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1 /*
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2 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // Optimization - Graph Style
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26
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27 #include "incls/_precompiled.incl"
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28 #include "incls/_block.cpp.incl"
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29
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30
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31 //-----------------------------------------------------------------------------
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32 void Block_Array::grow( uint i ) {
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33 assert(i >= Max(), "must be an overflow");
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34 debug_only(_limit = i+1);
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35 if( i < _size ) return;
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36 if( !_size ) {
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37 _size = 1;
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38 _blocks = (Block**)_arena->Amalloc( _size * sizeof(Block*) );
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39 _blocks[0] = NULL;
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40 }
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41 uint old = _size;
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42 while( i >= _size ) _size <<= 1; // Double to fit
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43 _blocks = (Block**)_arena->Arealloc( _blocks, old*sizeof(Block*),_size*sizeof(Block*));
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44 Copy::zero_to_bytes( &_blocks[old], (_size-old)*sizeof(Block*) );
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45 }
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46
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47 //=============================================================================
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48 void Block_List::remove(uint i) {
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49 assert(i < _cnt, "index out of bounds");
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50 Copy::conjoint_words_to_lower((HeapWord*)&_blocks[i+1], (HeapWord*)&_blocks[i], ((_cnt-i-1)*sizeof(Block*)));
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51 pop(); // shrink list by one block
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52 }
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53
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54 void Block_List::insert(uint i, Block *b) {
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55 push(b); // grow list by one block
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56 Copy::conjoint_words_to_higher((HeapWord*)&_blocks[i], (HeapWord*)&_blocks[i+1], ((_cnt-i-1)*sizeof(Block*)));
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57 _blocks[i] = b;
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58 }
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59
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60
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61 //=============================================================================
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62
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63 uint Block::code_alignment() {
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64 // Check for Root block
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65 if( _pre_order == 0 ) return CodeEntryAlignment;
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66 // Check for Start block
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67 if( _pre_order == 1 ) return InteriorEntryAlignment;
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68 // Check for loop alignment
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69 Node *h = head();
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70 if( h->is_Loop() && h->as_Loop()->is_inner_loop() ) {
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71 // Pre- and post-loops have low trip count so do not bother with
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72 // NOPs for align loop head. The constants are hidden from tuning
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73 // but only because my "divide by 4" heuristic surely gets nearly
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74 // all possible gain (a "do not align at all" heuristic has a
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75 // chance of getting a really tiny gain).
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76 if( h->is_CountedLoop() && (h->as_CountedLoop()->is_pre_loop() ||
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77 h->as_CountedLoop()->is_post_loop()) )
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78 return (OptoLoopAlignment > 4) ? (OptoLoopAlignment>>2) : 1;
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79 // Loops with low backedge frequency should not be aligned.
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80 Node *n = h->in(LoopNode::LoopBackControl)->in(0);
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81 if( n->is_MachIf() && n->as_MachIf()->_prob < 0.01 ) {
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82 return 1; // Loop does not loop, more often than not!
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83 }
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84 return OptoLoopAlignment; // Otherwise align loop head
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85 }
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86 return 1; // no particular alignment
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87 }
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88
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89 //-----------------------------------------------------------------------------
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90 // Compute the size of first 'inst_cnt' instructions in this block.
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91 // Return the number of instructions left to compute if the block has
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92 // less then 'inst_cnt' instructions.
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93 uint Block::compute_first_inst_size(uint& sum_size, uint inst_cnt,
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94 PhaseRegAlloc* ra) {
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95 uint last_inst = _nodes.size();
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96 for( uint j = 0; j < last_inst && inst_cnt > 0; j++ ) {
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97 uint inst_size = _nodes[j]->size(ra);
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98 if( inst_size > 0 ) {
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99 inst_cnt--;
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100 uint sz = sum_size + inst_size;
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101 if( sz <= (uint)OptoLoopAlignment ) {
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102 // Compute size of instructions which fit into fetch buffer only
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103 // since all inst_cnt instructions will not fit even if we align them.
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104 sum_size = sz;
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105 } else {
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106 return 0;
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107 }
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108 }
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109 }
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110 return inst_cnt;
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111 }
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112
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113 //-----------------------------------------------------------------------------
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114 uint Block::find_node( const Node *n ) const {
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115 for( uint i = 0; i < _nodes.size(); i++ ) {
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116 if( _nodes[i] == n )
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117 return i;
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118 }
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119 ShouldNotReachHere();
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120 return 0;
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121 }
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122
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123 // Find and remove n from block list
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124 void Block::find_remove( const Node *n ) {
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125 _nodes.remove(find_node(n));
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126 }
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127
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128 //------------------------------is_Empty---------------------------------------
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129 // Return empty status of a block. Empty blocks contain only the head, other
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130 // ideal nodes, and an optional trailing goto.
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131 int Block::is_Empty() const {
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132
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133 // Root or start block is not considered empty
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134 if (head()->is_Root() || head()->is_Start()) {
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135 return not_empty;
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136 }
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137
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138 int success_result = completely_empty;
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139 int end_idx = _nodes.size()-1;
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140
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141 // Check for ending goto
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142 if ((end_idx > 0) && (_nodes[end_idx]->is_Goto())) {
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143 success_result = empty_with_goto;
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144 end_idx--;
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145 }
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146
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147 // Unreachable blocks are considered empty
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148 if (num_preds() <= 1) {
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149 return success_result;
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150 }
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151
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152 // Ideal nodes are allowable in empty blocks: skip them Only MachNodes
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153 // turn directly into code, because only MachNodes have non-trivial
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154 // emit() functions.
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155 while ((end_idx > 0) && !_nodes[end_idx]->is_Mach()) {
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156 end_idx--;
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157 }
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158
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159 // No room for any interesting instructions?
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160 if (end_idx == 0) {
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161 return success_result;
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162 }
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163
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164 return not_empty;
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165 }
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166
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167 //------------------------------has_uncommon_code------------------------------
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168 // Return true if the block's code implies that it is not likely to be
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169 // executed infrequently. Check to see if the block ends in a Halt or
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170 // a low probability call.
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171 bool Block::has_uncommon_code() const {
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172 Node* en = end();
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173
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174 if (en->is_Goto())
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175 en = en->in(0);
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176 if (en->is_Catch())
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177 en = en->in(0);
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178 if (en->is_Proj() && en->in(0)->is_MachCall()) {
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179 MachCallNode* call = en->in(0)->as_MachCall();
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180 if (call->cnt() != COUNT_UNKNOWN && call->cnt() <= PROB_UNLIKELY_MAG(4)) {
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181 // This is true for slow-path stubs like new_{instance,array},
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182 // slow_arraycopy, complete_monitor_locking, uncommon_trap.
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183 // The magic number corresponds to the probability of an uncommon_trap,
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184 // even though it is a count not a probability.
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185 return true;
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186 }
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187 }
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188
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189 int op = en->is_Mach() ? en->as_Mach()->ideal_Opcode() : en->Opcode();
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190 return op == Op_Halt;
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191 }
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192
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193 //------------------------------is_uncommon------------------------------------
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194 // True if block is low enough frequency or guarded by a test which
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195 // mostly does not go here.
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196 bool Block::is_uncommon( Block_Array &bbs ) const {
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197 // Initial blocks must never be moved, so are never uncommon.
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198 if (head()->is_Root() || head()->is_Start()) return false;
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199
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200 // Check for way-low freq
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201 if( _freq < BLOCK_FREQUENCY(0.00001f) ) return true;
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202
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203 // Look for code shape indicating uncommon_trap or slow path
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204 if (has_uncommon_code()) return true;
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205
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206 const float epsilon = 0.05f;
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207 const float guard_factor = PROB_UNLIKELY_MAG(4) / (1.f - epsilon);
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208 uint uncommon_preds = 0;
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209 uint freq_preds = 0;
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210 uint uncommon_for_freq_preds = 0;
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211
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212 for( uint i=1; i<num_preds(); i++ ) {
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213 Block* guard = bbs[pred(i)->_idx];
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214 // Check to see if this block follows its guard 1 time out of 10000
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215 // or less.
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216 //
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217 // See list of magnitude-4 unlikely probabilities in cfgnode.hpp which
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218 // we intend to be "uncommon", such as slow-path TLE allocation,
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219 // predicted call failure, and uncommon trap triggers.
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220 //
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221 // Use an epsilon value of 5% to allow for variability in frequency
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222 // predictions and floating point calculations. The net effect is
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223 // that guard_factor is set to 9500.
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224 //
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225 // Ignore low-frequency blocks.
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226 // The next check is (guard->_freq < 1.e-5 * 9500.).
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227 if(guard->_freq*BLOCK_FREQUENCY(guard_factor) < BLOCK_FREQUENCY(0.00001f)) {
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228 uncommon_preds++;
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229 } else {
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230 freq_preds++;
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231 if( _freq < guard->_freq * guard_factor ) {
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232 uncommon_for_freq_preds++;
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233 }
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234 }
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235 }
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236 if( num_preds() > 1 &&
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237 // The block is uncommon if all preds are uncommon or
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238 (uncommon_preds == (num_preds()-1) ||
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239 // it is uncommon for all frequent preds.
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240 uncommon_for_freq_preds == freq_preds) ) {
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241 return true;
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242 }
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243 return false;
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244 }
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245
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246 //------------------------------dump-------------------------------------------
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247 #ifndef PRODUCT
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248 void Block::dump_bidx(const Block* orig) const {
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249 if (_pre_order) tty->print("B%d",_pre_order);
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250 else tty->print("N%d", head()->_idx);
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251
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252 if (Verbose && orig != this) {
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253 // Dump the original block's idx
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254 tty->print(" (");
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255 orig->dump_bidx(orig);
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256 tty->print(")");
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257 }
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258 }
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259
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260 void Block::dump_pred(const Block_Array *bbs, Block* orig) const {
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261 if (is_connector()) {
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262 for (uint i=1; i<num_preds(); i++) {
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263 Block *p = ((*bbs)[pred(i)->_idx]);
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264 p->dump_pred(bbs, orig);
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265 }
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266 } else {
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267 dump_bidx(orig);
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268 tty->print(" ");
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269 }
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270 }
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271
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272 void Block::dump_head( const Block_Array *bbs ) const {
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273 // Print the basic block
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274 dump_bidx(this);
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275 tty->print(": #\t");
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276
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277 // Print the incoming CFG edges and the outgoing CFG edges
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278 for( uint i=0; i<_num_succs; i++ ) {
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279 non_connector_successor(i)->dump_bidx(_succs[i]);
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280 tty->print(" ");
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281 }
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282 tty->print("<- ");
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283 if( head()->is_block_start() ) {
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284 for (uint i=1; i<num_preds(); i++) {
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285 Node *s = pred(i);
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286 if (bbs) {
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287 Block *p = (*bbs)[s->_idx];
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288 p->dump_pred(bbs, p);
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289 } else {
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290 while (!s->is_block_start())
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291 s = s->in(0);
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292 tty->print("N%d ", s->_idx );
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293 }
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294 }
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295 } else
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296 tty->print("BLOCK HEAD IS JUNK ");
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297
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298 // Print loop, if any
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299 const Block *bhead = this; // Head of self-loop
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300 Node *bh = bhead->head();
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301 if( bbs && bh->is_Loop() && !head()->is_Root() ) {
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302 LoopNode *loop = bh->as_Loop();
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303 const Block *bx = (*bbs)[loop->in(LoopNode::LoopBackControl)->_idx];
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304 while (bx->is_connector()) {
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305 bx = (*bbs)[bx->pred(1)->_idx];
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306 }
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307 tty->print("\tLoop: B%d-B%d ", bhead->_pre_order, bx->_pre_order);
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308 // Dump any loop-specific bits, especially for CountedLoops.
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309 loop->dump_spec(tty);
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310 }
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311 tty->print(" Freq: %g",_freq);
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312 if( Verbose || WizardMode ) {
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313 tty->print(" IDom: %d/#%d", _idom ? _idom->_pre_order : 0, _dom_depth);
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314 tty->print(" RegPressure: %d",_reg_pressure);
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315 tty->print(" IHRP Index: %d",_ihrp_index);
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316 tty->print(" FRegPressure: %d",_freg_pressure);
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317 tty->print(" FHRP Index: %d",_fhrp_index);
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318 }
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319 tty->print_cr("");
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320 }
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321
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322 void Block::dump() const { dump(0); }
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323
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324 void Block::dump( const Block_Array *bbs ) const {
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325 dump_head(bbs);
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326 uint cnt = _nodes.size();
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327 for( uint i=0; i<cnt; i++ )
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328 _nodes[i]->dump();
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329 tty->print("\n");
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330 }
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331 #endif
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332
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333 //=============================================================================
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334 //------------------------------PhaseCFG---------------------------------------
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335 PhaseCFG::PhaseCFG( Arena *a, RootNode *r, Matcher &m ) :
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336 Phase(CFG),
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337 _bbs(a),
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338 _root(r)
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339 #ifndef PRODUCT
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340 , _trace_opto_pipelining(TraceOptoPipelining || C->method_has_option("TraceOptoPipelining"))
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341 #endif
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342 {
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343 ResourceMark rm;
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344 // I'll need a few machine-specific GotoNodes. Make an Ideal GotoNode,
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345 // then Match it into a machine-specific Node. Then clone the machine
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346 // Node on demand.
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347 Node *x = new (C, 1) GotoNode(NULL);
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348 x->init_req(0, x);
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349 _goto = m.match_tree(x);
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350 assert(_goto != NULL, "");
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351 _goto->set_req(0,_goto);
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352
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353 // Build the CFG in Reverse Post Order
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354 _num_blocks = build_cfg();
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355 _broot = _bbs[_root->_idx];
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356 }
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357
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358 //------------------------------build_cfg--------------------------------------
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359 // Build a proper looking CFG. Make every block begin with either a StartNode
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360 // or a RegionNode. Make every block end with either a Goto, If or Return.
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361 // The RootNode both starts and ends it's own block. Do this with a recursive
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362 // backwards walk over the control edges.
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363 uint PhaseCFG::build_cfg() {
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364 Arena *a = Thread::current()->resource_area();
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365 VectorSet visited(a);
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366
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367 // Allocate stack with enough space to avoid frequent realloc
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368 Node_Stack nstack(a, C->unique() >> 1);
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369 nstack.push(_root, 0);
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370 uint sum = 0; // Counter for blocks
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371
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372 while (nstack.is_nonempty()) {
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373 // node and in's index from stack's top
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374 // 'np' is _root (see above) or RegionNode, StartNode: we push on stack
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375 // only nodes which point to the start of basic block (see below).
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376 Node *np = nstack.node();
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377 // idx > 0, except for the first node (_root) pushed on stack
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378 // at the beginning when idx == 0.
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379 // We will use the condition (idx == 0) later to end the build.
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380 uint idx = nstack.index();
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381 Node *proj = np->in(idx);
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382 const Node *x = proj->is_block_proj();
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383 // Does the block end with a proper block-ending Node? One of Return,
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384 // If or Goto? (This check should be done for visited nodes also).
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385 if (x == NULL) { // Does not end right...
|
|
|
386 Node *g = _goto->clone(); // Force it to end in a Goto
|
|
|
387 g->set_req(0, proj);
|
|
|
388 np->set_req(idx, g);
|
|
|
389 x = proj = g;
|
|
|
390 }
|
|
|
391 if (!visited.test_set(x->_idx)) { // Visit this block once
|
|
|
392 // Skip any control-pinned middle'in stuff
|
|
|
393 Node *p = proj;
|
|
|
394 do {
|
|
|
395 proj = p; // Update pointer to last Control
|
|
|
396 p = p->in(0); // Move control forward
|
|
|
397 } while( !p->is_block_proj() &&
|
|
|
398 !p->is_block_start() );
|
|
|
399 // Make the block begin with one of Region or StartNode.
|
|
|
400 if( !p->is_block_start() ) {
|
|
|
401 RegionNode *r = new (C, 2) RegionNode( 2 );
|
|
|
402 r->init_req(1, p); // Insert RegionNode in the way
|
|
|
403 proj->set_req(0, r); // Insert RegionNode in the way
|
|
|
404 p = r;
|
|
|
405 }
|
|
|
406 // 'p' now points to the start of this basic block
|
|
|
407
|
|
|
408 // Put self in array of basic blocks
|
|
|
409 Block *bb = new (_bbs._arena) Block(_bbs._arena,p);
|
|
|
410 _bbs.map(p->_idx,bb);
|
|
|
411 _bbs.map(x->_idx,bb);
|
|
|
412 if( x != p ) // Only for root is x == p
|
|
|
413 bb->_nodes.push((Node*)x);
|
|
|
414
|
|
|
415 // Now handle predecessors
|
|
|
416 ++sum; // Count 1 for self block
|
|
|
417 uint cnt = bb->num_preds();
|
|
|
418 for (int i = (cnt - 1); i > 0; i-- ) { // For all predecessors
|
|
|
419 Node *prevproj = p->in(i); // Get prior input
|
|
|
420 assert( !prevproj->is_Con(), "dead input not removed" );
|
|
|
421 // Check to see if p->in(i) is a "control-dependent" CFG edge -
|
|
|
422 // i.e., it splits at the source (via an IF or SWITCH) and merges
|
|
|
423 // at the destination (via a many-input Region).
|
|
|
424 // This breaks critical edges. The RegionNode to start the block
|
|
|
425 // will be added when <p,i> is pulled off the node stack
|
|
|
426 if ( cnt > 2 ) { // Merging many things?
|
|
|
427 assert( prevproj== bb->pred(i),"");
|
|
|
428 if(prevproj->is_block_proj() != prevproj) { // Control-dependent edge?
|
|
|
429 // Force a block on the control-dependent edge
|
|
|
430 Node *g = _goto->clone(); // Force it to end in a Goto
|
|
|
431 g->set_req(0,prevproj);
|
|
|
432 p->set_req(i,g);
|
|
|
433 }
|
|
|
434 }
|
|
|
435 nstack.push(p, i); // 'p' is RegionNode or StartNode
|
|
|
436 }
|
|
|
437 } else { // Post-processing visited nodes
|
|
|
438 nstack.pop(); // remove node from stack
|
|
|
439 // Check if it the fist node pushed on stack at the beginning.
|
|
|
440 if (idx == 0) break; // end of the build
|
|
|
441 // Find predecessor basic block
|
|
|
442 Block *pb = _bbs[x->_idx];
|
|
|
443 // Insert into nodes array, if not already there
|
|
|
444 if( !_bbs.lookup(proj->_idx) ) {
|
|
|
445 assert( x != proj, "" );
|
|
|
446 // Map basic block of projection
|
|
|
447 _bbs.map(proj->_idx,pb);
|
|
|
448 pb->_nodes.push(proj);
|
|
|
449 }
|
|
|
450 // Insert self as a child of my predecessor block
|
|
|
451 pb->_succs.map(pb->_num_succs++, _bbs[np->_idx]);
|
|
|
452 assert( pb->_nodes[ pb->_nodes.size() - pb->_num_succs ]->is_block_proj(),
|
|
|
453 "too many control users, not a CFG?" );
|
|
|
454 }
|
|
|
455 }
|
|
|
456 // Return number of basic blocks for all children and self
|
|
|
457 return sum;
|
|
|
458 }
|
|
|
459
|
|
|
460 //------------------------------insert_goto_at---------------------------------
|
|
|
461 // Inserts a goto & corresponding basic block between
|
|
|
462 // block[block_no] and its succ_no'th successor block
|
|
|
463 void PhaseCFG::insert_goto_at(uint block_no, uint succ_no) {
|
|
|
464 // get block with block_no
|
|
|
465 assert(block_no < _num_blocks, "illegal block number");
|
|
|
466 Block* in = _blocks[block_no];
|
|
|
467 // get successor block succ_no
|
|
|
468 assert(succ_no < in->_num_succs, "illegal successor number");
|
|
|
469 Block* out = in->_succs[succ_no];
|
|
|
470 // get ProjNode corresponding to the succ_no'th successor of the in block
|
|
|
471 ProjNode* proj = in->_nodes[in->_nodes.size() - in->_num_succs + succ_no]->as_Proj();
|
|
|
472 // create region for basic block
|
|
|
473 RegionNode* region = new (C, 2) RegionNode(2);
|
|
|
474 region->init_req(1, proj);
|
|
|
475 // setup corresponding basic block
|
|
|
476 Block* block = new (_bbs._arena) Block(_bbs._arena, region);
|
|
|
477 _bbs.map(region->_idx, block);
|
|
|
478 C->regalloc()->set_bad(region->_idx);
|
|
|
479 // add a goto node
|
|
|
480 Node* gto = _goto->clone(); // get a new goto node
|
|
|
481 gto->set_req(0, region);
|
|
|
482 // add it to the basic block
|
|
|
483 block->_nodes.push(gto);
|
|
|
484 _bbs.map(gto->_idx, block);
|
|
|
485 C->regalloc()->set_bad(gto->_idx);
|
|
|
486 // hook up successor block
|
|
|
487 block->_succs.map(block->_num_succs++, out);
|
|
|
488 // remap successor's predecessors if necessary
|
|
|
489 for (uint i = 1; i < out->num_preds(); i++) {
|
|
|
490 if (out->pred(i) == proj) out->head()->set_req(i, gto);
|
|
|
491 }
|
|
|
492 // remap predecessor's successor to new block
|
|
|
493 in->_succs.map(succ_no, block);
|
|
|
494 // add new basic block to basic block list
|
|
|
495 _blocks.insert(block_no + 1, block);
|
|
|
496 _num_blocks++;
|
|
|
497 }
|
|
|
498
|
|
|
499 //------------------------------no_flip_branch---------------------------------
|
|
|
500 // Does this block end in a multiway branch that cannot have the default case
|
|
|
501 // flipped for another case?
|
|
|
502 static bool no_flip_branch( Block *b ) {
|
|
|
503 int branch_idx = b->_nodes.size() - b->_num_succs-1;
|
|
|
504 if( branch_idx < 1 ) return false;
|
|
|
505 Node *bra = b->_nodes[branch_idx];
|
|
|
506 if( bra->is_Catch() ) return true;
|
|
|
507 if( bra->is_Mach() ) {
|
|
|
508 if( bra->is_MachNullCheck() ) return true;
|
|
|
509 int iop = bra->as_Mach()->ideal_Opcode();
|
|
|
510 if( iop == Op_FastLock || iop == Op_FastUnlock )
|
|
|
511 return true;
|
|
|
512 }
|
|
|
513 return false;
|
|
|
514 }
|
|
|
515
|
|
|
516 //------------------------------convert_NeverBranch_to_Goto--------------------
|
|
|
517 // Check for NeverBranch at block end. This needs to become a GOTO to the
|
|
|
518 // true target. NeverBranch are treated as a conditional branch that always
|
|
|
519 // goes the same direction for most of the optimizer and are used to give a
|
|
|
520 // fake exit path to infinite loops. At this late stage they need to turn
|
|
|
521 // into Goto's so that when you enter the infinite loop you indeed hang.
|
|
|
522 void PhaseCFG::convert_NeverBranch_to_Goto(Block *b) {
|
|
|
523 // Find true target
|
|
|
524 int end_idx = b->end_idx();
|
|
|
525 int idx = b->_nodes[end_idx+1]->as_Proj()->_con;
|
|
|
526 Block *succ = b->_succs[idx];
|
|
|
527 Node* gto = _goto->clone(); // get a new goto node
|
|
|
528 gto->set_req(0, b->head());
|
|
|
529 Node *bp = b->_nodes[end_idx];
|
|
|
530 b->_nodes.map(end_idx,gto); // Slam over NeverBranch
|
|
|
531 _bbs.map(gto->_idx, b);
|
|
|
532 C->regalloc()->set_bad(gto->_idx);
|
|
|
533 b->_nodes.pop(); // Yank projections
|
|
|
534 b->_nodes.pop(); // Yank projections
|
|
|
535 b->_succs.map(0,succ); // Map only successor
|
|
|
536 b->_num_succs = 1;
|
|
|
537 // remap successor's predecessors if necessary
|
|
|
538 uint j;
|
|
|
539 for( j = 1; j < succ->num_preds(); j++)
|
|
|
540 if( succ->pred(j)->in(0) == bp )
|
|
|
541 succ->head()->set_req(j, gto);
|
|
|
542 // Kill alternate exit path
|
|
|
543 Block *dead = b->_succs[1-idx];
|
|
|
544 for( j = 1; j < dead->num_preds(); j++)
|
|
|
545 if( dead->pred(j)->in(0) == bp )
|
|
|
546 break;
|
|
|
547 // Scan through block, yanking dead path from
|
|
|
548 // all regions and phis.
|
|
|
549 dead->head()->del_req(j);
|
|
|
550 for( int k = 1; dead->_nodes[k]->is_Phi(); k++ )
|
|
|
551 dead->_nodes[k]->del_req(j);
|
|
|
552 }
|
|
|
553
|
|
|
554 //------------------------------MoveToNext-------------------------------------
|
|
|
555 // Helper function to move block bx to the slot following b_index. Return
|
|
|
556 // true if the move is successful, otherwise false
|
|
|
557 bool PhaseCFG::MoveToNext(Block* bx, uint b_index) {
|
|
|
558 if (bx == NULL) return false;
|
|
|
559
|
|
|
560 // Return false if bx is already scheduled.
|
|
|
561 uint bx_index = bx->_pre_order;
|
|
|
562 if ((bx_index <= b_index) && (_blocks[bx_index] == bx)) {
|
|
|
563 return false;
|
|
|
564 }
|
|
|
565
|
|
|
566 // Find the current index of block bx on the block list
|
|
|
567 bx_index = b_index + 1;
|
|
|
568 while( bx_index < _num_blocks && _blocks[bx_index] != bx ) bx_index++;
|
|
|
569 assert(_blocks[bx_index] == bx, "block not found");
|
|
|
570
|
|
|
571 // If the previous block conditionally falls into bx, return false,
|
|
|
572 // because moving bx will create an extra jump.
|
|
|
573 for(uint k = 1; k < bx->num_preds(); k++ ) {
|
|
|
574 Block* pred = _bbs[bx->pred(k)->_idx];
|
|
|
575 if (pred == _blocks[bx_index-1]) {
|
|
|
576 if (pred->_num_succs != 1) {
|
|
|
577 return false;
|
|
|
578 }
|
|
|
579 }
|
|
|
580 }
|
|
|
581
|
|
|
582 // Reinsert bx just past block 'b'
|
|
|
583 _blocks.remove(bx_index);
|
|
|
584 _blocks.insert(b_index + 1, bx);
|
|
|
585 return true;
|
|
|
586 }
|
|
|
587
|
|
|
588 //------------------------------MoveToEnd--------------------------------------
|
|
|
589 // Move empty and uncommon blocks to the end.
|
|
|
590 void PhaseCFG::MoveToEnd(Block *b, uint i) {
|
|
|
591 int e = b->is_Empty();
|
|
|
592 if (e != Block::not_empty) {
|
|
|
593 if (e == Block::empty_with_goto) {
|
|
|
594 // Remove the goto, but leave the block.
|
|
|
595 b->_nodes.pop();
|
|
|
596 }
|
|
|
597 // Mark this block as a connector block, which will cause it to be
|
|
|
598 // ignored in certain functions such as non_connector_successor().
|
|
|
599 b->set_connector();
|
|
|
600 }
|
|
|
601 // Move the empty block to the end, and don't recheck.
|
|
|
602 _blocks.remove(i);
|
|
|
603 _blocks.push(b);
|
|
|
604 }
|
|
|
605
|
|
|
606 //------------------------------RemoveEmpty------------------------------------
|
|
|
607 // Remove empty basic blocks and useless branches.
|
|
|
608 void PhaseCFG::RemoveEmpty() {
|
|
|
609 // Move uncommon blocks to the end
|
|
|
610 uint last = _num_blocks;
|
|
|
611 uint i;
|
|
|
612 assert( _blocks[0] == _broot, "" );
|
|
|
613 for( i = 1; i < last; i++ ) {
|
|
|
614 Block *b = _blocks[i];
|
|
|
615
|
|
|
616 // Check for NeverBranch at block end. This needs to become a GOTO to the
|
|
|
617 // true target. NeverBranch are treated as a conditional branch that
|
|
|
618 // always goes the same direction for most of the optimizer and are used
|
|
|
619 // to give a fake exit path to infinite loops. At this late stage they
|
|
|
620 // need to turn into Goto's so that when you enter the infinite loop you
|
|
|
621 // indeed hang.
|
|
|
622 if( b->_nodes[b->end_idx()]->Opcode() == Op_NeverBranch )
|
|
|
623 convert_NeverBranch_to_Goto(b);
|
|
|
624
|
|
|
625 // Look for uncommon blocks and move to end.
|
|
|
626 if( b->is_uncommon(_bbs) ) {
|
|
|
627 MoveToEnd(b, i);
|
|
|
628 last--; // No longer check for being uncommon!
|
|
|
629 if( no_flip_branch(b) ) { // Fall-thru case must follow?
|
|
|
630 b = _blocks[i]; // Find the fall-thru block
|
|
|
631 MoveToEnd(b, i);
|
|
|
632 last--;
|
|
|
633 }
|
|
|
634 i--; // backup block counter post-increment
|
|
|
635 }
|
|
|
636 }
|
|
|
637
|
|
|
638 // Remove empty blocks
|
|
|
639 uint j1;
|
|
|
640 last = _num_blocks;
|
|
|
641 for( i=0; i < last; i++ ) {
|
|
|
642 Block *b = _blocks[i];
|
|
|
643 if (i > 0) {
|
|
|
644 if (b->is_Empty() != Block::not_empty) {
|
|
|
645 MoveToEnd(b, i);
|
|
|
646 last--;
|
|
|
647 i--;
|
|
|
648 }
|
|
|
649 }
|
|
|
650 } // End of for all blocks
|
|
|
651
|
|
|
652 // Fixup final control flow for the blocks. Remove jump-to-next
|
|
|
653 // block. If neither arm of a IF follows the conditional branch, we
|
|
|
654 // have to add a second jump after the conditional. We place the
|
|
|
655 // TRUE branch target in succs[0] for both GOTOs and IFs.
|
|
|
656 for( i=0; i < _num_blocks; i++ ) {
|
|
|
657 Block *b = _blocks[i];
|
|
|
658 b->_pre_order = i; // turn pre-order into block-index
|
|
|
659
|
|
|
660 // Connector blocks need no further processing.
|
|
|
661 if (b->is_connector()) {
|
|
|
662 assert((i+1) == _num_blocks || _blocks[i+1]->is_connector(),
|
|
|
663 "All connector blocks should sink to the end");
|
|
|
664 continue;
|
|
|
665 }
|
|
|
666 assert(b->is_Empty() != Block::completely_empty,
|
|
|
667 "Empty blocks should be connectors");
|
|
|
668
|
|
|
669 Block *bnext = (i < _num_blocks-1) ? _blocks[i+1] : NULL;
|
|
|
670 Block *bs0 = b->non_connector_successor(0);
|
|
|
671
|
|
|
672 // Check for multi-way branches where I cannot negate the test to
|
|
|
673 // exchange the true and false targets.
|
|
|
674 if( no_flip_branch( b ) ) {
|
|
|
675 // Find fall through case - if must fall into its target
|
|
|
676 int branch_idx = b->_nodes.size() - b->_num_succs;
|
|
|
677 for (uint j2 = 0; j2 < b->_num_succs; j2++) {
|
|
|
678 const ProjNode* p = b->_nodes[branch_idx + j2]->as_Proj();
|
|
|
679 if (p->_con == 0) {
|
|
|
680 // successor j2 is fall through case
|
|
|
681 if (b->non_connector_successor(j2) != bnext) {
|
|
|
682 // but it is not the next block => insert a goto
|
|
|
683 insert_goto_at(i, j2);
|
|
|
684 }
|
|
|
685 // Put taken branch in slot 0
|
|
|
686 if( j2 == 0 && b->_num_succs == 2) {
|
|
|
687 // Flip targets in succs map
|
|
|
688 Block *tbs0 = b->_succs[0];
|
|
|
689 Block *tbs1 = b->_succs[1];
|
|
|
690 b->_succs.map( 0, tbs1 );
|
|
|
691 b->_succs.map( 1, tbs0 );
|
|
|
692 }
|
|
|
693 break;
|
|
|
694 }
|
|
|
695 }
|
|
|
696 // Remove all CatchProjs
|
|
|
697 for (j1 = 0; j1 < b->_num_succs; j1++) b->_nodes.pop();
|
|
|
698
|
|
|
699 } else if (b->_num_succs == 1) {
|
|
|
700 // Block ends in a Goto?
|
|
|
701 if (bnext == bs0) {
|
|
|
702 // We fall into next block; remove the Goto
|
|
|
703 b->_nodes.pop();
|
|
|
704 }
|
|
|
705
|
|
|
706 } else if( b->_num_succs == 2 ) { // Block ends in a If?
|
|
|
707 // Get opcode of 1st projection (matches _succs[0])
|
|
|
708 // Note: Since this basic block has 2 exits, the last 2 nodes must
|
|
|
709 // be projections (in any order), the 3rd last node must be
|
|
|
710 // the IfNode (we have excluded other 2-way exits such as
|
|
|
711 // CatchNodes already).
|
|
|
712 MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach();
|
|
|
713 ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj();
|
|
|
714 ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj();
|
|
|
715
|
|
|
716 // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1].
|
|
|
717 assert(proj0->raw_out(0) == b->_succs[0]->head(), "Mismatch successor 0");
|
|
|
718 assert(proj1->raw_out(0) == b->_succs[1]->head(), "Mismatch successor 1");
|
|
|
719
|
|
|
720 Block *bs1 = b->non_connector_successor(1);
|
|
|
721
|
|
|
722 // Check for neither successor block following the current
|
|
|
723 // block ending in a conditional. If so, move one of the
|
|
|
724 // successors after the current one, provided that the
|
|
|
725 // successor was previously unscheduled, but moveable
|
|
|
726 // (i.e., all paths to it involve a branch).
|
|
|
727 if( bnext != bs0 && bnext != bs1 ) {
|
|
|
728
|
|
|
729 // Choose the more common successor based on the probability
|
|
|
730 // of the conditional branch.
|
|
|
731 Block *bx = bs0;
|
|
|
732 Block *by = bs1;
|
|
|
733
|
|
|
734 // _prob is the probability of taking the true path. Make
|
|
|
735 // p the probability of taking successor #1.
|
|
|
736 float p = iff->as_MachIf()->_prob;
|
|
|
737 if( proj0->Opcode() == Op_IfTrue ) {
|
|
|
738 p = 1.0 - p;
|
|
|
739 }
|
|
|
740
|
|
|
741 // Prefer successor #1 if p > 0.5
|
|
|
742 if (p > PROB_FAIR) {
|
|
|
743 bx = bs1;
|
|
|
744 by = bs0;
|
|
|
745 }
|
|
|
746
|
|
|
747 // Attempt the more common successor first
|
|
|
748 if (MoveToNext(bx, i)) {
|
|
|
749 bnext = bx;
|
|
|
750 } else if (MoveToNext(by, i)) {
|
|
|
751 bnext = by;
|
|
|
752 }
|
|
|
753 }
|
|
|
754
|
|
|
755 // Check for conditional branching the wrong way. Negate
|
|
|
756 // conditional, if needed, so it falls into the following block
|
|
|
757 // and branches to the not-following block.
|
|
|
758
|
|
|
759 // Check for the next block being in succs[0]. We are going to branch
|
|
|
760 // to succs[0], so we want the fall-thru case as the next block in
|
|
|
761 // succs[1].
|
|
|
762 if (bnext == bs0) {
|
|
|
763 // Fall-thru case in succs[0], so flip targets in succs map
|
|
|
764 Block *tbs0 = b->_succs[0];
|
|
|
765 Block *tbs1 = b->_succs[1];
|
|
|
766 b->_succs.map( 0, tbs1 );
|
|
|
767 b->_succs.map( 1, tbs0 );
|
|
|
768 // Flip projection for each target
|
|
|
769 { ProjNode *tmp = proj0; proj0 = proj1; proj1 = tmp; }
|
|
|
770
|
|
|
771 } else if( bnext == bs1 ) { // Fall-thru is already in succs[1]
|
|
|
772
|
|
|
773 } else { // Else need a double-branch
|
|
|
774
|
|
|
775 // The existing conditional branch need not change.
|
|
|
776 // Add a unconditional branch to the false target.
|
|
|
777 // Alas, it must appear in its own block and adding a
|
|
|
778 // block this late in the game is complicated. Sigh.
|
|
|
779 insert_goto_at(i, 1);
|
|
|
780 }
|
|
|
781
|
|
|
782 // Make sure we TRUE branch to the target
|
|
|
783 if( proj0->Opcode() == Op_IfFalse )
|
|
|
784 iff->negate();
|
|
|
785
|
|
|
786 b->_nodes.pop(); // Remove IfFalse & IfTrue projections
|
|
|
787 b->_nodes.pop();
|
|
|
788
|
|
|
789 } else {
|
|
|
790 // Multi-exit block, e.g. a switch statement
|
|
|
791 // But we don't need to do anything here
|
|
|
792 }
|
|
|
793
|
|
|
794 } // End of for all blocks
|
|
|
795
|
|
|
796 }
|
|
|
797
|
|
|
798
|
|
|
799 //------------------------------dump-------------------------------------------
|
|
|
800 #ifndef PRODUCT
|
|
|
801 void PhaseCFG::_dump_cfg( const Node *end, VectorSet &visited ) const {
|
|
|
802 const Node *x = end->is_block_proj();
|
|
|
803 assert( x, "not a CFG" );
|
|
|
804
|
|
|
805 // Do not visit this block again
|
|
|
806 if( visited.test_set(x->_idx) ) return;
|
|
|
807
|
|
|
808 // Skip through this block
|
|
|
809 const Node *p = x;
|
|
|
810 do {
|
|
|
811 p = p->in(0); // Move control forward
|
|
|
812 assert( !p->is_block_proj() || p->is_Root(), "not a CFG" );
|
|
|
813 } while( !p->is_block_start() );
|
|
|
814
|
|
|
815 // Recursively visit
|
|
|
816 for( uint i=1; i<p->req(); i++ )
|
|
|
817 _dump_cfg(p->in(i),visited);
|
|
|
818
|
|
|
819 // Dump the block
|
|
|
820 _bbs[p->_idx]->dump(&_bbs);
|
|
|
821 }
|
|
|
822
|
|
|
823 void PhaseCFG::dump( ) const {
|
|
|
824 tty->print("\n--- CFG --- %d BBs\n",_num_blocks);
|
|
|
825 if( _blocks.size() ) { // Did we do basic-block layout?
|
|
|
826 for( uint i=0; i<_num_blocks; i++ )
|
|
|
827 _blocks[i]->dump(&_bbs);
|
|
|
828 } else { // Else do it with a DFS
|
|
|
829 VectorSet visited(_bbs._arena);
|
|
|
830 _dump_cfg(_root,visited);
|
|
|
831 }
|
|
|
832 }
|
|
|
833
|
|
|
834 void PhaseCFG::dump_headers() {
|
|
|
835 for( uint i = 0; i < _num_blocks; i++ ) {
|
|
|
836 if( _blocks[i] == NULL ) continue;
|
|
|
837 _blocks[i]->dump_head(&_bbs);
|
|
|
838 }
|
|
|
839 }
|
|
|
840
|
|
|
841 void PhaseCFG::verify( ) const {
|
|
|
842 // Verify sane CFG
|
|
|
843 for( uint i = 0; i < _num_blocks; i++ ) {
|
|
|
844 Block *b = _blocks[i];
|
|
|
845 uint cnt = b->_nodes.size();
|
|
|
846 uint j;
|
|
|
847 for( j = 0; j < cnt; j++ ) {
|
|
|
848 Node *n = b->_nodes[j];
|
|
|
849 assert( _bbs[n->_idx] == b, "" );
|
|
|
850 if( j >= 1 && n->is_Mach() &&
|
|
|
851 n->as_Mach()->ideal_Opcode() == Op_CreateEx ) {
|
|
|
852 assert( j == 1 || b->_nodes[j-1]->is_Phi(),
|
|
|
853 "CreateEx must be first instruction in block" );
|
|
|
854 }
|
|
|
855 for( uint k = 0; k < n->req(); k++ ) {
|
|
|
856 Node *use = n->in(k);
|
|
|
857 if( use && use != n ) {
|
|
|
858 assert( _bbs[use->_idx] || use->is_Con(),
|
|
|
859 "must have block; constants for debug info ok" );
|
|
|
860 }
|
|
|
861 }
|
|
|
862 }
|
|
|
863
|
|
|
864 j = b->end_idx();
|
|
|
865 Node *bp = (Node*)b->_nodes[b->_nodes.size()-1]->is_block_proj();
|
|
|
866 assert( bp, "last instruction must be a block proj" );
|
|
|
867 assert( bp == b->_nodes[j], "wrong number of successors for this block" );
|
|
|
868 if( bp->is_Catch() ) {
|
|
|
869 while( b->_nodes[--j]->Opcode() == Op_MachProj ) ;
|
|
|
870 assert( b->_nodes[j]->is_Call(), "CatchProj must follow call" );
|
|
|
871 }
|
|
|
872 else if( bp->is_Mach() && bp->as_Mach()->ideal_Opcode() == Op_If ) {
|
|
|
873 assert( b->_num_succs == 2, "Conditional branch must have two targets");
|
|
|
874 }
|
|
|
875 }
|
|
|
876 }
|
|
|
877 #endif
|
|
|
878
|
|
|
879 //=============================================================================
|
|
|
880 //------------------------------UnionFind--------------------------------------
|
|
|
881 UnionFind::UnionFind( uint max ) : _cnt(max), _max(max), _indices(NEW_RESOURCE_ARRAY(uint,max)) {
|
|
|
882 Copy::zero_to_bytes( _indices, sizeof(uint)*max );
|
|
|
883 }
|
|
|
884
|
|
|
885 void UnionFind::extend( uint from_idx, uint to_idx ) {
|
|
|
886 _nesting.check();
|
|
|
887 if( from_idx >= _max ) {
|
|
|
888 uint size = 16;
|
|
|
889 while( size <= from_idx ) size <<=1;
|
|
|
890 _indices = REALLOC_RESOURCE_ARRAY( uint, _indices, _max, size );
|
|
|
891 _max = size;
|
|
|
892 }
|
|
|
893 while( _cnt <= from_idx ) _indices[_cnt++] = 0;
|
|
|
894 _indices[from_idx] = to_idx;
|
|
|
895 }
|
|
|
896
|
|
|
897 void UnionFind::reset( uint max ) {
|
|
|
898 assert( max <= max_uint, "Must fit within uint" );
|
|
|
899 // Force the Union-Find mapping to be at least this large
|
|
|
900 extend(max,0);
|
|
|
901 // Initialize to be the ID mapping.
|
|
|
902 for( uint i=0; i<_max; i++ ) map(i,i);
|
|
|
903 }
|
|
|
904
|
|
|
905 //------------------------------Find_compress----------------------------------
|
|
|
906 // Straight out of Tarjan's union-find algorithm
|
|
|
907 uint UnionFind::Find_compress( uint idx ) {
|
|
|
908 uint cur = idx;
|
|
|
909 uint next = lookup(cur);
|
|
|
910 while( next != cur ) { // Scan chain of equivalences
|
|
|
911 assert( next < cur, "always union smaller" );
|
|
|
912 cur = next; // until find a fixed-point
|
|
|
913 next = lookup(cur);
|
|
|
914 }
|
|
|
915 // Core of union-find algorithm: update chain of
|
|
|
916 // equivalences to be equal to the root.
|
|
|
917 while( idx != next ) {
|
|
|
918 uint tmp = lookup(idx);
|
|
|
919 map(idx, next);
|
|
|
920 idx = tmp;
|
|
|
921 }
|
|
|
922 return idx;
|
|
|
923 }
|
|
|
924
|
|
|
925 //------------------------------Find_const-------------------------------------
|
|
|
926 // Like Find above, but no path compress, so bad asymptotic behavior
|
|
|
927 uint UnionFind::Find_const( uint idx ) const {
|
|
|
928 if( idx == 0 ) return idx; // Ignore the zero idx
|
|
|
929 // Off the end? This can happen during debugging dumps
|
|
|
930 // when data structures have not finished being updated.
|
|
|
931 if( idx >= _max ) return idx;
|
|
|
932 uint next = lookup(idx);
|
|
|
933 while( next != idx ) { // Scan chain of equivalences
|
|
|
934 assert( next < idx, "always union smaller" );
|
|
|
935 idx = next; // until find a fixed-point
|
|
|
936 next = lookup(idx);
|
|
|
937 }
|
|
|
938 return next;
|
|
|
939 }
|
|
|
940
|
|
|
941 //------------------------------Union------------------------------------------
|
|
|
942 // union 2 sets together.
|
|
|
943 void UnionFind::Union( uint idx1, uint idx2 ) {
|
|
|
944 uint src = Find(idx1);
|
|
|
945 uint dst = Find(idx2);
|
|
|
946 assert( src, "" );
|
|
|
947 assert( dst, "" );
|
|
|
948 assert( src < _max, "oob" );
|
|
|
949 assert( dst < _max, "oob" );
|
|
|
950 assert( src < dst, "always union smaller" );
|
|
|
951 map(dst,src);
|
|
|
952 }
|
