-/* This file contains the definitions and documentation for the
- builtins used in the GNU compiler.
- Copyright (C) 2001 Free Software Foundation, Inc.
+/* Definitions for the branch prediction routines in the GNU compiler.
+ Copyright (C) 2001-2015 Free Software Foundation, Inc.
-This file is part of GNU CC.
+This file is part of GCC.
-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.
+GCC 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 3, 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.
+GCC 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. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
/* Before including this file, you should define a macro:
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. */
+
+/* A value used as final outcome of all heuristics. */
DEF_PREDICTOR (PRED_COMBINED, "combined", PROB_ALWAYS, 0)
-/* An combined heuristics using probability determined by first
+/* An outcome estimated by Dempster-Shaffer theory. */
+DEF_PREDICTOR (PRED_DS_THEORY, "DS theory", PROB_ALWAYS, 0)
+
+/* A combined heuristics using probability determined by first
matching heuristics from this list. */
DEF_PREDICTOR (PRED_FIRST_MATCH, "first match", PROB_ALWAYS, 0)
+/* Heuristic applying when no heuristic below applies. */
+DEF_PREDICTOR (PRED_NO_PREDICTION, "no prediction", 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. */
+/* Use number of loop iterations determined by # of iterations
+ analysis 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. */
+/* Assume that any given atomic operation has low contention,
+ and thus the compare-and-swap operation succeeds. */
+DEF_PREDICTOR (PRED_COMPARE_AND_SWAP, "compare and swap", PROB_VERY_LIKELY,
+ PRED_FLAG_FIRST_MATCH)
+
+/* Hints dropped by user via __builtin_expect feature. Note: the
+ probability of PROB_VERY_LIKELY is now overwritten by param
+ builtin_expect_probability with a default value of HITRATE(90).
+ Refer to param.def for details. */
DEF_PREDICTOR (PRED_BUILTIN_EXPECT, "__builtin_expect", PROB_VERY_LIKELY,
PRED_FLAG_FIRST_MATCH)
+/* Use number of loop iterations guessed by the contents of the loop. */
+DEF_PREDICTOR (PRED_LOOP_ITERATIONS_GUESSED, "guessed loop iterations",
+ PROB_ALWAYS, PRED_FLAG_FIRST_MATCH)
+
+/* Branch containing goto is probably not taken. */
+DEF_PREDICTOR (PRED_CONTINUE, "continue", HITRATE (50), 0)
+
/* Branch to basic block containing call marked by noreturn attribute. */
-DEF_PREDICTOR (PRED_NORETURN, "noreturn call", PROB_ALWAYS,
+DEF_PREDICTOR (PRED_NORETURN, "noreturn call", PROB_VERY_LIKELY,
PRED_FLAG_FIRST_MATCH)
-/* Loopback edge is taken. */
-DEF_PREDICTOR (PRED_LOOP_BRANCH, "loop branch", HITRATE (88),
+/* Branch to basic block containing call marked by cold function attribute. */
+DEF_PREDICTOR (PRED_COLD_FUNCTION, "cold function call", PROB_VERY_LIKELY,
PRED_FLAG_FIRST_MATCH)
-/* Edge causing loop to terminate is probably not taken. */
-DEF_PREDICTOR (PRED_LOOP_EXIT, "loop exit", HITRATE (80),
+/* Loopback edge is taken. */
+DEF_PREDICTOR (PRED_LOOP_BRANCH, "loop branch", HITRATE (86),
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)
+/* Edge causing loop to terminate is probably not taken. */
+DEF_PREDICTOR (PRED_LOOP_EXIT, "loop exit", HITRATE (91),
+ PRED_FLAG_FIRST_MATCH)
/* Pointers are usually not NULL. */
-DEF_PREDICTOR (PRED_POINTER, "pointer", HITRATE (60), 0)
+DEF_PREDICTOR (PRED_POINTER, "pointer", HITRATE (85), 0)
+DEF_PREDICTOR (PRED_TREE_POINTER, "pointer (on trees)", HITRATE (85), 0)
/* NE is probable, EQ not etc... */
-DEF_PREDICTOR (PRED_OPCODE, "opcode", HITRATE (84), 0)
+DEF_PREDICTOR (PRED_OPCODE_POSITIVE, "opcode values positive", HITRATE (79), 0)
+DEF_PREDICTOR (PRED_OPCODE_NONEQUAL, "opcode values nonequal", HITRATE (71), 0)
+DEF_PREDICTOR (PRED_FPOPCODE, "fp_opcode", HITRATE (90), 0)
+DEF_PREDICTOR (PRED_TREE_OPCODE_POSITIVE, "opcode values positive (on trees)", HITRATE (73), 0)
+DEF_PREDICTOR (PRED_TREE_OPCODE_NONEQUAL, "opcode values nonequal (on trees)", HITRATE (72), 0)
+DEF_PREDICTOR (PRED_TREE_FPOPCODE, "fp_opcode (on trees)", HITRATE (90), 0)
/* Branch guarding call is probably taken. */
-DEF_PREDICTOR (PRED_CALL, "call", HITRATE (78), 0)
+DEF_PREDICTOR (PRED_CALL, "call", HITRATE (71), 0)
/* Branch causing function to terminate is probably not taken. */
-DEF_PREDICTOR (PRED_ERROR_RETURN, "error return", PROB_LIKELY, 0)
+DEF_PREDICTOR (PRED_TREE_EARLY_RETURN, "early return (on trees)", HITRATE (61), 0)
+
+/* Branch containing goto is probably not taken. */
+DEF_PREDICTOR (PRED_GOTO, "goto", HITRATE (70), 0)
+
+/* Branch ending with return constant is probably not taken. */
+DEF_PREDICTOR (PRED_CONST_RETURN, "const return", HITRATE (67), 0)
+
+/* Branch ending with return negative constant is probably not taken. */
+DEF_PREDICTOR (PRED_NEGATIVE_RETURN, "negative return", HITRATE (96), 0)
+
+/* Branch ending with return; is probably not taken */
+DEF_PREDICTOR (PRED_NULL_RETURN, "null return", HITRATE (90), 0)
+
+/* Branches to compare induction variable to a loop bound is
+ extremely likely. */
+DEF_PREDICTOR (PRED_LOOP_IV_COMPARE_GUESS, "guess loop iv compare",
+ PROB_VERY_LIKELY, 0)
+
+/* Use number of loop iterations determined by # of iterations analysis
+ to set probability of branches that compares IV to loop bound variable. */
+DEF_PREDICTOR (PRED_LOOP_IV_COMPARE, "loop iv compare", PROB_VERY_LIKELY,
+ PRED_FLAG_FIRST_MATCH)
+
+/* Branches to hot labels are likely. */
+DEF_PREDICTOR (PRED_HOT_LABEL, "hot label", HITRATE (85), 0)
+
+/* Branches to cold labels are extremely unlikely. */
+DEF_PREDICTOR (PRED_COLD_LABEL, "cold label", PROB_VERY_LIKELY,
+ PRED_FLAG_FIRST_MATCH)
+
+
+/* The following predictors are used in Fortran. */
+
+/* Branch leading to an integer overflow are extremely unlikely. */
+DEF_PREDICTOR (PRED_FORTRAN_OVERFLOW, "overflow", PROB_ALWAYS,
+ PRED_FLAG_FIRST_MATCH)
+
+/* Branch leading to a failure status are unlikely. This can occur for out
+ of memory or when trying to allocate an already allocated allocated or
+ deallocating an already deallocated allocatable. This predictor only
+ occurs when the user explicitly asked for a return status. By default,
+ the code aborts, which is handled via PRED_NORETURN. */
+DEF_PREDICTOR (PRED_FORTRAN_FAIL_ALLOC, "fail alloc", PROB_VERY_LIKELY, 0)
+
+/* Branch leading to an I/O failure status are unlikely. This predictor is
+ used for I/O failures such as for invalid unit numbers. This predictor
+ only occurs when the user explicitly asked for a return status. By default,
+ the code aborts, which is handled via PRED_NORETURN. */
+DEF_PREDICTOR (PRED_FORTRAN_FAIL_IO, "fail alloc", HITRATE(85), 0)
+
+/* Branch leading to a run-time warning message which is printed only once
+ are unlikely. The print-warning branch itself can be likely or unlikely. */
+DEF_PREDICTOR (PRED_FORTRAN_WARN_ONCE, "warn once", HITRATE (75), 0)
+
+/* Branch belonging to a zero-sized array. */
+DEF_PREDICTOR (PRED_FORTRAN_SIZE_ZERO, "zero-sized array", HITRATE(70), 0)
+
+/* Branch belonging to an invalid bound index, in a context where it is
+ standard conform and well defined but rather pointless and, hence, rather
+ unlikely to occur. */
+DEF_PREDICTOR (PRED_FORTRAN_INVALID_BOUND, "zero-sized array", HITRATE(90), 0)
+
+/* Branch belonging to the handling of absent optional arguments. This
+ predictor is used when an optional dummy argument, associated with an
+ absent argument, is passed on as actual argument to another procedure,
+ which in turn has an optional argument. */
+DEF_PREDICTOR (PRED_FORTRAN_ABSENT_DUMMY, "absent dummy", HITRATE(60), 0)