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1 /* Loop optimizer initialization routines and RTL loop optimization passes.
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2 Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008
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3 Free Software Foundation, Inc.
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4
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5 This file is part of GCC.
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6
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7 GCC is free software; you can redistribute it and/or modify it under
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8 the terms of the GNU General Public License as published by the Free
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9 Software Foundation; either version 3, or (at your option) any later
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10 version.
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11
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12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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15 for more details.
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16
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17 You should have received a copy of the GNU General Public License
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18 along with GCC; see the file COPYING3. If not see
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19 <http://www.gnu.org/licenses/>. */
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20
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21 #include "config.h"
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22 #include "system.h"
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23 #include "coretypes.h"
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24 #include "tm.h"
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25 #include "rtl.h"
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26 #include "hard-reg-set.h"
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27 #include "obstack.h"
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28 #include "basic-block.h"
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29 #include "cfgloop.h"
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30 #include "cfglayout.h"
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31 #include "tree-pass.h"
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32 #include "timevar.h"
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33 #include "flags.h"
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34 #include "df.h"
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35 #include "ggc.h"
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36
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37
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38 /* Initialize loop structures. This is used by the tree and RTL loop
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39 optimizers. FLAGS specify what properties to compute and/or ensure for
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40 loops. */
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41
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42 void
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43 loop_optimizer_init (unsigned flags)
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44 {
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45 struct loops *loops;
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46
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47 gcc_assert (!current_loops);
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48 loops = GGC_CNEW (struct loops);
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49
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50 /* Find the loops. */
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51
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52 flow_loops_find (loops);
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53 current_loops = loops;
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54
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55 if (flags & LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
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56 {
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57 /* If the loops may have multiple latches, we cannot canonicalize
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58 them further (and most of the loop manipulation functions will
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59 not work). However, we avoid modifying cfg, which some
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60 passes may want. */
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61 gcc_assert ((flags & ~(LOOPS_MAY_HAVE_MULTIPLE_LATCHES
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62 | LOOPS_HAVE_RECORDED_EXITS)) == 0);
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63 loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES);
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64 }
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65 else
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66 disambiguate_loops_with_multiple_latches ();
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67
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68 /* Create pre-headers. */
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69 if (flags & LOOPS_HAVE_PREHEADERS)
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70 {
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71 int cp_flags = CP_SIMPLE_PREHEADERS;
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72
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73 if (flags & LOOPS_HAVE_FALLTHRU_PREHEADERS)
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74 cp_flags |= CP_FALLTHRU_PREHEADERS;
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75
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76 create_preheaders (cp_flags);
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77 }
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78
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79 /* Force all latches to have only single successor. */
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80 if (flags & LOOPS_HAVE_SIMPLE_LATCHES)
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81 force_single_succ_latches ();
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82
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83 /* Mark irreducible loops. */
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84 if (flags & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
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85 mark_irreducible_loops ();
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86
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87 if (flags & LOOPS_HAVE_RECORDED_EXITS)
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88 record_loop_exits ();
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89
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90 /* Dump loops. */
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91 flow_loops_dump (dump_file, NULL, 1);
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92
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93 #ifdef ENABLE_CHECKING
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94 verify_dominators (CDI_DOMINATORS);
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95 verify_loop_structure ();
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96 #endif
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97 }
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98
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99 /* Finalize loop structures. */
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100
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101 void
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102 loop_optimizer_finalize (void)
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103 {
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104 loop_iterator li;
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105 struct loop *loop;
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106 basic_block bb;
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107
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108 gcc_assert (current_loops != NULL);
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109
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110 FOR_EACH_LOOP (li, loop, 0)
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111 {
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112 free_simple_loop_desc (loop);
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113 }
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114
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115 /* Clean up. */
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116 if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
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117 release_recorded_exits ();
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118 flow_loops_free (current_loops);
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119 ggc_free (current_loops);
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120 current_loops = NULL;
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121
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122 FOR_ALL_BB (bb)
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123 {
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124 bb->loop_father = NULL;
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125 }
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126
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127 /* Checking. */
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128 #ifdef ENABLE_CHECKING
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129 /* FIXME: no point to verify flow info after bundling on ia64. Use this
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130 hack for achieving this. */
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131 if (!reload_completed)
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132 verify_flow_info ();
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133 #endif
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134 }
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135
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136
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137 /* Gate for the RTL loop superpass. The actual passes are subpasses.
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138 See passes.c for more on that. */
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139
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140 static bool
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141 gate_handle_loop2 (void)
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142 {
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143 return (optimize > 0
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144 && (flag_move_loop_invariants
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145 || flag_unswitch_loops
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146 || flag_peel_loops
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147 || flag_unroll_loops
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148 #ifdef HAVE_doloop_end
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149 || (flag_branch_on_count_reg && HAVE_doloop_end)
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150 #endif
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151 ));
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152 }
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153
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154 struct rtl_opt_pass pass_loop2 =
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155 {
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156 {
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157 RTL_PASS,
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158 "loop2", /* name */
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159 gate_handle_loop2, /* gate */
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160 NULL, /* execute */
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161 NULL, /* sub */
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162 NULL, /* next */
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163 0, /* static_pass_number */
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164 TV_LOOP, /* tv_id */
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165 0, /* properties_required */
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166 0, /* properties_provided */
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167 0, /* properties_destroyed */
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168 0, /* todo_flags_start */
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169 TODO_dump_func |
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170 TODO_ggc_collect /* todo_flags_finish */
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171 }
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172 };
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173
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174
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175 /* Initialization of the RTL loop passes. */
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176 static unsigned int
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177 rtl_loop_init (void)
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178 {
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179 gcc_assert (current_ir_type () == IR_RTL_CFGLAYOUT);
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180
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181 if (dump_file)
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182 dump_flow_info (dump_file, dump_flags);
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183
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184 loop_optimizer_init (LOOPS_NORMAL);
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185 return 0;
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186 }
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187
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188 struct rtl_opt_pass pass_rtl_loop_init =
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189 {
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190 {
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191 RTL_PASS,
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192 "loop2_init", /* name */
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193 NULL, /* gate */
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194 rtl_loop_init, /* execute */
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195 NULL, /* sub */
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196 NULL, /* next */
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197 0, /* static_pass_number */
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198 TV_LOOP, /* tv_id */
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199 0, /* properties_required */
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200 0, /* properties_provided */
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201 0, /* properties_destroyed */
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202 0, /* todo_flags_start */
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203 TODO_dump_func | TODO_verify_rtl_sharing /* todo_flags_finish */
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204 }
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205 };
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206
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207
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208 /* Finalization of the RTL loop passes. */
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209
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210 static unsigned int
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211 rtl_loop_done (void)
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212 {
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213 loop_optimizer_finalize ();
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214 free_dominance_info (CDI_DOMINATORS);
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215
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216 cleanup_cfg (0);
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217 if (dump_file)
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218 dump_flow_info (dump_file, dump_flags);
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219
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220 return 0;
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221 }
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222
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223 struct rtl_opt_pass pass_rtl_loop_done =
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224 {
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225 {
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226 RTL_PASS,
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227 "loop2_done", /* name */
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228 NULL, /* gate */
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229 rtl_loop_done, /* execute */
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230 NULL, /* sub */
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231 NULL, /* next */
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232 0, /* static_pass_number */
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233 TV_LOOP, /* tv_id */
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234 0, /* properties_required */
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235 0, /* properties_provided */
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236 0, /* properties_destroyed */
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237 0, /* todo_flags_start */
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238 TODO_dump_func | TODO_verify_rtl_sharing /* todo_flags_finish */
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239 }
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240 };
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241
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242
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243 /* Loop invariant code motion. */
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244 static bool
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245 gate_rtl_move_loop_invariants (void)
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246 {
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247 return flag_move_loop_invariants;
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248 }
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249
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250 static unsigned int
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251 rtl_move_loop_invariants (void)
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252 {
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253 if (number_of_loops () > 1)
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254 move_loop_invariants ();
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255 return 0;
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256 }
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257
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258 struct rtl_opt_pass pass_rtl_move_loop_invariants =
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259 {
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260 {
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261 RTL_PASS,
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262 "loop2_invariant", /* name */
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263 gate_rtl_move_loop_invariants, /* gate */
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264 rtl_move_loop_invariants, /* execute */
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265 NULL, /* sub */
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266 NULL, /* next */
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267 0, /* static_pass_number */
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268 TV_LOOP, /* tv_id */
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269 0, /* properties_required */
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270 0, /* properties_provided */
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271 0, /* properties_destroyed */
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272 0, /* todo_flags_start */
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273 TODO_df_verify |
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274 TODO_df_finish | TODO_verify_rtl_sharing |
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275 TODO_dump_func /* todo_flags_finish */
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276 }
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277 };
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278
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279
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280 /* Loop unswitching for RTL. */
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281 static bool
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282 gate_rtl_unswitch (void)
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283 {
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284 return flag_unswitch_loops;
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285 }
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286
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287 static unsigned int
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288 rtl_unswitch (void)
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289 {
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290 if (number_of_loops () > 1)
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291 unswitch_loops ();
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292 return 0;
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293 }
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294
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295 struct rtl_opt_pass pass_rtl_unswitch =
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296 {
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297 {
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298 RTL_PASS,
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299 "loop2_unswitch", /* name */
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300 gate_rtl_unswitch, /* gate */
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301 rtl_unswitch, /* execute */
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302 NULL, /* sub */
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303 NULL, /* next */
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304 0, /* static_pass_number */
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305 TV_LOOP, /* tv_id */
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306 0, /* properties_required */
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307 0, /* properties_provided */
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308 0, /* properties_destroyed */
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309 0, /* todo_flags_start */
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310 TODO_dump_func | TODO_verify_rtl_sharing, /* todo_flags_finish */
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311 }
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312 };
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313
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314
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315 /* Loop unswitching for RTL. */
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316 static bool
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317 gate_rtl_unroll_and_peel_loops (void)
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318 {
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319 return (flag_peel_loops || flag_unroll_loops || flag_unroll_all_loops);
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320 }
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321
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322 static unsigned int
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323 rtl_unroll_and_peel_loops (void)
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324 {
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325 if (number_of_loops () > 1)
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326 {
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327 int flags = 0;
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328 if (dump_file)
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329 df_dump (dump_file);
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330
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331 if (flag_peel_loops)
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332 flags |= UAP_PEEL;
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333 if (flag_unroll_loops)
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334 flags |= UAP_UNROLL;
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335 if (flag_unroll_all_loops)
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336 flags |= UAP_UNROLL_ALL;
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337
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338 unroll_and_peel_loops (flags);
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339 }
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340 return 0;
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341 }
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342
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343 struct rtl_opt_pass pass_rtl_unroll_and_peel_loops =
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344 {
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345 {
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346 RTL_PASS,
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347 "loop2_unroll", /* name */
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348 gate_rtl_unroll_and_peel_loops, /* gate */
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349 rtl_unroll_and_peel_loops, /* execute */
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350 NULL, /* sub */
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351 NULL, /* next */
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352 0, /* static_pass_number */
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353 TV_LOOP, /* tv_id */
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354 0, /* properties_required */
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355 0, /* properties_provided */
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356 0, /* properties_destroyed */
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357 0, /* todo_flags_start */
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358 TODO_dump_func | TODO_verify_rtl_sharing, /* todo_flags_finish */
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359 }
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360 };
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361
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362
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363 /* The doloop optimization. */
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364 static bool
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365 gate_rtl_doloop (void)
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366 {
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367 #ifdef HAVE_doloop_end
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368 return (flag_branch_on_count_reg && HAVE_doloop_end);
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369 #else
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370 return 0;
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371 #endif
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372 }
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373
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374 static unsigned int
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375 rtl_doloop (void)
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376 {
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377 #ifdef HAVE_doloop_end
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378 if (number_of_loops () > 1)
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379 doloop_optimize_loops ();
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380 #endif
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381 return 0;
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382 }
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383
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384 struct rtl_opt_pass pass_rtl_doloop =
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385 {
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386 {
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387 RTL_PASS,
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388 "loop2_doloop", /* name */
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389 gate_rtl_doloop, /* gate */
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390 rtl_doloop, /* execute */
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391 NULL, /* sub */
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392 NULL, /* next */
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393 0, /* static_pass_number */
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394 TV_LOOP, /* tv_id */
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395 0, /* properties_required */
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396 0, /* properties_provided */
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397 0, /* properties_destroyed */
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398 0, /* todo_flags_start */
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399 TODO_dump_func | TODO_verify_rtl_sharing /* todo_flags_finish */
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400 }
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401 };
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402
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