/* Branch prediction routines for the GNU compiler.
- Copyright (C) 2000, 2001 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005
+ Free Software Foundation, Inc.
- This file is part of GCC.
+This file is part of GCC.
- 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.
+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.
- 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.
+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 GCC; 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 "cfgloop.h"
+#include "tree-flow.h"
+#include "ggc.h"
+#include "tree-dump.h"
+#include "tree-pass.h"
+#include "timevar.h"
+#include "tree-scalar-evolution.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_VERY_UNLIKELY (REG_BR_PROB_BASE / 100 - 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 void combine_predictions_for_insn PARAMS ((rtx, basic_block));
-static void dump_prediction PARAMS ((enum br_predictor, int,
- basic_block, int));
-static void estimate_loops_at_level PARAMS ((struct loop *loop));
-static void propagate_freq PARAMS ((basic_block));
-static void estimate_bb_frequencies PARAMS ((struct loops *));
-static void counts_to_freqs PARAMS ((void));
+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 *, bitmap);
+static void propagate_freq (struct loop *, bitmap);
+static void estimate_bb_frequencies (struct loops *);
+static void predict_paths_leading_to (basic_block, int *, enum br_predictor, enum prediction);
+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. */
/* Recompute hitrate in percent to our representation. */
-#define HITRATE(VAL) ((int)((VAL) * REG_BR_PROB_BASE + 50) / 100)
+#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[] = {
+static const struct predictor_info predictor_info[]= {
#include "predict.def"
/* Upper bound on predictors. */
};
#undef DEF_PREDICTOR
-void
-predict_insn (insn, predictor, probability)
- rtx insn;
- int probability;
- enum br_predictor predictor;
+/* Return true in case BB can be CPU intensive and should be optimized
+ for maximal performance. */
+
+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;
+}
+
+static 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,
}
/* Predict insn by given predictor. */
+
void
-predict_insn_def (insn, predictor, taken)
- rtx insn;
- enum br_predictor predictor;
- enum prediction taken;
+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
-predict_edge (e, predictor, probability)
- edge e;
- int probability;
- enum br_predictor predictor;
+rtl_predict_edge (edge e, enum br_predictor predictor, int probability)
{
rtx last_insn;
- last_insn = e->src->end;
+ last_insn = BB_END (e->src);
/* We can store the branch prediction information only about
conditional jumps. */
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)
+ && EDGE_COUNT (BLOCK_FOR_INSN (insn)->succs) >= 2);
+}
+
/* Predict edge E by given predictor if possible. */
+
void
-predict_edge_def (e, predictor, taken)
- edge e;
- enum br_predictor predictor;
- enum prediction taken;
+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 (insn)
- rtx insn;
+invert_br_probabilities (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, used)
- enum br_predictor predictor;
- int probability;
- basic_block bb;
- int used;
+dump_prediction (FILE *file, enum br_predictor predictor, int probability,
+ basic_block bb, int used)
{
- edge e = bb->succ;
+ edge e;
+ edge_iterator ei;
- if (!rtl_dump_file)
+ if (!file)
return;
- while (e->flags & EDGE_FALLTHRU)
- e = e->succ_next;
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if (! (e->flags & EDGE_FALLTHRU))
+ break;
- fprintf (rtl_dump_file, " %s heuristics%s: %.1f%%",
+ fprintf (file, " %s heuristics%s: %.1f%%",
predictor_info[predictor].name,
- used ? "" : " (ignored)",
- probability * 100.0 / REG_BR_PROB_BASE);
+ used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE);
if (bb->count)
{
- fprintf (rtl_dump_file, " exec ");
- fprintf (rtl_dump_file, HOST_WIDEST_INT_PRINT_DEC,
- (HOST_WIDEST_INT) bb->count);
- fprintf (rtl_dump_file, " hit ");
- fprintf (rtl_dump_file, HOST_WIDEST_INT_PRINT_DEC,
- (HOST_WIDEST_INT) e->count);
- fprintf (rtl_dump_file, " (%.1f%%)",
- e->count * 100.0 / 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 (rtl_dump_file, "\n");
+
+ fprintf (file, "\n");
+}
+
+/* We can not predict the probabilities of outgoing edges of bb. Set them
+ evenly and hope for the best. */
+static void
+set_even_probabilities (basic_block bb)
+{
+ int nedges = 0;
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if (!(e->flags & (EDGE_EH | EDGE_FAKE)))
+ nedges ++;
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if (!(e->flags & (EDGE_EH | EDGE_FAKE)))
+ e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges;
+ else
+ e->probability = 0;
}
/* 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;
- basic_block bb;
+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 = REG_NOTES (insn);
+ rtx prob_note;
+ rtx *pnote;
+ rtx note;
int best_probability = PROB_EVEN;
int best_predictor = END_PREDICTORS;
int combined_probability = REG_BR_PROB_BASE / 2;
bool first_match = false;
bool found = false;
- if (rtl_dump_file)
- fprintf (rtl_dump_file, "Predictions for insn %i bb %i\n", INSN_UID (insn),
+ if (!can_predict_insn_p (insn))
+ {
+ set_even_probabilities (bb);
+ return;
+ }
+
+ prob_note = find_reg_note (insn, REG_BR_PROB, 0);
+ pnote = ®_NOTES (insn);
+ 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. In the future we will use better
- probability combination techniques. */
- while (note)
- {
- 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));
- /* An FP math to avoid overflows of 32bit integers. */
- combined_probability = (((double)combined_probability) * probability
+ 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);
- }
- note = XEXP (note, 1);
- }
+ }
- /* Decide heuristic to use. In case we didn't match anything, use
- no_prediction heuristic, in case we did match, use either
+ /* 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);
+ dump_prediction (dump_file, 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);
+ 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 (PRED_COMBINED, combined_probability, bb, true);
+ dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true);
while (*pnote)
{
int predictor = INTVAL (XEXP (XEXP (*pnote, 0), 0));
int probability = INTVAL (XEXP (XEXP (*pnote, 0), 1));
- dump_prediction (predictor, probability, bb,
+ dump_prediction (dump_file, predictor, probability, bb,
!first_match || best_predictor == predictor);
- *pnote = XEXP (*pnote, 1);
+ *pnote = XEXP (*pnote, 1);
}
else
- pnote = &XEXP (*pnote, 1);
+ 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)
+ if (EDGE_COUNT (bb->succs) > 1)
{
BRANCH_EDGE (bb)->probability = combined_probability;
- FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - combined_probability;
+ FALLTHRU_EDGE (bb)->probability
+ = REG_BR_PROB_BASE - combined_probability;
}
}
+ else if (EDGE_COUNT (bb->succs) > 1)
+ {
+ int prob = INTVAL (XEXP (prob_note, 0));
+
+ BRANCH_EDGE (bb)->probability = prob;
+ FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - prob;
+ }
+ else
+ EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
}
-/* 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). */
+/* Combine predictions into single probability and store them into CFG.
+ Remove now useless prediction entries. */
-void
-estimate_probability (loops_info)
- struct loops *loops_info;
+static void
+combine_predictions_for_bb (FILE *file, basic_block bb)
+{
+ 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;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ 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)
+ {
+ if (!bb->count)
+ set_even_probabilities (bb);
+ 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 != EDGE_SUCC (bb, 0))
+ probability = REG_BR_PROB_BASE - probability;
+ dump_prediction (file, predictor, probability, bb,
+ !first_match || best_predictor == predictor);
+ }
+ bb_ann (bb)->predictions = NULL;
+
+ if (!bb->count)
+ {
+ first->probability = combined_probability;
+ second->probability = REG_BR_PROB_BASE - combined_probability;
+ }
+}
+
+/* Predict edge probabilities by exploiting loop structure.
+ When RTLSIMPLELOOPS is set, attempt to count number of iterations by analyzing
+ RTL otherwise use tree based approach. */
+static void
+predict_loops (struct loops *loops_info, bool rtlsimpleloops)
{
- sbitmap *dominators, *post_dominators;
- int i;
- int found_noreturn = 0;
+ 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, CDI_DOMINATORS);
- calculate_dominance_info (NULL, post_dominators, CDI_POST_DOMINATORS);
+ if (!rtlsimpleloops)
+ scev_initialize (loops_info);
/* 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;
+ unsigned n_exits;
+ struct loop *loop = loops_info->parray[i];
+ struct niter_desc desc;
+ unsigned HOST_WIDE_INT niter;
+ edge *exits;
- for (j = loops_info->array[i].first->index;
- j <= loops_info->array[i].last->index;
- ++j)
+ exits = get_loop_exit_edges (loop, &n_exits);
+
+ if (rtlsimpleloops)
{
- if (TEST_BIT (loops_info->array[i].nodes, j))
+ iv_analysis_loop_init (loop);
+ find_simple_exit (loop, &desc);
+
+ if (desc.simple_p && desc.const_iter)
{
- int header_found = 0;
- edge e;
-
- /* Loop branch heuristics - 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
- && e->src == loops_info->array[i].latch)
- {
- header_found = 1;
- predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN);
- }
- /* Loop exit heuristics - 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 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);
+ }
+ }
+ else
+ {
+ struct tree_niter_desc niter_desc;
+
+ for (j = 0; j < n_exits; j++)
+ {
+ tree niter = NULL;
+
+ if (number_of_iterations_exit (loop, exits[j], &niter_desc))
+ niter = niter_desc.niter;
+ if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST)
+ niter = loop_niter_by_eval (loop, exits[j]);
+
+ if (TREE_CODE (niter) == INTEGER_CST)
+ {
+ int probability;
+ if (host_integerp (niter, 1)
+ && tree_int_cst_lt (niter,
+ build_int_cstu (NULL_TREE,
+ REG_BR_PROB_BASE - 1)))
+ {
+ HOST_WIDE_INT nitercst = tree_low_cst (niter, 1) + 1;
+ probability = (REG_BR_PROB_BASE + nitercst / 2) / nitercst;
+ }
+ else
+ probability = 1;
+
+ predict_edge (exits[j], PRED_LOOP_ITERATIONS, probability);
+ }
+ }
+
+ }
+ free (exits);
+
+ bbs = get_loop_body (loop);
+
+ for (j = 0; j < loop->num_nodes; j++)
+ {
+ int header_found = 0;
+ edge e;
+ edge_iterator ei;
+
+ 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 ((rtlsimpleloops && !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. */
+ if (bb == loop->latch)
+ {
+ e = find_edge (loop->latch, loop->header);
+ if (e)
+ {
+ 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_EACH_EDGE (e, ei, bb->succs)
+ 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)
+ / n_exits);
}
+
+ /* Free basic blocks from get_loop_body. */
+ free (bbs);
}
+ if (!rtlsimpleloops)
+ scev_finalize ();
+}
+
+/* Attempt to predict probabilities of BB outgoing edges using local
+ properties. */
+static void
+bb_estimate_probability_locally (basic_block bb)
+{
+ rtx last_insn = BB_END (bb);
+ rtx cond;
+
+ if (! can_predict_insn_p (last_insn))
+ return;
+ cond = get_condition (last_insn, NULL, false, false);
+ if (! cond)
+ return;
+
+ /* Try "pointer heuristic."
+ A comparison ptr == 0 is predicted as false.
+ Similarly, a comparison ptr1 == ptr2 is predicted as false. */
+ if (COMPARISON_P (cond)
+ && ((REG_P (XEXP (cond, 0)) && REG_POINTER (XEXP (cond, 0)))
+ || (REG_P (XEXP (cond, 1)) && REG_POINTER (XEXP (cond, 1)))))
+ {
+ 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))
+ {
+ 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;
+ }
+}
+
+/* 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;
+
+ 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 (i = 0; i < n_basic_blocks; i++)
+ FOR_EACH_BB (bb)
{
- basic_block bb = BASIC_BLOCK (i);
- rtx last_insn = bb->end;
- rtx cond, earliest;
+ rtx last_insn = BB_END (bb);
edge e;
+ edge_iterator ei;
- /* If block has no successor, 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 && !found_noreturn)
- {
- int y;
-
- /* ??? Postdominator claims each noreturn block to be postdominated
- by each, so we need to run only once. This needs to be changed
- once postdominace algorithm is updated to say something more sane.
- */
- found_noreturn = 1;
- 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)
+ FOR_EACH_EDGE (e, ei, bb->succs)
{
- /* 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);
-
- /* Look for block we are guarding (ie we dominate it,
+ /* 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
+ || (EDGE_COUNT (e->dest->succs) == 1
+ && EDGE_SUCC (e->dest, 0)->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 (i.e. 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 (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 = e->dest->head; insn != NEXT_INSN (e->dest->end);
+ for (insn = BB_HEAD (e->dest); insn != NEXT_INSN (BB_END (e->dest));
insn = NEXT_INSN (insn))
- if (GET_CODE (insn) == CALL_INSN
+ if (CALL_P (insn)
/* Constant and pure calls are hardly used to signalize
something exceptional. */
&& ! CONST_OR_PURE_CALL_P (insn))
}
}
}
+ bb_estimate_probability_locally (bb);
+ }
- cond = get_condition (last_insn, &earliest);
- if (! cond)
- continue;
+ /* Attach the combined probability to each conditional jump. */
+ FOR_EACH_BB (bb)
+ combine_predictions_for_insn (BB_END (bb), bb);
+
+ remove_fake_edges ();
+ estimate_bb_frequencies (loops_info);
+ free_dominance_info (CDI_POST_DOMINATORS);
+ if (profile_status == PROFILE_ABSENT)
+ profile_status = PROFILE_GUESSED;
+}
- /* Try "pointer heuristic."
- A comparison ptr == 0 is predicted as false.
- Similarly, a comparison ptr1 == ptr2 is predicted as false. */
- switch (GET_CODE (cond))
+/* Set edge->probability for each successor edge of BB. */
+void
+guess_outgoing_edge_probabilities (basic_block bb)
+{
+ bb_estimate_probability_locally (bb);
+ combine_predictions_for_insn (BB_END (bb), bb);
+}
+\f
+/* Return constant EXPR will likely have at execution time, NULL if unknown.
+ The function is used by builtin_expect branch predictor so the evidence
+ must come from this construct and additional possible constant folding.
+
+ We may want to implement more involved value guess (such as value range
+ propagation based prediction), but such tricks shall go to new
+ implementation. */
+
+static tree
+expr_expected_value (tree expr, bitmap visited)
+{
+ if (TREE_CONSTANT (expr))
+ return expr;
+ else if (TREE_CODE (expr) == SSA_NAME)
+ {
+ tree def = SSA_NAME_DEF_STMT (expr);
+
+ /* If we were already here, break the infinite cycle. */
+ if (bitmap_bit_p (visited, SSA_NAME_VERSION (expr)))
+ return NULL;
+ bitmap_set_bit (visited, SSA_NAME_VERSION (expr));
+
+ if (TREE_CODE (def) == PHI_NODE)
{
- 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)))))
-
- 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)))))
- predict_insn_def (last_insn, PRED_POINTER, TAKEN);
- break;
+ /* All the arguments of the PHI node must have the same constant
+ length. */
+ int i;
+ tree val = NULL, new_val;
- default:
- break;
+ for (i = 0; i < PHI_NUM_ARGS (def); i++)
+ {
+ tree arg = PHI_ARG_DEF (def, i);
+
+ /* If this PHI has itself as an argument, we cannot
+ determine the string length of this argument. However,
+ if we can find an expected constant value for the other
+ PHI args then we can still be sure that this is
+ likely a constant. So be optimistic and just
+ continue with the next argument. */
+ if (arg == PHI_RESULT (def))
+ continue;
+
+ new_val = expr_expected_value (arg, visited);
+ if (!new_val)
+ return NULL;
+ if (!val)
+ val = new_val;
+ else if (!operand_equal_p (val, new_val, false))
+ return NULL;
+ }
+ return val;
}
-
- /* 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))
+ if (TREE_CODE (def) != MODIFY_EXPR || TREE_OPERAND (def, 0) != expr)
+ return NULL;
+ return expr_expected_value (TREE_OPERAND (def, 1), visited);
+ }
+ else if (TREE_CODE (expr) == CALL_EXPR)
+ {
+ tree decl = get_callee_fndecl (expr);
+ if (!decl)
+ return NULL;
+ if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
+ && DECL_FUNCTION_CODE (decl) == BUILT_IN_EXPECT)
{
- case CONST_INT:
- /* Unconditional branch. */
- predict_insn_def (last_insn, PRED_UNCONDITIONAL,
- cond == const0_rtx ? NOT_TAKEN : TAKEN);
- break;
+ tree arglist = TREE_OPERAND (expr, 1);
+ tree val;
+
+ if (arglist == NULL_TREE
+ || TREE_CHAIN (arglist) == NULL_TREE)
+ return NULL;
+ val = TREE_VALUE (TREE_CHAIN (TREE_OPERAND (expr, 1)));
+ if (TREE_CONSTANT (val))
+ return val;
+ return TREE_VALUE (TREE_CHAIN (TREE_OPERAND (expr, 1)));
+ }
+ }
+ if (BINARY_CLASS_P (expr) || COMPARISON_CLASS_P (expr))
+ {
+ tree op0, op1, res;
+ op0 = expr_expected_value (TREE_OPERAND (expr, 0), visited);
+ if (!op0)
+ return NULL;
+ op1 = expr_expected_value (TREE_OPERAND (expr, 1), visited);
+ if (!op1)
+ return NULL;
+ res = fold (build (TREE_CODE (expr), TREE_TYPE (expr), op0, op1));
+ if (TREE_CONSTANT (res))
+ return res;
+ return NULL;
+ }
+ if (UNARY_CLASS_P (expr))
+ {
+ tree op0, res;
+ op0 = expr_expected_value (TREE_OPERAND (expr, 0), visited);
+ if (!op0)
+ return NULL;
+ res = fold (build1 (TREE_CODE (expr), TREE_TYPE (expr), op0));
+ if (TREE_CONSTANT (res))
+ return res;
+ return NULL;
+ }
+ return NULL;
+}
+\f
+/* Get rid of all builtin_expect calls we no longer need. */
+static void
+strip_builtin_expect (void)
+{
+ basic_block bb;
+ FOR_EACH_BB (bb)
+ {
+ block_stmt_iterator bi;
+ for (bi = bsi_start (bb); !bsi_end_p (bi); bsi_next (&bi))
+ {
+ tree stmt = bsi_stmt (bi);
+ tree fndecl;
+ tree arglist;
+
+ if (TREE_CODE (stmt) == MODIFY_EXPR
+ && TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR
+ && (fndecl = get_callee_fndecl (TREE_OPERAND (stmt, 1)))
+ && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
+ && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT
+ && (arglist = TREE_OPERAND (TREE_OPERAND (stmt, 1), 1))
+ && TREE_CHAIN (arglist))
+ {
+ TREE_OPERAND (stmt, 1) = TREE_VALUE (arglist);
+ modify_stmt (stmt);
+ }
+ }
+ }
+}
+\f
+/* 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;
+ tree val;
+ bitmap visited;
+ edge_iterator ei;
+
+ if (!stmt || TREE_CODE (stmt) != COND_EXPR)
+ return;
+ FOR_EACH_EDGE (then_edge, ei, bb->succs)
+ if (then_edge->flags & EDGE_TRUE_VALUE)
+ break;
+ cond = TREE_OPERAND (stmt, 0);
+ if (!COMPARISON_CLASS_P (cond))
+ return;
+ op0 = TREE_OPERAND (cond, 0);
+ type = TREE_TYPE (op0);
+ visited = BITMAP_ALLOC (NULL);
+ val = expr_expected_value (cond, visited);
+ BITMAP_FREE (visited);
+ if (val)
+ {
+ if (integer_zerop (val))
+ predict_edge_def (then_edge, PRED_BUILTIN_EXPECT, NOT_TAKEN);
+ else
+ predict_edge_def (then_edge, PRED_BUILTIN_EXPECT, TAKEN);
+ return;
+ }
+ /* 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
- 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;
+ /* 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;
+ }
+}
- default:
- break;
+/* Try to guess whether the value of return means error code. */
+static enum br_predictor
+return_prediction (tree val, enum prediction *prediction)
+{
+ /* VOID. */
+ if (!val)
+ return PRED_NO_PREDICTION;
+ /* Different heuristics for pointers and scalars. */
+ if (POINTER_TYPE_P (TREE_TYPE (val)))
+ {
+ /* NULL is usually not returned. */
+ if (integer_zerop (val))
+ {
+ *prediction = NOT_TAKEN;
+ return PRED_NULL_RETURN;
+ }
+ }
+ else if (INTEGRAL_TYPE_P (TREE_TYPE (val)))
+ {
+ /* Negative return values are often used to indicate
+ errors. */
+ if (TREE_CODE (val) == INTEGER_CST
+ && tree_int_cst_sgn (val) < 0)
+ {
+ *prediction = NOT_TAKEN;
+ return PRED_NEGATIVE_RETURN;
+ }
+ /* Constant return values seems to be commonly taken.
+ Zero/one often represent booleans so exclude them from the
+ heuristics. */
+ if (TREE_CONSTANT (val)
+ && (!integer_zerop (val) && !integer_onep (val)))
+ {
+ *prediction = TAKEN;
+ return PRED_NEGATIVE_RETURN;
}
}
+ return PRED_NO_PREDICTION;
+}
- /* Attach the combined probability to each conditional jump. */
- for (i = 0; i < n_basic_blocks; i++)
+/* Find the basic block with return expression and look up for possible
+ return value trying to apply RETURN_PREDICTION heuristics. */
+static void
+apply_return_prediction (int *heads)
+{
+ tree return_stmt;
+ tree return_val;
+ edge e;
+ tree phi;
+ int phi_num_args, i;
+ enum br_predictor pred;
+ enum prediction direction;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
{
- rtx last_insn = BLOCK_END (i);
+ return_stmt = last_stmt (e->src);
+ if (TREE_CODE (return_stmt) == RETURN_EXPR)
+ break;
+ }
+ if (!e)
+ return;
+ return_val = TREE_OPERAND (return_stmt, 0);
+ if (!return_val)
+ return;
+ if (TREE_CODE (return_val) == MODIFY_EXPR)
+ return_val = TREE_OPERAND (return_val, 1);
+ if (TREE_CODE (return_val) != SSA_NAME
+ || !SSA_NAME_DEF_STMT (return_val)
+ || TREE_CODE (SSA_NAME_DEF_STMT (return_val)) != PHI_NODE)
+ return;
+ phi = SSA_NAME_DEF_STMT (return_val);
+ while (phi)
+ {
+ tree next = PHI_CHAIN (phi);
+ if (PHI_RESULT (phi) == return_val)
+ break;
+ phi = next;
+ }
+ if (!phi)
+ return;
+ phi_num_args = PHI_NUM_ARGS (phi);
+ pred = return_prediction (PHI_ARG_DEF (phi, 0), &direction);
+
+ /* Avoid the degenerate case where all return values form the function
+ belongs to same category (ie they are all positive constants)
+ so we can hardly say something about them. */
+ for (i = 1; i < phi_num_args; i++)
+ if (pred != return_prediction (PHI_ARG_DEF (phi, i), &direction))
+ break;
+ if (i != phi_num_args)
+ for (i = 0; i < phi_num_args; i++)
+ {
+ pred = return_prediction (PHI_ARG_DEF (phi, i), &direction);
+ if (pred != PRED_NO_PREDICTION)
+ predict_paths_leading_to (PHI_ARG_EDGE (phi, i)->src, heads, pred,
+ direction);
+ }
+}
- if (GET_CODE (last_insn) != JUMP_INSN
- || ! any_condjump_p (last_insn))
- continue;
- combine_predictions_for_insn (last_insn, BASIC_BLOCK (i));
+/* Look for basic block that contains unlikely to happen events
+ (such as noreturn calls) and mark all paths leading to execution
+ of this basic blocks as unlikely. */
+
+static void
+tree_bb_level_predictions (void)
+{
+ basic_block bb;
+ int *heads;
+
+ 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;
+
+ apply_return_prediction (heads);
+
+ FOR_EACH_BB (bb)
+ {
+ block_stmt_iterator bsi = bsi_last (bb);
+
+ for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ {
+ tree stmt = bsi_stmt (bsi);
+ switch (TREE_CODE (stmt))
+ {
+ case MODIFY_EXPR:
+ if (TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR)
+ {
+ stmt = TREE_OPERAND (stmt, 1);
+ goto call_expr;
+ }
+ break;
+ case CALL_EXPR:
+call_expr:;
+ if (call_expr_flags (stmt) & ECF_NORETURN)
+ predict_paths_leading_to (bb, heads, PRED_NORETURN,
+ NOT_TAKEN);
+ break;
+ default:
+ break;
+ }
+ }
}
- sbitmap_vector_free (post_dominators);
- sbitmap_vector_free (dominators);
- estimate_bb_frequencies (loops_info);
+ free (heads);
+}
+
+/* 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);
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ flow_loops_dump (&loops_info, dump_file, NULL, 0);
+
+ add_noreturn_fake_exit_edges ();
+ connect_infinite_loops_to_exit ();
+ calculate_dominance_info (CDI_DOMINATORS);
+ calculate_dominance_info (CDI_POST_DOMINATORS);
+
+ tree_bb_level_predictions ();
+
+ mark_irreducible_loops (&loops_info);
+ predict_loops (&loops_info, false);
+
+ FOR_EACH_BB (bb)
+ {
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ /* Predict early returns to be probable, as we've already taken
+ care for error returns and other cases are often used for
+ fast paths trought function. */
+ if (e->dest == EXIT_BLOCK_PTR
+ && TREE_CODE (last_stmt (bb)) == RETURN_EXPR
+ && EDGE_COUNT (bb->preds) > 1)
+ {
+ edge e1;
+ edge_iterator ei1;
+
+ FOR_EACH_EDGE (e1, ei1, bb->preds)
+ if (!predicted_by_p (e1->src, PRED_NULL_RETURN)
+ && !predicted_by_p (e1->src, PRED_CONST_RETURN)
+ && !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN)
+ && !last_basic_block_p (e1->src))
+ predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_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);
+
+ if (0) /* FIXME: Enable once we are pass down the profile to RTL level. */
+ strip_builtin_expect ();
+ 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 = 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 (! any_condjump_p (insn))
- continue;
- break;
}
/* Collect the branch condition, hopefully relative to EV_REG. */
(lt r70, r71)
Could use cselib to try and reduce this further. */
cond = XEXP (SET_SRC (pc_set (insn)), 0);
- cond = canonicalize_condition (insn, cond, 0, NULL, ev_reg);
- if (! cond
- || XEXP (cond, 0) != ev_reg
+ 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;
}
}
\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
+ && EDGE_COUNT (bb->succs) == 1
+ && EDGE_SUCC (bb, 0)->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
+predict_paths_leading_to (basic_block bb, int *heads, enum br_predictor pred,
+ enum prediction taken)
+{
+ edge e;
+ edge_iterator ei;
+ int y;
+
+ 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 (CDI_DOMINATORS, bb);
+ int head;
+
+ while (heads[next_ai->index] < 0)
+ {
+ if (!dominated_by_p (CDI_POST_DOMINATORS, next_ai, bb))
+ break;
+ heads[next_ai->index] = ai->index;
+ ai = next_ai;
+ next_ai = get_immediate_dominator (CDI_DOMINATORS, next_ai);
+ }
+ if (!dominated_by_p (CDI_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)
+ return;
+ FOR_EACH_EDGE (e, ei, BASIC_BLOCK (y)->succs)
+ if (e->dest->index >= 0
+ && dominated_by_p (CDI_POST_DOMINATORS, e->dest, bb))
+ predict_edge_def (e, pred, taken);
+}
+\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. */
- double frequency;
+ sreal frequency;
/* To keep queue of basic blocks to process. */
basic_block next;
- /* True if block needs to be visited in prop_freqency. */
- int tovisit:1;
-
/* Number of predecessors we need to visit first. */
- int npredecesors;
+ 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;
+ 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 loops headed by HEAD. */
+ Propagate the frequencies for LOOP. */
+
static void
-propagate_freq (head)
- basic_block head;
+propagate_freq (struct loop *loop, bitmap tovisit)
{
- basic_block bb = head;
- basic_block last = bb;
+ basic_block head = loop->header;
+ basic_block bb;
+ basic_block last;
+ unsigned i;
edge e;
basic_block nextbb;
- int n;
+ bitmap_iterator bi;
/* For each basic block we need to visit count number of his predecessors
we need to visit first. */
- for (n = 0; n < n_basic_blocks; n++)
+ EXECUTE_IF_SET_IN_BITMAP (tovisit, 0, i, bi)
{
- basic_block bb = BASIC_BLOCK (n);
- if (BLOCK_INFO (bb)->tovisit)
+ edge_iterator ei;
+ int count = 0;
+
+ /* The outermost "loop" includes the exit block, which we can not
+ look up via BASIC_BLOCK. Detect this and use EXIT_BLOCK_PTR
+ directly. Do the same for the entry block. */
+ if (i == (unsigned)ENTRY_BLOCK)
+ bb = ENTRY_BLOCK_PTR;
+ else if (i == (unsigned)EXIT_BLOCK)
+ bb = EXIT_BLOCK_PTR;
+ else
+ bb = BASIC_BLOCK (i);
+
+ FOR_EACH_EDGE (e, ei, bb->preds)
{
- 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)->npredecesors = count;
+ bool visit = bitmap_bit_p (tovisit, e->src->index);
+
+ if (visit && !(e->flags & EDGE_DFS_BACK))
+ count++;
+ else if (visit && 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;
}
- BLOCK_INFO (head)->frequency = 1;
- for (; bb; bb = nextbb)
+ memcpy (&BLOCK_INFO (head)->frequency, &real_one, sizeof (real_one));
+ last = head;
+ for (bb = head; bb; bb = nextbb)
{
- double cyclic_probability = 0, frequency = 0;
+ edge_iterator ei;
+ 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;
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))
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (bitmap_bit_p (tovisit, e->src->index)
+ && !(e->flags & EDGE_DFS_BACK))
abort ();
#endif
- for (e = bb->pred; e; e = e->pred_next)
+ FOR_EACH_EDGE (e, ei, bb->preds)
if (EDGE_INFO (e)->back_edge)
- cyclic_probability += EDGE_INFO (e)->back_edge_prob;
+ {
+ sreal_add (&cyclic_probability, &cyclic_probability,
+ &EDGE_INFO (e)->back_edge_prob);
+ }
else if (!(e->flags & EDGE_DFS_BACK))
- frequency += (e->probability
- * BLOCK_INFO (e->src)->frequency /
- REG_BR_PROB_BASE);
+ {
+ sreal tmp;
+
+ /* frequency += (e->probability
+ * BLOCK_INFO (e->src)->frequency /
+ REG_BR_PROB_BASE); */
- if (cyclic_probability > 1.0 - 1.0 / REG_BR_PROB_BASE)
- cyclic_probability = 1.0 - 1.0 / 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);
+ }
- BLOCK_INFO (bb)->frequency = frequency / (1 - cyclic_probability);
+ 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;
+ bitmap_clear_bit (tovisit, bb->index);
- /* 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);
+ e = find_edge (bb, head);
+ if (e)
+ {
+ 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)
+ FOR_EACH_EDGE (e, ei, bb->succs)
if (!(e->flags & EDGE_DFS_BACK)
- && BLOCK_INFO (e->dest)->npredecesors)
+ && BLOCK_INFO (e->dest)->npredecessors)
{
- BLOCK_INFO (e->dest)->npredecesors--;
- if (!BLOCK_INFO (e->dest)->npredecesors)
+ 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 (first_loop)
- struct loop *first_loop;
+estimate_loops_at_level (struct loop *first_loop, bitmap tovisit)
{
- 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;
+ estimate_loops_at_level (loop->inner, tovisit);
- /* In case the loop header is shared, ensure that it is the last
- one sharing the same header, so we avoid redundant work. */
- if (loop->shared)
+ /* Do not do this for dummy function loop. */
+ if (EDGE_COUNT (loop->latch->succs) > 0)
{
- 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))->tovisit = 1
- );
- 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++)
+ bitmap_set_bit (tovisit, bbs[i]->index);
+ free (bbs);
+ propagate_freq (loop, tovisit);
}
}
-/* Convert counts measured by profile driven feedback to frequencies. */
-static void
-counts_to_freqs ()
+/* Convert counts measured by profile driven feedback to frequencies.
+ Return nonzero iff there was any nonzero execution count. */
+
+int
+counts_to_freqs (void)
{
- HOST_WIDEST_INT count_max = 1;
- int i;
+ gcov_type count_max, true_count_max = 0;
+ basic_block bb;
- for (i = 0; i < n_basic_blocks; i++)
- if (BASIC_BLOCK (i)->count > count_max)
- count_max = BASIC_BLOCK (i)->count;
+ FOR_EACH_BB (bb)
+ true_count_max = MAX (bb->count, true_count_max);
- 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 = ((bb->count * BB_FREQ_MAX + count_max / 2)
- / 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 optimizer performance of prologue, epilogue or do inlining at the
- expense of code size growth. THRESHOLD is the limit of number
- of isntructions function can execute at average to be still considered
- not expensive. */
+/* 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;
+expensive_function_p (int threshold)
{
unsigned int sum = 0;
- int i;
+ basic_block bb;
unsigned int limit;
/* We can not compute accurately for large thresholds due to scaled
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 (i = 0; i < n_basic_blocks; i++)
+ FOR_EACH_BB (bb)
{
- basic_block bb = BASIC_BLOCK (i);
rtx insn;
- for (insn = bb->head; insn != NEXT_INSN (bb->end);
+ 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;
- }
+ 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;
+estimate_bb_frequencies (struct loops *loops)
{
- int i;
- double freq_max = 0;
+ basic_block bb;
+ sreal freq_max;
- mark_dfs_back_edges ();
- if (flag_branch_probabilities)
+ if (!flag_branch_probabilities || !counts_to_freqs ())
{
- counts_to_freqs ();
- return;
- }
+ static int real_values_initialized = 0;
+ bitmap tovisit;
+
+ 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 ();
- if (GET_CODE (last_insn) != JUMP_INSN || !any_condjump_p (last_insn)
- /* Avoid handling of conditional jumps jumping to fallthru edge. */
- || BASIC_BLOCK (i)->succ->succ_next == NULL)
+ EDGE_SUCC (ENTRY_BLOCK_PTR, 0)->probability = REG_BR_PROB_BASE;
+
+ /* Set up block info for each basic block. */
+ tovisit = BITMAP_ALLOC (NULL);
+ 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 equally probable.
- ?? In the future we want to make abnormal edges improbable. */
- int nedges = 0;
edge e;
+ edge_iterator ei;
- for (e = BASIC_BLOCK (i)->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, bb->succs)
{
- 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, tovisit);
+
+ 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 ();
+ BITMAP_FREE (tovisit);
}
- 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. */
- alloc_aux_for_blocks (sizeof (struct block_info_def));
- alloc_aux_for_edges (sizeof (struct edge_info_def));
- 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 (void)
+{
+ basic_block bb;
- if (i == -2)
- bb = ENTRY_BLOCK_PTR;
- else if (i == -1)
- bb = EXIT_BLOCK_PTR;
- else
- bb = BASIC_BLOCK (i);
- BLOCK_INFO (bb)->tovisit = 0;
- for (e = bb->succ; e; e = e->succ_next)
- EDGE_INFO (e)->back_edge_prob = ((double) e->probability
- / REG_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);
-
- /* Now fake loop around whole function to finalize probabilities. */
- for (i = 0; i < n_basic_blocks; i++)
- BLOCK_INFO (BASIC_BLOCK (i))->tovisit = 1;
- BLOCK_INFO (ENTRY_BLOCK_PTR)->tovisit = 1;
- BLOCK_INFO (EXIT_BLOCK_PTR)->tovisit = 1;
- 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);
+ 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 we are doing the partitioning optimization, let the optimization
+ choose the correct section into which to put things. */
- free_aux_for_blocks ();
- free_aux_for_edges ();
+ if (flag_reorder_blocks_and_partition)
+ 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 */
+ 0 /* letter */
+};
OSDN Git Service
