/* Branch prediction routines for the GNU compiler.
- Copyright (C) 2000, 2001 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2001, 2002, 2003 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 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.
+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. */
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING. If not, write to the Free
+Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+02111-1307, USA. */
/* References:
[2] "Static Branch Frequency and Program Profile Analysis"
Wu and Larus; MICRO-27.
[3] "Corpus-based Static Branch Prediction"
- Calder, Grunwald, Lindsay, Martin, Mozer, and Zorn; PLDI '95.
-
-*/
+ Calder, Grunwald, Lindsay, Martin, Mozer, and Zorn; PLDI '95. */
#include "config.h"
#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "tm_p.h"
#include "recog.h"
#include "expr.h"
#include "predict.h"
+#include "coverage.h"
+#include "sreal.h"
+#include "params.h"
+#include "target.h"
+#include "loop.h"
+#include "cfgloop.h"
+
+/* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE,
+ 1/REG_BR_PROB_BASE, 0.5, BB_FREQ_MAX. */
+static sreal real_zero, real_one, real_almost_one, real_br_prob_base,
+ real_inv_br_prob_base, real_one_half, real_bb_freq_max;
/* Random guesstimation given names. */
-#define PROB_NEVER (0)
#define PROB_VERY_UNLIKELY (REG_BR_PROB_BASE / 10 - 1)
-#define PROB_UNLIKELY (REG_BR_PROB_BASE * 4 / 10 - 1)
#define PROB_EVEN (REG_BR_PROB_BASE / 2)
-#define PROB_LIKELY (REG_BR_PROB_BASE - PROB_UNLIKELY)
#define PROB_VERY_LIKELY (REG_BR_PROB_BASE - PROB_VERY_UNLIKELY)
#define PROB_ALWAYS (REG_BR_PROB_BASE)
+static bool predicted_by_p PARAMS ((basic_block,
+ enum br_predictor));
static void combine_predictions_for_insn PARAMS ((rtx, basic_block));
static void dump_prediction PARAMS ((enum br_predictor, int,
- basic_block));
+ basic_block, int));
static void estimate_loops_at_level PARAMS ((struct loop *loop));
-static void propagate_freq PARAMS ((basic_block));
+static void propagate_freq PARAMS ((struct loop *));
static void estimate_bb_frequencies PARAMS ((struct loops *));
static void counts_to_freqs PARAMS ((void));
+static void process_note_predictions PARAMS ((basic_block, int *,
+ dominance_info,
+ dominance_info));
+static void process_note_prediction PARAMS ((basic_block, int *,
+ dominance_info,
+ dominance_info, int, int));
+static bool last_basic_block_p PARAMS ((basic_block));
+static void compute_function_frequency PARAMS ((void));
+static void choose_function_section PARAMS ((void));
+static bool can_predict_insn_p PARAMS ((rtx));
/* Information we hold about each branch predictor.
Filled using information from predict.def. */
+
struct predictor_info
{
- const char *name; /* Name used in the debugging dumps. */
- int hitrate; /* Expected hitrate used by
- predict_insn_def call. */
+ const char *const name; /* Name used in the debugging dumps. */
+ const int hitrate; /* Expected hitrate used by
+ predict_insn_def call. */
+ const int flags;
};
-#define DEF_PREDICTOR(ENUM, NAME, HITRATE) {NAME, HITRATE},
-struct predictor_info predictor_info[] = {
+/* Use given predictor without Dempster-Shaffer theory if it matches
+ using first_match heuristics. */
+#define PRED_FLAG_FIRST_MATCH 1
+
+/* Recompute hitrate in percent to our representation. */
+
+#define HITRATE(VAL) ((int) ((VAL) * REG_BR_PROB_BASE + 50) / 100)
+
+#define DEF_PREDICTOR(ENUM, NAME, HITRATE, FLAGS) {NAME, HITRATE, FLAGS},
+static const struct predictor_info predictor_info[]= {
#include "predict.def"
- /* Upper bound on non-language-specific builtins. */
- {NULL, 0}
+ /* Upper bound on predictors. */
+ {NULL, 0, 0}
};
#undef DEF_PREDICTOR
+/* Return true in case BB can be CPU intensive and should be optimized
+ for maximal performance. */
+
+bool
+maybe_hot_bb_p (bb)
+ basic_block bb;
+{
+ if (profile_info && flag_branch_probabilities
+ && (bb->count
+ < profile_info->sum_max / PARAM_VALUE (HOT_BB_COUNT_FRACTION)))
+ return false;
+ if (bb->frequency < BB_FREQ_MAX / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))
+ return false;
+ return true;
+}
+
+/* Return true in case BB is cold and should be optimized for size. */
+
+bool
+probably_cold_bb_p (bb)
+ basic_block bb;
+{
+ if (profile_info && flag_branch_probabilities
+ && (bb->count
+ < profile_info->sum_max / PARAM_VALUE (HOT_BB_COUNT_FRACTION)))
+ return true;
+ if (bb->frequency < BB_FREQ_MAX / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))
+ return true;
+ return false;
+}
+
+/* Return true in case BB is probably never executed. */
+bool
+probably_never_executed_bb_p (bb)
+ basic_block bb;
+{
+ if (profile_info && flag_branch_probabilities)
+ return ((bb->count + profile_info->runs / 2) / profile_info->runs) == 0;
+ return false;
+}
+
+/* Return true if the one of outgoing edges is already predicted by
+ PREDICTOR. */
+
+static bool
+predicted_by_p (bb, predictor)
+ basic_block bb;
+ enum br_predictor predictor;
+{
+ rtx note;
+ if (!INSN_P (bb->end))
+ return false;
+ for (note = REG_NOTES (bb->end); note; note = XEXP (note, 1))
+ if (REG_NOTE_KIND (note) == REG_BR_PRED
+ && INTVAL (XEXP (XEXP (note, 0), 0)) == (int)predictor)
+ return true;
+ return false;
+}
+
void
predict_insn (insn, predictor, probability)
rtx insn;
{
if (!any_condjump_p (insn))
abort ();
+ if (!flag_guess_branch_prob)
+ return;
+
REG_NOTES (insn)
= gen_rtx_EXPR_LIST (REG_BR_PRED,
gen_rtx_CONCAT (VOIDmode,
}
/* Predict insn by given predictor. */
+
void
predict_insn_def (insn, predictor, taken)
rtx insn;
enum prediction taken;
{
int probability = predictor_info[(int) predictor].hitrate;
+
if (taken != TAKEN)
probability = REG_BR_PROB_BASE - probability;
+
predict_insn (insn, predictor, probability);
}
/* Predict edge E with given probability if possible. */
+
void
predict_edge (e, predictor, probability)
edge e;
predict_insn (last_insn, predictor, probability);
}
+/* Return true when we can store prediction on insn INSN.
+ At the moment we represent predictions only on conditional
+ jumps, not at computed jump or other complicated cases. */
+static bool
+can_predict_insn_p (insn)
+ rtx insn;
+{
+ return (GET_CODE (insn) == JUMP_INSN
+ && any_condjump_p (insn)
+ && BLOCK_FOR_INSN (insn)->succ->succ_next);
+}
+
/* Predict edge E by given predictor if possible. */
+
void
predict_edge_def (e, predictor, taken)
edge e;
if (taken != TAKEN)
probability = REG_BR_PROB_BASE - probability;
+
predict_edge (e, predictor, probability);
}
/* Invert all branch predictions or probability notes in the INSN. This needs
to be done each time we invert the condition used by the jump. */
+
void
invert_br_probabilities (insn)
rtx insn;
{
- rtx note = REG_NOTES (insn);
-
- while (note)
- {
- if (REG_NOTE_KIND (note) == REG_BR_PROB)
- XEXP (note, 0) = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (note, 0)));
- else if (REG_NOTE_KIND (note) == REG_BR_PRED)
- XEXP (XEXP (note, 0), 1)
- = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (XEXP (note, 0), 1)));
- note = XEXP (note, 1);
- }
+ rtx note;
+
+ for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
+ if (REG_NOTE_KIND (note) == REG_BR_PROB)
+ XEXP (note, 0) = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (note, 0)));
+ else if (REG_NOTE_KIND (note) == REG_BR_PRED)
+ XEXP (XEXP (note, 0), 1)
+ = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (XEXP (note, 0), 1)));
}
/* Dump information about the branch prediction to the output file. */
+
static void
-dump_prediction (predictor, probability, bb)
+dump_prediction (predictor, probability, bb, used)
enum br_predictor predictor;
int probability;
basic_block bb;
+ int used;
{
edge e = bb->succ;
if (!rtl_dump_file)
return;
- while (e->flags & EDGE_FALLTHRU)
+ while (e && (e->flags & EDGE_FALLTHRU))
e = e->succ_next;
- fprintf (rtl_dump_file, " %s heuristics: %.1f%%",
+ fprintf (rtl_dump_file, " %s heuristics%s: %.1f%%",
predictor_info[predictor].name,
- probability * 100.0 / REG_BR_PROB_BASE);
+ used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE);
if (bb->count)
{
- fprintf (rtl_dump_file, " exec ",
- bb->count, e->count, e->count * 100.0 / bb->count);
- fprintf (rtl_dump_file, HOST_WIDEST_INT_PRINT_DEC,
- (HOST_WIDEST_INT) bb->count);
- fprintf (rtl_dump_file, " hit ",
- e->count, e->count * 100.0 / bb->count);
- fprintf (rtl_dump_file, HOST_WIDEST_INT_PRINT_DEC,
- (HOST_WIDEST_INT) e->count);
- fprintf (rtl_dump_file, " (%.1f%%)",
- e->count, e->count * 100.0 / bb->count);
+ fprintf (rtl_dump_file, " exec ");
+ fprintf (rtl_dump_file, HOST_WIDEST_INT_PRINT_DEC, bb->count);
+ if (e)
+ {
+ fprintf (rtl_dump_file, " hit ");
+ fprintf (rtl_dump_file, HOST_WIDEST_INT_PRINT_DEC, e->count);
+ fprintf (rtl_dump_file, " (%.1f%%)", e->count * 100.0 / bb->count);
+ }
}
+
fprintf (rtl_dump_file, "\n");
}
/* Combine all REG_BR_PRED notes into single probability and attach REG_BR_PROB
note if not already present. Remove now useless REG_BR_PRED notes. */
+
static void
combine_predictions_for_insn (insn, bb)
rtx insn;
{
rtx prob_note = find_reg_note (insn, REG_BR_PROB, 0);
rtx *pnote = ®_NOTES (insn);
+ rtx note;
int best_probability = PROB_EVEN;
int best_predictor = END_PREDICTORS;
+ int combined_probability = REG_BR_PROB_BASE / 2;
+ int d;
+ bool first_match = false;
+ bool found = false;
if (rtl_dump_file)
- fprintf (rtl_dump_file, "Predictions for insn %i\n", INSN_UID (insn));
+ fprintf (rtl_dump_file, "Predictions for insn %i bb %i\n", INSN_UID (insn),
+ bb->index);
/* We implement "first match" heuristics and use probability guessed
- by predictor with smallest index. In future we will use better
+ by predictor with smallest index. In the future we will use better
probability combination techniques. */
+ for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
+ if (REG_NOTE_KIND (note) == REG_BR_PRED)
+ {
+ int predictor = INTVAL (XEXP (XEXP (note, 0), 0));
+ int probability = INTVAL (XEXP (XEXP (note, 0), 1));
+
+ found = true;
+ if (best_predictor > predictor)
+ best_probability = probability, best_predictor = predictor;
+
+ d = (combined_probability * probability
+ + (REG_BR_PROB_BASE - combined_probability)
+ * (REG_BR_PROB_BASE - probability));
+
+ /* Use FP math to avoid overflows of 32bit integers. */
+ if (d == 0)
+ /* If one probability is 0% and one 100%, avoid division by zero. */
+ combined_probability = REG_BR_PROB_BASE / 2;
+ else
+ combined_probability = (((double) combined_probability) * probability
+ * REG_BR_PROB_BASE / d + 0.5);
+ }
+
+ /* Decide which heuristic to use. In case we didn't match anything,
+ use no_prediction heuristic, in case we did match, use either
+ first match or Dempster-Shaffer theory depending on the flags. */
+
+ if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH)
+ first_match = true;
+
+ if (!found)
+ dump_prediction (PRED_NO_PREDICTION, combined_probability, bb, true);
+ else
+ {
+ dump_prediction (PRED_DS_THEORY, combined_probability, bb, !first_match);
+ dump_prediction (PRED_FIRST_MATCH, best_probability, bb, first_match);
+ }
+
+ if (first_match)
+ combined_probability = best_probability;
+ dump_prediction (PRED_COMBINED, combined_probability, bb, true);
+
while (*pnote)
{
if (REG_NOTE_KIND (*pnote) == REG_BR_PRED)
int predictor = INTVAL (XEXP (XEXP (*pnote, 0), 0));
int probability = INTVAL (XEXP (XEXP (*pnote, 0), 1));
- dump_prediction (predictor, probability, bb);
- if (best_predictor > predictor)
- best_probability = probability, best_predictor = predictor;
+ dump_prediction (predictor, probability, bb,
+ !first_match || best_predictor == predictor);
*pnote = XEXP (*pnote, 1);
}
else
- pnote = &XEXP (*pnote, 1);
+ pnote = &XEXP (*pnote, 1);
}
- dump_prediction (PRED_FIRST_MATCH, best_probability, bb);
+
if (!prob_note)
{
REG_NOTES (insn)
= gen_rtx_EXPR_LIST (REG_BR_PROB,
- GEN_INT (best_probability), REG_NOTES (insn));
+ GEN_INT (combined_probability), REG_NOTES (insn));
+
+ /* Save the prediction into CFG in case we are seeing non-degenerated
+ conditional jump. */
+ if (bb->succ->succ_next)
+ {
+ BRANCH_EDGE (bb)->probability = combined_probability;
+ FALLTHRU_EDGE (bb)->probability
+ = REG_BR_PROB_BASE - combined_probability;
+ }
}
}
estimate_probability (loops_info)
struct loops *loops_info;
{
- sbitmap *dominators, *post_dominators;
- int i;
+ dominance_info dominators, post_dominators;
+ basic_block bb;
+ unsigned i;
- dominators = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
- post_dominators = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
- calculate_dominance_info (NULL, dominators, 0);
- calculate_dominance_info (NULL, post_dominators, 1);
+ connect_infinite_loops_to_exit ();
+ dominators = calculate_dominance_info (CDI_DOMINATORS);
+ post_dominators = calculate_dominance_info (CDI_POST_DOMINATORS);
/* Try to predict out blocks in a loop that are not part of a
natural loop. */
- for (i = 0; i < loops_info->num; i++)
+ for (i = 1; i < loops_info->num; i++)
{
- int j;
+ basic_block bb, *bbs;
+ unsigned j;
+ int exits;
+ struct loop *loop = loops_info->parray[i];
+ struct loop_desc desc;
+ unsigned HOST_WIDE_INT niter;
+
+ flow_loop_scan (loops_info, loop, LOOP_EXIT_EDGES);
+ exits = loop->num_exits;
+
+ if (simple_loop_p (loops_info, loop, &desc)
+ && desc.const_iter)
+ {
+ int prob;
+ niter = desc.niter + 1;
+ if (niter == 0) /* We might overflow here. */
+ niter = desc.niter;
+
+ prob = (REG_BR_PROB_BASE
+ - (REG_BR_PROB_BASE + niter /2) / niter);
+ /* Branch prediction algorithm gives 0 frequency for everything
+ after the end of loop for loop having 0 probability to finish. */
+ if (prob == REG_BR_PROB_BASE)
+ prob = REG_BR_PROB_BASE - 1;
+ predict_edge (desc.in_edge, PRED_LOOP_ITERATIONS,
+ prob);
+ }
- for (j = loops_info->array[i].first->index;
- j <= loops_info->array[i].last->index;
- ++j)
+ bbs = get_loop_body (loop);
+ for (j = 0; j < loop->num_nodes; j++)
{
- if (TEST_BIT (loops_info->array[i].nodes, j))
- {
- int header_found = 0;
- edge e;
-
- /* Loop branch heruistics - predict as taken an edge back to
- a loop's head. */
- for (e = BASIC_BLOCK(j)->succ; e; e = e->succ_next)
- if (e->dest == loops_info->array[i].header)
- {
- header_found = 1;
- predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN);
- }
- /* Loop exit heruistics - predict as not taken an edge exiting
- the loop if the conditinal has no loop header successors */
- if (!header_found)
- for (e = BASIC_BLOCK(j)->succ; e; e = e->succ_next)
- if (e->dest->index <= 0
- || !TEST_BIT (loops_info->array[i].nodes, e->dest->index))
- predict_edge_def (e, PRED_LOOP_EXIT, NOT_TAKEN);
- }
+ int header_found = 0;
+ edge e;
+
+ bb = bbs[j];
+
+ /* Bypass loop heuristics on continue statement. These
+ statements construct loops via "non-loop" constructs
+ in the source language and are better to be handled
+ separately. */
+ if (!can_predict_insn_p (bb->end)
+ || predicted_by_p (bb, PRED_CONTINUE))
+ continue;
+
+ /* Loop branch heuristics - predict an edge back to a
+ loop's head as taken. */
+ for (e = bb->succ; e; e = e->succ_next)
+ if (e->dest == loop->header
+ && e->src == loop->latch)
+ {
+ header_found = 1;
+ predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN);
+ }
+
+ /* Loop exit heuristics - predict an edge exiting the loop if the
+ conditional has no loop header successors as not taken. */
+ if (!header_found)
+ for (e = bb->succ; e; e = e->succ_next)
+ if (e->dest->index < 0
+ || !flow_bb_inside_loop_p (loop, e->dest))
+ predict_edge
+ (e, PRED_LOOP_EXIT,
+ (REG_BR_PROB_BASE
+ - predictor_info [(int) PRED_LOOP_EXIT].hitrate)
+ / exits);
}
}
- /* Attempt to predict conditional jumps using a number of heuristics.
- For each conditional jump, we try each heuristic in a fixed order.
- If more than one heuristic applies to a particular branch, the first
- is used as the prediction for the branch. */
- for (i = 0; i < n_basic_blocks; i++)
+ /* Attempt to predict conditional jumps using a number of heuristics. */
+ FOR_EACH_BB (bb)
{
- basic_block bb = BASIC_BLOCK (i);
rtx last_insn = bb->end;
rtx cond, earliest;
edge e;
- /* If block has no sucessor, predict all possible paths to
- it as improbable, as the block contains a call to a noreturn
- function and thus can be executed only once. */
- if (bb->succ == NULL)
- {
- int y;
- for (y = 0; y < n_basic_blocks; y++)
- if (!TEST_BIT (post_dominators[y], i))
- {
- for (e = BASIC_BLOCK (y)->succ; e; e = e->succ_next)
- if (e->dest->index >= 0
- && TEST_BIT (post_dominators[e->dest->index], i))
- predict_edge_def (e, PRED_NORETURN, NOT_TAKEN);
- }
- }
-
- if (GET_CODE (last_insn) != JUMP_INSN
- || ! any_condjump_p (last_insn))
+ if (! can_predict_insn_p (last_insn))
continue;
for (e = bb->succ; e; e = e->succ_next)
{
- /* Predict edges to blocks that return immediately to be
- improbable. These are usually used to signal error states. */
- if (e->dest == EXIT_BLOCK_PTR
- || (e->dest->succ && !e->dest->succ->succ_next
- && e->dest->succ->dest == EXIT_BLOCK_PTR))
- predict_edge_def (e, PRED_ERROR_RETURN, NOT_TAKEN);
+ /* Predict early returns to be probable, as we've already taken
+ care for error returns and other are often used for fast paths
+ trought function. */
+ if ((e->dest == EXIT_BLOCK_PTR
+ || (e->dest->succ && !e->dest->succ->succ_next
+ && e->dest->succ->dest == EXIT_BLOCK_PTR))
+ && !predicted_by_p (bb, PRED_NULL_RETURN)
+ && !predicted_by_p (bb, PRED_CONST_RETURN)
+ && !predicted_by_p (bb, PRED_NEGATIVE_RETURN)
+ && !last_basic_block_p (e->dest))
+ predict_edge_def (e, PRED_EARLY_RETURN, TAKEN);
/* Look for block we are guarding (ie we dominate it,
but it doesn't postdominate us). */
- if (e->dest != EXIT_BLOCK_PTR
- && e->dest != bb
- && TEST_BIT (dominators[e->dest->index], e->src->index)
- && !TEST_BIT (post_dominators[e->src->index], e->dest->index))
+ if (e->dest != EXIT_BLOCK_PTR && e->dest != bb
+ && dominated_by_p (dominators, e->dest, e->src)
+ && !dominated_by_p (post_dominators, e->src, e->dest))
{
rtx insn;
+
/* The call heuristic claims that a guarded function call
is improbable. This is because such calls are often used
to signal exceptional situations such as printing error
if (GET_CODE (insn) == CALL_INSN
/* Constant and pure calls are hardly used to signalize
something exceptional. */
- && ! CONST_CALL_P (insn))
+ && ! CONST_OR_PURE_CALL_P (insn))
{
predict_edge_def (e, PRED_CALL, NOT_TAKEN);
break;
/* Try "pointer heuristic."
A comparison ptr == 0 is predicted as false.
Similarly, a comparison ptr1 == ptr2 is predicted as false. */
- switch (GET_CODE (cond))
+ if (GET_RTX_CLASS (GET_CODE (cond)) == '<'
+ && ((REG_P (XEXP (cond, 0)) && REG_POINTER (XEXP (cond, 0)))
+ || (REG_P (XEXP (cond, 1)) && REG_POINTER (XEXP (cond, 1)))))
{
- case EQ:
- if (GET_CODE (XEXP (cond, 0)) == REG
- && REG_POINTER (XEXP (cond, 0))
- && (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == REG
- && REG_POINTER (XEXP (cond, 1)))))
-
+ if (GET_CODE (cond) == EQ)
predict_insn_def (last_insn, PRED_POINTER, NOT_TAKEN);
- break;
- case NE:
- if (GET_CODE (XEXP (cond, 0)) == REG
- && REG_POINTER (XEXP (cond, 0))
- && (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == REG
- && REG_POINTER (XEXP (cond, 1)))))
+ else if (GET_CODE (cond) == NE)
predict_insn_def (last_insn, PRED_POINTER, TAKEN);
- break;
-
- default:
- break;
}
+ else
/* Try "opcode heuristic."
EQ tests are usually false and NE tests are usually true. Also,
most quantities are positive, so we can make the appropriate guesses
about signed comparisons against zero. */
- switch (GET_CODE (cond))
- {
- case CONST_INT:
- /* Unconditional branch. */
- predict_insn_def (last_insn, PRED_UNCONDITIONAL,
- cond == const0_rtx ? NOT_TAKEN : TAKEN);
- break;
-
- case EQ:
- case UNEQ:
- predict_insn_def (last_insn, PRED_OPCODE, NOT_TAKEN);
- break;
- case NE:
- case LTGT:
- predict_insn_def (last_insn, PRED_OPCODE, TAKEN);
- break;
- case ORDERED:
- predict_insn_def (last_insn, PRED_OPCODE, TAKEN);
- break;
- case UNORDERED:
- predict_insn_def (last_insn, PRED_OPCODE, NOT_TAKEN);
- break;
- case LE:
- case LT:
- if (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == CONST_INT
- && INTVAL (XEXP (cond, 1)) == -1))
- predict_insn_def (last_insn, PRED_OPCODE, NOT_TAKEN);
- break;
- case GE:
- case GT:
- if (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == CONST_INT
- && INTVAL (XEXP (cond, 1)) == -1))
- predict_insn_def (last_insn, PRED_OPCODE, TAKEN);
- break;
-
- default:
- break;
- }
+ switch (GET_CODE (cond))
+ {
+ case CONST_INT:
+ /* Unconditional branch. */
+ predict_insn_def (last_insn, PRED_UNCONDITIONAL,
+ cond == const0_rtx ? NOT_TAKEN : TAKEN);
+ break;
+
+ case EQ:
+ case UNEQ:
+ /* Floating point comparisons appears to behave in a very
+ unpredictable way because of special role of = tests in
+ FP code. */
+ if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0))))
+ ;
+ /* Comparisons with 0 are often used for booleans and there is
+ nothing useful to predict about them. */
+ else if (XEXP (cond, 1) == const0_rtx
+ || XEXP (cond, 0) == const0_rtx)
+ ;
+ else
+ predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, NOT_TAKEN);
+ break;
+
+ case NE:
+ case LTGT:
+ /* Floating point comparisons appears to behave in a very
+ unpredictable way because of special role of = tests in
+ FP code. */
+ if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0))))
+ ;
+ /* Comparisons with 0 are often used for booleans and there is
+ nothing useful to predict about them. */
+ else if (XEXP (cond, 1) == const0_rtx
+ || XEXP (cond, 0) == const0_rtx)
+ ;
+ else
+ predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, TAKEN);
+ break;
+
+ case ORDERED:
+ predict_insn_def (last_insn, PRED_FPOPCODE, TAKEN);
+ break;
+
+ case UNORDERED:
+ predict_insn_def (last_insn, PRED_FPOPCODE, NOT_TAKEN);
+ break;
+
+ case LE:
+ case LT:
+ if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx
+ || XEXP (cond, 1) == constm1_rtx)
+ predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, NOT_TAKEN);
+ break;
+
+ case GE:
+ case GT:
+ if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx
+ || XEXP (cond, 1) == constm1_rtx)
+ predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, TAKEN);
+ break;
+
+ default:
+ break;
+ }
}
/* Attach the combined probability to each conditional jump. */
- for (i = 0; i < n_basic_blocks; i++)
- {
- rtx last_insn = BLOCK_END (i);
+ FOR_EACH_BB (bb)
+ if (GET_CODE (bb->end) == JUMP_INSN
+ && any_condjump_p (bb->end)
+ && bb->succ->succ_next != NULL)
+ combine_predictions_for_insn (bb->end, bb);
- if (GET_CODE (last_insn) != JUMP_INSN
- || ! any_condjump_p (last_insn))
- continue;
- combine_predictions_for_insn (last_insn, BASIC_BLOCK (i));
- }
- sbitmap_vector_free (post_dominators);
- sbitmap_vector_free (dominators);
+ free_dominance_info (post_dominators);
+ free_dominance_info (dominators);
+ remove_fake_edges ();
estimate_bb_frequencies (loops_info);
}
\f
-/* __builtin_expect dropped tokens into the insn stream describing
- expected values of registers. Generate branch probabilities
- based off these values. */
+/* __builtin_expect dropped tokens into the insn stream describing expected
+ values of registers. Generate branch probabilities based off these
+ values. */
void
expected_value_to_br_prob ()
{
ev = NOTE_EXPECTED_VALUE (insn);
ev_reg = XEXP (ev, 0);
+ delete_insn (insn);
}
continue;
ev = NULL_RTX;
continue;
+ case JUMP_INSN:
+ /* Look for simple conditional branches. If we haven't got an
+ expected value yet, no point going further. */
+ if (GET_CODE (insn) != JUMP_INSN || ev == NULL_RTX
+ || ! any_condjump_p (insn))
+ continue;
+ break;
+
default:
/* Look for insns that clobber the EV register. */
if (ev && reg_set_p (ev_reg, insn))
ev = NULL_RTX;
continue;
-
- case JUMP_INSN:
- /* Look for simple conditional branches. If we havn't got an
- expected value yet, no point going further. */
- if (GET_CODE (insn) != JUMP_INSN || ev == NULL_RTX)
- continue;
- if (! any_condjump_p (insn))
- continue;
- break;
}
/* Collect the branch condition, hopefully relative to EV_REG. */
(set r71 -1)
(set r80 (lt r70 r71))
(set pc (if_then_else (ne r80 0) ...))
- as canonicalize_condition will render this to us as
+ as canonicalize_condition will render this to us as
(lt r70, r71)
Could use cselib to try and reduce this further. */
- cond = XEXP (SET_SRC (PATTERN (insn)), 0);
+ cond = XEXP (SET_SRC (pc_set (insn)), 0);
cond = canonicalize_condition (insn, cond, 0, NULL, ev_reg);
- if (! cond
- || XEXP (cond, 0) != ev_reg
+ if (! cond || XEXP (cond, 0) != ev_reg
|| GET_CODE (XEXP (cond, 1)) != CONST_INT)
continue;
- /* Substitute and simplify. Given that the expression we're
+ /* Substitute and simplify. Given that the expression we're
building involves two constants, we should wind up with either
true or false. */
cond = gen_rtx_fmt_ee (GET_CODE (cond), VOIDmode,
cond = simplify_rtx (cond);
/* Turn the condition into a scaled branch probability. */
- if (cond != const1_rtx && cond != const0_rtx)
+ if (cond != const_true_rtx && cond != const0_rtx)
abort ();
predict_insn_def (insn, PRED_BUILTIN_EXPECT,
- cond == const1_rtx ? TAKEN : NOT_TAKEN);
+ cond == const_true_rtx ? TAKEN : NOT_TAKEN);
+ }
+}
+\f
+/* Check whether this is the last basic block of function. Commonly tehre
+ is one extra common cleanup block. */
+static bool
+last_basic_block_p (bb)
+ basic_block bb;
+{
+ if (bb == EXIT_BLOCK_PTR)
+ return false;
+
+ return (bb->next_bb == EXIT_BLOCK_PTR
+ || (bb->next_bb->next_bb == EXIT_BLOCK_PTR
+ && bb->succ && !bb->succ->succ_next
+ && bb->succ->dest->next_bb == EXIT_BLOCK_PTR));
+}
+
+/* Sets branch probabilities according to PREDiction and FLAGS. HEADS[bb->index]
+ should be index of basic block in that we need to alter branch predictions
+ (i.e. the first of our dominators such that we do not post-dominate it)
+ (but we fill this information on demand, so -1 may be there in case this
+ was not needed yet). */
+
+static void
+process_note_prediction (bb, heads, dominators, post_dominators, pred, flags)
+ basic_block bb;
+ int *heads;
+ dominance_info dominators;
+ dominance_info post_dominators;
+ int pred;
+ int flags;
+{
+ edge e;
+ int y;
+ bool taken;
+
+ taken = flags & IS_TAKEN;
+
+ if (heads[bb->index] < 0)
+ {
+ /* This is first time we need this field in heads array; so
+ find first dominator that we do not post-dominate (we are
+ using already known members of heads array). */
+ basic_block ai = bb;
+ basic_block next_ai = get_immediate_dominator (dominators, bb);
+ int head;
+
+ while (heads[next_ai->index] < 0)
+ {
+ if (!dominated_by_p (post_dominators, next_ai, bb))
+ break;
+ heads[next_ai->index] = ai->index;
+ ai = next_ai;
+ next_ai = get_immediate_dominator (dominators, next_ai);
+ }
+ if (!dominated_by_p (post_dominators, next_ai, bb))
+ head = next_ai->index;
+ else
+ head = heads[next_ai->index];
+ while (next_ai != bb)
+ {
+ next_ai = ai;
+ if (heads[ai->index] == ENTRY_BLOCK)
+ ai = ENTRY_BLOCK_PTR;
+ else
+ ai = BASIC_BLOCK (heads[ai->index]);
+ heads[next_ai->index] = head;
+ }
+ }
+ y = heads[bb->index];
+
+ /* Now find the edge that leads to our branch and aply the prediction. */
+
+ if (y == last_basic_block || !can_predict_insn_p (BASIC_BLOCK (y)->end))
+ return;
+ for (e = BASIC_BLOCK (y)->succ; e; e = e->succ_next)
+ if (e->dest->index >= 0
+ && dominated_by_p (post_dominators, e->dest, bb))
+ predict_edge_def (e, pred, taken);
+}
+
+/* Gathers NOTE_INSN_PREDICTIONs in given basic block and turns them
+ into branch probabilities. For description of heads array, see
+ process_note_prediction. */
+
+static void
+process_note_predictions (bb, heads, dominators, post_dominators)
+ basic_block bb;
+ int *heads;
+ dominance_info dominators;
+ dominance_info post_dominators;
+{
+ rtx insn;
+ edge e;
+
+ /* Additionally, we check here for blocks with no successors. */
+ int contained_noreturn_call = 0;
+ int was_bb_head = 0;
+ int noreturn_block = 1;
+
+ for (insn = bb->end; insn;
+ was_bb_head |= (insn == bb->head), insn = PREV_INSN (insn))
+ {
+ if (GET_CODE (insn) != NOTE)
+ {
+ if (was_bb_head)
+ break;
+ else
+ {
+ /* Noreturn calls cause program to exit, therefore they are
+ always predicted as not taken. */
+ if (GET_CODE (insn) == CALL_INSN
+ && find_reg_note (insn, REG_NORETURN, NULL))
+ contained_noreturn_call = 1;
+ continue;
+ }
+ }
+ if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_PREDICTION)
+ {
+ int alg = (int) NOTE_PREDICTION_ALG (insn);
+ /* Process single prediction note. */
+ process_note_prediction (bb,
+ heads,
+ dominators,
+ post_dominators,
+ alg, (int) NOTE_PREDICTION_FLAGS (insn));
+ delete_insn (insn);
+ }
+ }
+ for (e = bb->succ; e; e = e->succ_next)
+ if (!(e->flags & EDGE_FAKE))
+ noreturn_block = 0;
+ if (contained_noreturn_call)
+ {
+ /* This block ended from other reasons than because of return.
+ If it is because of noreturn call, this should certainly not
+ be taken. Otherwise it is probably some error recovery. */
+ process_note_prediction (bb,
+ heads,
+ dominators,
+ post_dominators, PRED_NORETURN, NOT_TAKEN);
}
}
+
+/* Gathers NOTE_INSN_PREDICTIONs and turns them into
+ branch probabilities. */
+
+void
+note_prediction_to_br_prob ()
+{
+ basic_block bb;
+ dominance_info post_dominators, dominators;
+ int *heads;
+
+ /* To enable handling of noreturn blocks. */
+ add_noreturn_fake_exit_edges ();
+ connect_infinite_loops_to_exit ();
+
+ post_dominators = calculate_dominance_info (CDI_POST_DOMINATORS);
+ dominators = calculate_dominance_info (CDI_DOMINATORS);
+
+ heads = xmalloc (sizeof (int) * last_basic_block);
+ memset (heads, -1, sizeof (int) * last_basic_block);
+ heads[ENTRY_BLOCK_PTR->next_bb->index] = last_basic_block;
+
+ /* Process all prediction notes. */
+
+ FOR_EACH_BB (bb)
+ process_note_predictions (bb, heads, dominators, post_dominators);
+
+ free_dominance_info (post_dominators);
+ free_dominance_info (dominators);
+ free (heads);
+
+ remove_fake_edges ();
+}
\f
-/* This is used to carry information about basic blocks. It is
+/* This is used to carry information about basic blocks. It is
attached to the AUX field of the standard CFG block. */
typedef struct block_info_def
{
/* Estimated frequency of execution of basic_block. */
- double frequency;
+ sreal frequency;
/* To keep queue of basic blocks to process. */
basic_block next;
- /* True if block already converted. */
- int visited:1;
+ /* True if block needs to be visited in prop_freqency. */
+ int tovisit:1;
+
+ /* Number of predecessors we need to visit first. */
+ int npredecessors;
} *block_info;
/* Similar information for edges. */
/* In case edge is an loopback edge, the probability edge will be reached
in case header is. Estimated number of iterations of the loop can be
then computed as 1 / (1 - back_edge_prob). */
- double back_edge_prob;
+ sreal back_edge_prob;
/* True if the edge is an loopback edge in the natural loop. */
int back_edge:1;
} *edge_info;
#define EDGE_INFO(E) ((edge_info) (E)->aux)
/* Helper function for estimate_bb_frequencies.
- Propagate the frequencies for loops headed by HEAD. */
+ Propagate the frequencies for LOOP. */
+
static void
-propagate_freq (head)
- basic_block head;
+propagate_freq (loop)
+ struct loop *loop;
{
- basic_block bb = head;
- basic_block last = bb;
+ basic_block head = loop->header;
+ basic_block bb;
+ basic_block last;
edge e;
basic_block nextbb;
- BLOCK_INFO (head)->frequency = 1;
- for (; bb; bb = nextbb)
+ /* For each basic block we need to visit count number of his predecessors
+ we need to visit first. */
+ FOR_EACH_BB (bb)
{
- double cyclic_probability = 0, frequency = 0;
+ if (BLOCK_INFO (bb)->tovisit)
+ {
+ int count = 0;
+
+ for (e = bb->pred; e; e = e->pred_next)
+ if (BLOCK_INFO (e->src)->tovisit && !(e->flags & EDGE_DFS_BACK))
+ count++;
+ else if (BLOCK_INFO (e->src)->tovisit
+ && rtl_dump_file && !EDGE_INFO (e)->back_edge)
+ fprintf (rtl_dump_file,
+ "Irreducible region hit, ignoring edge to %i->%i\n",
+ e->src->index, bb->index);
+ BLOCK_INFO (bb)->npredecessors = count;
+ }
+ }
+
+ memcpy (&BLOCK_INFO (head)->frequency, &real_one, sizeof (real_one));
+ last = head;
+ for (bb = head; bb; bb = nextbb)
+ {
+ sreal cyclic_probability, frequency;
+
+ memcpy (&cyclic_probability, &real_zero, sizeof (real_zero));
+ memcpy (&frequency, &real_zero, sizeof (real_zero));
nextbb = BLOCK_INFO (bb)->next;
BLOCK_INFO (bb)->next = NULL;
/* Compute frequency of basic block. */
if (bb != head)
{
+#ifdef ENABLE_CHECKING
for (e = bb->pred; e; e = e->pred_next)
- if (!BLOCK_INFO (e->src)->visited && !EDGE_INFO (e)->back_edge)
- continue;
+ if (BLOCK_INFO (e->src)->tovisit && !(e->flags & EDGE_DFS_BACK))
+ abort ();
+#endif
for (e = bb->pred; e; e = e->pred_next)
if (EDGE_INFO (e)->back_edge)
- cyclic_probability += EDGE_INFO (e)->back_edge_prob;
- else
- frequency += (e->probability
- * BLOCK_INFO (e->src)->frequency /
- REG_BR_PROB_BASE);
+ {
+ sreal_add (&cyclic_probability, &cyclic_probability,
+ &EDGE_INFO (e)->back_edge_prob);
+ }
+ else if (!(e->flags & EDGE_DFS_BACK))
+ {
+ sreal tmp;
- if (cyclic_probability > 1.0 - 1.0 / REG_BR_PROB_BASE)
- cyclic_probability = 1.0 - 1.0 / REG_BR_PROB_BASE;
+ /* frequency += (e->probability
+ * BLOCK_INFO (e->src)->frequency /
+ REG_BR_PROB_BASE); */
- BLOCK_INFO (bb)->frequency = frequency / (1 - cyclic_probability);
+ sreal_init (&tmp, e->probability, 0);
+ sreal_mul (&tmp, &tmp, &BLOCK_INFO (e->src)->frequency);
+ sreal_mul (&tmp, &tmp, &real_inv_br_prob_base);
+ sreal_add (&frequency, &frequency, &tmp);
+ }
+
+ if (sreal_compare (&cyclic_probability, &real_zero) == 0)
+ {
+ memcpy (&BLOCK_INFO (bb)->frequency, &frequency,
+ sizeof (frequency));
+ }
+ else
+ {
+ if (sreal_compare (&cyclic_probability, &real_almost_one) > 0)
+ {
+ memcpy (&cyclic_probability, &real_almost_one,
+ sizeof (real_almost_one));
+ }
+
+ /* BLOCK_INFO (bb)->frequency = frequency
+ / (1 - cyclic_probability) */
+
+ sreal_sub (&cyclic_probability, &real_one, &cyclic_probability);
+ sreal_div (&BLOCK_INFO (bb)->frequency,
+ &frequency, &cyclic_probability);
+ }
}
- BLOCK_INFO (bb)->visited = 1;
+ BLOCK_INFO (bb)->tovisit = 0;
/* Compute back edge frequencies. */
for (e = bb->succ; e; e = e->succ_next)
if (e->dest == head)
- EDGE_INFO (e)->back_edge_prob = (e->probability
- * BLOCK_INFO (bb)->frequency
- / REG_BR_PROB_BASE);
+ {
+ sreal tmp;
+
+ /* EDGE_INFO (e)->back_edge_prob
+ = ((e->probability * BLOCK_INFO (bb)->frequency)
+ / REG_BR_PROB_BASE); */
- /* Propagate to succesor blocks. */
+ sreal_init (&tmp, e->probability, 0);
+ sreal_mul (&tmp, &tmp, &BLOCK_INFO (bb)->frequency);
+ sreal_mul (&EDGE_INFO (e)->back_edge_prob,
+ &tmp, &real_inv_br_prob_base);
+ }
+
+ /* Propagate to successor blocks. */
for (e = bb->succ; e; e = e->succ_next)
- if (!EDGE_INFO (e)->back_edge
- && !BLOCK_INFO (e->dest)->visited
- && !BLOCK_INFO (e->dest)->next && e->dest != last)
+ if (!(e->flags & EDGE_DFS_BACK)
+ && BLOCK_INFO (e->dest)->npredecessors)
{
- if (!nextbb)
- nextbb = e->dest;
- else
- BLOCK_INFO (last)->next = e->dest;
- last = e->dest;
- }
+ BLOCK_INFO (e->dest)->npredecessors--;
+ if (!BLOCK_INFO (e->dest)->npredecessors)
+ {
+ if (!nextbb)
+ nextbb = e->dest;
+ else
+ BLOCK_INFO (last)->next = e->dest;
+
+ last = e->dest;
+ }
+ }
}
}
-/* Estimate probabilities of the loopback edges in loops at same nest level. */
+/* Estimate probabilities of loopback edges in loops at same nest level. */
+
static void
estimate_loops_at_level (first_loop)
struct loop *first_loop;
{
- struct loop *l, *loop = first_loop;
+ struct loop *loop;
for (loop = first_loop; loop; loop = loop->next)
{
- int n;
edge e;
+ basic_block *bbs;
+ unsigned i;
estimate_loops_at_level (loop->inner);
-
- /* find current loop back edge and mark it. */
- for (e = loop->latch->succ; e->dest != loop->header; e = e->succ_next);
-
- EDGE_INFO (e)->back_edge = 1;
-
- /* In case loop header is shared, ensure that it is the last one sharing
- same header, so we avoid redundant work. */
- if (loop->shared)
+
+ if (loop->latch->succ) /* Do not do this for dummy function loop. */
{
- for (l = loop->next; l; l = l->next)
- if (l->header == loop->header)
- break;
- if (l)
- continue;
- }
-
- /* Now merge all nodes of all loops with given header as not visited. */
- for (l = loop->shared ? first_loop : loop; l != loop->next; l = l->next)
- if (loop->header == l->header)
- EXECUTE_IF_SET_IN_SBITMAP (l->nodes, 0, n,
- BLOCK_INFO (BASIC_BLOCK (n))->visited =
- 0);
- propagate_freq (loop->header);
+ /* Find current loop back edge and mark it. */
+ e = loop_latch_edge (loop);
+ EDGE_INFO (e)->back_edge = 1;
+ }
+
+ bbs = get_loop_body (loop);
+ for (i = 0; i < loop->num_nodes; i++)
+ BLOCK_INFO (bbs[i])->tovisit = 1;
+ free (bbs);
+ propagate_freq (loop);
}
}
/* Convert counts measured by profile driven feedback to frequencies. */
+
static void
counts_to_freqs ()
{
- HOST_WIDEST_INT count_max = 1;
- int i;
+ gcov_type count_max = 1;
+ basic_block bb;
+
+ FOR_EACH_BB (bb)
+ count_max = MAX (bb->count, count_max);
+
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
+ bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max;
+}
+
+/* Return true if function is likely to be expensive, so there is no point to
+ optimize performance of prologue, epilogue or do inlining at the expense
+ of code size growth. THRESHOLD is the limit of number of instructions
+ function can execute at average to be still considered not expensive. */
+
+bool
+expensive_function_p (threshold)
+ int threshold;
+{
+ unsigned int sum = 0;
+ basic_block bb;
+ unsigned int limit;
+
+ /* We can not compute accurately for large thresholds due to scaled
+ frequencies. */
+ if (threshold > BB_FREQ_MAX)
+ abort ();
- for (i = 0; i < n_basic_blocks; i++)
- if (BASIC_BLOCK (i)->count > count_max)
- count_max = BASIC_BLOCK (i)->count;
+ /* Frequencies are out of range. This either means that function contains
+ internal loop executing more than BB_FREQ_MAX times or profile feedback
+ is available and function has not been executed at all. */
+ if (ENTRY_BLOCK_PTR->frequency == 0)
+ return true;
- for (i = -2; i < n_basic_blocks; i++)
+ /* Maximally BB_FREQ_MAX^2 so overflow won't happen. */
+ limit = ENTRY_BLOCK_PTR->frequency * threshold;
+ FOR_EACH_BB (bb)
{
- basic_block bb;
- if (i == -2)
- bb = ENTRY_BLOCK_PTR;
- else if (i == -1)
- bb = EXIT_BLOCK_PTR;
- else
- bb = BASIC_BLOCK (i);
- bb->frequency = ((bb->count * BB_FREQ_MAX + count_max / 2)
- / count_max);
+ rtx insn;
+
+ for (insn = bb->head; insn != NEXT_INSN (bb->end);
+ insn = NEXT_INSN (insn))
+ if (active_insn_p (insn))
+ {
+ sum += bb->frequency;
+ if (sum > limit)
+ return true;
+ }
}
+
+ return false;
}
/* Estimate basic blocks frequency by given branch probabilities. */
+
static void
estimate_bb_frequencies (loops)
struct loops *loops;
{
- block_info bi;
- edge_info ei;
- int edgenum = 0;
- int i;
- double freq_max = 0;
+ basic_block bb;
+ sreal freq_max;
if (flag_branch_probabilities)
+ counts_to_freqs ();
+ else
{
- counts_to_freqs ();
- return;
- }
+ static int real_values_initialized = 0;
+
+ if (!real_values_initialized)
+ {
+ real_values_initialized = 1;
+ sreal_init (&real_zero, 0, 0);
+ sreal_init (&real_one, 1, 0);
+ sreal_init (&real_br_prob_base, REG_BR_PROB_BASE, 0);
+ sreal_init (&real_bb_freq_max, BB_FREQ_MAX, 0);
+ sreal_init (&real_one_half, 1, -1);
+ sreal_div (&real_inv_br_prob_base, &real_one, &real_br_prob_base);
+ sreal_sub (&real_almost_one, &real_one, &real_inv_br_prob_base);
+ }
- /* Fill in the probability values in flowgraph based on the REG_BR_PROB
- notes. */
- for (i = 0; i < n_basic_blocks; i++)
- {
- rtx last_insn = BLOCK_END (i);
- int probability;
- edge fallthru, branch;
+ mark_dfs_back_edges ();
+ /* Fill in the probability values in flowgraph based on the REG_BR_PROB
+ notes. */
+ FOR_EACH_BB (bb)
+ {
+ rtx last_insn = bb->end;
+
+ if (!can_predict_insn_p (last_insn))
+ {
+ /* We can predict only conditional jumps at the moment.
+ Expect each edge to be equally probable.
+ ?? In the future we want to make abnormal edges improbable. */
+ int nedges = 0;
+ edge e;
+
+ for (e = bb->succ; e; e = e->succ_next)
+ {
+ nedges++;
+ if (e->probability != 0)
+ break;
+ }
+ if (!e)
+ for (e = bb->succ; e; e = e->succ_next)
+ e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges;
+ }
+ }
- if (GET_CODE (last_insn) != JUMP_INSN || !any_condjump_p (last_insn)
- /* Avoid handling of conditionals jump jumping to fallthru edge. */
- || BASIC_BLOCK (i)->succ->succ_next == NULL)
+ ENTRY_BLOCK_PTR->succ->probability = REG_BR_PROB_BASE;
+
+ /* Set up block info for each basic block. */
+ alloc_aux_for_blocks (sizeof (struct block_info_def));
+ alloc_aux_for_edges (sizeof (struct edge_info_def));
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
{
- /* We can predict only conditional jumps at the moment.
- Expect each edge to be equall probable.
- ?? In future we want to make abnormal edges improbable. */
- int nedges = 0;
edge e;
- for (e = BASIC_BLOCK (i)->succ; e; e = e->succ_next)
+ BLOCK_INFO (bb)->tovisit = 0;
+ for (e = bb->succ; e; e = e->succ_next)
{
- nedges++;
- if (e->probability != 0)
- break;
+ sreal_init (&EDGE_INFO (e)->back_edge_prob, e->probability, 0);
+ sreal_mul (&EDGE_INFO (e)->back_edge_prob,
+ &EDGE_INFO (e)->back_edge_prob,
+ &real_inv_br_prob_base);
}
- if (!e)
- for (e = BASIC_BLOCK (i)->succ; e; e = e->succ_next)
- e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges;
}
- else
+
+ /* First compute probabilities locally for each loop from innermost
+ to outermost to examine probabilities for back edges. */
+ estimate_loops_at_level (loops->tree_root);
+
+ memcpy (&freq_max, &real_zero, sizeof (real_zero));
+ FOR_EACH_BB (bb)
+ if (sreal_compare (&freq_max, &BLOCK_INFO (bb)->frequency) < 0)
+ memcpy (&freq_max, &BLOCK_INFO (bb)->frequency, sizeof (freq_max));
+
+ sreal_div (&freq_max, &real_bb_freq_max, &freq_max);
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
{
- probability = INTVAL (XEXP (find_reg_note (last_insn,
- REG_BR_PROB, 0), 0));
- fallthru = BASIC_BLOCK (i)->succ;
- if (!fallthru->flags & EDGE_FALLTHRU)
- fallthru = fallthru->succ_next;
- branch = BASIC_BLOCK (i)->succ;
- if (branch->flags & EDGE_FALLTHRU)
- branch = branch->succ_next;
-
- branch->probability = probability;
- fallthru->probability = REG_BR_PROB_BASE - probability;
+ sreal tmp;
+
+ sreal_mul (&tmp, &BLOCK_INFO (bb)->frequency, &freq_max);
+ sreal_add (&tmp, &tmp, &real_one_half);
+ bb->frequency = sreal_to_int (&tmp);
}
+
+ free_aux_for_blocks ();
+ free_aux_for_edges ();
}
- ENTRY_BLOCK_PTR->succ->probability = REG_BR_PROB_BASE;
+ compute_function_frequency ();
+ if (flag_reorder_functions)
+ choose_function_section ();
+}
- /* Set up block info for each basic block. */
- bi = (block_info) xcalloc ((n_basic_blocks + 2), sizeof (*bi));
- ei = (edge_info) xcalloc ((n_edges), sizeof (*ei));
- for (i = -2; i < n_basic_blocks; i++)
- {
- edge e;
- basic_block bb;
+/* Decide whether function is hot, cold or unlikely executed. */
+static void
+compute_function_frequency ()
+{
+ basic_block bb;
- if (i == -2)
- bb = ENTRY_BLOCK_PTR;
- else if (i == -1)
- bb = EXIT_BLOCK_PTR;
- else
- bb = BASIC_BLOCK (i);
- bb->aux = bi + i + 2;
- BLOCK_INFO (bb)->visited = 1;
- for (e = bb->succ; e; e = e->succ_next)
+ if (!profile_info || !flag_branch_probabilities)
+ return;
+ cfun->function_frequency = FUNCTION_FREQUENCY_UNLIKELY_EXECUTED;
+ FOR_EACH_BB (bb)
+ {
+ if (maybe_hot_bb_p (bb))
{
- e->aux = ei + edgenum, edgenum++;
- EDGE_INFO (e)->back_edge_prob = ((double) e->probability
- / REG_BR_PROB_BASE);
+ cfun->function_frequency = FUNCTION_FREQUENCY_HOT;
+ return;
}
+ if (!probably_never_executed_bb_p (bb))
+ cfun->function_frequency = FUNCTION_FREQUENCY_NORMAL;
}
- /* First compute probabilities locally for each loop from innermost
- to outermost to examine probabilities for back edges. */
- estimate_loops_at_level (loops->tree);
-
- /* Now fake loop around whole function to finalize probabilities. */
- for (i = 0; i < n_basic_blocks; i++)
- BLOCK_INFO (BASIC_BLOCK (i))->visited = 0;
- BLOCK_INFO (ENTRY_BLOCK_PTR)->visited = 0;
- BLOCK_INFO (EXIT_BLOCK_PTR)->visited = 0;
- propagate_freq (ENTRY_BLOCK_PTR);
-
- for (i = 0; i < n_basic_blocks; i++)
- if (BLOCK_INFO (BASIC_BLOCK (i))->frequency > freq_max)
- freq_max = BLOCK_INFO (BASIC_BLOCK (i))->frequency;
- for (i = -2; i < n_basic_blocks; i++)
- {
- basic_block bb;
- if (i == -2)
- bb = ENTRY_BLOCK_PTR;
- else if (i == -1)
- bb = EXIT_BLOCK_PTR;
- else
- bb = BASIC_BLOCK (i);
- bb->frequency = (BLOCK_INFO (bb)->frequency * BB_FREQ_MAX / freq_max
- + 0.5);
- }
+}
- free (ei);
- free (bi);
+/* Choose appropriate section for the function. */
+static void
+choose_function_section ()
+{
+ if (DECL_SECTION_NAME (current_function_decl)
+ || !targetm.have_named_sections
+ /* Theoretically we can split the gnu.linkonce text section too,
+ but this requires more work as the frequency needs to match
+ for all generated objects so we need to merge the frequency
+ of all instances. For now just never set frequency for these. */
+ || DECL_ONE_ONLY (current_function_decl))
+ return;
+ if (cfun->function_frequency == FUNCTION_FREQUENCY_HOT)
+ DECL_SECTION_NAME (current_function_decl) =
+ build_string (strlen (HOT_TEXT_SECTION_NAME), HOT_TEXT_SECTION_NAME);
+ if (cfun->function_frequency == FUNCTION_FREQUENCY_UNLIKELY_EXECUTED)
+ DECL_SECTION_NAME (current_function_decl) =
+ build_string (strlen (UNLIKELY_EXECUTED_TEXT_SECTION_NAME),
+ UNLIKELY_EXECUTED_TEXT_SECTION_NAME);
}
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