Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-ssa-loop-ch.c @ 86:12b3180c7d07
modify calls.c.
| author | Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Thu, 15 Dec 2011 02:37:13 +0900 |
| parents | f6334be47118 |
| children | 04ced10e8804 |
| rev | line source |
|---|---|
| 0 | 1 /* Loop header copying on trees. |
|
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f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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2 Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010 |
|
f6334be47118
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parents:
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3 Free Software Foundation, Inc. |
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4 |
| 0 | 5 This file is part of GCC. |
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6 |
| 0 | 7 GCC is free software; you can redistribute it and/or modify it |
| 8 under the terms of the GNU General Public License as published by the | |
| 9 Free Software Foundation; either version 3, or (at your option) any | |
| 10 later version. | |
|
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11 |
| 0 | 12 GCC is distributed in the hope that it will be useful, but WITHOUT |
| 13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 15 for more details. | |
|
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16 |
| 0 | 17 You should have received a copy of the GNU General Public License |
| 18 along with GCC; see the file COPYING3. If not see | |
| 19 <http://www.gnu.org/licenses/>. */ | |
| 20 | |
| 21 #include "config.h" | |
| 22 #include "system.h" | |
| 23 #include "coretypes.h" | |
| 24 #include "tm.h" | |
| 25 #include "tree.h" | |
| 26 #include "tm_p.h" | |
| 27 #include "basic-block.h" | |
| 28 #include "output.h" | |
| 29 #include "tree-flow.h" | |
| 30 #include "tree-dump.h" | |
| 31 #include "tree-pass.h" | |
| 32 #include "timevar.h" | |
| 33 #include "cfgloop.h" | |
| 34 #include "tree-inline.h" | |
| 35 #include "flags.h" | |
| 36 #include "tree-inline.h" | |
| 37 | |
| 38 /* Duplicates headers of loops if they are small enough, so that the statements | |
| 39 in the loop body are always executed when the loop is entered. This | |
| 40 increases effectiveness of code motion optimizations, and reduces the need | |
| 41 for loop preconditioning. */ | |
| 42 | |
| 43 /* Check whether we should duplicate HEADER of LOOP. At most *LIMIT | |
| 44 instructions should be duplicated, limit is decreased by the actual | |
| 45 amount. */ | |
| 46 | |
| 47 static bool | |
| 48 should_duplicate_loop_header_p (basic_block header, struct loop *loop, | |
| 49 int *limit) | |
| 50 { | |
| 51 gimple_stmt_iterator bsi; | |
| 52 gimple last; | |
| 53 | |
| 54 /* Do not copy one block more than once (we do not really want to do | |
| 55 loop peeling here). */ | |
| 56 if (header->aux) | |
| 57 return false; | |
| 58 | |
| 59 /* Loop header copying usually increases size of the code. This used not to | |
| 60 be true, since quite often it is possible to verify that the condition is | |
| 61 satisfied in the first iteration and therefore to eliminate it. Jump | |
| 62 threading handles these cases now. */ | |
| 63 if (optimize_loop_for_size_p (loop)) | |
| 64 return false; | |
| 65 | |
| 66 gcc_assert (EDGE_COUNT (header->succs) > 0); | |
| 67 if (single_succ_p (header)) | |
| 68 return false; | |
| 69 if (flow_bb_inside_loop_p (loop, EDGE_SUCC (header, 0)->dest) | |
| 70 && flow_bb_inside_loop_p (loop, EDGE_SUCC (header, 1)->dest)) | |
| 71 return false; | |
| 72 | |
| 73 /* If this is not the original loop header, we want it to have just | |
| 74 one predecessor in order to match the && pattern. */ | |
| 75 if (header != loop->header && !single_pred_p (header)) | |
| 76 return false; | |
| 77 | |
| 78 last = last_stmt (header); | |
| 79 if (gimple_code (last) != GIMPLE_COND) | |
| 80 return false; | |
| 81 | |
| 82 /* Approximately copy the conditions that used to be used in jump.c -- | |
| 83 at most 20 insns and no calls. */ | |
| 84 for (bsi = gsi_start_bb (header); !gsi_end_p (bsi); gsi_next (&bsi)) | |
| 85 { | |
| 86 last = gsi_stmt (bsi); | |
| 87 | |
| 88 if (gimple_code (last) == GIMPLE_LABEL) | |
| 89 continue; | |
| 90 | |
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91 if (is_gimple_debug (last)) |
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92 continue; |
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93 |
| 0 | 94 if (is_gimple_call (last)) |
| 95 return false; | |
| 96 | |
| 97 *limit -= estimate_num_insns (last, &eni_size_weights); | |
| 98 if (*limit < 0) | |
| 99 return false; | |
| 100 } | |
| 101 | |
| 102 return true; | |
| 103 } | |
| 104 | |
| 105 /* Checks whether LOOP is a do-while style loop. */ | |
| 106 | |
| 107 static bool | |
| 108 do_while_loop_p (struct loop *loop) | |
| 109 { | |
| 110 gimple stmt = last_stmt (loop->latch); | |
| 111 | |
| 112 /* If the latch of the loop is not empty, it is not a do-while loop. */ | |
| 113 if (stmt | |
| 114 && gimple_code (stmt) != GIMPLE_LABEL) | |
| 115 return false; | |
| 116 | |
| 117 /* If the header contains just a condition, it is not a do-while loop. */ | |
| 118 stmt = last_and_only_stmt (loop->header); | |
| 119 if (stmt | |
| 120 && gimple_code (stmt) == GIMPLE_COND) | |
| 121 return false; | |
| 122 | |
| 123 return true; | |
| 124 } | |
| 125 | |
| 126 /* For all loops, copy the condition at the end of the loop body in front | |
| 127 of the loop. This is beneficial since it increases efficiency of | |
| 128 code motion optimizations. It also saves one jump on entry to the loop. */ | |
| 129 | |
| 130 static unsigned int | |
| 131 copy_loop_headers (void) | |
| 132 { | |
| 133 loop_iterator li; | |
| 134 struct loop *loop; | |
| 135 basic_block header; | |
| 136 edge exit, entry; | |
| 137 basic_block *bbs, *copied_bbs; | |
| 138 unsigned n_bbs; | |
| 139 unsigned bbs_size; | |
| 140 | |
| 141 loop_optimizer_init (LOOPS_HAVE_PREHEADERS | |
| 142 | LOOPS_HAVE_SIMPLE_LATCHES); | |
| 143 if (number_of_loops () <= 1) | |
| 144 { | |
| 145 loop_optimizer_finalize (); | |
| 146 return 0; | |
| 147 } | |
| 148 | |
| 149 #ifdef ENABLE_CHECKING | |
| 150 verify_loop_structure (); | |
| 151 #endif | |
| 152 | |
| 153 bbs = XNEWVEC (basic_block, n_basic_blocks); | |
| 154 copied_bbs = XNEWVEC (basic_block, n_basic_blocks); | |
| 155 bbs_size = n_basic_blocks; | |
| 156 | |
| 157 FOR_EACH_LOOP (li, loop, 0) | |
| 158 { | |
| 159 /* Copy at most 20 insns. */ | |
| 160 int limit = 20; | |
| 161 | |
| 162 header = loop->header; | |
| 163 | |
| 164 /* If the loop is already a do-while style one (either because it was | |
| 165 written as such, or because jump threading transformed it into one), | |
| 166 we might be in fact peeling the first iteration of the loop. This | |
| 167 in general is not a good idea. */ | |
| 168 if (do_while_loop_p (loop)) | |
| 169 continue; | |
| 170 | |
| 171 /* Iterate the header copying up to limit; this takes care of the cases | |
| 172 like while (a && b) {...}, where we want to have both of the conditions | |
| 173 copied. TODO -- handle while (a || b) - like cases, by not requiring | |
| 174 the header to have just a single successor and copying up to | |
| 175 postdominator. */ | |
| 176 | |
| 177 exit = NULL; | |
| 178 n_bbs = 0; | |
| 179 while (should_duplicate_loop_header_p (header, loop, &limit)) | |
| 180 { | |
| 181 /* Find a successor of header that is inside a loop; i.e. the new | |
| 182 header after the condition is copied. */ | |
| 183 if (flow_bb_inside_loop_p (loop, EDGE_SUCC (header, 0)->dest)) | |
| 184 exit = EDGE_SUCC (header, 0); | |
| 185 else | |
| 186 exit = EDGE_SUCC (header, 1); | |
| 187 bbs[n_bbs++] = header; | |
| 188 gcc_assert (bbs_size > n_bbs); | |
| 189 header = exit->dest; | |
| 190 } | |
| 191 | |
| 192 if (!exit) | |
| 193 continue; | |
| 194 | |
| 195 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 196 fprintf (dump_file, | |
| 197 "Duplicating header of the loop %d up to edge %d->%d.\n", | |
| 198 loop->num, exit->src->index, exit->dest->index); | |
| 199 | |
| 200 /* Ensure that the header will have just the latch as a predecessor | |
| 201 inside the loop. */ | |
| 202 if (!single_pred_p (exit->dest)) | |
| 203 exit = single_pred_edge (split_edge (exit)); | |
| 204 | |
| 205 entry = loop_preheader_edge (loop); | |
| 206 | |
| 207 if (!gimple_duplicate_sese_region (entry, exit, bbs, n_bbs, copied_bbs)) | |
| 208 { | |
| 209 fprintf (dump_file, "Duplication failed.\n"); | |
| 210 continue; | |
| 211 } | |
| 212 | |
| 213 /* If the loop has the form "for (i = j; i < j + 10; i++)" then | |
| 214 this copying can introduce a case where we rely on undefined | |
| 215 signed overflow to eliminate the preheader condition, because | |
| 216 we assume that "j < j + 10" is true. We don't want to warn | |
| 217 about that case for -Wstrict-overflow, because in general we | |
| 218 don't warn about overflow involving loops. Prevent the | |
| 219 warning by setting the no_warning flag in the condition. */ | |
| 220 if (warn_strict_overflow > 0) | |
| 221 { | |
| 222 unsigned int i; | |
| 223 | |
| 224 for (i = 0; i < n_bbs; ++i) | |
| 225 { | |
| 226 gimple_stmt_iterator bsi; | |
| 227 | |
| 228 for (bsi = gsi_start_bb (copied_bbs[i]); | |
| 229 !gsi_end_p (bsi); | |
| 230 gsi_next (&bsi)) | |
| 231 { | |
| 232 gimple stmt = gsi_stmt (bsi); | |
| 233 if (gimple_code (stmt) == GIMPLE_COND) | |
| 234 gimple_set_no_warning (stmt, true); | |
| 235 else if (is_gimple_assign (stmt)) | |
| 236 { | |
| 237 enum tree_code rhs_code = gimple_assign_rhs_code (stmt); | |
| 238 if (TREE_CODE_CLASS (rhs_code) == tcc_comparison) | |
| 239 gimple_set_no_warning (stmt, true); | |
| 240 } | |
| 241 } | |
| 242 } | |
| 243 } | |
| 244 | |
| 245 /* Ensure that the latch and the preheader is simple (we know that they | |
| 246 are not now, since there was the loop exit condition. */ | |
| 247 split_edge (loop_preheader_edge (loop)); | |
| 248 split_edge (loop_latch_edge (loop)); | |
| 249 } | |
| 250 | |
| 251 free (bbs); | |
| 252 free (copied_bbs); | |
| 253 | |
| 254 loop_optimizer_finalize (); | |
| 255 return 0; | |
| 256 } | |
| 257 | |
| 258 static bool | |
| 259 gate_ch (void) | |
| 260 { | |
| 261 return flag_tree_ch != 0; | |
| 262 } | |
| 263 | |
|
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77e2b8dfacca
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ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
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diff
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264 struct gimple_opt_pass pass_ch = |
| 0 | 265 { |
| 266 { | |
| 267 GIMPLE_PASS, | |
| 268 "ch", /* name */ | |
| 269 gate_ch, /* gate */ | |
| 270 copy_loop_headers, /* execute */ | |
| 271 NULL, /* sub */ | |
| 272 NULL, /* next */ | |
| 273 0, /* static_pass_number */ | |
| 274 TV_TREE_CH, /* tv_id */ | |
| 275 PROP_cfg | PROP_ssa, /* properties_required */ | |
| 276 0, /* properties_provided */ | |
| 277 0, /* properties_destroyed */ | |
| 278 0, /* todo_flags_start */ | |
|
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f6334be47118
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nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
63
diff
changeset
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279 TODO_cleanup_cfg |
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f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
63
diff
changeset
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280 | TODO_verify_ssa |
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f6334be47118
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nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
63
diff
changeset
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281 | TODO_verify_flow |
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f6334be47118
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nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
63
diff
changeset
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282 | TODO_dump_func /* todo_flags_finish */ |
| 0 | 283 } |
| 284 }; |