/* This file contains the definitions and documentation for the builtins used in the GNU compiler. Copyright (C) 2001 Free Software Foundation, Inc. This file is part of GNU CC. GNU CC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU CC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU CC; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* Before including this file, you should define a macro: DEF_PREDICTOR (ENUM, NAME, HITRATE) This macro will be called once for each predictor. The ENUM will be of type `enum predictor', and will enumerate all supported predictors. The order of DEF_PREDICTOR calls is important, as in the first match combining heuristics, the predictor appearing first in this file will win. NAME is used in the debugging output to determine predictor type. HITRATE is the probability that edge predicted by predictor as taken will be really taken (so it should be always above REG_BR_PROB_BASE / 2). */ /* An combined heuristics using Dempster-Shaffer theory. */ DEF_PREDICTOR (PRED_COMBINED, "combined", PROB_ALWAYS, 0) /* An combined heuristics using probability determined by first matching heuristics from this list. */ DEF_PREDICTOR (PRED_FIRST_MATCH, "first match", PROB_ALWAYS, 0) /* Mark unconditional jump as taken. */ DEF_PREDICTOR (PRED_UNCONDITIONAL, "unconditional jump", PROB_ALWAYS, PRED_FLAG_FIRST_MATCH) /* Use number of loop iterations determined by loop unroller to set probability. We don't want to use Dempster-Shaffer theory here, as the predictions is exact. */ DEF_PREDICTOR (PRED_LOOP_ITERATIONS, "loop iterations", PROB_ALWAYS, PRED_FLAG_FIRST_MATCH) /* Hints dropped by user via __builtin_expect feature. */ DEF_PREDICTOR (PRED_BUILTIN_EXPECT, "__builtin_expect", PROB_VERY_LIKELY, PRED_FLAG_FIRST_MATCH) /* Branch to basic block containing call marked by noreturn attribute. */ DEF_PREDICTOR (PRED_NORETURN, "noreturn call", PROB_ALWAYS, PRED_FLAG_FIRST_MATCH) /* Loopback edge is taken. */ DEF_PREDICTOR (PRED_LOOP_BRANCH, "loop branch", HITRATE (88), PRED_FLAG_FIRST_MATCH) /* Edge causing loop to terminate is probably not taken. */ DEF_PREDICTOR (PRED_LOOP_EXIT, "loop exit", HITRATE (80), PRED_FLAG_FIRST_MATCH) /* Condition emitted by preconditiong code to ensure that variable setting number of iterations is greater than initial value of iterator. */ DEF_PREDICTOR (PRED_LOOP_CONDITION, "loop condition", PROB_VERY_LIKELY, 0) /* Preconditioning makes linear list of branches. */ DEF_PREDICTOR (PRED_LOOP_PRECONDITIONING, "loop preconditioning", PROB_VERY_LIKELY, 0) /* Copied condition for the first iteration of loop is probably true. */ DEF_PREDICTOR (PRED_LOOP_HEADER, "loop header", HITRATE (75), 0) /* Pointers are usually not NULL. */ DEF_PREDICTOR (PRED_POINTER, "pointer", HITRATE (60), 0) /* NE is probable, EQ not etc... */ DEF_PREDICTOR (PRED_OPCODE, "opcode", HITRATE (84), 0) /* Branch guarding call is probably taken. */ DEF_PREDICTOR (PRED_CALL, "call", HITRATE (78), 0) /* Branch causing function to terminate is probably not taken. */ DEF_PREDICTOR (PRED_ERROR_RETURN, "error return", PROB_LIKELY, 0)