Mercurial > hg > truffle
annotate src/share/vm/opto/postaloc.cpp @ 17524:89152779163c
Merge with jdk8-b132
| author | Gilles Duboscq <duboscq@ssw.jku.at> |
|---|---|
| date | Wed, 15 Oct 2014 11:59:32 +0200 |
| parents | 4ca6dc0799b6 |
| children |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 17524 | 2 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 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. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
| 26 #include "memory/allocation.inline.hpp" | |
| 27 #include "opto/chaitin.hpp" | |
| 28 #include "opto/machnode.hpp" | |
| 0 | 29 |
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30 // See if this register (or pairs, or vector) already contains the value. |
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31 static bool register_contains_value(Node* val, OptoReg::Name reg, int n_regs, |
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32 Node_List& value) { |
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33 for (int i = 0; i < n_regs; i++) { |
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34 OptoReg::Name nreg = OptoReg::add(reg,-i); |
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35 if (value[nreg] != val) |
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36 return false; |
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37 } |
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38 return true; |
| 0 | 39 } |
| 40 | |
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41 //---------------------------may_be_copy_of_callee----------------------------- |
| 0 | 42 // Check to see if we can possibly be a copy of a callee-save value. |
| 43 bool PhaseChaitin::may_be_copy_of_callee( Node *def ) const { | |
| 44 // Short circuit if there are no callee save registers | |
| 45 if (_matcher.number_of_saved_registers() == 0) return false; | |
| 46 | |
| 47 // Expect only a spill-down and reload on exit for callee-save spills. | |
| 48 // Chains of copies cannot be deep. | |
| 49 // 5008997 - This is wishful thinking. Register allocator seems to | |
| 50 // be splitting live ranges for callee save registers to such | |
| 51 // an extent that in large methods the chains can be very long | |
| 52 // (50+). The conservative answer is to return true if we don't | |
| 605 | 53 // know as this prevents optimizations from occurring. |
| 0 | 54 |
| 55 const int limit = 60; | |
| 56 int i; | |
| 57 for( i=0; i < limit; i++ ) { | |
| 58 if( def->is_Proj() && def->in(0)->is_Start() && | |
| 10111 | 59 _matcher.is_save_on_entry(lrgs(_lrg_map.live_range_id(def)).reg())) |
| 0 | 60 return true; // Direct use of callee-save proj |
| 61 if( def->is_Copy() ) // Copies carry value through | |
| 62 def = def->in(def->is_Copy()); | |
| 63 else if( def->is_Phi() ) // Phis can merge it from any direction | |
| 64 def = def->in(1); | |
| 65 else | |
| 66 break; | |
| 67 guarantee(def != NULL, "must not resurrect dead copy"); | |
| 68 } | |
| 69 // If we reached the end and didn't find a callee save proj | |
| 70 // then this may be a callee save proj so we return true | |
| 71 // as the conservative answer. If we didn't reach then end | |
| 72 // we must have discovered that it was not a callee save | |
| 73 // else we would have returned. | |
| 74 return i == limit; | |
| 75 } | |
| 76 | |
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77 //------------------------------yank----------------------------------- |
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78 // Helper function for yank_if_dead |
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79 int PhaseChaitin::yank( Node *old, Block *current_block, Node_List *value, Node_List *regnd ) { |
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80 int blk_adjust=0; |
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81 Block *oldb = _cfg.get_block_for_node(old); |
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82 oldb->find_remove(old); |
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83 // Count 1 if deleting an instruction from the current block |
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84 if (oldb == current_block) { |
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85 blk_adjust++; |
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86 } |
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87 _cfg.unmap_node_from_block(old); |
| 10111 | 88 OptoReg::Name old_reg = lrgs(_lrg_map.live_range_id(old)).reg(); |
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89 if( regnd && (*regnd)[old_reg]==old ) { // Instruction is currently available? |
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90 value->map(old_reg,NULL); // Yank from value/regnd maps |
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91 regnd->map(old_reg,NULL); // This register's value is now unknown |
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92 } |
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93 return blk_adjust; |
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94 } |
| 0 | 95 |
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96 #ifdef ASSERT |
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97 static bool expected_yanked_node(Node *old, Node *orig_old) { |
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98 // This code is expected only next original nodes: |
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99 // - load from constant table node which may have next data input nodes: |
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100 // MachConstantBase, MachTemp, MachSpillCopy |
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101 // - Phi nodes that are considered Junk |
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102 // - load constant node which may have next data input nodes: |
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103 // MachTemp, MachSpillCopy |
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104 // - MachSpillCopy |
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105 // - MachProj and Copy dead nodes |
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106 if (old->is_MachSpillCopy()) { |
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107 return true; |
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108 } else if (old->is_Con()) { |
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109 return true; |
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110 } else if (old->is_MachProj()) { // Dead kills projection of Con node |
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111 return (old == orig_old); |
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112 } else if (old->is_Copy()) { // Dead copy of a callee-save value |
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113 return (old == orig_old); |
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114 } else if (old->is_MachTemp()) { |
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115 return orig_old->is_Con(); |
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116 } else if (old->is_Phi()) { // Junk phi's |
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117 return true; |
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118 } else if (old->is_MachConstantBase()) { |
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119 return (orig_old->is_Con() && orig_old->is_MachConstant()); |
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120 } |
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121 return false; |
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122 } |
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123 #endif |
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124 |
| 0 | 125 //------------------------------yank_if_dead----------------------------------- |
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126 // Removed edges from 'old'. Yank if dead. Return adjustment counts to |
| 0 | 127 // iterators in the current block. |
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128 int PhaseChaitin::yank_if_dead_recurse(Node *old, Node *orig_old, Block *current_block, |
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129 Node_List *value, Node_List *regnd) { |
| 0 | 130 int blk_adjust=0; |
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131 if (old->outcnt() == 0 && old != C->top()) { |
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132 #ifdef ASSERT |
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133 if (!expected_yanked_node(old, orig_old)) { |
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134 tty->print_cr("=============================================="); |
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135 tty->print_cr("orig_old:"); |
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136 orig_old->dump(); |
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137 tty->print_cr("old:"); |
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138 old->dump(); |
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139 assert(false, "unexpected yanked node"); |
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140 } |
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141 if (old->is_Con()) |
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142 orig_old = old; // Reset to satisfy expected nodes checks. |
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143 #endif |
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144 blk_adjust += yank(old, current_block, value, regnd); |
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145 |
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146 for (uint i = 1; i < old->req(); i++) { |
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147 Node* n = old->in(i); |
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148 if (n != NULL) { |
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149 old->set_req(i, NULL); |
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150 blk_adjust += yank_if_dead_recurse(n, orig_old, current_block, value, regnd); |
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151 } |
| 0 | 152 } |
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153 // Disconnect control and remove precedence edges if any exist |
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154 old->disconnect_inputs(NULL, C); |
| 0 | 155 } |
| 156 return blk_adjust; | |
| 157 } | |
| 158 | |
| 159 //------------------------------use_prior_register----------------------------- | |
| 160 // Use the prior value instead of the current value, in an effort to make | |
| 161 // the current value go dead. Return block iterator adjustment, in case | |
| 162 // we yank some instructions from this block. | |
| 163 int PhaseChaitin::use_prior_register( Node *n, uint idx, Node *def, Block *current_block, Node_List &value, Node_List ®nd ) { | |
| 164 // No effect? | |
| 165 if( def == n->in(idx) ) return 0; | |
| 166 // Def is currently dead and can be removed? Do not resurrect | |
| 167 if( def->outcnt() == 0 ) return 0; | |
| 168 | |
| 169 // Not every pair of physical registers are assignment compatible, | |
| 170 // e.g. on sparc floating point registers are not assignable to integer | |
| 171 // registers. | |
| 10111 | 172 const LRG &def_lrg = lrgs(_lrg_map.live_range_id(def)); |
| 0 | 173 OptoReg::Name def_reg = def_lrg.reg(); |
| 174 const RegMask &use_mask = n->in_RegMask(idx); | |
| 175 bool can_use = ( RegMask::can_represent(def_reg) ? (use_mask.Member(def_reg) != 0) | |
| 176 : (use_mask.is_AllStack() != 0)); | |
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177 if (!RegMask::is_vector(def->ideal_reg())) { |
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178 // Check for a copy to or from a misaligned pair. |
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179 // It is workaround for a sparc with misaligned pairs. |
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180 can_use = can_use && !use_mask.is_misaligned_pair() && !def_lrg.mask().is_misaligned_pair(); |
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181 } |
| 0 | 182 if (!can_use) |
| 183 return 0; | |
| 184 | |
| 185 // Capture the old def in case it goes dead... | |
| 186 Node *old = n->in(idx); | |
| 187 | |
| 188 // Save-on-call copies can only be elided if the entire copy chain can go | |
| 189 // away, lest we get the same callee-save value alive in 2 locations at | |
| 190 // once. We check for the obvious trivial case here. Although it can | |
| 191 // sometimes be elided with cooperation outside our scope, here we will just | |
| 192 // miss the opportunity. :-( | |
| 193 if( may_be_copy_of_callee(def) ) { | |
| 194 if( old->outcnt() > 1 ) return 0; // We're the not last user | |
| 195 int idx = old->is_Copy(); | |
| 196 assert( idx, "chain of copies being removed" ); | |
| 197 Node *old2 = old->in(idx); // Chain of copies | |
| 198 if( old2->outcnt() > 1 ) return 0; // old is not the last user | |
| 199 int idx2 = old2->is_Copy(); | |
| 200 if( !idx2 ) return 0; // Not a chain of 2 copies | |
| 201 if( def != old2->in(idx2) ) return 0; // Chain of exactly 2 copies | |
| 202 } | |
| 203 | |
| 204 // Use the new def | |
| 205 n->set_req(idx,def); | |
| 206 _post_alloc++; | |
| 207 | |
| 208 // Is old def now dead? We successfully yanked a copy? | |
| 209 return yank_if_dead(old,current_block,&value,®nd); | |
| 210 } | |
| 211 | |
| 212 | |
| 213 //------------------------------skip_copies------------------------------------ | |
| 214 // Skip through any number of copies (that don't mod oop-i-ness) | |
| 215 Node *PhaseChaitin::skip_copies( Node *c ) { | |
| 216 int idx = c->is_Copy(); | |
| 10111 | 217 uint is_oop = lrgs(_lrg_map.live_range_id(c))._is_oop; |
| 0 | 218 while (idx != 0) { |
| 219 guarantee(c->in(idx) != NULL, "must not resurrect dead copy"); | |
| 10111 | 220 if (lrgs(_lrg_map.live_range_id(c->in(idx)))._is_oop != is_oop) { |
| 0 | 221 break; // casting copy, not the same value |
| 10111 | 222 } |
| 0 | 223 c = c->in(idx); |
| 224 idx = c->is_Copy(); | |
| 225 } | |
| 226 return c; | |
| 227 } | |
| 228 | |
| 229 //------------------------------elide_copy------------------------------------- | |
| 230 // Remove (bypass) copies along Node n, edge k. | |
| 231 int PhaseChaitin::elide_copy( Node *n, int k, Block *current_block, Node_List &value, Node_List ®nd, bool can_change_regs ) { | |
| 232 int blk_adjust = 0; | |
| 233 | |
| 10111 | 234 uint nk_idx = _lrg_map.live_range_id(n->in(k)); |
| 235 OptoReg::Name nk_reg = lrgs(nk_idx).reg(); | |
| 0 | 236 |
| 237 // Remove obvious same-register copies | |
| 238 Node *x = n->in(k); | |
| 239 int idx; | |
| 240 while( (idx=x->is_Copy()) != 0 ) { | |
| 241 Node *copy = x->in(idx); | |
| 242 guarantee(copy != NULL, "must not resurrect dead copy"); | |
| 10111 | 243 if(lrgs(_lrg_map.live_range_id(copy)).reg() != nk_reg) { |
| 244 break; | |
| 245 } | |
| 0 | 246 blk_adjust += use_prior_register(n,k,copy,current_block,value,regnd); |
| 10111 | 247 if (n->in(k) != copy) { |
| 248 break; // Failed for some cutout? | |
| 249 } | |
| 0 | 250 x = copy; // Progress, try again |
| 251 } | |
| 252 | |
| 253 // Phis and 2-address instructions cannot change registers so easily - their | |
| 254 // outputs must match their input. | |
| 255 if( !can_change_regs ) | |
| 256 return blk_adjust; // Only check stupid copies! | |
| 257 | |
| 258 // Loop backedges won't have a value-mapping yet | |
| 259 if( &value == NULL ) return blk_adjust; | |
| 260 | |
| 261 // Skip through all copies to the _value_ being used. Do not change from | |
| 262 // int to pointer. This attempts to jump through a chain of copies, where | |
| 263 // intermediate copies might be illegal, i.e., value is stored down to stack | |
| 264 // then reloaded BUT survives in a register the whole way. | |
| 265 Node *val = skip_copies(n->in(k)); | |
| 266 | |
| 2008 | 267 if (val == x && nk_idx != 0 && |
| 268 regnd[nk_reg] != NULL && regnd[nk_reg] != x && | |
| 10111 | 269 _lrg_map.live_range_id(x) == _lrg_map.live_range_id(regnd[nk_reg])) { |
| 2008 | 270 // When rematerialzing nodes and stretching lifetimes, the |
| 271 // allocator will reuse the original def for multidef LRG instead | |
| 272 // of the current reaching def because it can't know it's safe to | |
| 273 // do so. After allocation completes if they are in the same LRG | |
| 274 // then it should use the current reaching def instead. | |
| 275 n->set_req(k, regnd[nk_reg]); | |
| 276 blk_adjust += yank_if_dead(val, current_block, &value, ®nd); | |
| 277 val = skip_copies(n->in(k)); | |
| 278 } | |
| 279 | |
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280 if (val == x) return blk_adjust; // No progress? |
| 0 | 281 |
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282 int n_regs = RegMask::num_registers(val->ideal_reg()); |
| 10111 | 283 uint val_idx = _lrg_map.live_range_id(val); |
| 0 | 284 OptoReg::Name val_reg = lrgs(val_idx).reg(); |
| 285 | |
| 286 // See if it happens to already be in the correct register! | |
| 287 // (either Phi's direct register, or the common case of the name | |
| 288 // never-clobbered original-def register) | |
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289 if (register_contains_value(val, val_reg, n_regs, value)) { |
| 0 | 290 blk_adjust += use_prior_register(n,k,regnd[val_reg],current_block,value,regnd); |
| 291 if( n->in(k) == regnd[val_reg] ) // Success! Quit trying | |
| 292 return blk_adjust; | |
| 293 } | |
| 294 | |
| 295 // See if we can skip the copy by changing registers. Don't change from | |
| 296 // using a register to using the stack unless we know we can remove a | |
| 297 // copy-load. Otherwise we might end up making a pile of Intel cisc-spill | |
| 298 // ops reading from memory instead of just loading once and using the | |
| 299 // register. | |
| 300 | |
| 301 // Also handle duplicate copies here. | |
| 302 const Type *t = val->is_Con() ? val->bottom_type() : NULL; | |
| 303 | |
| 304 // Scan all registers to see if this value is around already | |
| 305 for( uint reg = 0; reg < (uint)_max_reg; reg++ ) { | |
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306 if (reg == (uint)nk_reg) { |
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307 // Found ourselves so check if there is only one user of this |
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308 // copy and keep on searching for a better copy if so. |
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309 bool ignore_self = true; |
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310 x = n->in(k); |
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311 DUIterator_Fast imax, i = x->fast_outs(imax); |
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312 Node* first = x->fast_out(i); i++; |
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313 while (i < imax && ignore_self) { |
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314 Node* use = x->fast_out(i); i++; |
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315 if (use != first) ignore_self = false; |
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316 } |
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317 if (ignore_self) continue; |
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318 } |
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319 |
| 0 | 320 Node *vv = value[reg]; |
| 6185 | 321 if (n_regs > 1) { // Doubles and vectors check for aligned-adjacent set |
| 322 uint last = (n_regs-1); // Looking for the last part of a set | |
| 323 if ((reg&last) != last) continue; // Wrong part of a set | |
| 324 if (!register_contains_value(vv, reg, n_regs, value)) continue; // Different value | |
| 0 | 325 } |
| 326 if( vv == val || // Got a direct hit? | |
| 327 (t && vv && vv->bottom_type() == t && vv->is_Mach() && | |
| 328 vv->as_Mach()->rule() == val->as_Mach()->rule()) ) { // Or same constant? | |
| 329 assert( !n->is_Phi(), "cannot change registers at a Phi so easily" ); | |
| 330 if( OptoReg::is_stack(nk_reg) || // CISC-loading from stack OR | |
| 331 OptoReg::is_reg(reg) || // turning into a register use OR | |
| 332 regnd[reg]->outcnt()==1 ) { // last use of a spill-load turns into a CISC use | |
| 333 blk_adjust += use_prior_register(n,k,regnd[reg],current_block,value,regnd); | |
| 334 if( n->in(k) == regnd[reg] ) // Success! Quit trying | |
| 335 return blk_adjust; | |
| 336 } // End of if not degrading to a stack | |
| 337 } // End of if found value in another register | |
| 338 } // End of scan all machine registers | |
| 339 return blk_adjust; | |
| 340 } | |
| 341 | |
| 342 | |
| 343 // | |
| 344 // Check if nreg already contains the constant value val. Normal copy | |
| 345 // elimination doesn't doesn't work on constants because multiple | |
| 346 // nodes can represent the same constant so the type and rule of the | |
| 347 // MachNode must be checked to ensure equivalence. | |
| 348 // | |
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349 bool PhaseChaitin::eliminate_copy_of_constant(Node* val, Node* n, |
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350 Block *current_block, |
| 0 | 351 Node_List& value, Node_List& regnd, |
| 352 OptoReg::Name nreg, OptoReg::Name nreg2) { | |
| 353 if (value[nreg] != val && val->is_Con() && | |
| 354 value[nreg] != NULL && value[nreg]->is_Con() && | |
| 355 (nreg2 == OptoReg::Bad || value[nreg] == value[nreg2]) && | |
| 356 value[nreg]->bottom_type() == val->bottom_type() && | |
| 357 value[nreg]->as_Mach()->rule() == val->as_Mach()->rule()) { | |
| 358 // This code assumes that two MachNodes representing constants | |
| 359 // which have the same rule and the same bottom type will produce | |
| 360 // identical effects into a register. This seems like it must be | |
| 361 // objectively true unless there are hidden inputs to the nodes | |
| 362 // but if that were to change this code would need to updated. | |
| 363 // Since they are equivalent the second one if redundant and can | |
| 364 // be removed. | |
| 365 // | |
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366 // n will be replaced with the old value but n might have |
| 0 | 367 // kills projections associated with it so remove them now so that |
| 605 | 368 // yank_if_dead will be able to eliminate the copy once the uses |
| 0 | 369 // have been transferred to the old[value]. |
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370 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { |
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371 Node* use = n->fast_out(i); |
| 0 | 372 if (use->is_Proj() && use->outcnt() == 0) { |
| 373 // Kill projections have no users and one input | |
| 374 use->set_req(0, C->top()); | |
| 375 yank_if_dead(use, current_block, &value, ®nd); | |
| 376 --i; --imax; | |
| 377 } | |
| 378 } | |
| 379 _post_alloc++; | |
| 380 return true; | |
| 381 } | |
| 382 return false; | |
| 383 } | |
| 384 | |
| 385 | |
| 386 //------------------------------post_allocate_copy_removal--------------------- | |
| 387 // Post-Allocation peephole copy removal. We do this in 1 pass over the | |
| 388 // basic blocks. We maintain a mapping of registers to Nodes (an array of | |
| 389 // Nodes indexed by machine register or stack slot number). NULL means that a | |
| 390 // register is not mapped to any Node. We can (want to have!) have several | |
| 391 // registers map to the same Node. We walk forward over the instructions | |
| 392 // updating the mapping as we go. At merge points we force a NULL if we have | |
| 393 // to merge 2 different Nodes into the same register. Phi functions will give | |
| 394 // us a new Node if there is a proper value merging. Since the blocks are | |
| 395 // arranged in some RPO, we will visit all parent blocks before visiting any | |
| 396 // successor blocks (except at loops). | |
| 397 // | |
| 398 // If we find a Copy we look to see if the Copy's source register is a stack | |
| 399 // slot and that value has already been loaded into some machine register; if | |
| 400 // so we use machine register directly. This turns a Load into a reg-reg | |
| 401 // Move. We also look for reloads of identical constants. | |
| 402 // | |
| 403 // When we see a use from a reg-reg Copy, we will attempt to use the copy's | |
| 404 // source directly and make the copy go dead. | |
| 405 void PhaseChaitin::post_allocate_copy_removal() { | |
| 406 NOT_PRODUCT( Compile::TracePhase t3("postAllocCopyRemoval", &_t_postAllocCopyRemoval, TimeCompiler); ) | |
| 407 ResourceMark rm; | |
| 408 | |
| 409 // Need a mapping from basic block Node_Lists. We need a Node_List to | |
| 410 // map from register number to value-producing Node. | |
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411 Node_List **blk2value = NEW_RESOURCE_ARRAY( Node_List *, _cfg.number_of_blocks() + 1); |
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412 memset(blk2value, 0, sizeof(Node_List*) * (_cfg.number_of_blocks() + 1)); |
| 0 | 413 // Need a mapping from basic block Node_Lists. We need a Node_List to |
| 414 // map from register number to register-defining Node. | |
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415 Node_List **blk2regnd = NEW_RESOURCE_ARRAY( Node_List *, _cfg.number_of_blocks() + 1); |
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416 memset(blk2regnd, 0, sizeof(Node_List*) * (_cfg.number_of_blocks() + 1)); |
| 0 | 417 |
| 418 // We keep unused Node_Lists on a free_list to avoid wasting | |
| 419 // memory. | |
| 420 GrowableArray<Node_List*> free_list = GrowableArray<Node_List*>(16); | |
| 421 | |
| 422 // For all blocks | |
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423 for (uint i = 0; i < _cfg.number_of_blocks(); i++) { |
| 0 | 424 uint j; |
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425 Block* block = _cfg.get_block(i); |
| 0 | 426 |
| 427 // Count of Phis in block | |
| 428 uint phi_dex; | |
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429 for (phi_dex = 1; phi_dex < block->number_of_nodes(); phi_dex++) { |
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430 Node* phi = block->get_node(phi_dex); |
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431 if (!phi->is_Phi()) { |
| 0 | 432 break; |
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433 } |
| 0 | 434 } |
| 435 | |
| 436 // If any predecessor has not been visited, we do not know the state | |
| 437 // of registers at the start. Check for this, while updating copies | |
| 438 // along Phi input edges | |
| 439 bool missing_some_inputs = false; | |
| 440 Block *freed = NULL; | |
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441 for (j = 1; j < block->num_preds(); j++) { |
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442 Block* pb = _cfg.get_block_for_node(block->pred(j)); |
| 0 | 443 // Remove copies along phi edges |
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444 for (uint k = 1; k < phi_dex; k++) { |
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445 elide_copy(block->get_node(k), j, block, *blk2value[pb->_pre_order], *blk2regnd[pb->_pre_order], false); |
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446 } |
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447 if (blk2value[pb->_pre_order]) { // Have a mapping on this edge? |
| 0 | 448 // See if this predecessor's mappings have been used by everybody |
| 449 // who wants them. If so, free 'em. | |
| 450 uint k; | |
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451 for (k = 0; k < pb->_num_succs; k++) { |
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452 Block* pbsucc = pb->_succs[k]; |
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453 if (!blk2value[pbsucc->_pre_order] && pbsucc != block) { |
| 0 | 454 break; // Found a future user |
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455 } |
| 0 | 456 } |
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457 if (k >= pb->_num_succs) { // No more uses, free! |
| 0 | 458 freed = pb; // Record last block freed |
| 459 free_list.push(blk2value[pb->_pre_order]); | |
| 460 free_list.push(blk2regnd[pb->_pre_order]); | |
| 461 } | |
| 462 } else { // This block has unvisited (loopback) inputs | |
| 463 missing_some_inputs = true; | |
| 464 } | |
| 465 } | |
| 466 | |
| 467 | |
| 468 // Extract Node_List mappings. If 'freed' is non-zero, we just popped | |
| 469 // 'freed's blocks off the list | |
| 470 Node_List ®nd = *(free_list.is_empty() ? new Node_List() : free_list.pop()); | |
| 471 Node_List &value = *(free_list.is_empty() ? new Node_List() : free_list.pop()); | |
| 472 assert( !freed || blk2value[freed->_pre_order] == &value, "" ); | |
| 473 value.map(_max_reg,NULL); | |
| 474 regnd.map(_max_reg,NULL); | |
| 475 // Set mappings as OUR mappings | |
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476 blk2value[block->_pre_order] = &value; |
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477 blk2regnd[block->_pre_order] = ®nd; |
| 0 | 478 |
| 479 // Initialize value & regnd for this block | |
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480 if (missing_some_inputs) { |
| 0 | 481 // Some predecessor has not yet been visited; zap map to empty |
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482 for (uint k = 0; k < (uint)_max_reg; k++) { |
| 0 | 483 value.map(k,NULL); |
| 484 regnd.map(k,NULL); | |
| 485 } | |
| 486 } else { | |
| 487 if( !freed ) { // Didn't get a freebie prior block | |
| 488 // Must clone some data | |
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489 freed = _cfg.get_block_for_node(block->pred(1)); |
| 0 | 490 Node_List &f_value = *blk2value[freed->_pre_order]; |
| 491 Node_List &f_regnd = *blk2regnd[freed->_pre_order]; | |
| 492 for( uint k = 0; k < (uint)_max_reg; k++ ) { | |
| 493 value.map(k,f_value[k]); | |
| 494 regnd.map(k,f_regnd[k]); | |
| 495 } | |
| 496 } | |
| 497 // Merge all inputs together, setting to NULL any conflicts. | |
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498 for (j = 1; j < block->num_preds(); j++) { |
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499 Block* pb = _cfg.get_block_for_node(block->pred(j)); |
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500 if (pb == freed) { |
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501 continue; // Did self already via freelist |
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502 } |
| 0 | 503 Node_List &p_regnd = *blk2regnd[pb->_pre_order]; |
| 504 for( uint k = 0; k < (uint)_max_reg; k++ ) { | |
| 505 if( regnd[k] != p_regnd[k] ) { // Conflict on reaching defs? | |
| 506 value.map(k,NULL); // Then no value handy | |
| 507 regnd.map(k,NULL); | |
| 508 } | |
| 509 } | |
| 510 } | |
| 511 } | |
| 512 | |
| 513 // For all Phi's | |
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514 for (j = 1; j < phi_dex; j++) { |
| 0 | 515 uint k; |
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516 Node *phi = block->get_node(j); |
| 10111 | 517 uint pidx = _lrg_map.live_range_id(phi); |
| 518 OptoReg::Name preg = lrgs(_lrg_map.live_range_id(phi)).reg(); | |
| 0 | 519 |
| 520 // Remove copies remaining on edges. Check for junk phi. | |
| 521 Node *u = NULL; | |
| 10111 | 522 for (k = 1; k < phi->req(); k++) { |
| 0 | 523 Node *x = phi->in(k); |
| 524 if( phi != x && u != x ) // Found a different input | |
| 525 u = u ? NodeSentinel : x; // Capture unique input, or NodeSentinel for 2nd input | |
| 526 } | |
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527 if (u != NodeSentinel) { // Junk Phi. Remove |
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528 phi->replace_by(u); |
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529 j -= yank_if_dead(phi, block, &value, ®nd); |
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530 phi_dex--; |
| 0 | 531 continue; |
| 532 } | |
| 533 // Note that if value[pidx] exists, then we merged no new values here | |
| 534 // and the phi is useless. This can happen even with the above phi | |
| 535 // removal for complex flows. I cannot keep the better known value here | |
| 536 // because locally the phi appears to define a new merged value. If I | |
| 537 // keep the better value then a copy of the phi, being unable to use the | |
| 538 // global flow analysis, can't "peek through" the phi to the original | |
| 539 // reaching value and so will act like it's defining a new value. This | |
| 540 // can lead to situations where some uses are from the old and some from | |
| 541 // the new values. Not illegal by itself but throws the over-strong | |
| 542 // assert in scheduling. | |
| 543 if( pidx ) { | |
| 544 value.map(preg,phi); | |
| 545 regnd.map(preg,phi); | |
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546 int n_regs = RegMask::num_registers(phi->ideal_reg()); |
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547 for (int l = 1; l < n_regs; l++) { |
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548 OptoReg::Name preg_lo = OptoReg::add(preg,-l); |
| 0 | 549 value.map(preg_lo,phi); |
| 550 regnd.map(preg_lo,phi); | |
| 551 } | |
| 552 } | |
| 553 } | |
| 554 | |
| 555 // For all remaining instructions | |
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556 for (j = phi_dex; j < block->number_of_nodes(); j++) { |
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557 Node* n = block->get_node(j); |
| 0 | 558 |
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559 if(n->outcnt() == 0 && // Dead? |
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560 n != C->top() && // (ignore TOP, it has no du info) |
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561 !n->is_Proj() ) { // fat-proj kills |
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562 j -= yank_if_dead(n, block, &value, ®nd); |
| 0 | 563 continue; |
| 564 } | |
| 565 | |
| 566 // Improve reaching-def info. Occasionally post-alloc's liveness gives | |
| 567 // up (at loop backedges, because we aren't doing a full flow pass). | |
| 568 // The presence of a live use essentially asserts that the use's def is | |
| 569 // alive and well at the use (or else the allocator fubar'd). Take | |
| 570 // advantage of this info to set a reaching def for the use-reg. | |
| 571 uint k; | |
| 10111 | 572 for (k = 1; k < n->req(); k++) { |
| 0 | 573 Node *def = n->in(k); // n->in(k) is a USE; def is the DEF for this USE |
| 574 guarantee(def != NULL, "no disconnected nodes at this point"); | |
| 10111 | 575 uint useidx = _lrg_map.live_range_id(def); // useidx is the live range index for this USE |
| 0 | 576 |
| 577 if( useidx ) { | |
| 578 OptoReg::Name ureg = lrgs(useidx).reg(); | |
| 579 if( !value[ureg] ) { | |
| 580 int idx; // Skip occasional useless copy | |
| 581 while( (idx=def->is_Copy()) != 0 && | |
| 582 def->in(idx) != NULL && // NULL should not happen | |
| 10111 | 583 ureg == lrgs(_lrg_map.live_range_id(def->in(idx))).reg()) |
| 0 | 584 def = def->in(idx); |
| 585 Node *valdef = skip_copies(def); // tighten up val through non-useless copies | |
| 586 value.map(ureg,valdef); // record improved reaching-def info | |
| 587 regnd.map(ureg, def); | |
| 588 // Record other half of doubles | |
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589 uint def_ideal_reg = def->ideal_reg(); |
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590 int n_regs = RegMask::num_registers(def_ideal_reg); |
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591 for (int l = 1; l < n_regs; l++) { |
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592 OptoReg::Name ureg_lo = OptoReg::add(ureg,-l); |
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593 if (!value[ureg_lo] && |
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594 (!RegMask::can_represent(ureg_lo) || |
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595 lrgs(useidx).mask().Member(ureg_lo))) { // Nearly always adjacent |
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596 value.map(ureg_lo,valdef); // record improved reaching-def info |
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597 regnd.map(ureg_lo, def); |
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598 } |
| 0 | 599 } |
| 600 } | |
| 601 } | |
| 602 } | |
| 603 | |
| 604 const uint two_adr = n->is_Mach() ? n->as_Mach()->two_adr() : 0; | |
| 605 | |
| 606 // Remove copies along input edges | |
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607 for (k = 1; k < n->req(); k++) { |
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608 j -= elide_copy(n, k, block, value, regnd, two_adr != k); |
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609 } |
| 0 | 610 |
| 611 // Unallocated Nodes define no registers | |
| 10111 | 612 uint lidx = _lrg_map.live_range_id(n); |
| 613 if (!lidx) { | |
| 614 continue; | |
| 615 } | |
| 0 | 616 |
| 617 // Update the register defined by this instruction | |
| 618 OptoReg::Name nreg = lrgs(lidx).reg(); | |
| 619 // Skip through all copies to the _value_ being defined. | |
| 620 // Do not change from int to pointer | |
| 621 Node *val = skip_copies(n); | |
| 622 | |
| 923 | 623 // Clear out a dead definition before starting so that the |
| 624 // elimination code doesn't have to guard against it. The | |
| 625 // definition could in fact be a kill projection with a count of | |
| 626 // 0 which is safe but since those are uninteresting for copy | |
| 627 // elimination just delete them as well. | |
| 628 if (regnd[nreg] != NULL && regnd[nreg]->outcnt() == 0) { | |
| 629 regnd.map(nreg, NULL); | |
| 630 value.map(nreg, NULL); | |
| 631 } | |
| 632 | |
| 0 | 633 uint n_ideal_reg = n->ideal_reg(); |
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634 int n_regs = RegMask::num_registers(n_ideal_reg); |
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635 if (n_regs == 1) { |
| 0 | 636 // If Node 'n' does not change the value mapped by the register, |
| 637 // then 'n' is a useless copy. Do not update the register->node | |
| 638 // mapping so 'n' will go dead. | |
| 639 if( value[nreg] != val ) { | |
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640 if (eliminate_copy_of_constant(val, n, block, value, regnd, nreg, OptoReg::Bad)) { |
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641 j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
| 0 | 642 } else { |
| 643 // Update the mapping: record new Node defined by the register | |
| 644 regnd.map(nreg,n); | |
| 645 // Update mapping for defined *value*, which is the defined | |
| 646 // Node after skipping all copies. | |
| 647 value.map(nreg,val); | |
| 648 } | |
| 923 | 649 } else if( !may_be_copy_of_callee(n) ) { |
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650 assert(n->is_Copy(), ""); |
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651 j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
| 0 | 652 } |
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653 } else if (RegMask::is_vector(n_ideal_reg)) { |
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654 // If Node 'n' does not change the value mapped by the register, |
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655 // then 'n' is a useless copy. Do not update the register->node |
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656 // mapping so 'n' will go dead. |
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657 if (!register_contains_value(val, nreg, n_regs, value)) { |
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658 // Update the mapping: record new Node defined by the register |
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659 regnd.map(nreg,n); |
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660 // Update mapping for defined *value*, which is the defined |
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661 // Node after skipping all copies. |
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662 value.map(nreg,val); |
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663 for (int l = 1; l < n_regs; l++) { |
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664 OptoReg::Name nreg_lo = OptoReg::add(nreg,-l); |
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665 regnd.map(nreg_lo, n ); |
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666 value.map(nreg_lo,val); |
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667 } |
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668 } else if (n->is_Copy()) { |
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669 // Note: vector can't be constant and can't be copy of calee. |
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670 j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
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671 } |
| 0 | 672 } else { |
| 673 // If the value occupies a register pair, record same info | |
| 674 // in both registers. | |
| 675 OptoReg::Name nreg_lo = OptoReg::add(nreg,-1); | |
| 676 if( RegMask::can_represent(nreg_lo) && // Either a spill slot, or | |
| 677 !lrgs(lidx).mask().Member(nreg_lo) ) { // Nearly always adjacent | |
| 678 // Sparc occasionally has non-adjacent pairs. | |
| 679 // Find the actual other value | |
| 680 RegMask tmp = lrgs(lidx).mask(); | |
| 681 tmp.Remove(nreg); | |
| 682 nreg_lo = tmp.find_first_elem(); | |
| 683 } | |
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684 if (value[nreg] != val || value[nreg_lo] != val) { |
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685 if (eliminate_copy_of_constant(val, n, block, value, regnd, nreg, nreg_lo)) { |
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686 j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
| 0 | 687 } else { |
| 688 regnd.map(nreg , n ); | |
| 689 regnd.map(nreg_lo, n ); | |
| 690 value.map(nreg ,val); | |
| 691 value.map(nreg_lo,val); | |
| 692 } | |
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693 } else if (!may_be_copy_of_callee(n)) { |
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694 assert(n->is_Copy(), ""); |
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695 j -= replace_and_yank_if_dead(n, nreg, block, value, regnd); |
| 0 | 696 } |
| 697 } | |
| 698 | |
| 699 // Fat projections kill many registers | |
| 700 if( n_ideal_reg == MachProjNode::fat_proj ) { | |
| 701 RegMask rm = n->out_RegMask(); | |
| 702 // wow, what an expensive iterator... | |
| 703 nreg = rm.find_first_elem(); | |
| 704 while( OptoReg::is_valid(nreg)) { | |
| 705 rm.Remove(nreg); | |
| 706 value.map(nreg,n); | |
| 707 regnd.map(nreg,n); | |
| 708 nreg = rm.find_first_elem(); | |
| 709 } | |
| 710 } | |
| 711 | |
| 712 } // End of for all instructions in the block | |
| 713 | |
| 714 } // End for all blocks | |
| 715 } |