| 1 | /* This file contains the definitions and documentation for the
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| 2 | builtins used in the GNU compiler.
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| 3 | Copyright (C) 2001 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 2, 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 COPYING. If not, write to the Free
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| 19 | Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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| 20 | 02111-1307, USA. */
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| 21 |
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| 22 | /* Before including this file, you should define a macro:
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| 23 |
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| 24 | DEF_PREDICTOR (ENUM, NAME, HITRATE)
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| 25 |
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| 26 | This macro will be called once for each predictor. The ENUM will
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| 27 | be of type `enum predictor', and will enumerate all supported
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| 28 | predictors. The order of DEF_PREDICTOR calls is important, as
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| 29 | in the first match combining heuristics, the predictor appearing
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| 30 | first in this file will win.
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| 31 |
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| 32 | NAME is used in the debugging output to determine predictor type.
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| 33 |
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| 34 | HITRATE is the probability that edge predicted by predictor as taken
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| 35 | will be really taken (so it should be always above
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| 36 | REG_BR_PROB_BASE / 2). */
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| 37 |
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| 38 |
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| 39 | /* A value used as final outcome of all heuristics. */
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| 40 | DEF_PREDICTOR (PRED_COMBINED, "combined", PROB_ALWAYS, 0)
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| 41 |
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| 42 | /* An outcome estimated by Dempster-Shaffer theory. */
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| 43 | DEF_PREDICTOR (PRED_DS_THEORY, "DS theory", PROB_ALWAYS, 0)
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| 44 |
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| 45 | /* An combined heuristics using probability determined by first
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| 46 | matching heuristics from this list. */
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| 47 | DEF_PREDICTOR (PRED_FIRST_MATCH, "first match", PROB_ALWAYS, 0)
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| 48 |
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| 49 | /* Heuristic applying when no heuristic below applies. */
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| 50 | DEF_PREDICTOR (PRED_NO_PREDICTION, "no prediction", PROB_ALWAYS, 0)
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| 51 |
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| 52 | /* Mark unconditional jump as taken. */
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| 53 | DEF_PREDICTOR (PRED_UNCONDITIONAL, "unconditional jump", PROB_ALWAYS,
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| 54 | PRED_FLAG_FIRST_MATCH)
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| 55 |
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| 56 | /* Use number of loop iterations determined by loop unroller to set
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| 57 | probability. We don't want to use Dempster-Shaffer theory here,
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| 58 | as the predictions is exact. */
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| 59 | DEF_PREDICTOR (PRED_LOOP_ITERATIONS, "loop iterations", PROB_ALWAYS,
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| 60 | PRED_FLAG_FIRST_MATCH)
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| 61 |
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| 62 | /* Hints dropped by user via __builtin_expect feature. */
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| 63 | DEF_PREDICTOR (PRED_BUILTIN_EXPECT, "__builtin_expect", PROB_VERY_LIKELY,
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| 64 | PRED_FLAG_FIRST_MATCH)
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| 65 |
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| 66 | /* Branch to basic block containing call marked by noreturn attribute. */
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| 67 | DEF_PREDICTOR (PRED_NORETURN, "noreturn call", HITRATE (99),
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| 68 | PRED_FLAG_FIRST_MATCH)
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| 69 |
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| 70 | /* Loopback edge is taken. */
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| 71 | DEF_PREDICTOR (PRED_LOOP_BRANCH, "loop branch", HITRATE (89),
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| 72 | PRED_FLAG_FIRST_MATCH)
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| 73 |
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| 74 | /* Edge causing loop to terminate is probably not taken. */
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| 75 | DEF_PREDICTOR (PRED_LOOP_EXIT, "loop exit", HITRATE (90),
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| 76 | PRED_FLAG_FIRST_MATCH)
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| 77 |
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| 78 | /* Condition emitted by preconditiong code to ensure that variable
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| 79 | setting number of iterations is greater than initial value of iterator. */
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| 80 | DEF_PREDICTOR (PRED_LOOP_CONDITION, "loop condition", PROB_VERY_LIKELY, 0)
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| 81 |
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| 82 | /* Preconditioning makes linear list of branches. */
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| 83 | DEF_PREDICTOR (PRED_LOOP_PRECONDITIONING, "loop preconditioning", PROB_VERY_LIKELY, 0)
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| 84 |
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| 85 | /* Copied condition for the first iteration of loop is probably true. */
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| 86 | DEF_PREDICTOR (PRED_LOOP_HEADER, "loop header", HITRATE (64), 0)
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| 87 |
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| 88 | /* Pointers are usually not NULL. */
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| 89 | DEF_PREDICTOR (PRED_POINTER, "pointer", HITRATE (81), 0)
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| 90 |
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| 91 | /* NE is probable, EQ not etc... */
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| 92 | DEF_PREDICTOR (PRED_OPCODE_POSITIVE, "opcode values positive", HITRATE (79), 0)
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| 93 | DEF_PREDICTOR (PRED_OPCODE_NONEQUAL, "opcode values nonequal", HITRATE (71), 0)
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| 94 | DEF_PREDICTOR (PRED_FPOPCODE, "fp_opcode", HITRATE (90), 0)
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| 95 |
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| 96 | /* Branch guarding call is probably taken. */
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| 97 | DEF_PREDICTOR (PRED_CALL, "call", HITRATE (70), 0)
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| 98 |
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| 99 | /* Branch causing function to terminate is probably not taken. */
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| 100 | DEF_PREDICTOR (PRED_ERROR_RETURN, "error return", HITRATE (52), 0)
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