/* Branch prediction routines for the GNU compiler.
- Copyright (C) 2000, 2001 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
- This file is part of 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 "loop.h"
+#include "cfgloop.h"
+
+/* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE,
+ 1/REG_BR_PROB_BASE, 0.5, BB_FREQ_MAX. */
+static sreal real_zero, real_one, real_almost_one, real_br_prob_base,
+ real_inv_br_prob_base, real_one_half, real_bb_freq_max;
/* Random guesstimation given names. */
-#define PROB_NEVER (0)
#define PROB_VERY_UNLIKELY (REG_BR_PROB_BASE / 10 - 1)
-#define PROB_UNLIKELY (REG_BR_PROB_BASE * 4 / 10 - 1)
#define PROB_EVEN (REG_BR_PROB_BASE / 2)
-#define PROB_LIKELY (REG_BR_PROB_BASE - PROB_UNLIKELY)
#define PROB_VERY_LIKELY (REG_BR_PROB_BASE - PROB_VERY_UNLIKELY)
#define PROB_ALWAYS (REG_BR_PROB_BASE)
-static 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 bool predicted_by_p (basic_block, enum br_predictor);
+static void combine_predictions_for_insn (rtx, basic_block);
+static void dump_prediction (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 void counts_to_freqs (void);
+static void process_note_predictions (basic_block, int *, dominance_info,
+ dominance_info);
+static void process_note_prediction (basic_block, int *, dominance_info,
+ dominance_info, int, int);
+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
+/* 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. */
+
+static bool
+predicted_by_p (basic_block bb, enum br_predictor predictor)
+{
+ rtx note;
+ if (!INSN_P (bb->end))
+ return false;
+ for (note = REG_NOTES (bb->end); note; note = XEXP (note, 1))
+ if (REG_NOTE_KIND (note) == REG_BR_PRED
+ && INTVAL (XEXP (XEXP (note, 0), 0)) == (int)predictor)
+ return true;
+ return false;
+}
+
void
-predict_insn (insn, predictor, probability)
- rtx insn;
- int probability;
- enum br_predictor predictor;
+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;
+predict_edge (edge e, enum br_predictor predictor, int probability)
{
rtx last_insn;
last_insn = e->src->end;
predict_insn (last_insn, predictor, probability);
}
+/* Return true when we can store prediction on insn INSN.
+ At the moment we represent predictions only on conditional
+ jumps, not at computed jump or other complicated cases. */
+static bool
+can_predict_insn_p (rtx insn)
+{
+ return (GET_CODE (insn) == JUMP_INSN
+ && any_condjump_p (insn)
+ && BLOCK_FOR_INSN (insn)->succ->succ_next);
+}
+
/* Predict edge E by given predictor if possible. */
+
void
-predict_edge_def (e, predictor, taken)
- edge e;
- 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 (enum br_predictor predictor, int probability,
+ basic_block bb, int used)
{
edge e = bb->succ;
if (!rtl_dump_file)
return;
- while (e->flags & EDGE_FALLTHRU)
+ while (e && (e->flags & EDGE_FALLTHRU))
e = e->succ_next;
fprintf (rtl_dump_file, " %s heuristics%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 (rtl_dump_file, HOST_WIDEST_INT_PRINT_DEC, bb->count);
+ if (e)
+ {
+ fprintf (rtl_dump_file, " hit ");
+ fprintf (rtl_dump_file, HOST_WIDEST_INT_PRINT_DEC, e->count);
+ fprintf (rtl_dump_file, " (%.1f%%)", e->count * 100.0 / bb->count);
+ }
}
+
fprintf (rtl_dump_file, "\n");
}
/* Combine all REG_BR_PRED notes into single probability and attach REG_BR_PROB
note if not already present. Remove now useless REG_BR_PRED notes. */
+
static void
-combine_predictions_for_insn (insn, bb)
- rtx insn;
- 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 note;
int best_probability = PROB_EVEN;
int best_predictor = END_PREDICTORS;
int combined_probability = REG_BR_PROB_BASE / 2;
/* 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
+ 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)
dump_prediction (PRED_NO_PREDICTION, combined_probability, bb, true);
else
{
- dump_prediction (PRED_DS_THEORY, combined_probability, bb,
- !first_match);
+ dump_prediction (PRED_DS_THEORY, combined_probability, bb, !first_match);
dump_prediction (PRED_FIRST_MATCH, best_probability, bb, first_match);
}
dump_prediction (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)
{
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;
}
}
}
predictions). */
void
-estimate_probability (loops_info)
- struct loops *loops_info;
+estimate_probability (struct loops *loops_info)
{
- sbitmap *dominators, *post_dominators;
- int i;
- int found_noreturn = 0;
+ dominance_info dominators, post_dominators;
+ basic_block bb;
+ unsigned i;
- dominators = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
- post_dominators = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
- calculate_dominance_info (NULL, dominators, CDI_DOMINATORS);
- calculate_dominance_info (NULL, post_dominators, CDI_POST_DOMINATORS);
+ connect_infinite_loops_to_exit ();
+ dominators = calculate_dominance_info (CDI_DOMINATORS);
+ post_dominators = calculate_dominance_info (CDI_POST_DOMINATORS);
/* Try to predict out blocks in a loop that are not part of a
natural loop. */
- for (i = 0; i < loops_info->num; i++)
+ for (i = 1; i < loops_info->num; i++)
{
- int j;
+ basic_block bb, *bbs;
+ unsigned j;
+ int exits;
+ struct loop *loop = loops_info->parray[i];
+ struct loop_desc desc;
+ unsigned HOST_WIDE_INT niter;
+
+ flow_loop_scan (loops_info, loop, LOOP_EXIT_EDGES);
+ exits = loop->num_exits;
+
+ if (simple_loop_p (loops_info, loop, &desc)
+ && desc.const_iter)
+ {
+ int prob;
+ niter = desc.niter + 1;
+ if (niter == 0) /* We might overflow here. */
+ niter = desc.niter;
+
+ prob = (REG_BR_PROB_BASE
+ - (REG_BR_PROB_BASE + niter /2) / niter);
+ /* Branch prediction algorithm gives 0 frequency for everything
+ after the end of loop for loop having 0 probability to finish. */
+ if (prob == REG_BR_PROB_BASE)
+ prob = REG_BR_PROB_BASE - 1;
+ predict_edge (desc.in_edge, PRED_LOOP_ITERATIONS,
+ prob);
+ }
- for (j = loops_info->array[i].first->index;
- j <= loops_info->array[i].last->index;
- ++j)
+ bbs = get_loop_body (loop);
+ for (j = 0; j < loop->num_nodes; j++)
{
- if (TEST_BIT (loops_info->array[i].nodes, j))
- {
- int header_found = 0;
- edge e;
+ 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);
- }
+ bb = bbs[j];
+
+ /* Bypass loop heuristics on continue statement. These
+ statements construct loops via "non-loop" constructs
+ in the source language and are better to be handled
+ separately. */
+ if (!can_predict_insn_p (bb->end)
+ || predicted_by_p (bb, PRED_CONTINUE))
+ continue;
+
+ /* Loop branch heuristics - predict an edge back to a
+ loop's head as taken. */
+ for (e = bb->succ; e; e = e->succ_next)
+ if (e->dest == loop->header
+ && e->src == loop->latch)
+ {
+ header_found = 1;
+ predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN);
+ }
+
+ /* Loop exit heuristics - predict an edge exiting the loop if the
+ conditional has no loop header successors as not taken. */
+ if (!header_found)
+ for (e = bb->succ; e; e = e->succ_next)
+ if (e->dest->index < 0
+ || !flow_bb_inside_loop_p (loop, e->dest))
+ predict_edge
+ (e, PRED_LOOP_EXIT,
+ (REG_BR_PROB_BASE
+ - predictor_info [(int) PRED_LOOP_EXIT].hitrate)
+ / exits);
}
}
/* Attempt to predict conditional jumps using a number of heuristics. */
- for (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;
edge e;
- /* 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)
{
- /* Predict edges to blocks that return immediately to be
- improbable. These are usually used to signal error states. */
- if (e->dest == EXIT_BLOCK_PTR
- || (e->dest->succ && !e->dest->succ->succ_next
- && e->dest->succ->dest == EXIT_BLOCK_PTR))
- predict_edge_def (e, PRED_ERROR_RETURN, NOT_TAKEN);
+ /* Predict early returns to be probable, as we've already taken
+ care for error returns and other are often used for fast paths
+ trought function. */
+ if ((e->dest == EXIT_BLOCK_PTR
+ || (e->dest->succ && !e->dest->succ->succ_next
+ && e->dest->succ->dest == EXIT_BLOCK_PTR))
+ && !predicted_by_p (bb, PRED_NULL_RETURN)
+ && !predicted_by_p (bb, PRED_CONST_RETURN)
+ && !predicted_by_p (bb, PRED_NEGATIVE_RETURN)
+ && !last_basic_block_p (e->dest))
+ predict_edge_def (e, PRED_EARLY_RETURN, TAKEN);
/* Look for block we are guarding (ie we dominate it,
but it doesn't postdominate us). */
- if (e->dest != EXIT_BLOCK_PTR
- && e->dest != bb
- && TEST_BIT (dominators[e->dest->index], e->src->index)
- && !TEST_BIT (post_dominators[e->src->index], e->dest->index))
+ if (e->dest != EXIT_BLOCK_PTR && e->dest != bb
+ && dominated_by_p (dominators, e->dest, e->src)
+ && !dominated_by_p (post_dominators, e->src, e->dest))
{
rtx insn;
+
/* The call heuristic claims that a guarded function call
is improbable. This is because such calls are often used
to signal exceptional situations such as printing error
/* Try "pointer heuristic."
A comparison ptr == 0 is predicted as false.
Similarly, a comparison ptr1 == ptr2 is predicted as false. */
- switch (GET_CODE (cond))
+ if (GET_RTX_CLASS (GET_CODE (cond)) == '<'
+ && ((REG_P (XEXP (cond, 0)) && REG_POINTER (XEXP (cond, 0)))
+ || (REG_P (XEXP (cond, 1)) && REG_POINTER (XEXP (cond, 1)))))
{
- case EQ:
- if (GET_CODE (XEXP (cond, 0)) == REG
- && REG_POINTER (XEXP (cond, 0))
- && (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == REG
- && REG_POINTER (XEXP (cond, 1)))))
-
+ if (GET_CODE (cond) == EQ)
predict_insn_def (last_insn, PRED_POINTER, NOT_TAKEN);
- break;
- case NE:
- if (GET_CODE (XEXP (cond, 0)) == REG
- && REG_POINTER (XEXP (cond, 0))
- && (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == REG
- && REG_POINTER (XEXP (cond, 1)))))
+ else if (GET_CODE (cond) == NE)
predict_insn_def (last_insn, PRED_POINTER, TAKEN);
- break;
-
- default:
- break;
}
+ else
/* Try "opcode heuristic."
EQ tests are usually false and NE tests are usually true. Also,
most quantities are positive, so we can make the appropriate guesses
about signed comparisons against zero. */
- switch (GET_CODE (cond))
- {
- case CONST_INT:
- /* Unconditional branch. */
- predict_insn_def (last_insn, PRED_UNCONDITIONAL,
- cond == const0_rtx ? NOT_TAKEN : TAKEN);
- break;
-
- case EQ:
- case UNEQ:
- predict_insn_def (last_insn, PRED_OPCODE, NOT_TAKEN);
- break;
- case NE:
- case LTGT:
- predict_insn_def (last_insn, PRED_OPCODE, TAKEN);
- break;
- case ORDERED:
- predict_insn_def (last_insn, PRED_OPCODE, TAKEN);
- break;
- case UNORDERED:
- predict_insn_def (last_insn, PRED_OPCODE, NOT_TAKEN);
- break;
- case LE:
- case LT:
- if (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == CONST_INT
- && INTVAL (XEXP (cond, 1)) == -1))
- predict_insn_def (last_insn, PRED_OPCODE, NOT_TAKEN);
- break;
- case GE:
- case GT:
- if (XEXP (cond, 1) == const0_rtx
- || (GET_CODE (XEXP (cond, 1)) == CONST_INT
- && INTVAL (XEXP (cond, 1)) == -1))
- predict_insn_def (last_insn, PRED_OPCODE, TAKEN);
- break;
-
- default:
- break;
- }
+ switch (GET_CODE (cond))
+ {
+ case CONST_INT:
+ /* Unconditional branch. */
+ predict_insn_def (last_insn, PRED_UNCONDITIONAL,
+ cond == const0_rtx ? NOT_TAKEN : TAKEN);
+ break;
+
+ case EQ:
+ case UNEQ:
+ /* Floating point comparisons appears to behave in a very
+ unpredictable way because of special role of = tests in
+ FP code. */
+ if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0))))
+ ;
+ /* Comparisons with 0 are often used for booleans and there is
+ nothing useful to predict about them. */
+ else if (XEXP (cond, 1) == const0_rtx
+ || XEXP (cond, 0) == const0_rtx)
+ ;
+ else
+ predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, NOT_TAKEN);
+ break;
+
+ case NE:
+ case LTGT:
+ /* Floating point comparisons appears to behave in a very
+ unpredictable way because of special role of = tests in
+ FP code. */
+ if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0))))
+ ;
+ /* Comparisons with 0 are often used for booleans and there is
+ nothing useful to predict about them. */
+ else if (XEXP (cond, 1) == const0_rtx
+ || XEXP (cond, 0) == const0_rtx)
+ ;
+ else
+ predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, TAKEN);
+ break;
+
+ case ORDERED:
+ predict_insn_def (last_insn, PRED_FPOPCODE, TAKEN);
+ break;
+
+ case UNORDERED:
+ predict_insn_def (last_insn, PRED_FPOPCODE, NOT_TAKEN);
+ break;
+
+ case LE:
+ case LT:
+ if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx
+ || XEXP (cond, 1) == constm1_rtx)
+ predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, NOT_TAKEN);
+ break;
+
+ case GE:
+ case GT:
+ if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx
+ || XEXP (cond, 1) == constm1_rtx)
+ predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, TAKEN);
+ break;
+
+ default:
+ break;
+ }
}
/* Attach the combined probability to each conditional jump. */
- for (i = 0; i < n_basic_blocks; i++)
- {
- rtx last_insn = BLOCK_END (i);
+ FOR_EACH_BB (bb)
+ if (GET_CODE (bb->end) == JUMP_INSN
+ && any_condjump_p (bb->end)
+ && bb->succ->succ_next != NULL)
+ combine_predictions_for_insn (bb->end, bb);
- if (GET_CODE (last_insn) != JUMP_INSN
- || ! any_condjump_p (last_insn))
- continue;
- combine_predictions_for_insn (last_insn, BASIC_BLOCK (i));
- }
- sbitmap_vector_free (post_dominators);
- sbitmap_vector_free (dominators);
+ free_dominance_info (post_dominators);
+ free_dominance_info (dominators);
+ remove_fake_edges ();
estimate_bb_frequencies (loops_info);
}
\f
-/* __builtin_expect dropped tokens into the insn stream describing
- expected values of registers. Generate branch probabilities
- based off these values. */
+/* __builtin_expect dropped tokens into the insn stream describing expected
+ values of registers. Generate branch probabilities based off these
+ values. */
void
-expected_value_to_br_prob ()
+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 (GET_CODE (insn) != JUMP_INSN || ev == NULL_RTX
+ || ! any_condjump_p (insn))
+ continue;
+ break;
+
default:
/* Look for insns that clobber the EV register. */
if (ev && reg_set_p (ev_reg, insn))
ev = NULL_RTX;
continue;
-
- case JUMP_INSN:
- /* Look for simple conditional branches. If we havn't got an
- expected value yet, no point going further. */
- if (GET_CODE (insn) != JUMP_INSN || ev == NULL_RTX)
- continue;
- if (! any_condjump_p (insn))
- continue;
- break;
}
/* Collect the branch condition, hopefully relative to EV_REG. */
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
+ 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
+ && bb->succ && !bb->succ->succ_next
+ && bb->succ->dest->next_bb == EXIT_BLOCK_PTR));
+}
+
+/* Sets branch probabilities according to PREDiction and
+ FLAGS. HEADS[bb->index] should be index of basic block in that we
+ need to alter branch predictions (i.e. the first of our dominators
+ such that we do not post-dominate it) (but we fill this information
+ on demand, so -1 may be there in case this was not needed yet). */
+
+static void
+process_note_prediction (basic_block bb, int *heads,
+ dominance_info dominators,
+ dominance_info post_dominators, int pred,
+ int flags)
+{
+ edge e;
+ int y;
+ bool taken;
+
+ taken = flags & IS_TAKEN;
+
+ if (heads[bb->index] < 0)
+ {
+ /* This is first time we need this field in heads array; so
+ find first dominator that we do not post-dominate (we are
+ using already known members of heads array). */
+ basic_block ai = bb;
+ basic_block next_ai = get_immediate_dominator (dominators, bb);
+ int head;
+
+ while (heads[next_ai->index] < 0)
+ {
+ if (!dominated_by_p (post_dominators, next_ai, bb))
+ break;
+ heads[next_ai->index] = ai->index;
+ ai = next_ai;
+ next_ai = get_immediate_dominator (dominators, next_ai);
+ }
+ if (!dominated_by_p (post_dominators, next_ai, bb))
+ head = next_ai->index;
+ else
+ head = heads[next_ai->index];
+ while (next_ai != bb)
+ {
+ next_ai = ai;
+ if (heads[ai->index] == ENTRY_BLOCK)
+ ai = ENTRY_BLOCK_PTR;
+ else
+ ai = BASIC_BLOCK (heads[ai->index]);
+ heads[next_ai->index] = head;
+ }
+ }
+ y = heads[bb->index];
+
+ /* Now find the edge that leads to our branch and aply the prediction. */
+
+ if (y == last_basic_block || !can_predict_insn_p (BASIC_BLOCK (y)->end))
+ return;
+ for (e = BASIC_BLOCK (y)->succ; e; e = e->succ_next)
+ if (e->dest->index >= 0
+ && dominated_by_p (post_dominators, e->dest, bb))
+ predict_edge_def (e, pred, taken);
+}
+
+/* Gathers NOTE_INSN_PREDICTIONs in given basic block and turns them
+ into branch probabilities. For description of heads array, see
+ process_note_prediction. */
+
+static void
+process_note_predictions (basic_block bb, int *heads,
+ dominance_info dominators,
+ dominance_info post_dominators)
+{
+ rtx insn;
+ edge e;
+
+ /* Additionally, we check here for blocks with no successors. */
+ int contained_noreturn_call = 0;
+ int was_bb_head = 0;
+ int noreturn_block = 1;
+
+ for (insn = bb->end; insn;
+ was_bb_head |= (insn == bb->head), insn = PREV_INSN (insn))
+ {
+ if (GET_CODE (insn) != NOTE)
+ {
+ if (was_bb_head)
+ break;
+ else
+ {
+ /* Noreturn calls cause program to exit, therefore they are
+ always predicted as not taken. */
+ if (GET_CODE (insn) == CALL_INSN
+ && find_reg_note (insn, REG_NORETURN, NULL))
+ contained_noreturn_call = 1;
+ continue;
+ }
+ }
+ if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_PREDICTION)
+ {
+ int alg = (int) NOTE_PREDICTION_ALG (insn);
+ /* Process single prediction note. */
+ process_note_prediction (bb,
+ heads,
+ dominators,
+ post_dominators,
+ alg, (int) NOTE_PREDICTION_FLAGS (insn));
+ delete_insn (insn);
+ }
+ }
+ for (e = bb->succ; e; e = e->succ_next)
+ if (!(e->flags & EDGE_FAKE))
+ noreturn_block = 0;
+ if (contained_noreturn_call)
+ {
+ /* This block ended from other reasons than because of return.
+ If it is because of noreturn call, this should certainly not
+ be taken. Otherwise it is probably some error recovery. */
+ process_note_prediction (bb,
+ heads,
+ dominators,
+ post_dominators, PRED_NORETURN, NOT_TAKEN);
+ }
+}
+
+/* Gathers NOTE_INSN_PREDICTIONs and turns them into
+ branch probabilities. */
+
+void
+note_prediction_to_br_prob (void)
+{
+ basic_block bb;
+ dominance_info post_dominators, dominators;
+ int *heads;
+
+ /* To enable handling of noreturn blocks. */
+ add_noreturn_fake_exit_edges ();
+ connect_infinite_loops_to_exit ();
+
+ post_dominators = calculate_dominance_info (CDI_POST_DOMINATORS);
+ dominators = calculate_dominance_info (CDI_DOMINATORS);
+
+ heads = xmalloc (sizeof (int) * last_basic_block);
+ memset (heads, -1, sizeof (int) * last_basic_block);
+ heads[ENTRY_BLOCK_PTR->next_bb->index] = last_basic_block;
+
+ /* Process all prediction notes. */
+
+ FOR_EACH_BB (bb)
+ process_note_predictions (bb, heads, dominators, post_dominators);
+
+ free_dominance_info (post_dominators);
+ free_dominance_info (dominators);
+ free (heads);
+
+ remove_fake_edges ();
+}
+\f
/* This is used to carry information about basic blocks. It is
attached to the AUX field of the standard CFG block. */
typedef struct block_info_def
{
/* Estimated frequency of execution of basic_block. */
- volatile double frequency;
+ sreal frequency;
/* To keep queue of basic blocks to process. */
basic_block next;
{
/* 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).
-
- Volatile is needed to avoid differences in the optimized and unoptimized
- builds on machines where FP registers are wider than double. */
- volatile double back_edge_prob;
+ then computed as 1 / (1 - back_edge_prob). */
+ sreal back_edge_prob;
/* True if the edge is an loopback edge in the natural loop. */
int back_edge:1;
} *edge_info;
#define EDGE_INFO(E) ((edge_info) (E)->aux)
/* Helper function for estimate_bb_frequencies.
- Propagate the frequencies for loops headed by HEAD. */
+ Propagate the frequencies for LOOP. */
+
static void
-propagate_freq (head)
- basic_block head;
+propagate_freq (struct loop *loop)
{
- basic_block bb = head;
- basic_block last = bb;
+ basic_block head = loop->header;
+ basic_block bb;
+ basic_block last;
edge e;
basic_block nextbb;
- int n;
/* 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++)
+ FOR_EACH_BB (bb)
{
- basic_block bb = BASIC_BLOCK (n);
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++;
}
}
- 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)
{
- volatile double cyclic_probability = 0, frequency = 0;
+ 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;
for (e = bb->pred; e; e = e->pred_next)
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;
- if (cyclic_probability > 1.0 - 1.0 / REG_BR_PROB_BASE)
- cyclic_probability = 1.0 - 1.0 / REG_BR_PROB_BASE;
+ /* frequency += (e->probability
+ * BLOCK_INFO (e->src)->frequency /
+ REG_BR_PROB_BASE); */
- BLOCK_INFO (bb)->frequency = frequency / (1 - cyclic_probability);
+ sreal_init (&tmp, e->probability, 0);
+ sreal_mul (&tmp, &tmp, &BLOCK_INFO (e->src)->frequency);
+ sreal_mul (&tmp, &tmp, &real_inv_br_prob_base);
+ sreal_add (&frequency, &frequency, &tmp);
+ }
+
+ if (sreal_compare (&cyclic_probability, &real_zero) == 0)
+ {
+ memcpy (&BLOCK_INFO (bb)->frequency, &frequency,
+ sizeof (frequency));
+ }
+ else
+ {
+ if (sreal_compare (&cyclic_probability, &real_almost_one) > 0)
+ {
+ memcpy (&cyclic_probability, &real_almost_one,
+ sizeof (real_almost_one));
+ }
+
+ /* BLOCK_INFO (bb)->frequency = frequency
+ / (1 - cyclic_probability) */
+
+ sreal_sub (&cyclic_probability, &real_one, &cyclic_probability);
+ sreal_div (&BLOCK_INFO (bb)->frequency,
+ &frequency, &cyclic_probability);
+ }
}
BLOCK_INFO (bb)->tovisit = 0;
/* Compute back edge frequencies. */
for (e = bb->succ; e; e = e->succ_next)
if (e->dest == head)
- EDGE_INFO (e)->back_edge_prob = (e->probability
- * BLOCK_INFO (bb)->frequency
- / REG_BR_PROB_BASE);
+ {
+ sreal tmp;
+
+ /* EDGE_INFO (e)->back_edge_prob
+ = ((e->probability * BLOCK_INFO (bb)->frequency)
+ / REG_BR_PROB_BASE); */
+
+ 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)
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)
{
- struct loop *l, *loop = first_loop;
+ struct loop *loop;
for (loop = first_loop; loop; loop = loop->next)
{
- int n;
edge e;
+ basic_block *bbs;
+ unsigned i;
estimate_loops_at_level (loop->inner);
- /* Find current loop back edge and mark it. */
- for (e = loop->latch->succ; e->dest != loop->header; e = e->succ_next);
-
- EDGE_INFO (e)->back_edge = 1;
-
- /* In case the loop header is shared, ensure that it is the last
- one sharing the same header, so we avoid redundant work. */
- if (loop->shared)
+ if (loop->latch->succ) /* Do not do this for dummy function loop. */
{
- for (l = loop->next; l; l = l->next)
- if (l->header == loop->header)
- break;
- if (l)
- continue;
- }
-
- /* Now merge all nodes of all loops with given header as not visited. */
- for (l = loop->shared ? first_loop : loop; l != loop->next; l = l->next)
- if (loop->header == l->header)
- EXECUTE_IF_SET_IN_SBITMAP (l->nodes, 0, n,
- BLOCK_INFO (BASIC_BLOCK (n))->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++)
+ BLOCK_INFO (bbs[i])->tovisit = 1;
+ free (bbs);
+ propagate_freq (loop);
}
}
/* Convert counts measured by profile driven feedback to frequencies. */
+
static void
-counts_to_freqs ()
+counts_to_freqs (void)
{
- HOST_WIDEST_INT count_max = 1;
- int i;
+ gcov_type count_max = 1;
+ 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)
+ count_max = MAX (bb->count, 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);
- }
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
+ bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max;
}
-/* Return true if function is likely to be expensive, so there is no point
- to 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);
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)
+ counts_to_freqs ();
+ else
{
- counts_to_freqs ();
- return;
- }
+ static int real_values_initialized = 0;
+
+ if (!real_values_initialized)
+ {
+ real_values_initialized = 1;
+ sreal_init (&real_zero, 0, 0);
+ sreal_init (&real_one, 1, 0);
+ sreal_init (&real_br_prob_base, REG_BR_PROB_BASE, 0);
+ sreal_init (&real_bb_freq_max, BB_FREQ_MAX, 0);
+ sreal_init (&real_one_half, 1, -1);
+ sreal_div (&real_inv_br_prob_base, &real_one, &real_br_prob_base);
+ sreal_sub (&real_almost_one, &real_one, &real_inv_br_prob_base);
+ }
- /* Fill in the probability values in flowgraph based on the REG_BR_PROB
- notes. */
- for (i = 0; i < n_basic_blocks; i++)
- {
- rtx last_insn = BLOCK_END (i);
- int probability;
- edge fallthru, branch;
+ mark_dfs_back_edges ();
+ /* Fill in the probability values in flowgraph based on the REG_BR_PROB
+ notes. */
+ FOR_EACH_BB (bb)
+ {
+ rtx last_insn = bb->end;
+
+ if (!can_predict_insn_p (last_insn))
+ {
+ /* We can predict only conditional jumps at the moment.
+ Expect each edge to be equally probable.
+ ?? In the future we want to make abnormal edges improbable. */
+ int nedges = 0;
+ edge e;
- 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)
+ for (e = bb->succ; e; e = e->succ_next)
+ {
+ nedges++;
+ if (e->probability != 0)
+ break;
+ }
+ if (!e)
+ for (e = bb->succ; e; e = e->succ_next)
+ e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges;
+ }
+ }
+
+ ENTRY_BLOCK_PTR->succ->probability = REG_BR_PROB_BASE;
+
+ /* Set up block info for each basic block. */
+ alloc_aux_for_blocks (sizeof (struct block_info_def));
+ alloc_aux_for_edges (sizeof (struct edge_info_def));
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
{
- /* We can predict only conditional jumps at the moment.
- Expect each edge to be equally probable.
- ?? In the future we want to make abnormal edges improbable. */
- int nedges = 0;
edge e;
- for (e = BASIC_BLOCK (i)->succ; e; e = e->succ_next)
+ BLOCK_INFO (bb)->tovisit = 0;
+ for (e = bb->succ; e; e = e->succ_next)
{
- nedges++;
- if (e->probability != 0)
- break;
+ sreal_init (&EDGE_INFO (e)->back_edge_prob, e->probability, 0);
+ sreal_mul (&EDGE_INFO (e)->back_edge_prob,
+ &EDGE_INFO (e)->back_edge_prob,
+ &real_inv_br_prob_base);
}
- if (!e)
- for (e = BASIC_BLOCK (i)->succ; e; e = e->succ_next)
- e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges;
}
- else
+
+ /* First compute probabilities locally for each loop from innermost
+ to outermost to examine probabilities for back edges. */
+ estimate_loops_at_level (loops->tree_root);
+
+ memcpy (&freq_max, &real_zero, sizeof (real_zero));
+ FOR_EACH_BB (bb)
+ if (sreal_compare (&freq_max, &BLOCK_INFO (bb)->frequency) < 0)
+ memcpy (&freq_max, &BLOCK_INFO (bb)->frequency, sizeof (freq_max));
+
+ sreal_div (&freq_max, &real_bb_freq_max, &freq_max);
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
{
- probability = INTVAL (XEXP (find_reg_note (last_insn,
- REG_BR_PROB, 0), 0));
- fallthru = BASIC_BLOCK (i)->succ;
- if (!fallthru->flags & EDGE_FALLTHRU)
- fallthru = fallthru->succ_next;
- branch = BASIC_BLOCK (i)->succ;
- if (branch->flags & EDGE_FALLTHRU)
- branch = branch->succ_next;
-
- branch->probability = probability;
- fallthru->probability = REG_BR_PROB_BASE - probability;
+ sreal tmp;
+
+ sreal_mul (&tmp, &BLOCK_INFO (bb)->frequency, &freq_max);
+ sreal_add (&tmp, &tmp, &real_one_half);
+ bb->frequency = sreal_to_int (&tmp);
}
+
+ free_aux_for_blocks ();
+ free_aux_for_edges ();
}
- ENTRY_BLOCK_PTR->succ->probability = REG_BR_PROB_BASE;
+ compute_function_frequency ();
+ if (flag_reorder_functions)
+ choose_function_section ();
+}
- /* Set up block info for each basic block. */
- 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++)
+ if (!profile_info || !flag_branch_probabilities)
+ return;
+ cfun->function_frequency = FUNCTION_FREQUENCY_UNLIKELY_EXECUTED;
+ FOR_EACH_BB (bb)
{
- basic_block bb;
- if (i == -2)
- bb = ENTRY_BLOCK_PTR;
- else if (i == -1)
- bb = EXIT_BLOCK_PTR;
- else
- bb = BASIC_BLOCK (i);
- bb->frequency = (BLOCK_INFO (bb)->frequency * BB_FREQ_MAX / freq_max
- + 0.5);
+ 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;
}
+}
- free_aux_for_blocks ();
- free_aux_for_edges ();
+/* 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);
}
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