |
|
1062 for (unsigned int l = 0; l < m->num_opnds(); ++l) { |
|
1063 if (MachOper::notAnOper(m->_opnds[l])) { |
|
1064 outputStream *os = tty; |
|
1065 os->print("Node %s ", m->Name()); |
|
1066 os->print("has invalid opnd %d: %p\n", l, m->_opnds[l]); |
|
1067 assert(0, "Invalid operands, see inline trace in hs_err_pid file."); |
|
1068 } |
|
1069 } |
|
1070 } |
|
1071 #endif |
|
1072 |
|
1073 // Collect succs of old node in remove (for projections) and in succs (for |
|
1074 // all other nodes) do _not_ collect projections in remove (but in succs) |
|
1075 // in case the node is a call. We need the projections for calls as they are |
|
1076 // associated with registes (i.e. they are defs). |
|
1077 succs.clear(); |
|
1078 for (DUIterator k = n->outs(); n->has_out(k); k++) { |
|
1079 if (n->out(k)->is_Proj() && !n->is_MachCall() && !n->is_MachBranch()) { |
|
1080 remove.push(n->out(k)); |
|
1081 } else { |
|
1082 succs.push(n->out(k)); |
|
1083 } |
|
1084 } |
|
1085 // Replace old node n as input of its succs by last of the new nodes. |
|
1086 for (int k = 0; k < succs.length(); ++k) { |
|
1087 Node *succ = succs.at(k); |
|
1088 for (uint l = 0; l < succ->req(); ++l) { |
|
1089 if (succ->in(l) == n) { |
|
1090 succ->set_req(l, new_nodes.at(new_nodes.length() - 1)); |
|
1091 } |
|
1092 } |
|
1093 for (uint l = succ->req(); l < succ->len(); ++l) { |
|
1094 if (succ->in(l) == n) { |
|
1095 succ->set_prec(l, new_nodes.at(new_nodes.length() - 1)); |
|
1096 } |
|
1097 } |
|
1098 } |
|
1099 |
|
1100 // Index of old node in block. |
|
1101 uint index = b->find_node(n); |
|
1102 // Insert new nodes into block and map them in nodes->blocks array |
|
1103 // and remember last node in n2. |
|
1104 Node *n2 = NULL; |
|
1105 for (int k = 0; k < new_nodes.length(); ++k) { |
|
1106 n2 = new_nodes.at(k); |
|
1107 b->insert_node(n2, ++index); |
|
1108 map_node_to_block(n2, b); |
|
1109 } |
|
1110 |
|
1111 // Add old node n to remove and remove them all from block. |
|
1112 remove.push(n); |
|
1113 j--; |
|
1114 #ifdef ASSERT |
|
1115 if (TracePostallocExpand && Verbose) { |
|
1116 tty->print(" removing:\n"); |
|
1117 for (int k = 0; k < remove.length(); ++k) { |
|
1118 tty->print(" "); remove.at(k)->dump(); |
|
1119 } |
|
1120 tty->print(" inserting:\n"); |
|
1121 for (int k = 0; k < new_nodes.length(); ++k) { |
|
1122 tty->print(" "); new_nodes.at(k)->dump(); |
|
1123 } |
|
1124 } |
|
1125 #endif |
|
1126 for (int k = 0; k < remove.length(); ++k) { |
|
1127 if (b->contains(remove.at(k))) { |
|
1128 b->find_remove(remove.at(k)); |
|
1129 } else { |
|
1130 assert(remove.at(k)->is_Proj() && (remove.at(k)->in(0)->is_MachBranch()), ""); |
|
1131 } |
|
1132 } |
|
1133 // If anything has been inserted (n2 != NULL), continue after last node inserted. |
|
1134 // This does not always work. Some postalloc expands don't insert any nodes, if they |
|
1135 // do optimizations (e.g., max(x,x)). In this case we decrement j accordingly. |
|
1136 j = n2 ? b->find_node(n2) : j; |
|
1137 } |
|
1138 } |
|
1139 } |
|
1140 |
|
1141 #ifdef ASSERT |
|
1142 if (foundNode) { |
|
1143 tty->print("FINISHED %d %s\n", C->compile_id(), |
|
1144 C->method() ? C->method()->name()->as_utf8() : C->stub_name()); |
|
1145 tty->flush(); |
|
1146 } |
|
1147 #endif |
|
1148 } |
|
1149 |
|
1150 |
|
1151 //------------------------------dump------------------------------------------- |
|
1152 #ifndef PRODUCT |
|
1153 void PhaseCFG::_dump_cfg( const Node *end, VectorSet &visited ) const { |
|
1154 const Node *x = end->is_block_proj(); |
|
1155 assert( x, "not a CFG" ); |
|
1156 |
|
1157 // Do not visit this block again |
|
1158 if( visited.test_set(x->_idx) ) return; |
|
1159 |
|
1160 // Skip through this block |
|
1161 const Node *p = x; |
|
1162 do { |
|
1163 p = p->in(0); // Move control forward |
|
1164 assert( !p->is_block_proj() || p->is_Root(), "not a CFG" ); |
|
1165 } while( !p->is_block_start() ); |
|
1166 |
|
1167 // Recursively visit |
|
1168 for (uint i = 1; i < p->req(); i++) { |
|
1169 _dump_cfg(p->in(i), visited); |
|
1170 } |
|
1171 |
|
1172 // Dump the block |
|
1173 get_block_for_node(p)->dump(this); |
|
1174 } |
|
1175 |
|
1176 void PhaseCFG::dump( ) const { |
|
1177 tty->print("\n--- CFG --- %d BBs\n", number_of_blocks()); |
|
1178 if (_blocks.size()) { // Did we do basic-block layout? |
|
1179 for (uint i = 0; i < number_of_blocks(); i++) { |
|
1180 const Block* block = get_block(i); |
|
1181 block->dump(this); |
|
1182 } |
|
1183 } else { // Else do it with a DFS |
|
1184 VectorSet visited(_block_arena); |
|
1185 _dump_cfg(_root,visited); |
|
1186 } |
|
1187 } |
|
1188 |
|
1189 void PhaseCFG::dump_headers() { |
|
1190 for (uint i = 0; i < number_of_blocks(); i++) { |
|
1191 Block* block = get_block(i); |
|
1192 if (block != NULL) { |
|
1193 block->dump_head(this); |
|
1194 } |
|
1195 } |
|
1196 } |
|
1197 |
|
1198 void PhaseCFG::verify() const { |
|
1199 #ifdef ASSERT |
|
1200 // Verify sane CFG |
|
1201 for (uint i = 0; i < number_of_blocks(); i++) { |
|
1202 Block* block = get_block(i); |
|
1203 uint cnt = block->number_of_nodes(); |
|
1204 uint j; |
|
1205 for (j = 0; j < cnt; j++) { |
|
1206 Node *n = block->get_node(j); |
|
1207 assert(get_block_for_node(n) == block, ""); |
|
1208 if (j >= 1 && n->is_Mach() && n->as_Mach()->ideal_Opcode() == Op_CreateEx) { |
|
1209 assert(j == 1 || block->get_node(j-1)->is_Phi(), "CreateEx must be first instruction in block"); |
|
1210 } |
|
1211 for (uint k = 0; k < n->req(); k++) { |
|
1212 Node *def = n->in(k); |
|
1213 if (def && def != n) { |
|
1214 assert(get_block_for_node(def) || def->is_Con(), "must have block; constants for debug info ok"); |
|
1215 // Verify that instructions in the block is in correct order. |
|
1216 // Uses must follow their definition if they are at the same block. |
|
1217 // Mostly done to check that MachSpillCopy nodes are placed correctly |
|
1218 // when CreateEx node is moved in build_ifg_physical(). |
|
1219 if (get_block_for_node(def) == block && !(block->head()->is_Loop() && n->is_Phi()) && |
|
1220 // See (+++) comment in reg_split.cpp |
|
1221 !(n->jvms() != NULL && n->jvms()->is_monitor_use(k))) { |
|
1222 bool is_loop = false; |
|
1223 if (n->is_Phi()) { |
|
1224 for (uint l = 1; l < def->req(); l++) { |
|
1225 if (n == def->in(l)) { |
|
1226 is_loop = true; |
|
1227 break; // Some kind of loop |
|
1228 } |
|
1229 } |
|
1230 } |
|
1231 assert(is_loop || block->find_node(def) < j, "uses must follow definitions"); |
|
1232 } |
|
1233 } |
|
1234 } |
|
1235 } |
|
1236 |
|
1237 j = block->end_idx(); |
|
1238 Node* bp = (Node*)block->get_node(block->number_of_nodes() - 1)->is_block_proj(); |
|
1239 assert(bp, "last instruction must be a block proj"); |
|
1240 assert(bp == block->get_node(j), "wrong number of successors for this block"); |
|
1241 if (bp->is_Catch()) { |
|
1242 while (block->get_node(--j)->is_MachProj()) { |
|
1243 ; |
|
1244 } |
|
1245 assert(block->get_node(j)->is_MachCall(), "CatchProj must follow call"); |
|
1246 } else if (bp->is_Mach() && bp->as_Mach()->ideal_Opcode() == Op_If) { |
|
1247 assert(block->_num_succs == 2, "Conditional branch must have two targets"); |
|
1248 } |
|
1249 } |
|
1250 #endif |
|
1251 } |
|
1252 #endif |
|
1253 |
|
1254 UnionFind::UnionFind( uint max ) : _cnt(max), _max(max), _indices(NEW_RESOURCE_ARRAY(uint,max)) { |
|
1255 Copy::zero_to_bytes( _indices, sizeof(uint)*max ); |
|
1256 } |
|
1257 |
|
1258 void UnionFind::extend( uint from_idx, uint to_idx ) { |
|
1259 _nesting.check(); |
|
1260 if( from_idx >= _max ) { |
|
1261 uint size = 16; |
|
1262 while( size <= from_idx ) size <<=1; |
|
1263 _indices = REALLOC_RESOURCE_ARRAY( uint, _indices, _max, size ); |
|
1264 _max = size; |
|
1265 } |
|
1266 while( _cnt <= from_idx ) _indices[_cnt++] = 0; |
|
1267 _indices[from_idx] = to_idx; |
|
1268 } |
|
1269 |
|
1270 void UnionFind::reset( uint max ) { |
|
1271 assert( max <= max_uint, "Must fit within uint" ); |
|
1272 // Force the Union-Find mapping to be at least this large |
|
1273 extend(max,0); |
|
1274 // Initialize to be the ID mapping. |
|
1275 for( uint i=0; i<max; i++ ) map(i,i); |
|
1276 } |
|
1277 |
|
1278 // Straight out of Tarjan's union-find algorithm |
|
1279 uint UnionFind::Find_compress( uint idx ) { |
|
1280 uint cur = idx; |
|
1281 uint next = lookup(cur); |
|
1282 while( next != cur ) { // Scan chain of equivalences |
|
1283 assert( next < cur, "always union smaller" ); |
|
1284 cur = next; // until find a fixed-point |
|
1285 next = lookup(cur); |
|
1286 } |
|
1287 // Core of union-find algorithm: update chain of |
|
1288 // equivalences to be equal to the root. |
|
1289 while( idx != next ) { |
|
1290 uint tmp = lookup(idx); |
|
1291 map(idx, next); |
|
1292 idx = tmp; |
|
1293 } |
|
1294 return idx; |
|
1295 } |
|
1296 |
|
1297 // Like Find above, but no path compress, so bad asymptotic behavior |
|
1298 uint UnionFind::Find_const( uint idx ) const { |
|
1299 if( idx == 0 ) return idx; // Ignore the zero idx |
|
1300 // Off the end? This can happen during debugging dumps |
|
1301 // when data structures have not finished being updated. |
|
1302 if( idx >= _max ) return idx; |
|
1303 uint next = lookup(idx); |
|
1304 while( next != idx ) { // Scan chain of equivalences |
|
1305 idx = next; // until find a fixed-point |
|
1306 next = lookup(idx); |
|
1307 } |
|
1308 return next; |
|
1309 } |
|
1310 |
|
1311 // union 2 sets together. |
|
1312 void UnionFind::Union( uint idx1, uint idx2 ) { |
|
1313 uint src = Find(idx1); |
|
1314 uint dst = Find(idx2); |
|
1315 assert( src, "" ); |
|
1316 assert( dst, "" ); |
|
1317 assert( src < _max, "oob" ); |
|
1318 assert( dst < _max, "oob" ); |
|
1319 assert( src < dst, "always union smaller" ); |
|
1320 map(dst,src); |
|
1321 } |
|
1322 |
|
1323 #ifndef PRODUCT |
|
1324 void Trace::dump( ) const { |
|
1325 tty->print_cr("Trace (freq %f)", first_block()->_freq); |
|
1326 for (Block *b = first_block(); b != NULL; b = next(b)) { |
|
1327 tty->print(" B%d", b->_pre_order); |
|
1328 if (b->head()->is_Loop()) { |
|
1329 tty->print(" (L%d)", b->compute_loop_alignment()); |
|
1330 } |
|
1331 if (b->has_loop_alignment()) { |
|
1332 tty->print(" (T%d)", b->code_alignment()); |
|
1333 } |
|
1334 } |
|
1335 tty->cr(); |
|
1336 } |
|
1337 |
|
1338 void CFGEdge::dump( ) const { |
|
1339 tty->print(" B%d --> B%d Freq: %f out:%3d%% in:%3d%% State: ", |
|
1340 from()->_pre_order, to()->_pre_order, freq(), _from_pct, _to_pct); |
|
1341 switch(state()) { |
|
1342 case connected: |
|
1343 tty->print("connected"); |
|
1344 break; |
|
1345 case open: |
|
1346 tty->print("open"); |
|
1347 break; |
|
1348 case interior: |
|
1349 tty->print("interior"); |
|
1350 break; |
|
1351 } |
|
1352 if (infrequent()) { |
|
1353 tty->print(" infrequent"); |
|
1354 } |
|
1355 tty->cr(); |
|
1356 } |
|
1357 #endif |
|
1358 |
|
1359 // Comparison function for edges |
|
1360 static int edge_order(CFGEdge **e0, CFGEdge **e1) { |
|
1361 float freq0 = (*e0)->freq(); |
|
1362 float freq1 = (*e1)->freq(); |
|
1363 if (freq0 != freq1) { |
|
1364 return freq0 > freq1 ? -1 : 1; |
|
1365 } |
|
1366 |
|
1367 int dist0 = (*e0)->to()->_rpo - (*e0)->from()->_rpo; |
|
1368 int dist1 = (*e1)->to()->_rpo - (*e1)->from()->_rpo; |
|
1369 |
|
1370 return dist1 - dist0; |
|
1371 } |
|
1372 |
|
1373 // Comparison function for edges |
|
1374 extern "C" int trace_frequency_order(const void *p0, const void *p1) { |
|
1375 Trace *tr0 = *(Trace **) p0; |
|
1376 Trace *tr1 = *(Trace **) p1; |
|
1377 Block *b0 = tr0->first_block(); |
|
1378 Block *b1 = tr1->first_block(); |
|
1379 |
|
1380 // The trace of connector blocks goes at the end; |
|
1381 // we only expect one such trace |
|
1382 if (b0->is_connector() != b1->is_connector()) { |
|
1383 return b1->is_connector() ? -1 : 1; |
|
1384 } |
|
1385 |
|
1386 // Pull more frequently executed blocks to the beginning |
|
1387 float freq0 = b0->_freq; |
|
1388 float freq1 = b1->_freq; |
|
1389 if (freq0 != freq1) { |
|
1390 return freq0 > freq1 ? -1 : 1; |
|
1391 } |
|
1392 |
|
1393 int diff = tr0->first_block()->_rpo - tr1->first_block()->_rpo; |
|
1394 |
|
1395 return diff; |
|
1396 } |
|
1397 |
|
1398 // Find edges of interest, i.e, those which can fall through. Presumes that |
|
1399 // edges which don't fall through are of low frequency and can be generally |
|
1400 // ignored. Initialize the list of traces. |
|
1401 void PhaseBlockLayout::find_edges() { |
|
1402 // Walk the blocks, creating edges and Traces |
|
1403 uint i; |
|
1404 Trace *tr = NULL; |
|
1405 for (i = 0; i < _cfg.number_of_blocks(); i++) { |
|
1406 Block* b = _cfg.get_block(i); |
|
1407 tr = new Trace(b, next, prev); |
|
1408 traces[tr->id()] = tr; |
|
1409 |
|
1410 // All connector blocks should be at the end of the list |
|
1411 if (b->is_connector()) break; |
|
1412 |
|
1413 // If this block and the next one have a one-to-one successor |
|
1414 // predecessor relationship, simply append the next block |
|
1415 int nfallthru = b->num_fall_throughs(); |
|
1416 while (nfallthru == 1 && |
|
1417 b->succ_fall_through(0)) { |
|
1418 Block *n = b->_succs[0]; |
|
1419 |
|
1420 // Skip over single-entry connector blocks, we don't want to |
|
1421 // add them to the trace. |
|
1422 while (n->is_connector() && n->num_preds() == 1) { |
|
1423 n = n->_succs[0]; |
|
1424 } |
|
1425 |
|
1426 // We see a merge point, so stop search for the next block |
|
1427 if (n->num_preds() != 1) break; |
|
1428 |
|
1429 i++; |
|
1430 assert(n = _cfg.get_block(i), "expecting next block"); |
|
1431 tr->append(n); |
|
1432 uf->map(n->_pre_order, tr->id()); |
|
1433 traces[n->_pre_order] = NULL; |
|
1434 nfallthru = b->num_fall_throughs(); |
|
1435 b = n; |
|
1436 } |
|
1437 |
|
1438 if (nfallthru > 0) { |
|
1439 // Create a CFGEdge for each outgoing |
|
1440 // edge that could be a fall-through. |
|
1441 for (uint j = 0; j < b->_num_succs; j++ ) { |
|
1442 if (b->succ_fall_through(j)) { |
|
1443 Block *target = b->non_connector_successor(j); |
|
1444 float freq = b->_freq * b->succ_prob(j); |
|
1445 int from_pct = (int) ((100 * freq) / b->_freq); |
|
1446 int to_pct = (int) ((100 * freq) / target->_freq); |
|
1447 edges->append(new CFGEdge(b, target, freq, from_pct, to_pct)); |
|
1448 } |
|
1449 } |
|
1450 } |
|
1451 } |
|
1452 |
|
1453 // Group connector blocks into one trace |
|
1454 for (i++; i < _cfg.number_of_blocks(); i++) { |
|
1455 Block *b = _cfg.get_block(i); |
|
1456 assert(b->is_connector(), "connector blocks at the end"); |
|
1457 tr->append(b); |
|
1458 uf->map(b->_pre_order, tr->id()); |
|
1459 traces[b->_pre_order] = NULL; |
|
1460 } |
|
1461 } |
|
1462 |
|
1463 // Union two traces together in uf, and null out the trace in the list |
|
1464 void PhaseBlockLayout::union_traces(Trace* updated_trace, Trace* old_trace) { |
|
1465 uint old_id = old_trace->id(); |
|
1466 uint updated_id = updated_trace->id(); |
|
1467 |
|
1468 uint lo_id = updated_id; |
|
1469 uint hi_id = old_id; |
|
1470 |
|
1471 // If from is greater than to, swap values to meet |
|
1472 // UnionFind guarantee. |
|
1473 if (updated_id > old_id) { |
|
1474 lo_id = old_id; |
|
1475 hi_id = updated_id; |
|
1476 |
|
1477 // Fix up the trace ids |
|
1478 traces[lo_id] = traces[updated_id]; |
|
1479 updated_trace->set_id(lo_id); |
|
1480 } |
|
1481 |
|
1482 // Union the lower with the higher and remove the pointer |
|
1483 // to the higher. |
|
1484 uf->Union(lo_id, hi_id); |
|
1485 traces[hi_id] = NULL; |
|
1486 } |
|
1487 |
|
1488 // Append traces together via the most frequently executed edges |
|
1489 void PhaseBlockLayout::grow_traces() { |
|
1490 // Order the edges, and drive the growth of Traces via the most |
|
1491 // frequently executed edges. |
|
1492 edges->sort(edge_order); |
|
1493 for (int i = 0; i < edges->length(); i++) { |
|
1494 CFGEdge *e = edges->at(i); |
|
1495 |
|
1496 if (e->state() != CFGEdge::open) continue; |
|
1497 |
|
1498 Block *src_block = e->from(); |
|
1499 Block *targ_block = e->to(); |
|
1500 |
|
1501 // Don't grow traces along backedges? |
|
1502 if (!BlockLayoutRotateLoops) { |
|
1503 if (targ_block->_rpo <= src_block->_rpo) { |
|
1504 targ_block->set_loop_alignment(targ_block); |
|
1505 continue; |
|
1506 } |
|
1507 } |
|
1508 |
|
1509 Trace *src_trace = trace(src_block); |
|
1510 Trace *targ_trace = trace(targ_block); |
|
1511 |
|
1512 // If the edge in question can join two traces at their ends, |
|
1513 // append one trace to the other. |
|
1514 if (src_trace->last_block() == src_block) { |
|
1515 if (src_trace == targ_trace) { |
|
1516 e->set_state(CFGEdge::interior); |
|
1517 if (targ_trace->backedge(e)) { |
|
1518 // Reset i to catch any newly eligible edge |
|
1519 // (Or we could remember the first "open" edge, and reset there) |
|
1520 i = 0; |
|
1521 } |
|
1522 } else if (targ_trace->first_block() == targ_block) { |
|
1523 e->set_state(CFGEdge::connected); |
|
1524 src_trace->append(targ_trace); |
|
1525 union_traces(src_trace, targ_trace); |
|
1526 } |
|
1527 } |
|
1528 } |
|
1529 } |
|
1530 |
|
1531 // Embed one trace into another, if the fork or join points are sufficiently |
|
1532 // balanced. |
|
1533 void PhaseBlockLayout::merge_traces(bool fall_thru_only) { |
|
1534 // Walk the edge list a another time, looking at unprocessed edges. |
|
1535 // Fold in diamonds |
|
1536 for (int i = 0; i < edges->length(); i++) { |
|
1537 CFGEdge *e = edges->at(i); |
|
1538 |
|
1539 if (e->state() != CFGEdge::open) continue; |
|
1540 if (fall_thru_only) { |
|
1541 if (e->infrequent()) continue; |
|
1542 } |
|
1543 |
|
1544 Block *src_block = e->from(); |
|
1545 Trace *src_trace = trace(src_block); |
|
1546 bool src_at_tail = src_trace->last_block() == src_block; |
|
1547 |
|
1548 Block *targ_block = e->to(); |
|
1549 Trace *targ_trace = trace(targ_block); |
|
1550 bool targ_at_start = targ_trace->first_block() == targ_block; |
|
1551 |
|
1552 if (src_trace == targ_trace) { |
|
1553 // This may be a loop, but we can't do much about it. |
|
1554 e->set_state(CFGEdge::interior); |
|
1555 continue; |
|
1556 } |
|
1557 |
|
1558 if (fall_thru_only) { |
|
1559 // If the edge links the middle of two traces, we can't do anything. |
|
1560 // Mark the edge and continue. |
|
1561 if (!src_at_tail & !targ_at_start) { |
|
1562 continue; |
|
1563 } |
|
1564 |
|
1565 // Don't grow traces along backedges? |
|
1566 if (!BlockLayoutRotateLoops && (targ_block->_rpo <= src_block->_rpo)) { |
|
1567 continue; |
|
1568 } |
|
1569 |
|
1570 // If both ends of the edge are available, why didn't we handle it earlier? |
|
1571 assert(src_at_tail ^ targ_at_start, "Should have caught this edge earlier."); |
|
1572 |
|
1573 if (targ_at_start) { |
|
1574 // Insert the "targ" trace in the "src" trace if the insertion point |
|
1575 // is a two way branch. |
|
1576 // Better profitability check possible, but may not be worth it. |
|
1577 // Someday, see if the this "fork" has an associated "join"; |
|
1578 // then make a policy on merging this trace at the fork or join. |
|
1579 // For example, other things being equal, it may be better to place this |
|
1580 // trace at the join point if the "src" trace ends in a two-way, but |
|
1581 // the insertion point is one-way. |
|
1582 assert(src_block->num_fall_throughs() == 2, "unexpected diamond"); |
|
1583 e->set_state(CFGEdge::connected); |
|
1584 src_trace->insert_after(src_block, targ_trace); |
|
1585 union_traces(src_trace, targ_trace); |
|
1586 } else if (src_at_tail) { |
|
1587 if (src_trace != trace(_cfg.get_root_block())) { |
|
1588 e->set_state(CFGEdge::connected); |
|
1589 targ_trace->insert_before(targ_block, src_trace); |
|
1590 union_traces(targ_trace, src_trace); |
|
1591 } |
|
1592 } |
|
1593 } else if (e->state() == CFGEdge::open) { |
|
1594 // Append traces, even without a fall-thru connection. |
|
1595 // But leave root entry at the beginning of the block list. |
|
1596 if (targ_trace != trace(_cfg.get_root_block())) { |
|
1597 e->set_state(CFGEdge::connected); |
|
1598 src_trace->append(targ_trace); |
|
1599 union_traces(src_trace, targ_trace); |
|
1600 } |
|
1601 } |
|
1602 } |
|
1603 } |
|
1604 |
|
1605 // Order the sequence of the traces in some desirable way, and fixup the |
|
1606 // jumps at the end of each block. |
|
1607 void PhaseBlockLayout::reorder_traces(int count) { |
|
1608 ResourceArea *area = Thread::current()->resource_area(); |
|
1609 Trace ** new_traces = NEW_ARENA_ARRAY(area, Trace *, count); |
|
1610 Block_List worklist; |
|
1611 int new_count = 0; |
|
1612 |
|
1613 // Compact the traces. |
|
1614 for (int i = 0; i < count; i++) { |
|
1615 Trace *tr = traces[i]; |
|
1616 if (tr != NULL) { |
|
1617 new_traces[new_count++] = tr; |
|
1618 } |
|
1619 } |
|
1620 |
|
1621 // The entry block should be first on the new trace list. |
|
1622 Trace *tr = trace(_cfg.get_root_block()); |
|
1623 assert(tr == new_traces[0], "entry trace misplaced"); |
|
1624 |
|
1625 // Sort the new trace list by frequency |
|
1626 qsort(new_traces + 1, new_count - 1, sizeof(new_traces[0]), trace_frequency_order); |
|
1627 |
|
1628 // Patch up the successor blocks |
|
1629 _cfg.clear_blocks(); |
|
1630 for (int i = 0; i < new_count; i++) { |
|
1631 Trace *tr = new_traces[i]; |
|
1632 if (tr != NULL) { |
|
1633 tr->fixup_blocks(_cfg); |
|
1634 } |
|
1635 } |
|
1636 } |
|
1637 |
|
1638 // Order basic blocks based on frequency |
|
1639 PhaseBlockLayout::PhaseBlockLayout(PhaseCFG &cfg) |
|
1640 : Phase(BlockLayout) |
|
1641 , _cfg(cfg) { |
|
1642 ResourceMark rm; |
|
1643 ResourceArea *area = Thread::current()->resource_area(); |
|
1644 |
|
1645 // List of traces |
|
1646 int size = _cfg.number_of_blocks() + 1; |
|
1647 traces = NEW_ARENA_ARRAY(area, Trace *, size); |
|
1648 memset(traces, 0, size*sizeof(Trace*)); |
|
1649 next = NEW_ARENA_ARRAY(area, Block *, size); |
|
1650 memset(next, 0, size*sizeof(Block *)); |
|
1651 prev = NEW_ARENA_ARRAY(area, Block *, size); |
|
1652 memset(prev , 0, size*sizeof(Block *)); |
|
1653 |
|
1654 // List of edges |
|
1655 edges = new GrowableArray<CFGEdge*>; |
|
1656 |
|
1657 // Mapping block index --> block_trace |
|
1658 uf = new UnionFind(size); |
|
1659 uf->reset(size); |
|
1660 |
|
1661 // Find edges and create traces. |
|
1662 find_edges(); |
|
1663 |
|
1664 // Grow traces at their ends via most frequent edges. |
|
1665 grow_traces(); |
|
1666 |
|
1667 // Merge one trace into another, but only at fall-through points. |
|
1668 // This may make diamonds and other related shapes in a trace. |
|
1669 merge_traces(true); |
|
1670 |
|
1671 // Run merge again, allowing two traces to be catenated, even if |
|
1672 // one does not fall through into the other. This appends loosely |
|
1673 // related traces to be near each other. |
|
1674 merge_traces(false); |
|
1675 |
|
1676 // Re-order all the remaining traces by frequency |
|
1677 reorder_traces(size); |
|
1678 |
|
1679 assert(_cfg.number_of_blocks() >= (uint) (size - 1), "number of blocks can not shrink"); |
|
1680 } |
|
1681 |
|
1682 |
|
1683 // Edge e completes a loop in a trace. If the target block is head of the |
|
1684 // loop, rotate the loop block so that the loop ends in a conditional branch. |
|
1685 bool Trace::backedge(CFGEdge *e) { |
|
1686 bool loop_rotated = false; |
|
1687 Block *src_block = e->from(); |
|
1688 Block *targ_block = e->to(); |
|
1689 |
|
1690 assert(last_block() == src_block, "loop discovery at back branch"); |
|
1691 if (first_block() == targ_block) { |
|
1692 if (BlockLayoutRotateLoops && last_block()->num_fall_throughs() < 2) { |
|
1693 // Find the last block in the trace that has a conditional |
|
1694 // branch. |
|
1695 Block *b; |
|
1696 for (b = last_block(); b != NULL; b = prev(b)) { |
|
1697 if (b->num_fall_throughs() == 2) { |
|
1698 break; |
|
1699 } |
|
1700 } |
|
1701 |
|
1702 if (b != last_block() && b != NULL) { |
|
1703 loop_rotated = true; |
|
1704 |
|
1705 // Rotate the loop by doing two-part linked-list surgery. |
|
1706 append(first_block()); |
|
1707 break_loop_after(b); |
|
1708 } |
|
1709 } |
|
1710 |
|
1711 // Backbranch to the top of a trace |
|
1712 // Scroll forward through the trace from the targ_block. If we find |
|
1713 // a loop head before another loop top, use the the loop head alignment. |
|
1714 for (Block *b = targ_block; b != NULL; b = next(b)) { |
|
1715 if (b->has_loop_alignment()) { |
|
1716 break; |
|
1717 } |
|
1718 if (b->head()->is_Loop()) { |
|
1719 targ_block = b; |
|
1720 break; |
|
1721 } |
|
1722 } |
|
1723 |
|
1724 first_block()->set_loop_alignment(targ_block); |
|
1725 |
|
1726 } else { |
|
1727 // Backbranch into the middle of a trace |
|
1728 targ_block->set_loop_alignment(targ_block); |
|
1729 } |
|
1730 |
|
1731 return loop_rotated; |
|
1732 } |
|
1733 |
|
1734 // push blocks onto the CFG list |
|
1735 // ensure that blocks have the correct two-way branch sense |
|
1736 void Trace::fixup_blocks(PhaseCFG &cfg) { |
|
1737 Block *last = last_block(); |
|
1738 for (Block *b = first_block(); b != NULL; b = next(b)) { |
|
1739 cfg.add_block(b); |
|
1740 if (!b->is_connector()) { |
|
1741 int nfallthru = b->num_fall_throughs(); |
|
1742 if (b != last) { |
|
1743 if (nfallthru == 2) { |
|
1744 // Ensure that the sense of the branch is correct |
|
1745 Block *bnext = next(b); |
|
1746 Block *bs0 = b->non_connector_successor(0); |
|
1747 |
|
1748 MachNode *iff = b->get_node(b->number_of_nodes() - 3)->as_Mach(); |
|
1749 ProjNode *proj0 = b->get_node(b->number_of_nodes() - 2)->as_Proj(); |
|
1750 ProjNode *proj1 = b->get_node(b->number_of_nodes() - 1)->as_Proj(); |
|
1751 |
|
1752 if (bnext == bs0) { |
|
1753 // Fall-thru case in succs[0], should be in succs[1] |
|
1754 |
|
1755 // Flip targets in _succs map |
|
1756 Block *tbs0 = b->_succs[0]; |
|
1757 Block *tbs1 = b->_succs[1]; |
|
1758 b->_succs.map( 0, tbs1 ); |
|
1759 b->_succs.map( 1, tbs0 ); |
|
1760 |
|
1761 // Flip projections to match targets |
|
1762 b->map_node(proj1, b->number_of_nodes() - 2); |
|
1763 b->map_node(proj0, b->number_of_nodes() - 1); |
|
1764 } |
|
1765 } |
|
1766 } |
|
1767 } |
|
1768 } |
|
1769 } |