Mercurial > hg > graal-compiler
annotate src/share/vm/opto/postaloc.cpp @ 4776:5da7201222d5
7110824: ctw/jarfiles/GUI3rdParty_jar/ob_mask_DateField crashes VM
Summary: Change yank_if_dead() to recursive method to remove all dead inputs.
Reviewed-by: never
| author | kvn |
|---|---|
| date | Sat, 07 Jan 2012 10:39:23 -0800 |
| parents | 2209834ccb59 |
| children | 8c92982cbbc4 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 1972 | 2 * Copyright (c) 1998, 2010, 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 |
| 30 // see if this register kind does not requires two registers | |
| 31 static bool is_single_register(uint x) { | |
| 32 #ifdef _LP64 | |
| 33 return (x != Op_RegD && x != Op_RegL && x != Op_RegP); | |
| 34 #else | |
| 35 return (x != Op_RegD && x != Op_RegL); | |
| 36 #endif | |
| 37 } | |
| 38 | |
|
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39 //---------------------------may_be_copy_of_callee----------------------------- |
| 0 | 40 // Check to see if we can possibly be a copy of a callee-save value. |
| 41 bool PhaseChaitin::may_be_copy_of_callee( Node *def ) const { | |
| 42 // Short circuit if there are no callee save registers | |
| 43 if (_matcher.number_of_saved_registers() == 0) return false; | |
| 44 | |
| 45 // Expect only a spill-down and reload on exit for callee-save spills. | |
| 46 // Chains of copies cannot be deep. | |
| 47 // 5008997 - This is wishful thinking. Register allocator seems to | |
| 48 // be splitting live ranges for callee save registers to such | |
| 49 // an extent that in large methods the chains can be very long | |
| 50 // (50+). The conservative answer is to return true if we don't | |
| 605 | 51 // know as this prevents optimizations from occurring. |
| 0 | 52 |
| 53 const int limit = 60; | |
| 54 int i; | |
| 55 for( i=0; i < limit; i++ ) { | |
| 56 if( def->is_Proj() && def->in(0)->is_Start() && | |
| 57 _matcher.is_save_on_entry(lrgs(n2lidx(def)).reg()) ) | |
| 58 return true; // Direct use of callee-save proj | |
| 59 if( def->is_Copy() ) // Copies carry value through | |
| 60 def = def->in(def->is_Copy()); | |
| 61 else if( def->is_Phi() ) // Phis can merge it from any direction | |
| 62 def = def->in(1); | |
| 63 else | |
| 64 break; | |
| 65 guarantee(def != NULL, "must not resurrect dead copy"); | |
| 66 } | |
| 67 // If we reached the end and didn't find a callee save proj | |
| 68 // then this may be a callee save proj so we return true | |
| 69 // as the conservative answer. If we didn't reach then end | |
| 70 // we must have discovered that it was not a callee save | |
| 71 // else we would have returned. | |
| 72 return i == limit; | |
| 73 } | |
| 74 | |
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75 //------------------------------yank----------------------------------- |
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76 // Helper function for yank_if_dead |
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77 int PhaseChaitin::yank( Node *old, Block *current_block, Node_List *value, Node_List *regnd ) { |
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78 int blk_adjust=0; |
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79 Block *oldb = _cfg._bbs[old->_idx]; |
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80 oldb->find_remove(old); |
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81 // Count 1 if deleting an instruction from the current block |
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82 if( oldb == current_block ) blk_adjust++; |
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83 _cfg._bbs.map(old->_idx,NULL); |
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84 OptoReg::Name old_reg = lrgs(n2lidx(old)).reg(); |
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85 if( regnd && (*regnd)[old_reg]==old ) { // Instruction is currently available? |
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86 value->map(old_reg,NULL); // Yank from value/regnd maps |
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87 regnd->map(old_reg,NULL); // This register's value is now unknown |
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88 } |
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89 return blk_adjust; |
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90 } |
| 0 | 91 |
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92 #ifdef ASSERT |
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93 static bool expected_yanked_node(Node *old, Node *orig_old) { |
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94 // This code is expected only next original nodes: |
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95 // - load from constant table node which may have next data input nodes: |
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96 // MachConstantBase, Phi, MachTemp, MachSpillCopy |
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97 // - load constant node which may have next data input nodes: |
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98 // MachTemp, MachSpillCopy |
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99 // - MachSpillCopy |
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100 // - MachProj and Copy dead nodes |
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101 if (old->is_MachSpillCopy()) { |
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102 return true; |
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103 } else if (old->is_Con()) { |
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104 return true; |
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105 } else if (old->is_MachProj()) { // Dead kills projection of Con node |
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106 return (old == orig_old); |
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107 } else if (old->is_Copy()) { // Dead copy of a callee-save value |
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108 return (old == orig_old); |
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109 } else if (old->is_MachTemp()) { |
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110 return orig_old->is_Con(); |
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111 } else if (old->is_Phi() || old->is_MachConstantBase()) { |
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112 return (orig_old->is_Con() && orig_old->is_MachConstant()); |
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113 } |
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114 return false; |
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115 } |
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116 #endif |
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117 |
| 0 | 118 //------------------------------yank_if_dead----------------------------------- |
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119 // Removed edges from 'old'. Yank if dead. Return adjustment counts to |
| 0 | 120 // iterators in the current block. |
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121 int PhaseChaitin::yank_if_dead_recurse(Node *old, Node *orig_old, Block *current_block, |
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122 Node_List *value, Node_List *regnd) { |
| 0 | 123 int blk_adjust=0; |
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124 if (old->outcnt() == 0 && old != C->top()) { |
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125 #ifdef ASSERT |
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126 if (!expected_yanked_node(old, orig_old)) { |
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127 tty->print_cr("=============================================="); |
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128 tty->print_cr("orig_old:"); |
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129 orig_old->dump(); |
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130 tty->print_cr("old:"); |
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131 old->dump(); |
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132 assert(false, "unexpected yanked node"); |
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133 } |
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134 if (old->is_Con()) |
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135 orig_old = old; // Reset to satisfy expected nodes checks. |
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136 #endif |
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137 blk_adjust += yank(old, current_block, value, regnd); |
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138 |
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139 for (uint i = 1; i < old->req(); i++) { |
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140 Node* n = old->in(i); |
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141 if (n != NULL) { |
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142 old->set_req(i, NULL); |
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143 blk_adjust += yank_if_dead_recurse(n, orig_old, current_block, value, regnd); |
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144 } |
| 0 | 145 } |
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146 // Disconnect control and remove precedence edges if any exist |
| 0 | 147 old->disconnect_inputs(NULL); |
| 148 } | |
| 149 return blk_adjust; | |
| 150 } | |
| 151 | |
| 152 //------------------------------use_prior_register----------------------------- | |
| 153 // Use the prior value instead of the current value, in an effort to make | |
| 154 // the current value go dead. Return block iterator adjustment, in case | |
| 155 // we yank some instructions from this block. | |
| 156 int PhaseChaitin::use_prior_register( Node *n, uint idx, Node *def, Block *current_block, Node_List &value, Node_List ®nd ) { | |
| 157 // No effect? | |
| 158 if( def == n->in(idx) ) return 0; | |
| 159 // Def is currently dead and can be removed? Do not resurrect | |
| 160 if( def->outcnt() == 0 ) return 0; | |
| 161 | |
| 162 // Not every pair of physical registers are assignment compatible, | |
| 163 // e.g. on sparc floating point registers are not assignable to integer | |
| 164 // registers. | |
| 165 const LRG &def_lrg = lrgs(n2lidx(def)); | |
| 166 OptoReg::Name def_reg = def_lrg.reg(); | |
| 167 const RegMask &use_mask = n->in_RegMask(idx); | |
| 168 bool can_use = ( RegMask::can_represent(def_reg) ? (use_mask.Member(def_reg) != 0) | |
| 169 : (use_mask.is_AllStack() != 0)); | |
| 170 // Check for a copy to or from a misaligned pair. | |
| 171 can_use = can_use && !use_mask.is_misaligned_Pair() && !def_lrg.mask().is_misaligned_Pair(); | |
| 172 | |
| 173 if (!can_use) | |
| 174 return 0; | |
| 175 | |
| 176 // Capture the old def in case it goes dead... | |
| 177 Node *old = n->in(idx); | |
| 178 | |
| 179 // Save-on-call copies can only be elided if the entire copy chain can go | |
| 180 // away, lest we get the same callee-save value alive in 2 locations at | |
| 181 // once. We check for the obvious trivial case here. Although it can | |
| 182 // sometimes be elided with cooperation outside our scope, here we will just | |
| 183 // miss the opportunity. :-( | |
| 184 if( may_be_copy_of_callee(def) ) { | |
| 185 if( old->outcnt() > 1 ) return 0; // We're the not last user | |
| 186 int idx = old->is_Copy(); | |
| 187 assert( idx, "chain of copies being removed" ); | |
| 188 Node *old2 = old->in(idx); // Chain of copies | |
| 189 if( old2->outcnt() > 1 ) return 0; // old is not the last user | |
| 190 int idx2 = old2->is_Copy(); | |
| 191 if( !idx2 ) return 0; // Not a chain of 2 copies | |
| 192 if( def != old2->in(idx2) ) return 0; // Chain of exactly 2 copies | |
| 193 } | |
| 194 | |
| 195 // Use the new def | |
| 196 n->set_req(idx,def); | |
| 197 _post_alloc++; | |
| 198 | |
| 199 // Is old def now dead? We successfully yanked a copy? | |
| 200 return yank_if_dead(old,current_block,&value,®nd); | |
| 201 } | |
| 202 | |
| 203 | |
| 204 //------------------------------skip_copies------------------------------------ | |
| 205 // Skip through any number of copies (that don't mod oop-i-ness) | |
| 206 Node *PhaseChaitin::skip_copies( Node *c ) { | |
| 207 int idx = c->is_Copy(); | |
| 208 uint is_oop = lrgs(n2lidx(c))._is_oop; | |
| 209 while (idx != 0) { | |
| 210 guarantee(c->in(idx) != NULL, "must not resurrect dead copy"); | |
| 211 if (lrgs(n2lidx(c->in(idx)))._is_oop != is_oop) | |
| 212 break; // casting copy, not the same value | |
| 213 c = c->in(idx); | |
| 214 idx = c->is_Copy(); | |
| 215 } | |
| 216 return c; | |
| 217 } | |
| 218 | |
| 219 //------------------------------elide_copy------------------------------------- | |
| 220 // Remove (bypass) copies along Node n, edge k. | |
| 221 int PhaseChaitin::elide_copy( Node *n, int k, Block *current_block, Node_List &value, Node_List ®nd, bool can_change_regs ) { | |
| 222 int blk_adjust = 0; | |
| 223 | |
| 224 uint nk_idx = n2lidx(n->in(k)); | |
| 225 OptoReg::Name nk_reg = lrgs(nk_idx ).reg(); | |
| 226 | |
| 227 // Remove obvious same-register copies | |
| 228 Node *x = n->in(k); | |
| 229 int idx; | |
| 230 while( (idx=x->is_Copy()) != 0 ) { | |
| 231 Node *copy = x->in(idx); | |
| 232 guarantee(copy != NULL, "must not resurrect dead copy"); | |
| 233 if( lrgs(n2lidx(copy)).reg() != nk_reg ) break; | |
| 234 blk_adjust += use_prior_register(n,k,copy,current_block,value,regnd); | |
| 235 if( n->in(k) != copy ) break; // Failed for some cutout? | |
| 236 x = copy; // Progress, try again | |
| 237 } | |
| 238 | |
| 239 // Phis and 2-address instructions cannot change registers so easily - their | |
| 240 // outputs must match their input. | |
| 241 if( !can_change_regs ) | |
| 242 return blk_adjust; // Only check stupid copies! | |
| 243 | |
| 244 // Loop backedges won't have a value-mapping yet | |
| 245 if( &value == NULL ) return blk_adjust; | |
| 246 | |
| 247 // Skip through all copies to the _value_ being used. Do not change from | |
| 248 // int to pointer. This attempts to jump through a chain of copies, where | |
| 249 // intermediate copies might be illegal, i.e., value is stored down to stack | |
| 250 // then reloaded BUT survives in a register the whole way. | |
| 251 Node *val = skip_copies(n->in(k)); | |
| 252 | |
| 2008 | 253 if (val == x && nk_idx != 0 && |
| 254 regnd[nk_reg] != NULL && regnd[nk_reg] != x && | |
| 255 n2lidx(x) == n2lidx(regnd[nk_reg])) { | |
| 256 // When rematerialzing nodes and stretching lifetimes, the | |
| 257 // allocator will reuse the original def for multidef LRG instead | |
| 258 // of the current reaching def because it can't know it's safe to | |
| 259 // do so. After allocation completes if they are in the same LRG | |
| 260 // then it should use the current reaching def instead. | |
| 261 n->set_req(k, regnd[nk_reg]); | |
| 262 blk_adjust += yank_if_dead(val, current_block, &value, ®nd); | |
| 263 val = skip_copies(n->in(k)); | |
| 264 } | |
| 265 | |
| 0 | 266 if( val == x ) return blk_adjust; // No progress? |
| 267 | |
| 268 bool single = is_single_register(val->ideal_reg()); | |
| 269 uint val_idx = n2lidx(val); | |
| 270 OptoReg::Name val_reg = lrgs(val_idx).reg(); | |
| 271 | |
| 272 // See if it happens to already be in the correct register! | |
| 273 // (either Phi's direct register, or the common case of the name | |
| 274 // never-clobbered original-def register) | |
| 275 if( value[val_reg] == val && | |
| 276 // Doubles check both halves | |
| 277 ( single || value[val_reg-1] == val ) ) { | |
| 278 blk_adjust += use_prior_register(n,k,regnd[val_reg],current_block,value,regnd); | |
| 279 if( n->in(k) == regnd[val_reg] ) // Success! Quit trying | |
| 280 return blk_adjust; | |
| 281 } | |
| 282 | |
| 283 // See if we can skip the copy by changing registers. Don't change from | |
| 284 // using a register to using the stack unless we know we can remove a | |
| 285 // copy-load. Otherwise we might end up making a pile of Intel cisc-spill | |
| 286 // ops reading from memory instead of just loading once and using the | |
| 287 // register. | |
| 288 | |
| 289 // Also handle duplicate copies here. | |
| 290 const Type *t = val->is_Con() ? val->bottom_type() : NULL; | |
| 291 | |
| 292 // Scan all registers to see if this value is around already | |
| 293 for( uint reg = 0; reg < (uint)_max_reg; reg++ ) { | |
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294 if (reg == (uint)nk_reg) { |
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295 // Found ourselves so check if there is only one user of this |
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296 // copy and keep on searching for a better copy if so. |
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297 bool ignore_self = true; |
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298 x = n->in(k); |
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299 DUIterator_Fast imax, i = x->fast_outs(imax); |
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300 Node* first = x->fast_out(i); i++; |
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301 while (i < imax && ignore_self) { |
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302 Node* use = x->fast_out(i); i++; |
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303 if (use != first) ignore_self = false; |
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304 } |
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305 if (ignore_self) continue; |
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306 } |
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307 |
| 0 | 308 Node *vv = value[reg]; |
| 309 if( !single ) { // Doubles check for aligned-adjacent pair | |
| 310 if( (reg&1)==0 ) continue; // Wrong half of a pair | |
| 311 if( vv != value[reg-1] ) continue; // Not a complete pair | |
| 312 } | |
| 313 if( vv == val || // Got a direct hit? | |
| 314 (t && vv && vv->bottom_type() == t && vv->is_Mach() && | |
| 315 vv->as_Mach()->rule() == val->as_Mach()->rule()) ) { // Or same constant? | |
| 316 assert( !n->is_Phi(), "cannot change registers at a Phi so easily" ); | |
| 317 if( OptoReg::is_stack(nk_reg) || // CISC-loading from stack OR | |
| 318 OptoReg::is_reg(reg) || // turning into a register use OR | |
| 319 regnd[reg]->outcnt()==1 ) { // last use of a spill-load turns into a CISC use | |
| 320 blk_adjust += use_prior_register(n,k,regnd[reg],current_block,value,regnd); | |
| 321 if( n->in(k) == regnd[reg] ) // Success! Quit trying | |
| 322 return blk_adjust; | |
| 323 } // End of if not degrading to a stack | |
| 324 } // End of if found value in another register | |
| 325 } // End of scan all machine registers | |
| 326 return blk_adjust; | |
| 327 } | |
| 328 | |
| 329 | |
| 330 // | |
| 331 // Check if nreg already contains the constant value val. Normal copy | |
| 332 // elimination doesn't doesn't work on constants because multiple | |
| 333 // nodes can represent the same constant so the type and rule of the | |
| 334 // MachNode must be checked to ensure equivalence. | |
| 335 // | |
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336 bool PhaseChaitin::eliminate_copy_of_constant(Node* val, Node* n, |
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337 Block *current_block, |
| 0 | 338 Node_List& value, Node_List& regnd, |
| 339 OptoReg::Name nreg, OptoReg::Name nreg2) { | |
| 340 if (value[nreg] != val && val->is_Con() && | |
| 341 value[nreg] != NULL && value[nreg]->is_Con() && | |
| 342 (nreg2 == OptoReg::Bad || value[nreg] == value[nreg2]) && | |
| 343 value[nreg]->bottom_type() == val->bottom_type() && | |
| 344 value[nreg]->as_Mach()->rule() == val->as_Mach()->rule()) { | |
| 345 // This code assumes that two MachNodes representing constants | |
| 346 // which have the same rule and the same bottom type will produce | |
| 347 // identical effects into a register. This seems like it must be | |
| 348 // objectively true unless there are hidden inputs to the nodes | |
| 349 // but if that were to change this code would need to updated. | |
| 350 // Since they are equivalent the second one if redundant and can | |
| 351 // be removed. | |
| 352 // | |
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353 // n will be replaced with the old value but n might have |
| 0 | 354 // kills projections associated with it so remove them now so that |
| 605 | 355 // yank_if_dead will be able to eliminate the copy once the uses |
| 0 | 356 // have been transferred to the old[value]. |
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357 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { |
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358 Node* use = n->fast_out(i); |
| 0 | 359 if (use->is_Proj() && use->outcnt() == 0) { |
| 360 // Kill projections have no users and one input | |
| 361 use->set_req(0, C->top()); | |
| 362 yank_if_dead(use, current_block, &value, ®nd); | |
| 363 --i; --imax; | |
| 364 } | |
| 365 } | |
| 366 _post_alloc++; | |
| 367 return true; | |
| 368 } | |
| 369 return false; | |
| 370 } | |
| 371 | |
| 372 | |
| 373 //------------------------------post_allocate_copy_removal--------------------- | |
| 374 // Post-Allocation peephole copy removal. We do this in 1 pass over the | |
| 375 // basic blocks. We maintain a mapping of registers to Nodes (an array of | |
| 376 // Nodes indexed by machine register or stack slot number). NULL means that a | |
| 377 // register is not mapped to any Node. We can (want to have!) have several | |
| 378 // registers map to the same Node. We walk forward over the instructions | |
| 379 // updating the mapping as we go. At merge points we force a NULL if we have | |
| 380 // to merge 2 different Nodes into the same register. Phi functions will give | |
| 381 // us a new Node if there is a proper value merging. Since the blocks are | |
| 382 // arranged in some RPO, we will visit all parent blocks before visiting any | |
| 383 // successor blocks (except at loops). | |
| 384 // | |
| 385 // If we find a Copy we look to see if the Copy's source register is a stack | |
| 386 // slot and that value has already been loaded into some machine register; if | |
| 387 // so we use machine register directly. This turns a Load into a reg-reg | |
| 388 // Move. We also look for reloads of identical constants. | |
| 389 // | |
| 390 // When we see a use from a reg-reg Copy, we will attempt to use the copy's | |
| 391 // source directly and make the copy go dead. | |
| 392 void PhaseChaitin::post_allocate_copy_removal() { | |
| 393 NOT_PRODUCT( Compile::TracePhase t3("postAllocCopyRemoval", &_t_postAllocCopyRemoval, TimeCompiler); ) | |
| 394 ResourceMark rm; | |
| 395 | |
| 396 // Need a mapping from basic block Node_Lists. We need a Node_List to | |
| 397 // map from register number to value-producing Node. | |
| 398 Node_List **blk2value = NEW_RESOURCE_ARRAY( Node_List *, _cfg._num_blocks+1); | |
| 399 memset( blk2value, 0, sizeof(Node_List*)*(_cfg._num_blocks+1) ); | |
| 400 // Need a mapping from basic block Node_Lists. We need a Node_List to | |
| 401 // map from register number to register-defining Node. | |
| 402 Node_List **blk2regnd = NEW_RESOURCE_ARRAY( Node_List *, _cfg._num_blocks+1); | |
| 403 memset( blk2regnd, 0, sizeof(Node_List*)*(_cfg._num_blocks+1) ); | |
| 404 | |
| 405 // We keep unused Node_Lists on a free_list to avoid wasting | |
| 406 // memory. | |
| 407 GrowableArray<Node_List*> free_list = GrowableArray<Node_List*>(16); | |
| 408 | |
| 409 // For all blocks | |
| 410 for( uint i = 0; i < _cfg._num_blocks; i++ ) { | |
| 411 uint j; | |
| 412 Block *b = _cfg._blocks[i]; | |
| 413 | |
| 414 // Count of Phis in block | |
| 415 uint phi_dex; | |
| 416 for( phi_dex = 1; phi_dex < b->_nodes.size(); phi_dex++ ) { | |
| 417 Node *phi = b->_nodes[phi_dex]; | |
| 418 if( !phi->is_Phi() ) | |
| 419 break; | |
| 420 } | |
| 421 | |
| 422 // If any predecessor has not been visited, we do not know the state | |
| 423 // of registers at the start. Check for this, while updating copies | |
| 424 // along Phi input edges | |
| 425 bool missing_some_inputs = false; | |
| 426 Block *freed = NULL; | |
| 427 for( j = 1; j < b->num_preds(); j++ ) { | |
| 428 Block *pb = _cfg._bbs[b->pred(j)->_idx]; | |
| 429 // Remove copies along phi edges | |
| 430 for( uint k=1; k<phi_dex; k++ ) | |
| 431 elide_copy( b->_nodes[k], j, b, *blk2value[pb->_pre_order], *blk2regnd[pb->_pre_order], false ); | |
| 432 if( blk2value[pb->_pre_order] ) { // Have a mapping on this edge? | |
| 433 // See if this predecessor's mappings have been used by everybody | |
| 434 // who wants them. If so, free 'em. | |
| 435 uint k; | |
| 436 for( k=0; k<pb->_num_succs; k++ ) { | |
| 437 Block *pbsucc = pb->_succs[k]; | |
| 438 if( !blk2value[pbsucc->_pre_order] && pbsucc != b ) | |
| 439 break; // Found a future user | |
| 440 } | |
| 441 if( k >= pb->_num_succs ) { // No more uses, free! | |
| 442 freed = pb; // Record last block freed | |
| 443 free_list.push(blk2value[pb->_pre_order]); | |
| 444 free_list.push(blk2regnd[pb->_pre_order]); | |
| 445 } | |
| 446 } else { // This block has unvisited (loopback) inputs | |
| 447 missing_some_inputs = true; | |
| 448 } | |
| 449 } | |
| 450 | |
| 451 | |
| 452 // Extract Node_List mappings. If 'freed' is non-zero, we just popped | |
| 453 // 'freed's blocks off the list | |
| 454 Node_List ®nd = *(free_list.is_empty() ? new Node_List() : free_list.pop()); | |
| 455 Node_List &value = *(free_list.is_empty() ? new Node_List() : free_list.pop()); | |
| 456 assert( !freed || blk2value[freed->_pre_order] == &value, "" ); | |
| 457 value.map(_max_reg,NULL); | |
| 458 regnd.map(_max_reg,NULL); | |
| 459 // Set mappings as OUR mappings | |
| 460 blk2value[b->_pre_order] = &value; | |
| 461 blk2regnd[b->_pre_order] = ®nd; | |
| 462 | |
| 463 // Initialize value & regnd for this block | |
| 464 if( missing_some_inputs ) { | |
| 465 // Some predecessor has not yet been visited; zap map to empty | |
| 466 for( uint k = 0; k < (uint)_max_reg; k++ ) { | |
| 467 value.map(k,NULL); | |
| 468 regnd.map(k,NULL); | |
| 469 } | |
| 470 } else { | |
| 471 if( !freed ) { // Didn't get a freebie prior block | |
| 472 // Must clone some data | |
| 473 freed = _cfg._bbs[b->pred(1)->_idx]; | |
| 474 Node_List &f_value = *blk2value[freed->_pre_order]; | |
| 475 Node_List &f_regnd = *blk2regnd[freed->_pre_order]; | |
| 476 for( uint k = 0; k < (uint)_max_reg; k++ ) { | |
| 477 value.map(k,f_value[k]); | |
| 478 regnd.map(k,f_regnd[k]); | |
| 479 } | |
| 480 } | |
| 481 // Merge all inputs together, setting to NULL any conflicts. | |
| 482 for( j = 1; j < b->num_preds(); j++ ) { | |
| 483 Block *pb = _cfg._bbs[b->pred(j)->_idx]; | |
| 484 if( pb == freed ) continue; // Did self already via freelist | |
| 485 Node_List &p_regnd = *blk2regnd[pb->_pre_order]; | |
| 486 for( uint k = 0; k < (uint)_max_reg; k++ ) { | |
| 487 if( regnd[k] != p_regnd[k] ) { // Conflict on reaching defs? | |
| 488 value.map(k,NULL); // Then no value handy | |
| 489 regnd.map(k,NULL); | |
| 490 } | |
| 491 } | |
| 492 } | |
| 493 } | |
| 494 | |
| 495 // For all Phi's | |
| 496 for( j = 1; j < phi_dex; j++ ) { | |
| 497 uint k; | |
| 498 Node *phi = b->_nodes[j]; | |
| 499 uint pidx = n2lidx(phi); | |
| 500 OptoReg::Name preg = lrgs(n2lidx(phi)).reg(); | |
| 501 | |
| 502 // Remove copies remaining on edges. Check for junk phi. | |
| 503 Node *u = NULL; | |
| 504 for( k=1; k<phi->req(); k++ ) { | |
| 505 Node *x = phi->in(k); | |
| 506 if( phi != x && u != x ) // Found a different input | |
| 507 u = u ? NodeSentinel : x; // Capture unique input, or NodeSentinel for 2nd input | |
| 508 } | |
| 509 if( u != NodeSentinel ) { // Junk Phi. Remove | |
| 510 b->_nodes.remove(j--); phi_dex--; | |
| 511 _cfg._bbs.map(phi->_idx,NULL); | |
| 512 phi->replace_by(u); | |
| 513 phi->disconnect_inputs(NULL); | |
| 514 continue; | |
| 515 } | |
| 516 // Note that if value[pidx] exists, then we merged no new values here | |
| 517 // and the phi is useless. This can happen even with the above phi | |
| 518 // removal for complex flows. I cannot keep the better known value here | |
| 519 // because locally the phi appears to define a new merged value. If I | |
| 520 // keep the better value then a copy of the phi, being unable to use the | |
| 521 // global flow analysis, can't "peek through" the phi to the original | |
| 522 // reaching value and so will act like it's defining a new value. This | |
| 523 // can lead to situations where some uses are from the old and some from | |
| 524 // the new values. Not illegal by itself but throws the over-strong | |
| 525 // assert in scheduling. | |
| 526 if( pidx ) { | |
| 527 value.map(preg,phi); | |
| 528 regnd.map(preg,phi); | |
| 529 OptoReg::Name preg_lo = OptoReg::add(preg,-1); | |
| 530 if( !is_single_register(phi->ideal_reg()) ) { | |
| 531 value.map(preg_lo,phi); | |
| 532 regnd.map(preg_lo,phi); | |
| 533 } | |
| 534 } | |
| 535 } | |
| 536 | |
| 537 // For all remaining instructions | |
| 538 for( j = phi_dex; j < b->_nodes.size(); j++ ) { | |
| 539 Node *n = b->_nodes[j]; | |
| 540 | |
| 541 if( n->outcnt() == 0 && // Dead? | |
| 542 n != C->top() && // (ignore TOP, it has no du info) | |
| 543 !n->is_Proj() ) { // fat-proj kills | |
| 544 j -= yank_if_dead(n,b,&value,®nd); | |
| 545 continue; | |
| 546 } | |
| 547 | |
| 548 // Improve reaching-def info. Occasionally post-alloc's liveness gives | |
| 549 // up (at loop backedges, because we aren't doing a full flow pass). | |
| 550 // The presence of a live use essentially asserts that the use's def is | |
| 551 // alive and well at the use (or else the allocator fubar'd). Take | |
| 552 // advantage of this info to set a reaching def for the use-reg. | |
| 553 uint k; | |
| 554 for( k = 1; k < n->req(); k++ ) { | |
| 555 Node *def = n->in(k); // n->in(k) is a USE; def is the DEF for this USE | |
| 556 guarantee(def != NULL, "no disconnected nodes at this point"); | |
| 557 uint useidx = n2lidx(def); // useidx is the live range index for this USE | |
| 558 | |
| 559 if( useidx ) { | |
| 560 OptoReg::Name ureg = lrgs(useidx).reg(); | |
| 561 if( !value[ureg] ) { | |
| 562 int idx; // Skip occasional useless copy | |
| 563 while( (idx=def->is_Copy()) != 0 && | |
| 564 def->in(idx) != NULL && // NULL should not happen | |
| 565 ureg == lrgs(n2lidx(def->in(idx))).reg() ) | |
| 566 def = def->in(idx); | |
| 567 Node *valdef = skip_copies(def); // tighten up val through non-useless copies | |
| 568 value.map(ureg,valdef); // record improved reaching-def info | |
| 569 regnd.map(ureg, def); | |
| 570 // Record other half of doubles | |
| 571 OptoReg::Name ureg_lo = OptoReg::add(ureg,-1); | |
| 572 if( !is_single_register(def->ideal_reg()) && | |
| 573 ( !RegMask::can_represent(ureg_lo) || | |
| 574 lrgs(useidx).mask().Member(ureg_lo) ) && // Nearly always adjacent | |
| 575 !value[ureg_lo] ) { | |
| 576 value.map(ureg_lo,valdef); // record improved reaching-def info | |
| 577 regnd.map(ureg_lo, def); | |
| 578 } | |
| 579 } | |
| 580 } | |
| 581 } | |
| 582 | |
| 583 const uint two_adr = n->is_Mach() ? n->as_Mach()->two_adr() : 0; | |
| 584 | |
| 585 // Remove copies along input edges | |
| 586 for( k = 1; k < n->req(); k++ ) | |
| 587 j -= elide_copy( n, k, b, value, regnd, two_adr!=k ); | |
| 588 | |
| 589 // Unallocated Nodes define no registers | |
| 590 uint lidx = n2lidx(n); | |
| 591 if( !lidx ) continue; | |
| 592 | |
| 593 // Update the register defined by this instruction | |
| 594 OptoReg::Name nreg = lrgs(lidx).reg(); | |
| 595 // Skip through all copies to the _value_ being defined. | |
| 596 // Do not change from int to pointer | |
| 597 Node *val = skip_copies(n); | |
| 598 | |
| 923 | 599 // Clear out a dead definition before starting so that the |
| 600 // elimination code doesn't have to guard against it. The | |
| 601 // definition could in fact be a kill projection with a count of | |
| 602 // 0 which is safe but since those are uninteresting for copy | |
| 603 // elimination just delete them as well. | |
| 604 if (regnd[nreg] != NULL && regnd[nreg]->outcnt() == 0) { | |
| 605 regnd.map(nreg, NULL); | |
| 606 value.map(nreg, NULL); | |
| 607 } | |
| 608 | |
| 0 | 609 uint n_ideal_reg = n->ideal_reg(); |
| 610 if( is_single_register(n_ideal_reg) ) { | |
| 611 // If Node 'n' does not change the value mapped by the register, | |
| 612 // then 'n' is a useless copy. Do not update the register->node | |
| 613 // mapping so 'n' will go dead. | |
| 614 if( value[nreg] != val ) { | |
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615 if (eliminate_copy_of_constant(val, n, b, value, regnd, nreg, OptoReg::Bad)) { |
| 923 | 616 j -= replace_and_yank_if_dead(n, nreg, b, value, regnd); |
| 0 | 617 } else { |
| 618 // Update the mapping: record new Node defined by the register | |
| 619 regnd.map(nreg,n); | |
| 620 // Update mapping for defined *value*, which is the defined | |
| 621 // Node after skipping all copies. | |
| 622 value.map(nreg,val); | |
| 623 } | |
| 923 | 624 } else if( !may_be_copy_of_callee(n) ) { |
| 0 | 625 assert( n->is_Copy(), "" ); |
| 923 | 626 j -= replace_and_yank_if_dead(n, nreg, b, value, regnd); |
| 0 | 627 } |
| 628 } else { | |
| 629 // If the value occupies a register pair, record same info | |
| 630 // in both registers. | |
| 631 OptoReg::Name nreg_lo = OptoReg::add(nreg,-1); | |
| 632 if( RegMask::can_represent(nreg_lo) && // Either a spill slot, or | |
| 633 !lrgs(lidx).mask().Member(nreg_lo) ) { // Nearly always adjacent | |
| 634 // Sparc occasionally has non-adjacent pairs. | |
| 635 // Find the actual other value | |
| 636 RegMask tmp = lrgs(lidx).mask(); | |
| 637 tmp.Remove(nreg); | |
| 638 nreg_lo = tmp.find_first_elem(); | |
| 639 } | |
| 640 if( value[nreg] != val || value[nreg_lo] != val ) { | |
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6661247: Internal bug in 32-bit HotSpot optimizer while bit manipulations
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641 if (eliminate_copy_of_constant(val, n, b, value, regnd, nreg, nreg_lo)) { |
| 923 | 642 j -= replace_and_yank_if_dead(n, nreg, b, value, regnd); |
| 0 | 643 } else { |
| 644 regnd.map(nreg , n ); | |
| 645 regnd.map(nreg_lo, n ); | |
| 646 value.map(nreg ,val); | |
| 647 value.map(nreg_lo,val); | |
| 648 } | |
| 923 | 649 } else if( !may_be_copy_of_callee(n) ) { |
| 0 | 650 assert( n->is_Copy(), "" ); |
| 923 | 651 j -= replace_and_yank_if_dead(n, nreg, b, value, regnd); |
| 0 | 652 } |
| 653 } | |
| 654 | |
| 655 // Fat projections kill many registers | |
| 656 if( n_ideal_reg == MachProjNode::fat_proj ) { | |
| 657 RegMask rm = n->out_RegMask(); | |
| 658 // wow, what an expensive iterator... | |
| 659 nreg = rm.find_first_elem(); | |
| 660 while( OptoReg::is_valid(nreg)) { | |
| 661 rm.Remove(nreg); | |
| 662 value.map(nreg,n); | |
| 663 regnd.map(nreg,n); | |
| 664 nreg = rm.find_first_elem(); | |
| 665 } | |
| 666 } | |
| 667 | |
| 668 } // End of for all instructions in the block | |
| 669 | |
| 670 } // End for all blocks | |
| 671 } |