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1 /* |
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2 * Copyright 1998-2007 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 class CmpNode; |
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26 class CountedLoopEndNode; |
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27 class CountedLoopNode; |
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28 class IdealLoopTree; |
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29 class LoopNode; |
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30 class Node; |
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31 class PhaseIdealLoop; |
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32 class VectorSet; |
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33 struct small_cache; |
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34 |
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35 // |
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36 // I D E A L I Z E D L O O P S |
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37 // |
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38 // Idealized loops are the set of loops I perform more interesting |
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39 // transformations on, beyond simple hoisting. |
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40 |
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41 //------------------------------LoopNode--------------------------------------- |
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42 // Simple loop header. Fall in path on left, loop-back path on right. |
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43 class LoopNode : public RegionNode { |
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44 // Size is bigger to hold the flags. However, the flags do not change |
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45 // the semantics so it does not appear in the hash & cmp functions. |
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46 virtual uint size_of() const { return sizeof(*this); } |
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47 protected: |
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48 short _loop_flags; |
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49 // Names for flag bitfields |
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50 enum { pre_post_main=0, inner_loop=8, partial_peel_loop=16, partial_peel_failed=32 }; |
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51 char _unswitch_count; |
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52 enum { _unswitch_max=3 }; |
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53 |
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54 public: |
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55 // Names for edge indices |
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56 enum { Self=0, EntryControl, LoopBackControl }; |
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57 |
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58 int is_inner_loop() const { return _loop_flags & inner_loop; } |
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59 void set_inner_loop() { _loop_flags |= inner_loop; } |
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60 |
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61 int is_partial_peel_loop() const { return _loop_flags & partial_peel_loop; } |
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62 void set_partial_peel_loop() { _loop_flags |= partial_peel_loop; } |
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63 int partial_peel_has_failed() const { return _loop_flags & partial_peel_failed; } |
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64 void mark_partial_peel_failed() { _loop_flags |= partial_peel_failed; } |
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65 |
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66 int unswitch_max() { return _unswitch_max; } |
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67 int unswitch_count() { return _unswitch_count; } |
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68 void set_unswitch_count(int val) { |
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69 assert (val <= unswitch_max(), "too many unswitches"); |
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70 _unswitch_count = val; |
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71 } |
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72 |
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73 LoopNode( Node *entry, Node *backedge ) : RegionNode(3), _loop_flags(0), _unswitch_count(0) { |
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74 init_class_id(Class_Loop); |
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75 init_req(EntryControl, entry); |
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76 init_req(LoopBackControl, backedge); |
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77 } |
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78 |
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79 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); |
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80 virtual int Opcode() const; |
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81 bool can_be_counted_loop(PhaseTransform* phase) const { |
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82 return req() == 3 && in(0) != NULL && |
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83 in(1) != NULL && phase->type(in(1)) != Type::TOP && |
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84 in(2) != NULL && phase->type(in(2)) != Type::TOP; |
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85 } |
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86 #ifndef PRODUCT |
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87 virtual void dump_spec(outputStream *st) const; |
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88 #endif |
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89 }; |
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90 |
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91 //------------------------------Counted Loops---------------------------------- |
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92 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit |
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93 // path (and maybe some other exit paths). The trip-counter exit is always |
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94 // last in the loop. The trip-counter does not have to stride by a constant, |
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95 // but it does have to stride by a loop-invariant amount; the exit value is |
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96 // also loop invariant. |
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97 |
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98 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs. The |
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99 // CountedLoopNode has the incoming loop control and the loop-back-control |
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100 // which is always the IfTrue before the matching CountedLoopEndNode. The |
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101 // CountedLoopEndNode has an incoming control (possibly not the |
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102 // CountedLoopNode if there is control flow in the loop), the post-increment |
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103 // trip-counter value, and the limit. The trip-counter value is always of |
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104 // the form (Op old-trip-counter stride). The old-trip-counter is produced |
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105 // by a Phi connected to the CountedLoopNode. The stride is loop invariant. |
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106 // The Op is any commutable opcode, including Add, Mul, Xor. The |
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107 // CountedLoopEndNode also takes in the loop-invariant limit value. |
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108 |
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109 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the |
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110 // loop-back control. From CountedLoopEndNodes I can reach CountedLoopNodes |
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111 // via the old-trip-counter from the Op node. |
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112 |
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113 //------------------------------CountedLoopNode-------------------------------- |
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114 // CountedLoopNodes head simple counted loops. CountedLoopNodes have as |
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115 // inputs the incoming loop-start control and the loop-back control, so they |
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116 // act like RegionNodes. They also take in the initial trip counter, the |
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117 // loop-invariant stride and the loop-invariant limit value. CountedLoopNodes |
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118 // produce a loop-body control and the trip counter value. Since |
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119 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model. |
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120 |
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121 class CountedLoopNode : public LoopNode { |
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122 // Size is bigger to hold _main_idx. However, _main_idx does not change |
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123 // the semantics so it does not appear in the hash & cmp functions. |
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124 virtual uint size_of() const { return sizeof(*this); } |
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125 |
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126 // For Pre- and Post-loops during debugging ONLY, this holds the index of |
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127 // the Main CountedLoop. Used to assert that we understand the graph shape. |
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128 node_idx_t _main_idx; |
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129 |
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130 // Known trip count calculated by policy_maximally_unroll |
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131 int _trip_count; |
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132 |
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133 // Expected trip count from profile data |
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134 float _profile_trip_cnt; |
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135 |
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136 // Log2 of original loop bodies in unrolled loop |
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137 int _unrolled_count_log2; |
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138 |
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139 // Node count prior to last unrolling - used to decide if |
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140 // unroll,optimize,unroll,optimize,... is making progress |
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141 int _node_count_before_unroll; |
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142 |
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143 public: |
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144 CountedLoopNode( Node *entry, Node *backedge ) |
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145 : LoopNode(entry, backedge), _trip_count(max_jint), |
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146 _profile_trip_cnt(COUNT_UNKNOWN), _unrolled_count_log2(0), |
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147 _node_count_before_unroll(0) { |
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148 init_class_id(Class_CountedLoop); |
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149 // Initialize _trip_count to the largest possible value. |
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150 // Will be reset (lower) if the loop's trip count is known. |
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151 } |
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152 |
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153 virtual int Opcode() const; |
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154 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape); |
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155 |
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156 Node *init_control() const { return in(EntryControl); } |
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157 Node *back_control() const { return in(LoopBackControl); } |
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158 CountedLoopEndNode *loopexit() const; |
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159 Node *init_trip() const; |
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160 Node *stride() const; |
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161 int stride_con() const; |
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162 bool stride_is_con() const; |
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163 Node *limit() const; |
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164 Node *incr() const; |
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165 Node *phi() const; |
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166 |
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167 // Match increment with optional truncation |
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168 static Node* match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type); |
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169 |
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170 // A 'main' loop has a pre-loop and a post-loop. The 'main' loop |
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171 // can run short a few iterations and may start a few iterations in. |
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172 // It will be RCE'd and unrolled and aligned. |
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173 |
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174 // A following 'post' loop will run any remaining iterations. Used |
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175 // during Range Check Elimination, the 'post' loop will do any final |
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176 // iterations with full checks. Also used by Loop Unrolling, where |
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177 // the 'post' loop will do any epilog iterations needed. Basically, |
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178 // a 'post' loop can not profitably be further unrolled or RCE'd. |
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179 |
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180 // A preceding 'pre' loop will run at least 1 iteration (to do peeling), |
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181 // it may do under-flow checks for RCE and may do alignment iterations |
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182 // so the following main loop 'knows' that it is striding down cache |
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183 // lines. |
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184 |
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185 // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or |
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186 // Aligned, may be missing it's pre-loop. |
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187 enum { Normal=0, Pre=1, Main=2, Post=3, PrePostFlagsMask=3, Main_Has_No_Pre_Loop=4 }; |
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188 int is_normal_loop() const { return (_loop_flags&PrePostFlagsMask) == Normal; } |
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189 int is_pre_loop () const { return (_loop_flags&PrePostFlagsMask) == Pre; } |
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190 int is_main_loop () const { return (_loop_flags&PrePostFlagsMask) == Main; } |
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191 int is_post_loop () const { return (_loop_flags&PrePostFlagsMask) == Post; } |
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192 int is_main_no_pre_loop() const { return _loop_flags & Main_Has_No_Pre_Loop; } |
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193 void set_main_no_pre_loop() { _loop_flags |= Main_Has_No_Pre_Loop; } |
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194 |
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195 |
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196 void set_pre_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; } |
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197 void set_main_loop ( ) { assert(is_normal_loop(),""); _loop_flags |= Main; } |
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198 void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; } |
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199 void set_normal_loop( ) { _loop_flags &= ~PrePostFlagsMask; } |
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200 |
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201 void set_trip_count(int tc) { _trip_count = tc; } |
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202 int trip_count() { return _trip_count; } |
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203 |
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204 void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; } |
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205 float profile_trip_cnt() { return _profile_trip_cnt; } |
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206 |
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207 void double_unrolled_count() { _unrolled_count_log2++; } |
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208 int unrolled_count() { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); } |
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209 |
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210 void set_node_count_before_unroll(int ct) { _node_count_before_unroll = ct; } |
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211 int node_count_before_unroll() { return _node_count_before_unroll; } |
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212 |
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213 #ifndef PRODUCT |
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214 virtual void dump_spec(outputStream *st) const; |
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215 #endif |
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216 }; |
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217 |
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218 //------------------------------CountedLoopEndNode----------------------------- |
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219 // CountedLoopEndNodes end simple trip counted loops. They act much like |
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220 // IfNodes. |
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221 class CountedLoopEndNode : public IfNode { |
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222 public: |
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223 enum { TestControl, TestValue }; |
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224 |
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225 CountedLoopEndNode( Node *control, Node *test, float prob, float cnt ) |
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226 : IfNode( control, test, prob, cnt) { |
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227 init_class_id(Class_CountedLoopEnd); |
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228 } |
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229 virtual int Opcode() const; |
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230 |
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231 Node *cmp_node() const { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : NULL; } |
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232 Node *incr() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } |
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233 Node *limit() const { Node *tmp = cmp_node(); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } |
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234 Node *stride() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(2) : NULL; } |
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235 Node *phi() const { Node *tmp = incr (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } |
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236 Node *init_trip() const { Node *tmp = phi (); return (tmp && tmp->req()==3) ? tmp->in(1) : NULL; } |
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237 int stride_con() const; |
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238 bool stride_is_con() const { Node *tmp = stride (); return (tmp != NULL && tmp->is_Con()); } |
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239 BoolTest::mask test_trip() const { return in(TestValue)->as_Bool()->_test._test; } |
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240 CountedLoopNode *loopnode() const { |
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241 Node *ln = phi()->in(0); |
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242 assert( ln->Opcode() == Op_CountedLoop, "malformed loop" ); |
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243 return (CountedLoopNode*)ln; } |
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244 |
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245 #ifndef PRODUCT |
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246 virtual void dump_spec(outputStream *st) const; |
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247 #endif |
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248 }; |
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249 |
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250 |
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251 inline CountedLoopEndNode *CountedLoopNode::loopexit() const { |
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252 Node *bc = back_control(); |
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253 if( bc == NULL ) return NULL; |
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254 Node *le = bc->in(0); |
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255 if( le->Opcode() != Op_CountedLoopEnd ) |
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256 return NULL; |
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257 return (CountedLoopEndNode*)le; |
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258 } |
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259 inline Node *CountedLoopNode::init_trip() const { return loopexit() ? loopexit()->init_trip() : NULL; } |
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260 inline Node *CountedLoopNode::stride() const { return loopexit() ? loopexit()->stride() : NULL; } |
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261 inline int CountedLoopNode::stride_con() const { return loopexit() ? loopexit()->stride_con() : 0; } |
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262 inline bool CountedLoopNode::stride_is_con() const { return loopexit() && loopexit()->stride_is_con(); } |
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263 inline Node *CountedLoopNode::limit() const { return loopexit() ? loopexit()->limit() : NULL; } |
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264 inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; } |
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265 inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; } |
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266 |
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267 |
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268 // -----------------------------IdealLoopTree---------------------------------- |
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269 class IdealLoopTree : public ResourceObj { |
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270 public: |
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271 IdealLoopTree *_parent; // Parent in loop tree |
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272 IdealLoopTree *_next; // Next sibling in loop tree |
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273 IdealLoopTree *_child; // First child in loop tree |
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274 |
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275 // The head-tail backedge defines the loop. |
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276 // If tail is NULL then this loop has multiple backedges as part of the |
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277 // same loop. During cleanup I'll peel off the multiple backedges; merge |
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278 // them at the loop bottom and flow 1 real backedge into the loop. |
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279 Node *_head; // Head of loop |
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280 Node *_tail; // Tail of loop |
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281 inline Node *tail(); // Handle lazy update of _tail field |
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282 PhaseIdealLoop* _phase; |
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283 |
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284 Node_List _body; // Loop body for inner loops |
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285 |
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286 uint8 _nest; // Nesting depth |
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287 uint8 _irreducible:1, // True if irreducible |
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288 _has_call:1, // True if has call safepoint |
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289 _has_sfpt:1, // True if has non-call safepoint |
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290 _rce_candidate:1; // True if candidate for range check elimination |
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291 |
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292 Node_List* _required_safept; // A inner loop cannot delete these safepts; |
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293 |
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294 IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail ) |
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295 : _parent(0), _next(0), _child(0), |
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296 _head(head), _tail(tail), |
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297 _phase(phase), |
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298 _required_safept(NULL), |
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299 _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0) |
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300 { } |
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301 |
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302 // Is 'l' a member of 'this'? |
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303 int is_member( const IdealLoopTree *l ) const; // Test for nested membership |
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304 |
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305 // Set loop nesting depth. Accumulate has_call bits. |
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306 int set_nest( uint depth ); |
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307 |
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308 // Split out multiple fall-in edges from the loop header. Move them to a |
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309 // private RegionNode before the loop. This becomes the loop landing pad. |
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310 void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ); |
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311 |
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312 // Split out the outermost loop from this shared header. |
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313 void split_outer_loop( PhaseIdealLoop *phase ); |
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314 |
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315 // Merge all the backedges from the shared header into a private Region. |
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316 // Feed that region as the one backedge to this loop. |
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317 void merge_many_backedges( PhaseIdealLoop *phase ); |
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318 |
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319 // Split shared headers and insert loop landing pads. |
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320 // Insert a LoopNode to replace the RegionNode. |
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321 // Returns TRUE if loop tree is structurally changed. |
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322 bool beautify_loops( PhaseIdealLoop *phase ); |
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323 |
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324 // Perform iteration-splitting on inner loops. Split iterations to avoid |
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325 // range checks or one-shot null checks. |
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326 void iteration_split( PhaseIdealLoop *phase, Node_List &old_new ); |
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327 |
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328 // Driver for various flavors of iteration splitting |
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329 void iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ); |
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330 |
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331 // Given dominators, try to find loops with calls that must always be |
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332 // executed (call dominates loop tail). These loops do not need non-call |
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333 // safepoints (ncsfpt). |
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334 void check_safepts(VectorSet &visited, Node_List &stack); |
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335 |
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336 // Allpaths backwards scan from loop tail, terminating each path at first safepoint |
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337 // encountered. |
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338 void allpaths_check_safepts(VectorSet &visited, Node_List &stack); |
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339 |
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340 // Convert to counted loops where possible |
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341 void counted_loop( PhaseIdealLoop *phase ); |
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342 |
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343 // Check for Node being a loop-breaking test |
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344 Node *is_loop_exit(Node *iff) const; |
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345 |
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346 // Returns true if ctrl is executed on every complete iteration |
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347 bool dominates_backedge(Node* ctrl); |
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348 |
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349 // Remove simplistic dead code from loop body |
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350 void DCE_loop_body(); |
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351 |
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352 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. |
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353 // Replace with a 1-in-10 exit guess. |
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354 void adjust_loop_exit_prob( PhaseIdealLoop *phase ); |
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355 |
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356 // Return TRUE or FALSE if the loop should never be RCE'd or aligned. |
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357 // Useful for unrolling loops with NO array accesses. |
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358 bool policy_peel_only( PhaseIdealLoop *phase ) const; |
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359 |
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360 // Return TRUE or FALSE if the loop should be unswitched -- clone |
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361 // loop with an invariant test |
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362 bool policy_unswitching( PhaseIdealLoop *phase ) const; |
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363 |
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364 // Micro-benchmark spamming. Remove empty loops. |
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365 bool policy_do_remove_empty_loop( PhaseIdealLoop *phase ); |
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366 |
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367 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can |
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368 // make some loop-invariant test (usually a null-check) happen before the |
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369 // loop. |
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370 bool policy_peeling( PhaseIdealLoop *phase ) const; |
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371 |
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372 // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any |
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373 // known trip count in the counted loop node. |
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374 bool policy_maximally_unroll( PhaseIdealLoop *phase ) const; |
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375 |
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376 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if |
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377 // the loop is a CountedLoop and the body is small enough. |
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378 bool policy_unroll( PhaseIdealLoop *phase ) const; |
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379 |
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380 // Return TRUE or FALSE if the loop should be range-check-eliminated. |
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381 // Gather a list of IF tests that are dominated by iteration splitting; |
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382 // also gather the end of the first split and the start of the 2nd split. |
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383 bool policy_range_check( PhaseIdealLoop *phase ) const; |
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384 |
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385 // Return TRUE or FALSE if the loop should be cache-line aligned. |
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386 // Gather the expression that does the alignment. Note that only |
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387 // one array base can be aligned in a loop (unless the VM guarentees |
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388 // mutual alignment). Note that if we vectorize short memory ops |
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389 // into longer memory ops, we may want to increase alignment. |
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390 bool policy_align( PhaseIdealLoop *phase ) const; |
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391 |
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392 // Compute loop trip count from profile data |
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393 void compute_profile_trip_cnt( PhaseIdealLoop *phase ); |
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394 |
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395 // Reassociate invariant expressions. |
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396 void reassociate_invariants(PhaseIdealLoop *phase); |
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397 // Reassociate invariant add and subtract expressions. |
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398 Node* reassociate_add_sub(Node* n1, PhaseIdealLoop *phase); |
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399 // Return nonzero index of invariant operand if invariant and variant |
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400 // are combined with an Add or Sub. Helper for reassoicate_invariants. |
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401 int is_invariant_addition(Node* n, PhaseIdealLoop *phase); |
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402 |
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403 // Return true if n is invariant |
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404 bool is_invariant(Node* n) const; |
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405 |
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406 // Put loop body on igvn work list |
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407 void record_for_igvn(); |
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408 |
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409 bool is_loop() { return !_irreducible && _tail && !_tail->is_top(); } |
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410 bool is_inner() { return is_loop() && _child == NULL; } |
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411 bool is_counted() { return is_loop() && _head != NULL && _head->is_CountedLoop(); } |
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412 |
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413 #ifndef PRODUCT |
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414 void dump_head( ) const; // Dump loop head only |
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415 void dump() const; // Dump this loop recursively |
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416 void verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const; |
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417 #endif |
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418 |
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419 }; |
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420 |
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421 // -----------------------------PhaseIdealLoop--------------------------------- |
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422 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees into a |
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423 // loop tree. Drives the loop-based transformations on the ideal graph. |
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424 class PhaseIdealLoop : public PhaseTransform { |
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425 friend class IdealLoopTree; |
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426 friend class SuperWord; |
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427 // Pre-computed def-use info |
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428 PhaseIterGVN &_igvn; |
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429 |
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430 // Head of loop tree |
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431 IdealLoopTree *_ltree_root; |
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432 |
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433 // Array of pre-order numbers, plus post-visited bit. |
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434 // ZERO for not pre-visited. EVEN for pre-visited but not post-visited. |
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435 // ODD for post-visited. Other bits are the pre-order number. |
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436 uint *_preorders; |
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437 uint _max_preorder; |
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438 |
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439 // Allocate _preorders[] array |
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440 void allocate_preorders() { |
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441 _max_preorder = C->unique()+8; |
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442 _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder); |
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443 memset(_preorders, 0, sizeof(uint) * _max_preorder); |
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444 } |
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445 |
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446 // Allocate _preorders[] array |
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447 void reallocate_preorders() { |
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448 if ( _max_preorder < C->unique() ) { |
|
449 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique()); |
|
450 _max_preorder = C->unique(); |
|
451 } |
|
452 memset(_preorders, 0, sizeof(uint) * _max_preorder); |
|
453 } |
|
454 |
|
455 // Check to grow _preorders[] array for the case when build_loop_tree_impl() |
|
456 // adds new nodes. |
|
457 void check_grow_preorders( ) { |
|
458 if ( _max_preorder < C->unique() ) { |
|
459 uint newsize = _max_preorder<<1; // double size of array |
|
460 _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize); |
|
461 memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder)); |
|
462 _max_preorder = newsize; |
|
463 } |
|
464 } |
|
465 // Check for pre-visited. Zero for NOT visited; non-zero for visited. |
|
466 int is_visited( Node *n ) const { return _preorders[n->_idx]; } |
|
467 // Pre-order numbers are written to the Nodes array as low-bit-set values. |
|
468 void set_preorder_visited( Node *n, int pre_order ) { |
|
469 assert( !is_visited( n ), "already set" ); |
|
470 _preorders[n->_idx] = (pre_order<<1); |
|
471 }; |
|
472 // Return pre-order number. |
|
473 int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; } |
|
474 |
|
475 // Check for being post-visited. |
|
476 // Should be previsited already (checked with assert(is_visited(n))). |
|
477 int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; } |
|
478 |
|
479 // Mark as post visited |
|
480 void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; } |
|
481 |
|
482 // Set/get control node out. Set lower bit to distinguish from IdealLoopTree |
|
483 // Returns true if "n" is a data node, false if it's a control node. |
|
484 bool has_ctrl( Node *n ) const { return ((intptr_t)_nodes[n->_idx]) & 1; } |
|
485 |
|
486 // clear out dead code after build_loop_late |
|
487 Node_List _deadlist; |
|
488 |
|
489 // Support for faster execution of get_late_ctrl()/dom_lca() |
|
490 // when a node has many uses and dominator depth is deep. |
|
491 Node_Array _dom_lca_tags; |
|
492 void init_dom_lca_tags(); |
|
493 void clear_dom_lca_tags(); |
|
494 // Inline wrapper for frequent cases: |
|
495 // 1) only one use |
|
496 // 2) a use is the same as the current LCA passed as 'n1' |
|
497 Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) { |
|
498 assert( n->is_CFG(), "" ); |
|
499 // Fast-path NULL lca |
|
500 if( lca != NULL && lca != n ) { |
|
501 assert( lca->is_CFG(), "" ); |
|
502 // find LCA of all uses |
|
503 n = dom_lca_for_get_late_ctrl_internal( lca, n, tag ); |
|
504 } |
|
505 return find_non_split_ctrl(n); |
|
506 } |
|
507 Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag ); |
|
508 // true if CFG node d dominates CFG node n |
|
509 bool is_dominator(Node *d, Node *n); |
|
510 |
|
511 // Helper function for directing control inputs away from CFG split |
|
512 // points. |
|
513 Node *find_non_split_ctrl( Node *ctrl ) const { |
|
514 if (ctrl != NULL) { |
|
515 if (ctrl->is_MultiBranch()) { |
|
516 ctrl = ctrl->in(0); |
|
517 } |
|
518 assert(ctrl->is_CFG(), "CFG"); |
|
519 } |
|
520 return ctrl; |
|
521 } |
|
522 |
|
523 public: |
|
524 bool has_node( Node* n ) const { return _nodes[n->_idx] != NULL; } |
|
525 // check if transform created new nodes that need _ctrl recorded |
|
526 Node *get_late_ctrl( Node *n, Node *early ); |
|
527 Node *get_early_ctrl( Node *n ); |
|
528 void set_early_ctrl( Node *n ); |
|
529 void set_subtree_ctrl( Node *root ); |
|
530 void set_ctrl( Node *n, Node *ctrl ) { |
|
531 assert( !has_node(n) || has_ctrl(n), "" ); |
|
532 assert( ctrl->in(0), "cannot set dead control node" ); |
|
533 assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" ); |
|
534 _nodes.map( n->_idx, (Node*)((intptr_t)ctrl + 1) ); |
|
535 } |
|
536 // Set control and update loop membership |
|
537 void set_ctrl_and_loop(Node* n, Node* ctrl) { |
|
538 IdealLoopTree* old_loop = get_loop(get_ctrl(n)); |
|
539 IdealLoopTree* new_loop = get_loop(ctrl); |
|
540 if (old_loop != new_loop) { |
|
541 if (old_loop->_child == NULL) old_loop->_body.yank(n); |
|
542 if (new_loop->_child == NULL) new_loop->_body.push(n); |
|
543 } |
|
544 set_ctrl(n, ctrl); |
|
545 } |
|
546 // Control nodes can be replaced or subsumed. During this pass they |
|
547 // get their replacement Node in slot 1. Instead of updating the block |
|
548 // location of all Nodes in the subsumed block, we lazily do it. As we |
|
549 // pull such a subsumed block out of the array, we write back the final |
|
550 // correct block. |
|
551 Node *get_ctrl( Node *i ) { |
|
552 assert(has_node(i), ""); |
|
553 Node *n = get_ctrl_no_update(i); |
|
554 _nodes.map( i->_idx, (Node*)((intptr_t)n + 1) ); |
|
555 assert(has_node(i) && has_ctrl(i), ""); |
|
556 assert(n == find_non_split_ctrl(n), "must return legal ctrl" ); |
|
557 return n; |
|
558 } |
|
559 |
|
560 private: |
|
561 Node *get_ctrl_no_update( Node *i ) const { |
|
562 assert( has_ctrl(i), "" ); |
|
563 Node *n = (Node*)(((intptr_t)_nodes[i->_idx]) & ~1); |
|
564 if (!n->in(0)) { |
|
565 // Skip dead CFG nodes |
|
566 do { |
|
567 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); |
|
568 } while (!n->in(0)); |
|
569 n = find_non_split_ctrl(n); |
|
570 } |
|
571 return n; |
|
572 } |
|
573 |
|
574 // Check for loop being set |
|
575 // "n" must be a control node. Returns true if "n" is known to be in a loop. |
|
576 bool has_loop( Node *n ) const { |
|
577 assert(!has_node(n) || !has_ctrl(n), ""); |
|
578 return has_node(n); |
|
579 } |
|
580 // Set loop |
|
581 void set_loop( Node *n, IdealLoopTree *loop ) { |
|
582 _nodes.map(n->_idx, (Node*)loop); |
|
583 } |
|
584 // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms. Replace |
|
585 // the 'old_node' with 'new_node'. Kill old-node. Add a reference |
|
586 // from old_node to new_node to support the lazy update. Reference |
|
587 // replaces loop reference, since that is not neede for dead node. |
|
588 public: |
|
589 void lazy_update( Node *old_node, Node *new_node ) { |
|
590 assert( old_node != new_node, "no cycles please" ); |
|
591 //old_node->set_req( 1, new_node /*NO DU INFO*/ ); |
|
592 // Nodes always have DU info now, so re-use the side array slot |
|
593 // for this node to provide the forwarding pointer. |
|
594 _nodes.map( old_node->_idx, (Node*)((intptr_t)new_node + 1) ); |
|
595 } |
|
596 void lazy_replace( Node *old_node, Node *new_node ) { |
|
597 _igvn.hash_delete(old_node); |
|
598 _igvn.subsume_node( old_node, new_node ); |
|
599 lazy_update( old_node, new_node ); |
|
600 } |
|
601 void lazy_replace_proj( Node *old_node, Node *new_node ) { |
|
602 assert( old_node->req() == 1, "use this for Projs" ); |
|
603 _igvn.hash_delete(old_node); // Must hash-delete before hacking edges |
|
604 old_node->add_req( NULL ); |
|
605 lazy_replace( old_node, new_node ); |
|
606 } |
|
607 |
|
608 private: |
|
609 |
|
610 // Place 'n' in some loop nest, where 'n' is a CFG node |
|
611 void build_loop_tree(); |
|
612 int build_loop_tree_impl( Node *n, int pre_order ); |
|
613 // Insert loop into the existing loop tree. 'innermost' is a leaf of the |
|
614 // loop tree, not the root. |
|
615 IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost ); |
|
616 |
|
617 // Place Data nodes in some loop nest |
|
618 void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me ); |
|
619 void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me ); |
|
620 void build_loop_late_post ( Node* n, const PhaseIdealLoop *verify_me ); |
|
621 |
|
622 // Array of immediate dominance info for each CFG node indexed by node idx |
|
623 private: |
|
624 uint _idom_size; |
|
625 Node **_idom; // Array of immediate dominators |
|
626 uint *_dom_depth; // Used for fast LCA test |
|
627 GrowableArray<uint>* _dom_stk; // For recomputation of dom depth |
|
628 |
|
629 Node* idom_no_update(Node* d) const { |
|
630 assert(d->_idx < _idom_size, "oob"); |
|
631 Node* n = _idom[d->_idx]; |
|
632 assert(n != NULL,"Bad immediate dominator info."); |
|
633 while (n->in(0) == NULL) { // Skip dead CFG nodes |
|
634 //n = n->in(1); |
|
635 n = (Node*)(((intptr_t)_nodes[n->_idx]) & ~1); |
|
636 assert(n != NULL,"Bad immediate dominator info."); |
|
637 } |
|
638 return n; |
|
639 } |
|
640 Node *idom(Node* d) const { |
|
641 uint didx = d->_idx; |
|
642 Node *n = idom_no_update(d); |
|
643 _idom[didx] = n; // Lazily remove dead CFG nodes from table. |
|
644 return n; |
|
645 } |
|
646 uint dom_depth(Node* d) const { |
|
647 assert(d->_idx < _idom_size, ""); |
|
648 return _dom_depth[d->_idx]; |
|
649 } |
|
650 void set_idom(Node* d, Node* n, uint dom_depth); |
|
651 // Locally compute IDOM using dom_lca call |
|
652 Node *compute_idom( Node *region ) const; |
|
653 // Recompute dom_depth |
|
654 void recompute_dom_depth(); |
|
655 |
|
656 // Is safept not required by an outer loop? |
|
657 bool is_deleteable_safept(Node* sfpt); |
|
658 |
|
659 public: |
|
660 // Dominators for the sea of nodes |
|
661 void Dominators(); |
|
662 Node *dom_lca( Node *n1, Node *n2 ) const { |
|
663 return find_non_split_ctrl(dom_lca_internal(n1, n2)); |
|
664 } |
|
665 Node *dom_lca_internal( Node *n1, Node *n2 ) const; |
|
666 |
|
667 // Compute the Ideal Node to Loop mapping |
|
668 PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me, bool do_split_ifs ); |
|
669 |
|
670 // True if the method has at least 1 irreducible loop |
|
671 bool _has_irreducible_loops; |
|
672 |
|
673 // Per-Node transform |
|
674 virtual Node *transform( Node *a_node ) { return 0; } |
|
675 |
|
676 Node *is_counted_loop( Node *x, IdealLoopTree *loop ); |
|
677 |
|
678 // Return a post-walked LoopNode |
|
679 IdealLoopTree *get_loop( Node *n ) const { |
|
680 // Dead nodes have no loop, so return the top level loop instead |
|
681 if (!has_node(n)) return _ltree_root; |
|
682 assert(!has_ctrl(n), ""); |
|
683 return (IdealLoopTree*)_nodes[n->_idx]; |
|
684 } |
|
685 |
|
686 // Is 'n' a (nested) member of 'loop'? |
|
687 int is_member( const IdealLoopTree *loop, Node *n ) const { |
|
688 return loop->is_member(get_loop(n)); } |
|
689 |
|
690 // This is the basic building block of the loop optimizations. It clones an |
|
691 // entire loop body. It makes an old_new loop body mapping; with this |
|
692 // mapping you can find the new-loop equivalent to an old-loop node. All |
|
693 // new-loop nodes are exactly equal to their old-loop counterparts, all |
|
694 // edges are the same. All exits from the old-loop now have a RegionNode |
|
695 // that merges the equivalent new-loop path. This is true even for the |
|
696 // normal "loop-exit" condition. All uses of loop-invariant old-loop values |
|
697 // now come from (one or more) Phis that merge their new-loop equivalents. |
|
698 // Parameter side_by_side_idom: |
|
699 // When side_by_size_idom is NULL, the dominator tree is constructed for |
|
700 // the clone loop to dominate the original. Used in construction of |
|
701 // pre-main-post loop sequence. |
|
702 // When nonnull, the clone and original are side-by-side, both are |
|
703 // dominated by the passed in side_by_side_idom node. Used in |
|
704 // construction of unswitched loops. |
|
705 void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth, |
|
706 Node* side_by_side_idom = NULL); |
|
707 |
|
708 // If we got the effect of peeling, either by actually peeling or by |
|
709 // making a pre-loop which must execute at least once, we can remove |
|
710 // all loop-invariant dominated tests in the main body. |
|
711 void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ); |
|
712 |
|
713 // Generate code to do a loop peel for the given loop (and body). |
|
714 // old_new is a temp array. |
|
715 void do_peeling( IdealLoopTree *loop, Node_List &old_new ); |
|
716 |
|
717 // Add pre and post loops around the given loop. These loops are used |
|
718 // during RCE, unrolling and aligning loops. |
|
719 void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ); |
|
720 // If Node n lives in the back_ctrl block, we clone a private version of n |
|
721 // in preheader_ctrl block and return that, otherwise return n. |
|
722 Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n ); |
|
723 |
|
724 // Take steps to maximally unroll the loop. Peel any odd iterations, then |
|
725 // unroll to do double iterations. The next round of major loop transforms |
|
726 // will repeat till the doubled loop body does all remaining iterations in 1 |
|
727 // pass. |
|
728 void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ); |
|
729 |
|
730 // Unroll the loop body one step - make each trip do 2 iterations. |
|
731 void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ); |
|
732 |
|
733 // Return true if exp is a constant times an induction var |
|
734 bool is_scaled_iv(Node* exp, Node* iv, int* p_scale); |
|
735 |
|
736 // Return true if exp is a scaled induction var plus (or minus) constant |
|
737 bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0); |
|
738 |
|
739 // Eliminate range-checks and other trip-counter vs loop-invariant tests. |
|
740 void do_range_check( IdealLoopTree *loop, Node_List &old_new ); |
|
741 |
|
742 // Create a slow version of the loop by cloning the loop |
|
743 // and inserting an if to select fast-slow versions. |
|
744 ProjNode* create_slow_version_of_loop(IdealLoopTree *loop, |
|
745 Node_List &old_new); |
|
746 |
|
747 // Clone loop with an invariant test (that does not exit) and |
|
748 // insert a clone of the test that selects which version to |
|
749 // execute. |
|
750 void do_unswitching (IdealLoopTree *loop, Node_List &old_new); |
|
751 |
|
752 // Find candidate "if" for unswitching |
|
753 IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const; |
|
754 |
|
755 // Range Check Elimination uses this function! |
|
756 // Constrain the main loop iterations so the affine function: |
|
757 // scale_con * I + offset < limit |
|
758 // always holds true. That is, either increase the number of iterations in |
|
759 // the pre-loop or the post-loop until the condition holds true in the main |
|
760 // loop. Scale_con, offset and limit are all loop invariant. |
|
761 void add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ); |
|
762 |
|
763 // Partially peel loop up through last_peel node. |
|
764 bool partial_peel( IdealLoopTree *loop, Node_List &old_new ); |
|
765 |
|
766 // Create a scheduled list of nodes control dependent on ctrl set. |
|
767 void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched ); |
|
768 // Has a use in the vector set |
|
769 bool has_use_in_set( Node* n, VectorSet& vset ); |
|
770 // Has use internal to the vector set (ie. not in a phi at the loop head) |
|
771 bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ); |
|
772 // clone "n" for uses that are outside of loop |
|
773 void clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ); |
|
774 // clone "n" for special uses that are in the not_peeled region |
|
775 void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n, |
|
776 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ); |
|
777 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist |
|
778 void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ); |
|
779 #ifdef ASSERT |
|
780 // Validate the loop partition sets: peel and not_peel |
|
781 bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel ); |
|
782 // Ensure that uses outside of loop are of the right form |
|
783 bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list, |
|
784 uint orig_exit_idx, uint clone_exit_idx); |
|
785 bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx); |
|
786 #endif |
|
787 |
|
788 // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.) |
|
789 int stride_of_possible_iv( Node* iff ); |
|
790 bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; } |
|
791 // Return the (unique) control output node that's in the loop (if it exists.) |
|
792 Node* stay_in_loop( Node* n, IdealLoopTree *loop); |
|
793 // Insert a signed compare loop exit cloned from an unsigned compare. |
|
794 IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop); |
|
795 void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop); |
|
796 // Utility to register node "n" with PhaseIdealLoop |
|
797 void register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth); |
|
798 // Utility to create an if-projection |
|
799 ProjNode* proj_clone(ProjNode* p, IfNode* iff); |
|
800 // Force the iff control output to be the live_proj |
|
801 Node* short_circuit_if(IfNode* iff, ProjNode* live_proj); |
|
802 // Insert a region before an if projection |
|
803 RegionNode* insert_region_before_proj(ProjNode* proj); |
|
804 // Insert a new if before an if projection |
|
805 ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj); |
|
806 |
|
807 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps. |
|
808 // "Nearly" because all Nodes have been cloned from the original in the loop, |
|
809 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs |
|
810 // through the Phi recursively, and return a Bool. |
|
811 BoolNode *clone_iff( PhiNode *phi, IdealLoopTree *loop ); |
|
812 CmpNode *clone_bool( PhiNode *phi, IdealLoopTree *loop ); |
|
813 |
|
814 |
|
815 // Rework addressing expressions to get the most loop-invariant stuff |
|
816 // moved out. We'd like to do all associative operators, but it's especially |
|
817 // important (common) to do address expressions. |
|
818 Node *remix_address_expressions( Node *n ); |
|
819 |
|
820 // Attempt to use a conditional move instead of a phi/branch |
|
821 Node *conditional_move( Node *n ); |
|
822 |
|
823 // Reorganize offset computations to lower register pressure. |
|
824 // Mostly prevent loop-fallout uses of the pre-incremented trip counter |
|
825 // (which are then alive with the post-incremented trip counter |
|
826 // forcing an extra register move) |
|
827 void reorg_offsets( IdealLoopTree *loop ); |
|
828 |
|
829 // Check for aggressive application of 'split-if' optimization, |
|
830 // using basic block level info. |
|
831 void split_if_with_blocks ( VectorSet &visited, Node_Stack &nstack ); |
|
832 Node *split_if_with_blocks_pre ( Node *n ); |
|
833 void split_if_with_blocks_post( Node *n ); |
|
834 Node *has_local_phi_input( Node *n ); |
|
835 // Mark an IfNode as being dominated by a prior test, |
|
836 // without actually altering the CFG (and hence IDOM info). |
|
837 void dominated_by( Node *prevdom, Node *iff ); |
|
838 |
|
839 // Split Node 'n' through merge point |
|
840 Node *split_thru_region( Node *n, Node *region ); |
|
841 // Split Node 'n' through merge point if there is enough win. |
|
842 Node *split_thru_phi( Node *n, Node *region, int policy ); |
|
843 // Found an If getting its condition-code input from a Phi in the |
|
844 // same block. Split thru the Region. |
|
845 void do_split_if( Node *iff ); |
|
846 |
|
847 private: |
|
848 // Return a type based on condition control flow |
|
849 const TypeInt* filtered_type( Node *n, Node* n_ctrl); |
|
850 const TypeInt* filtered_type( Node *n ) { return filtered_type(n, NULL); } |
|
851 // Helpers for filtered type |
|
852 const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl); |
|
853 const TypeInt* filtered_type_at_if( Node* val, Node *if_proj); |
|
854 |
|
855 // Helper functions |
|
856 void register_new_node( Node *n, Node *blk ); |
|
857 Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache ); |
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858 Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ); |
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859 void handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true ); |
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860 bool split_up( Node *n, Node *blk1, Node *blk2 ); |
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861 void sink_use( Node *use, Node *post_loop ); |
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862 Node *place_near_use( Node *useblock ) const; |
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863 |
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864 bool _created_loop_node; |
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865 public: |
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866 void set_created_loop_node() { _created_loop_node = true; } |
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867 bool created_loop_node() { return _created_loop_node; } |
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868 |
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869 #ifndef PRODUCT |
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870 void dump( ) const; |
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871 void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const; |
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872 void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const; |
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873 void verify() const; // Major slow :-) |
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874 void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const; |
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875 IdealLoopTree *get_loop_idx(Node* n) const { |
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876 // Dead nodes have no loop, so return the top level loop instead |
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877 return _nodes[n->_idx] ? (IdealLoopTree*)_nodes[n->_idx] : _ltree_root; |
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878 } |
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879 // Print some stats |
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880 static void print_statistics(); |
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881 static int _loop_invokes; // Count of PhaseIdealLoop invokes |
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882 static int _loop_work; // Sum of PhaseIdealLoop x _unique |
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883 #endif |
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884 }; |
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885 |
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886 inline Node* IdealLoopTree::tail() { |
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887 // Handle lazy update of _tail field |
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888 Node *n = _tail; |
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889 //while( !n->in(0) ) // Skip dead CFG nodes |
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890 //n = n->in(1); |
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891 if (n->in(0) == NULL) |
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892 n = _phase->get_ctrl(n); |
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893 _tail = n; |
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894 return n; |
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895 } |
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896 |
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897 |
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898 // Iterate over the loop tree using a preorder, left-to-right traversal. |
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899 // |
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900 // Example that visits all counted loops from within PhaseIdealLoop |
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901 // |
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902 // for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { |
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903 // IdealLoopTree* lpt = iter.current(); |
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904 // if (!lpt->is_counted()) continue; |
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905 // ... |
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906 class LoopTreeIterator : public StackObj { |
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907 private: |
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908 IdealLoopTree* _root; |
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909 IdealLoopTree* _curnt; |
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910 |
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911 public: |
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912 LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {} |
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913 |
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914 bool done() { return _curnt == NULL; } // Finished iterating? |
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915 |
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916 void next(); // Advance to next loop tree |
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917 |
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918 IdealLoopTree* current() { return _curnt; } // Return current value of iterator. |
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919 }; |