/* Branch prediction routines for the GNU compiler.
- Copyright (C) 2000 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2001, 2002, 2003, 2004 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 "hard-reg-set.h"
#include "basic-block.h"
#include "insn-config.h"
#include "regs.h"
-#include "hard-reg-set.h"
#include "flags.h"
#include "output.h"
#include "function.h"
#include "except.h"
#include "toplev.h"
#include "recog.h"
-#include "insn-flags.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"
+#include "tree-flow.h"
+#include "ggc.h"
+#include "tree-dump.h"
+#include "tree-pass.h"
+#include "timevar.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_VERY_UNLIKELY (REG_BR_PROB_BASE / 10 - 1)
+#define PROB_EVEN (REG_BR_PROB_BASE / 2)
+#define PROB_VERY_LIKELY (REG_BR_PROB_BASE - PROB_VERY_UNLIKELY)
+#define PROB_ALWAYS (REG_BR_PROB_BASE)
+
+static void combine_predictions_for_insn (rtx, basic_block);
+static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int);
+static void estimate_loops_at_level (struct loop *loop);
+static void propagate_freq (struct loop *);
+static void estimate_bb_frequencies (struct loops *);
+static int counts_to_freqs (void);
+static bool last_basic_block_p (basic_block);
+static void compute_function_frequency (void);
+static void choose_function_section (void);
+static bool can_predict_insn_p (rtx);
+
+/* Information we hold about each branch predictor.
+ Filled using information from predict.def. */
+
+struct predictor_info
+{
+ const char *const name; /* Name used in the debugging dumps. */
+ const int hitrate; /* Expected hitrate used by
+ predict_insn_def call. */
+ const int flags;
+};
+
+/* 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 predictors. */
+ {NULL, 0, 0}
+};
+#undef DEF_PREDICTOR
+/* Return true in case BB can be CPU intensive and should be optimized
+ for maximal performance. */
-/* Statically estimate the probability that a branch will be taken.
- ??? In the next revision there will be a number of other predictors added
- from the above references. Further, each heuristic will be factored out
- into its own function for clarity (and to facilitate the combination of
- predictions). */
+bool
+maybe_hot_bb_p (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 (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 (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. */
+
+bool
+rtl_predicted_by_p (basic_block bb, enum br_predictor predictor)
+{
+ rtx note;
+ if (!INSN_P (BB_END (bb)))
+ return false;
+ for (note = REG_NOTES (BB_END (bb)); 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;
+}
+
+/* Return true if the one of outgoing edges is already predicted by
+ PREDICTOR. */
+
+bool
+tree_predicted_by_p (basic_block bb, enum br_predictor predictor)
+{
+ struct edge_prediction *i = bb_ann (bb)->predictions;
+ for (i = bb_ann (bb)->predictions; i; i = i->next)
+ if (i->predictor == predictor)
+ return true;
+ return false;
+}
+
+void
+predict_insn (rtx insn, enum br_predictor predictor, int probability)
+{
+ 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,
+ GEN_INT ((int) predictor),
+ GEN_INT ((int) probability)),
+ REG_NOTES (insn));
+}
+
+/* Predict insn by given predictor. */
void
-estimate_probability (loops_info)
- struct loops *loops_info;
+predict_insn_def (rtx insn, enum br_predictor predictor,
+ 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
+rtl_predict_edge (edge e, enum br_predictor predictor, int probability)
+{
+ rtx last_insn;
+ last_insn = BB_END (e->src);
+
+ /* We can store the branch prediction information only about
+ conditional jumps. */
+ if (!any_condjump_p (last_insn))
+ return;
+
+ /* We always store probability of branching. */
+ if (e->flags & EDGE_FALLTHRU)
+ probability = REG_BR_PROB_BASE - probability;
+
+ predict_insn (last_insn, predictor, probability);
+}
+
+/* Predict edge E with the given PROBABILITY. */
+void
+tree_predict_edge (edge e, enum br_predictor predictor, int probability)
+{
+ struct edge_prediction *i = ggc_alloc (sizeof (struct edge_prediction));
+
+ i->next = bb_ann (e->src)->predictions;
+ bb_ann (e->src)->predictions = i;
+ i->probability = probability;
+ i->predictor = predictor;
+ i->edge = e;
+}
+
+/* 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 (rtx insn)
+{
+ return (JUMP_P (insn)
+ && any_condjump_p (insn)
+ && BLOCK_FOR_INSN (insn)->succ->succ_next);
+}
+
+/* Predict edge E by given predictor if possible. */
+
+void
+predict_edge_def (edge e, enum br_predictor predictor,
+ enum prediction taken)
+{
+ int probability = predictor_info[(int) predictor].hitrate;
+
+ 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 (rtx insn)
+{
+ 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 (FILE *file, enum br_predictor predictor, int probability,
+ basic_block bb, int used)
+{
+ edge e = bb->succ;
+
+ if (!file)
+ return;
+
+ while (e && (e->flags & EDGE_FALLTHRU))
+ e = e->succ_next;
+
+ fprintf (file, " %s heuristics%s: %.1f%%",
+ predictor_info[predictor].name,
+ used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE);
+
+ if (bb->count)
+ {
+ fprintf (file, " exec ");
+ fprintf (file, HOST_WIDEST_INT_PRINT_DEC, bb->count);
+ if (e)
+ {
+ fprintf (file, " hit ");
+ fprintf (file, HOST_WIDEST_INT_PRINT_DEC, e->count);
+ fprintf (file, " (%.1f%%)", e->count * 100.0 / bb->count);
+ }
+ }
+
+ fprintf (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 (rtx insn, basic_block bb)
+{
+ 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 (dump_file)
+ fprintf (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. */
+ 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 (dump_file, PRED_NO_PREDICTION,
+ combined_probability, bb, true);
+ else
+ {
+ dump_prediction (dump_file, PRED_DS_THEORY, combined_probability,
+ bb, !first_match);
+ dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability,
+ bb, first_match);
+ }
+
+ if (first_match)
+ combined_probability = best_probability;
+ dump_prediction (dump_file, 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 (dump_file, predictor, probability, bb,
+ !first_match || best_predictor == predictor);
+ *pnote = XEXP (*pnote, 1);
+ }
+ else
+ pnote = &XEXP (*pnote, 1);
+ }
+
+ if (!prob_note)
+ {
+ REG_NOTES (insn)
+ = gen_rtx_EXPR_LIST (REG_BR_PROB,
+ 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;
+ }
+ }
+}
+
+/* Combine predictions into single probability and store them into CFG.
+ Remove now useless prediction entries. */
+
+static void
+combine_predictions_for_bb (FILE *file, basic_block bb)
{
- int i;
+ 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;
+ struct edge_prediction *pred;
+ int nedges = 0;
+ edge e, first = NULL, second = NULL;
+
+ for (e = bb->succ; e; e = e->succ_next)
+ if (!(e->flags & (EDGE_EH | EDGE_FAKE)))
+ {
+ nedges ++;
+ if (first && !second)
+ second = e;
+ if (!first)
+ first = e;
+ }
+
+ /* When there is no successor or only one choice, prediction is easy.
+
+ We are lazy for now and predict only basic blocks with two outgoing
+ edges. It is possible to predict generic case too, but we have to
+ ignore first match heuristics and do more involved combining. Implement
+ this later. */
+ if (nedges != 2)
+ {
+ for (e = bb->succ; e; e = e->succ_next)
+ if (!(e->flags & (EDGE_EH | EDGE_FAKE)))
+ e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges;
+ else
+ e->probability = 0;
+ bb_ann (bb)->predictions = NULL;
+ if (file)
+ fprintf (file, "%i edges in bb %i predicted to even probabilities\n",
+ nedges, bb->index);
+ return;
+ }
+
+ if (file)
+ fprintf (file, "Predictions for bb %i\n", bb->index);
+
+ /* We implement "first match" heuristics and use probability guessed
+ by predictor with smallest index. */
+ for (pred = bb_ann (bb)->predictions; pred; pred = pred->next)
+ {
+ int predictor = pred->predictor;
+ int probability = pred->probability;
+
+ if (pred->edge != first)
+ probability = REG_BR_PROB_BASE - probability;
+
+ 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 (file, PRED_NO_PREDICTION, combined_probability, bb, true);
+ else
+ {
+ dump_prediction (file, PRED_DS_THEORY, combined_probability, bb,
+ !first_match);
+ dump_prediction (file, PRED_FIRST_MATCH, best_probability, bb,
+ first_match);
+ }
+
+ if (first_match)
+ combined_probability = best_probability;
+ dump_prediction (file, PRED_COMBINED, combined_probability, bb, true);
+
+ for (pred = bb_ann (bb)->predictions; pred; pred = pred->next)
+ {
+ int predictor = pred->predictor;
+ int probability = pred->probability;
+
+ if (pred->edge != bb->succ)
+ probability = REG_BR_PROB_BASE - probability;
+ dump_prediction (file, predictor, probability, bb,
+ !first_match || best_predictor == predictor);
+ }
+ bb_ann (bb)->predictions = NULL;
+
+ first->probability = combined_probability;
+ second->probability = REG_BR_PROB_BASE - combined_probability;
+}
+
+/* Predict edge probabilities by exploiting loop structure.
+ When SIMPLELOOPS is set, attempt to count number of iterations by analyzing
+ RTL. */
+static void
+predict_loops (struct loops *loops_info, bool simpleloops)
+{
+ unsigned i;
/* 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 niter_desc desc;
+ unsigned HOST_WIDE_INT niter;
+
+ flow_loop_scan (loop, LOOP_EXIT_EDGES);
+ exits = loop->num_exits;
- for (j = loops_info->array[i].first->index;
- j <= loops_info->array[i].last->index;
- ++j)
+ if (simpleloops)
{
+ iv_analysis_loop_init (loop);
+ find_simple_exit (loop, &desc);
+
+ if (desc.simple_p && 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);
+ }
+ }
+
+ bbs = get_loop_body (loop);
+
+ for (j = 0; j < loop->num_nodes; j++)
+ {
+ int header_found = 0;
edge e;
-
- if (! TEST_BIT (loops_info->array[i].nodes, j))
- for (e = BASIC_BLOCK(j)->pred; e; e = e->pred_next)
- if (TEST_BIT (loops_info->array[i].nodes, e->src->index))
- {
- rtx last_insn = BLOCK_END (e->src->index);
- rtx cond, earliest;
-
- if (GET_CODE (last_insn) != JUMP_INSN
- || ! condjump_p (last_insn) || simplejump_p (last_insn))
- continue;
- cond = get_condition (last_insn, &earliest);
- if (! cond)
- continue;
- if (! find_reg_note (last_insn, REG_BR_PROB, 0))
- REG_NOTES (last_insn)
- = gen_rtx_EXPR_LIST (REG_BR_PROB,
- GEN_INT (REG_BR_PROB_BASE),
- REG_NOTES (last_insn));
- }
+
+ 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 ((simpleloops && !can_predict_insn_p (BB_END (bb)))
+ || 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);
}
+
+ /* Free basic blocks from get_loop_body. */
+ free (bbs);
}
+}
+
+/* Statically estimate the probability that a branch will be taken and produce
+ estimated profile. When profile feedback is present never executed portions
+ of function gets estimated. */
+
+void
+estimate_probability (struct loops *loops_info)
+{
+ basic_block bb;
- /* 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 - 1; i++)
+ connect_infinite_loops_to_exit ();
+ calculate_dominance_info (CDI_DOMINATORS);
+ calculate_dominance_info (CDI_POST_DOMINATORS);
+
+ predict_loops (loops_info, true);
+
+ iv_analysis_done ();
+
+ /* Attempt to predict conditional jumps using a number of heuristics. */
+ FOR_EACH_BB (bb)
{
- rtx last_insn = BLOCK_END (i);
- rtx cond, earliest;
- int prob;
+ rtx last_insn = BB_END (bb);
+ rtx cond;
edge e;
- if (GET_CODE (last_insn) != JUMP_INSN
- || ! condjump_p (last_insn) || simplejump_p (last_insn))
+ if (! can_predict_insn_p (last_insn))
continue;
- if (find_reg_note (last_insn, REG_BR_PROB, 0))
- continue;
+ for (e = bb->succ; e; e = e->succ_next)
+ {
+ /* 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);
- cond = get_condition (last_insn, &earliest);
+ /* 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
+ && dominated_by_p (CDI_DOMINATORS, e->dest, e->src)
+ && !dominated_by_p (CDI_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
+ messages. */
+ for (insn = BB_HEAD (e->dest); insn != NEXT_INSN (BB_END (e->dest));
+ insn = NEXT_INSN (insn))
+ if (CALL_P (insn)
+ /* Constant and pure calls are hardly used to signalize
+ something exceptional. */
+ && ! CONST_OR_PURE_CALL_P (insn))
+ {
+ predict_edge_def (e, PRED_CALL, NOT_TAKEN);
+ break;
+ }
+ }
+ }
+
+ cond = get_condition (last_insn, NULL, false, false);
if (! cond)
continue;
- /* If one of the successor blocks has no successors, predict
- that side not taken. */
- /* ??? Ought to do the same for any subgraph with no exit. */
- for (e = BASIC_BLOCK (i)->succ; e; e = e->succ_next)
- if (e->dest->succ == NULL)
- {
- if (e->flags & EDGE_FALLTHRU)
- prob = REG_BR_PROB_BASE;
- else
- prob = 0;
- goto emitnote;
- }
-
/* 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 (COMPARISON_P (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
- && REGNO_POINTER_FLAG (REGNO (XEXP (cond, 0)))
- && (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == REG
- && REGNO_POINTER_FLAG (REGNO (XEXP (cond, 1))))))
- {
- prob = REG_BR_PROB_BASE / 10;
- goto emitnote;
- }
- break;
- case NE:
- if (GET_CODE (XEXP (cond, 0)) == REG
- && REGNO_POINTER_FLAG (REGNO (XEXP (cond, 0)))
- && (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == REG
- && REGNO_POINTER_FLAG (REGNO (XEXP (cond, 1))))))
- {
- prob = REG_BR_PROB_BASE - (REG_BR_PROB_BASE / 10);
- goto emitnote;
- }
- break;
-
- default:
- break;
+ if (GET_CODE (cond) == EQ)
+ predict_insn_def (last_insn, PRED_POINTER, NOT_TAKEN);
+ else if (GET_CODE (cond) == NE)
+ predict_insn_def (last_insn, PRED_POINTER, TAKEN);
}
+ 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))
+ 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_EACH_BB (bb)
+ if (JUMP_P (BB_END (bb))
+ && any_condjump_p (BB_END (bb))
+ && bb->succ->succ_next != NULL)
+ combine_predictions_for_insn (BB_END (bb), bb);
+
+ remove_fake_exit_edges ();
+ /* Fill in the probability values in flowgraph based on the REG_BR_PROB
+ notes. */
+ FOR_EACH_BB (bb)
+ {
+ rtx last_insn = BB_END (bb);
+
+ if (!can_predict_insn_p (last_insn))
{
- case CONST_INT:
- /* Unconditional branch. */
- prob = (cond == const0_rtx ? 0 : REG_BR_PROB_BASE);
- goto emitnote;
-
- case EQ:
- prob = REG_BR_PROB_BASE / 10;
- goto emitnote;
- case NE:
- prob = REG_BR_PROB_BASE - (REG_BR_PROB_BASE / 10);
- goto emitnote;
- case LE:
- case LT:
- if (XEXP (cond, 1) == const0_rtx)
- {
- prob = REG_BR_PROB_BASE / 10;
- goto emitnote;
- }
- break;
- case GE:
- case GT:
- if (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == CONST_INT
- && INTVAL (XEXP (cond, 1)) == -1))
+ /* 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)
{
- prob = REG_BR_PROB_BASE - (REG_BR_PROB_BASE / 10);
- goto emitnote;
+ nedges++;
+ if (e->probability != 0)
+ break;
}
- break;
-
- default:
- break;
+ if (!e)
+ for (e = bb->succ; e; e = e->succ_next)
+ e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges;
}
+ }
+ estimate_bb_frequencies (loops_info);
+ free_dominance_info (CDI_POST_DOMINATORS);
+ if (profile_status == PROFILE_ABSENT)
+ profile_status = PROFILE_GUESSED;
+}
+\f
- /* If we havn't chosen something by now, predict 50-50. */
- prob = REG_BR_PROB_BASE / 2;
+/* Predict using opcode of the last statement in basic block. */
+static void
+tree_predict_by_opcode (basic_block bb)
+{
+ tree stmt = last_stmt (bb);
+ edge then_edge;
+ tree cond;
+ tree op0;
+ tree type;
- emitnote:
- REG_NOTES (last_insn)
- = gen_rtx_EXPR_LIST (REG_BR_PROB, GEN_INT (prob),
- REG_NOTES (last_insn));
+ if (!stmt || TREE_CODE (stmt) != COND_EXPR)
+ return;
+ for (then_edge = bb->succ; then_edge; then_edge = then_edge->succ_next)
+ if (then_edge->flags & EDGE_TRUE_VALUE)
+ break;
+ cond = TREE_OPERAND (stmt, 0);
+ if (TREE_CODE_CLASS (TREE_CODE (cond)) != '<')
+ return;
+ op0 = TREE_OPERAND (cond, 0);
+ type = TREE_TYPE (op0);
+ /* Try "pointer heuristic."
+ A comparison ptr == 0 is predicted as false.
+ Similarly, a comparison ptr1 == ptr2 is predicted as false. */
+ if (POINTER_TYPE_P (type))
+ {
+ if (TREE_CODE (cond) == EQ_EXPR)
+ predict_edge_def (then_edge, PRED_TREE_POINTER, NOT_TAKEN);
+ else if (TREE_CODE (cond) == NE_EXPR)
+ predict_edge_def (then_edge, PRED_TREE_POINTER, TAKEN);
}
+ 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 (TREE_CODE (cond))
+ {
+ case EQ_EXPR:
+ case UNEQ_EXPR:
+ /* Floating point comparisons appears to behave in a very
+ unpredictable way because of special role of = tests in
+ FP code. */
+ if (FLOAT_TYPE_P (type))
+ ;
+ /* Comparisons with 0 are often used for booleans and there is
+ nothing useful to predict about them. */
+ else if (integer_zerop (op0)
+ || integer_zerop (TREE_OPERAND (cond, 1)))
+ ;
+ else
+ predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, NOT_TAKEN);
+ break;
+
+ case NE_EXPR:
+ case LTGT_EXPR:
+ /* Floating point comparisons appears to behave in a very
+ unpredictable way because of special role of = tests in
+ FP code. */
+ if (FLOAT_TYPE_P (type))
+ ;
+ /* Comparisons with 0 are often used for booleans and there is
+ nothing useful to predict about them. */
+ else if (integer_zerop (op0)
+ || integer_zerop (TREE_OPERAND (cond, 1)))
+ ;
+ else
+ predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, TAKEN);
+ break;
+
+ case ORDERED_EXPR:
+ predict_edge_def (then_edge, PRED_TREE_FPOPCODE, TAKEN);
+ break;
+
+ case UNORDERED_EXPR:
+ predict_edge_def (then_edge, PRED_TREE_FPOPCODE, NOT_TAKEN);
+ break;
+
+ case LE_EXPR:
+ case LT_EXPR:
+ if (integer_zerop (TREE_OPERAND (cond, 1))
+ || integer_onep (TREE_OPERAND (cond, 1))
+ || integer_all_onesp (TREE_OPERAND (cond, 1))
+ || real_zerop (TREE_OPERAND (cond, 1))
+ || real_onep (TREE_OPERAND (cond, 1))
+ || real_minus_onep (TREE_OPERAND (cond, 1)))
+ predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, NOT_TAKEN);
+ break;
+
+ case GE_EXPR:
+ case GT_EXPR:
+ if (integer_zerop (TREE_OPERAND (cond, 1))
+ || integer_onep (TREE_OPERAND (cond, 1))
+ || integer_all_onesp (TREE_OPERAND (cond, 1))
+ || real_zerop (TREE_OPERAND (cond, 1))
+ || real_onep (TREE_OPERAND (cond, 1))
+ || real_minus_onep (TREE_OPERAND (cond, 1)))
+ predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, TAKEN);
+ break;
+
+ default:
+ break;
+ }
+}
+
+/* Predict branch probabilities and estimate profile of the tree CFG. */
+static void
+tree_estimate_probability (void)
+{
+ basic_block bb;
+ struct loops loops_info;
+
+ flow_loops_find (&loops_info, LOOP_TREE);
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ flow_loops_dump (&loops_info, dump_file, NULL, 0);
+
+ connect_infinite_loops_to_exit ();
+ calculate_dominance_info (CDI_DOMINATORS);
+ calculate_dominance_info (CDI_POST_DOMINATORS);
+
+ predict_loops (&loops_info, false);
+
+ FOR_EACH_BB (bb)
+ {
+ edge e;
+
+ for (e = bb->succ; e; e = e->succ_next)
+ {
+ /* 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
+ && dominated_by_p (CDI_DOMINATORS, e->dest, e->src)
+ && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest))
+ {
+ block_stmt_iterator bi;
+
+ /* 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
+ messages. */
+ for (bi = bsi_start (e->dest); !bsi_end_p (bi);
+ bsi_next (&bi))
+ {
+ tree stmt = bsi_stmt (bi);
+ if ((TREE_CODE (stmt) == CALL_EXPR
+ || (TREE_CODE (stmt) == MODIFY_EXPR
+ && TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR))
+ /* Constant and pure calls are hardly used to signalize
+ something exceptional. */
+ && TREE_SIDE_EFFECTS (stmt))
+ {
+ predict_edge_def (e, PRED_CALL, NOT_TAKEN);
+ break;
+ }
+ }
+ }
+ }
+ tree_predict_by_opcode (bb);
+ }
+ FOR_EACH_BB (bb)
+ combine_predictions_for_bb (dump_file, bb);
+
+ estimate_bb_frequencies (&loops_info);
+ free_dominance_info (CDI_POST_DOMINATORS);
+ remove_fake_exit_edges ();
+ flow_loops_free (&loops_info);
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ dump_tree_cfg (dump_file, dump_flags);
+ if (profile_status == PROFILE_ABSENT)
+ profile_status = PROFILE_GUESSED;
}
\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 ()
+expected_value_to_br_prob (void)
{
rtx insn, cond, ev = NULL_RTX, ev_reg = NULL_RTX;
{
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 (!JUMP_P (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 (! condjump_p (insn) || simplejump_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 = canonicalize_condition (insn, cond, 0, NULL, ev_reg);
- if (! cond
- || XEXP (cond, 0) != ev_reg
+ cond = XEXP (SET_SRC (pc_set (insn)), 0);
+ cond = canonicalize_condition (insn, cond, 0, NULL, ev_reg,
+ false, false);
+ 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 = GEN_INT (REG_BR_PROB_BASE);
- else if (cond != const0_rtx)
+ if (cond != const_true_rtx && cond != const0_rtx)
abort ();
- REG_NOTES (insn) = alloc_EXPR_LIST (REG_BR_PROB, cond, REG_NOTES (insn));
+ predict_insn_def (insn, PRED_BUILTIN_EXPECT,
+ cond == const_true_rtx ? TAKEN : NOT_TAKEN);
}
}
+\f
+/* Check whether this is the last basic block of function. Commonly
+ there is one extra common cleanup block. */
+static bool
+last_basic_block_p (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));
+}
+\f
+/* 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. */
+ sreal frequency;
+
+ /* To keep queue of basic blocks to process. */
+ basic_block next;
+
+ /* True if block needs to be visited in propagate_freq. */
+ unsigned int tovisit:1;
+
+ /* Number of predecessors we need to visit first. */
+ int npredecessors;
+} *block_info;
+
+/* Similar information for edges. */
+typedef struct edge_info_def
+{
+ /* 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). */
+ sreal back_edge_prob;
+ /* True if the edge is an loopback edge in the natural loop. */
+ unsigned int back_edge:1;
+} *edge_info;
+
+#define BLOCK_INFO(B) ((block_info) (B)->aux)
+#define EDGE_INFO(E) ((edge_info) (E)->aux)
+
+/* Helper function for estimate_bb_frequencies.
+ Propagate the frequencies for LOOP. */
+
+static void
+propagate_freq (struct loop *loop)
+{
+ basic_block head = loop->header;
+ basic_block bb;
+ basic_block last;
+ edge e;
+ basic_block nextbb;
+
+ /* For each basic block we need to visit count number of his predecessors
+ we need to visit first. */
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
+ {
+ 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
+ && dump_file && !EDGE_INFO (e)->back_edge)
+ fprintf (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)->tovisit && !(e->flags & EDGE_DFS_BACK))
+ abort ();
+#endif
+
+ for (e = bb->pred; e; e = e->pred_next)
+ if (EDGE_INFO (e)->back_edge)
+ {
+ sreal_add (&cyclic_probability, &cyclic_probability,
+ &EDGE_INFO (e)->back_edge_prob);
+ }
+ else if (!(e->flags & EDGE_DFS_BACK))
+ {
+ sreal tmp;
+
+ /* frequency += (e->probability
+ * BLOCK_INFO (e->src)->frequency /
+ REG_BR_PROB_BASE); */
+
+ 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)->tovisit = 0;
+
+ /* Compute back edge frequencies. */
+ for (e = bb->succ; e; e = e->succ_next)
+ if (e->dest == head)
+ {
+ sreal tmp;
+
+ /* EDGE_INFO (e)->back_edge_prob
+ = ((e->probability * BLOCK_INFO (bb)->frequency)
+ / REG_BR_PROB_BASE); */
+
+ 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 (!(e->flags & EDGE_DFS_BACK)
+ && BLOCK_INFO (e->dest)->npredecessors)
+ {
+ 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 loopback edges in loops at same nest level. */
+
+static void
+estimate_loops_at_level (struct loop *first_loop)
+{
+ struct loop *loop;
+
+ for (loop = first_loop; loop; loop = loop->next)
+ {
+ edge e;
+ basic_block *bbs;
+ unsigned i;
+
+ estimate_loops_at_level (loop->inner);
+
+ if (loop->latch->succ) /* Do not do this for dummy function loop. */
+ {
+ /* 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.
+ Return nonzero iff there was any nonzero execution count. */
+
+static int
+counts_to_freqs (void)
+{
+ gcov_type count_max, true_count_max = 0;
+ basic_block bb;
+
+ FOR_EACH_BB (bb)
+ true_count_max = MAX (bb->count, true_count_max);
+
+ count_max = MAX (true_count_max, 1);
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
+ bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max;
+ return true_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 (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 ();
+
+ /* 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;
+
+ /* Maximally BB_FREQ_MAX^2 so overflow won't happen. */
+ limit = ENTRY_BLOCK_PTR->frequency * threshold;
+ FOR_EACH_BB (bb)
+ {
+ rtx insn;
+
+ for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
+ 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 (struct loops *loops)
+{
+ basic_block bb;
+ sreal freq_max;
+
+ if (!flag_branch_probabilities || !counts_to_freqs ())
+ {
+ 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);
+ }
+
+ mark_dfs_back_edges ();
+
+ 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)
+ {
+ edge e;
+
+ BLOCK_INFO (bb)->tovisit = 0;
+ for (e = bb->succ; e; e = e->succ_next)
+ {
+ 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);
+ }
+ }
+
+ /* 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)
+ {
+ 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 ();
+ }
+ compute_function_frequency ();
+ if (flag_reorder_functions)
+ choose_function_section ();
+}
+
+/* Decide whether function is hot, cold or unlikely executed. */
+static void
+compute_function_frequency (void)
+{
+ basic_block bb;
+
+ if (!profile_info || !flag_branch_probabilities)
+ return;
+ cfun->function_frequency = FUNCTION_FREQUENCY_UNLIKELY_EXECUTED;
+ FOR_EACH_BB (bb)
+ {
+ if (maybe_hot_bb_p (bb))
+ {
+ cfun->function_frequency = FUNCTION_FREQUENCY_HOT;
+ return;
+ }
+ if (!probably_never_executed_bb_p (bb))
+ cfun->function_frequency = FUNCTION_FREQUENCY_NORMAL;
+ }
+}
+
+/* Choose appropriate section for the function. */
+static void
+choose_function_section (void)
+{
+ 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);
+}
+
+
+struct tree_opt_pass pass_profile =
+{
+ "profile", /* name */
+ NULL, /* gate */
+ tree_estimate_probability, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ TV_BRANCH_PROB, /* tv_id */
+ PROP_cfg, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_ggc_collect | TODO_verify_ssa /* todo_flags_finish */
+};
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