X-Git-Url: http://git.sourceforge.jp/view?a=blobdiff_plain;f=gcc%2Fpredict.c;h=8555982e072fc7e28d94384e746517a4691b5d80;hb=a1ab46376685a6e38f8ba71c75dfd4c50d057f44;hp=e42eed04f1e32b1975dcfa465f5c226cd9c7a054;hpb=d598ad0d48dd8005e04d75abb1b2ae94026927a8;p=pf3gnuchains%2Fgcc-fork.git diff --git a/gcc/predict.c b/gcc/predict.c index e42eed04f1e..8555982e072 100644 --- a/gcc/predict.c +++ b/gcc/predict.c @@ -1,5 +1,6 @@ /* Branch prediction routines for the GNU compiler. - Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc. + Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005 + Free Software Foundation, Inc. This file is part of GCC. @@ -15,8 +16,8 @@ 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. */ +Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ /* References: @@ -51,7 +52,13 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "sreal.h" #include "params.h" #include "target.h" -#include "loop.h" +#include "cfgloop.h" +#include "tree-flow.h" +#include "ggc.h" +#include "tree-dump.h" +#include "tree-pass.h" +#include "timevar.h" +#include "tree-scalar-evolution.h" #include "cfgloop.h" /* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE, @@ -60,22 +67,17 @@ static sreal real_zero, real_one, real_almost_one, real_br_prob_base, real_inv_br_prob_base, real_one_half, real_bb_freq_max; /* Random guesstimation given names. */ -#define PROB_VERY_UNLIKELY (REG_BR_PROB_BASE / 10 - 1) +#define PROB_VERY_UNLIKELY (REG_BR_PROB_BASE / 100 - 1) #define PROB_EVEN (REG_BR_PROB_BASE / 2) #define PROB_VERY_LIKELY (REG_BR_PROB_BASE - PROB_VERY_UNLIKELY) #define PROB_ALWAYS (REG_BR_PROB_BASE) -static 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 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 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 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); @@ -150,24 +152,36 @@ probably_never_executed_bb_p (basic_block bb) /* 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) +bool +rtl_predicted_by_p (basic_block bb, enum br_predictor predictor) { rtx note; - if (!INSN_P (bb->end)) + if (!INSN_P (BB_END (bb))) return false; - for (note = REG_NOTES (bb->end); note; note = XEXP (note, 1)) + 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; } -void +/* 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; + for (i = bb->predictions; i; i = i->ep_next) + if (i->ep_predictor == predictor) + return true; + return false; +} + +static void predict_insn (rtx insn, enum br_predictor predictor, int probability) { - if (!any_condjump_p (insn)) - abort (); + gcc_assert (any_condjump_p (insn)); if (!flag_guess_branch_prob) return; @@ -196,10 +210,10 @@ predict_insn_def (rtx insn, enum br_predictor predictor, /* Predict edge E with given probability if possible. */ void -predict_edge (edge e, enum br_predictor predictor, int probability) +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. */ @@ -213,15 +227,51 @@ predict_edge (edge e, enum br_predictor predictor, int probability) predict_insn (last_insn, predictor, probability); } +/* Predict edge E with the given PROBABILITY. */ +void +tree_predict_edge (edge e, enum br_predictor predictor, int probability) +{ + gcc_assert (profile_status != PROFILE_GUESSED); + if ((e->src != ENTRY_BLOCK_PTR && EDGE_COUNT (e->src->succs) > 1) + && flag_guess_branch_prob && optimize) + { + struct edge_prediction *i = ggc_alloc (sizeof (struct edge_prediction)); + + i->ep_next = e->src->predictions; + e->src->predictions = i; + i->ep_probability = probability; + i->ep_predictor = predictor; + i->ep_edge = e; + } +} + +/* Remove all predictions on given basic block that are attached + to edge E. */ +void +remove_predictions_associated_with_edge (edge e) +{ + if (e->src->predictions) + { + struct edge_prediction **prediction = &e->src->predictions; + while (*prediction) + { + if ((*prediction)->ep_edge == e) + *prediction = (*prediction)->ep_next; + else + prediction = &((*prediction)->ep_next); + } + } +} + /* 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 + return (JUMP_P (insn) && any_condjump_p (insn) - && BLOCK_FOR_INSN (insn)->succ->succ_next); + && EDGE_COUNT (BLOCK_FOR_INSN (insn)->succs) >= 2); } /* Predict edge E by given predictor if possible. */ @@ -257,34 +307,55 @@ invert_br_probabilities (rtx insn) /* Dump information about the branch prediction to the output file. */ static void -dump_prediction (enum br_predictor predictor, int probability, +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 && (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); if (bb->count) { - fprintf (rtl_dump_file, " exec "); - fprintf (rtl_dump_file, HOST_WIDEST_INT_PRINT_DEC, bb->count); + fprintf (file, " exec "); + fprintf (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 (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 @@ -293,8 +364,8 @@ dump_prediction (enum br_predictor predictor, int probability, static void combine_predictions_for_insn (rtx insn, basic_block bb) { - rtx prob_note = find_reg_note (insn, REG_BR_PROB, 0); - rtx *pnote = ®_NOTES (insn); + rtx prob_note; + rtx *pnote; rtx note; int best_probability = PROB_EVEN; int best_predictor = END_PREDICTORS; @@ -303,13 +374,20 @@ combine_predictions_for_insn (rtx insn, basic_block bb) 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. */ + by predictor with smallest index. */ for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) if (REG_NOTE_KIND (note) == REG_BR_PRED) { @@ -341,16 +419,19 @@ combine_predictions_for_insn (rtx insn, basic_block bb) 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) { @@ -359,7 +440,7 @@ combine_predictions_for_insn (rtx insn, basic_block bb) 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); } @@ -375,31 +456,148 @@ combine_predictions_for_insn (rtx insn, basic_block bb) /* Save the prediction into CFG in case we are seeing non-degenerated conditional jump. */ - if (bb->succ->succ_next) + if (!single_succ_p (bb)) { BRANCH_EDGE (bb)->probability = combined_probability; FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - combined_probability; } } + else if (!single_succ_p (bb)) + { + int prob = INTVAL (XEXP (prob_note, 0)); + + BRANCH_EDGE (bb)->probability = prob; + FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - prob; + } + else + single_succ_edge (bb)->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 (struct loops *loops_info) +static void +combine_predictions_for_bb (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->predictions = NULL; + if (dump_file) + fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n", + nedges, bb->index); + return; + } + + if (dump_file) + fprintf (dump_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->predictions; pred; pred = pred->ep_next) + { + int predictor = pred->ep_predictor; + int probability = pred->ep_probability; + + if (pred->ep_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 (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true); + else + { + dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb, + !first_match); + dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb, + first_match); + } + + if (first_match) + combined_probability = best_probability; + dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); + + for (pred = bb->predictions; pred; pred = pred->ep_next) + { + int predictor = pred->ep_predictor; + int probability = pred->ep_probability; + + if (pred->ep_edge != EDGE_SUCC (bb, 0)) + probability = REG_BR_PROB_BASE - probability; + dump_prediction (dump_file, predictor, probability, bb, + !first_match || best_predictor == predictor); + } + 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) { - dominance_info dominators, post_dominators; - basic_block bb; unsigned i; - connect_infinite_loops_to_exit (); - dominators = calculate_dominance_info (CDI_DOMINATORS); - post_dominators = calculate_dominance_info (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. */ @@ -407,37 +605,81 @@ estimate_probability (struct loops *loops_info) { basic_block bb, *bbs; unsigned j; - int exits; + unsigned n_exits; struct loop *loop = loops_info->parray[i]; - struct loop_desc desc; + struct niter_desc desc; unsigned HOST_WIDE_INT niter; + edge *exits; + + exits = get_loop_exit_edges (loop, &n_exits); - flow_loop_scan (loops_info, loop, LOOP_EXIT_EDGES); - exits = loop->num_exits; + if (rtlsimpleloops) + { + iv_analysis_loop_init (loop); + find_simple_exit (loop, &desc); - if (simple_loop_p (loops_info, loop, &desc) - && desc.const_iter) + if (desc.simple_p && desc.const_iter) + { + int prob; + niter = desc.niter + 1; + if (niter == 0) /* We might overflow here. */ + niter = desc.niter; + if (niter + > (unsigned int) PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS)) + niter = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS); + + 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 { - 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); + 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, false)) + 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; + int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS); + if (host_integerp (niter, 1) + && tree_int_cst_lt (niter, + build_int_cstu (NULL_TREE, max - 1))) + { + HOST_WIDE_INT nitercst = tree_low_cst (niter, 1) + 1; + probability = ((REG_BR_PROB_BASE + nitercst / 2) + / nitercst); + } + else + probability = ((REG_BR_PROB_BASE + max / 2) / max); + + 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]; @@ -445,63 +687,191 @@ estimate_probability (struct loops *loops_info) 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) + 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. */ - 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); - } + 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 (e = bb->succ; e; e = e->succ_next) - if (e->dest->index < 0 + FOR_EACH_EDGE (e, ei, bb->succs) + if (e->dest->index < NUM_FIXED_BLOCKS || !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); + / n_exits); } + + /* Free basic blocks from get_loop_body. */ + free (bbs); + } + + if (!rtlsimpleloops) + { + scev_finalize (); + current_loops = NULL; } +} + +/* 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_EACH_BB (bb) { - rtx last_insn = bb->end; - rtx cond, earliest; + rtx last_insn = BB_END (bb); edge e; + edge_iterator ei; 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 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)) + || (single_succ_p (e->dest) + && single_succ (e->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, + /* 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 - && dominated_by_p (dominators, e->dest, e->src) - && !dominated_by_p (post_dominators, e->src, e->dest)) + && dominated_by_p (CDI_DOMINATORS, e->dest, e->src) + && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest)) { rtx insn; @@ -509,9 +879,9 @@ estimate_probability (struct loops *loops_info) 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)) @@ -521,108 +891,511 @@ estimate_probability (struct loops *loops_info) } } } + 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; +} + +/* 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); +} + +/* 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)); - /* Try "pointer heuristic." - A comparison ptr == 0 is predicted as false. - Similarly, a comparison ptr1 == ptr2 is predicted as false. */ - 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))))) + if (TREE_CODE (def) == PHI_NODE) + { + /* All the arguments of the PHI node must have the same constant + length. */ + int i; + tree val = NULL, new_val; + + 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; + } + 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) + { + 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_build2 (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; +} + +/* 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)) { - 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); + 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); + update_stmt (stmt); + } } + } +} + +/* 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 - /* 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; + /* 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; + } +} - 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; +/* 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; +} - 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; +/* 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 = NULL; + tree return_val; + edge e; + tree phi; + int phi_num_args, i; + enum br_predictor pred; + enum prediction direction; + edge_iterator ei; - case ORDERED: - predict_insn_def (last_insn, PRED_FPOPCODE, TAKEN); - break; + FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) + { + 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; + for (phi = SSA_NAME_DEF_STMT (return_val); phi; phi = PHI_CHAIN (phi)) + if (PHI_RESULT (phi) == return_val) + break; + 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); + } +} - case UNORDERED: - predict_insn_def (last_insn, PRED_FPOPCODE, NOT_TAKEN); - break; +/* 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. */ - 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; +static void +tree_bb_level_predictions (void) +{ + basic_block bb; + int *heads; - 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; + heads = XNEWVEC (int, last_basic_block); + memset (heads, ENTRY_BLOCK, sizeof (int) * last_basic_block); + heads[ENTRY_BLOCK_PTR->next_bb->index] = last_basic_block; - default: - break; - } + 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; + } + } } - /* Attach the combined probability to each conditional jump. */ + 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) - if (GET_CODE (bb->end) == JUMP_INSN - && any_condjump_p (bb->end) - && bb->succ->succ_next != NULL) - combine_predictions_for_insn (bb->end, bb); + { + edge e; + edge_iterator ei; - free_dominance_info (post_dominators); - free_dominance_info (dominators); + 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 + && !single_pred_p (bb)) + { + 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); + } - remove_fake_edges (); - estimate_bb_frequencies (loops_info); + /* 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 (bb); + + 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; } /* __builtin_expect dropped tokens into the insn stream describing expected @@ -656,7 +1429,7 @@ expected_value_to_br_prob (void) 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 + if (!JUMP_P (insn) || ev == NULL_RTX || ! any_condjump_p (insn)) continue; break; @@ -678,7 +1451,8 @@ expected_value_to_br_prob (void) (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); + 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; @@ -691,8 +1465,7 @@ expected_value_to_br_prob (void) cond = simplify_rtx (cond); /* Turn the condition into a scaled branch probability. */ - if (cond != const_true_rtx && cond != const0_rtx) - abort (); + gcc_assert (cond == const_true_rtx || cond == const0_rtx); predict_insn_def (insn, PRED_BUILTIN_EXPECT, cond == const_true_rtx ? TAKEN : NOT_TAKEN); } @@ -708,8 +1481,8 @@ last_basic_block_p (basic_block bb) 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)); + && single_succ_p (bb) + && single_succ (bb)->next_bb == EXIT_BLOCK_PTR)); } /* Sets branch probabilities according to PREDiction and @@ -719,45 +1492,38 @@ last_basic_block_p (basic_block bb) 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) +predict_paths_leading_to (basic_block bb, int *heads, enum br_predictor pred, + enum prediction taken) { edge e; + edge_iterator ei; int y; - bool taken; - - taken = flags & IS_TAKEN; - if (heads[bb->index] < 0) + if (heads[bb->index] == ENTRY_BLOCK) { /* 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); + basic_block next_ai = get_immediate_dominator (CDI_DOMINATORS, bb); int head; - while (heads[next_ai->index] < 0) + while (heads[next_ai->index] == ENTRY_BLOCK) { - if (!dominated_by_p (post_dominators, next_ai, bb)) + 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 (dominators, next_ai); + next_ai = get_immediate_dominator (CDI_DOMINATORS, next_ai); } - if (!dominated_by_p (post_dominators, next_ai, bb)) + 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]); + ai = BASIC_BLOCK (heads[ai->index]); heads[next_ai->index] = head; } } @@ -765,107 +1531,13 @@ process_note_prediction (basic_block bb, int *heads, /* 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)) + if (y == last_basic_block) 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)) + FOR_EACH_EDGE (e, ei, BASIC_BLOCK (y)->succs) + if (e->dest->index >= NUM_FIXED_BLOCKS + && dominated_by_p (CDI_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 (); -} /* This is used to carry information about basic blocks. It is attached to the AUX field of the standard CFG block. */ @@ -878,9 +1550,6 @@ typedef struct block_info_def /* 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 npredecessors; } *block_info; @@ -888,12 +1557,12 @@ typedef struct block_info_def /* Similar information for edges. */ typedef struct edge_info_def { - /* In case edge is an loopback edge, the probability edge will be reached + /* In case edge is a loopback edge, the probability edge will be reached in case header is. Estimated number of iterations of the loop can be then computed as 1 / (1 - back_edge_prob). */ sreal back_edge_prob; - /* True if the edge is an loopback edge in the natural loop. */ - int back_edge:1; + /* True if the edge is a loopback edge in the natural loop. */ + unsigned int back_edge:1; } *edge_info; #define BLOCK_INFO(B) ((block_info) (B)->aux) @@ -903,38 +1572,47 @@ typedef struct edge_info_def Propagate the frequencies for LOOP. */ static void -propagate_freq (struct loop *loop) +propagate_freq (struct loop *loop, bitmap tovisit) { basic_block head = loop->header; basic_block bb; basic_block last; + unsigned i; edge e; basic_block nextbb; + bitmap_iterator bi; /* For each basic block we need to visit count number of his predecessors we need to visit first. */ - FOR_EACH_BB (bb) + EXECUTE_IF_SET_IN_BITMAP (tovisit, 0, i, bi) { - 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. */ + 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)->npredecessors = 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; } memcpy (&BLOCK_INFO (head)->frequency, &real_one, sizeof (real_one)); last = head; for (bb = head; bb; bb = nextbb) { + edge_iterator ei; sreal cyclic_probability, frequency; memcpy (&cyclic_probability, &real_zero, sizeof (real_zero)); @@ -947,12 +1625,12 @@ propagate_freq (struct loop *loop) if (bb != head) { #ifdef ENABLE_CHECKING - for (e = bb->pred; e; e = e->pred_next) - if (BLOCK_INFO (e->src)->tovisit && !(e->flags & EDGE_DFS_BACK)) - abort (); + FOR_EACH_EDGE (e, ei, bb->preds) + gcc_assert (!bitmap_bit_p (tovisit, e->src->index) + || (e->flags & EDGE_DFS_BACK)); #endif - for (e = bb->pred; e; e = e->pred_next) + FOR_EACH_EDGE (e, ei, bb->preds) if (EDGE_INFO (e)->back_edge) { sreal_add (&cyclic_probability, &cyclic_probability, @@ -994,26 +1672,25 @@ propagate_freq (struct loop *loop) } } - BLOCK_INFO (bb)->tovisit = 0; - - /* Compute back edge frequencies. */ - for (e = bb->succ; e; e = e->succ_next) - if (e->dest == head) - { - sreal tmp; - - /* EDGE_INFO (e)->back_edge_prob - = ((e->probability * BLOCK_INFO (bb)->frequency) - / REG_BR_PROB_BASE); */ + bitmap_clear_bit (tovisit, bb->index); - 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); - } + 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)->npredecessors) { @@ -1024,17 +1701,17 @@ propagate_freq (struct loop *loop) nextbb = e->dest; else BLOCK_INFO (last)->next = e->dest; - + last = e->dest; } - } + } } } /* Estimate probabilities of loopback edges in loops at same nest level. */ static void -estimate_loops_at_level (struct loop *first_loop) +estimate_loops_at_level (struct loop *first_loop, bitmap tovisit) { struct loop *loop; @@ -1044,9 +1721,10 @@ estimate_loops_at_level (struct loop *first_loop) basic_block *bbs; unsigned i; - estimate_loops_at_level (loop->inner); + estimate_loops_at_level (loop->inner, tovisit); - if (loop->latch->succ) /* Do not do this for dummy function loop. */ + /* Do not do this for dummy function loop. */ + if (EDGE_COUNT (loop->latch->succs) > 0) { /* Find current loop back edge and mark it. */ e = loop_latch_edge (loop); @@ -1055,25 +1733,28 @@ estimate_loops_at_level (struct loop *first_loop) bbs = get_loop_body (loop); for (i = 0; i < loop->num_nodes; i++) - BLOCK_INFO (bbs[i])->tovisit = 1; + bitmap_set_bit (tovisit, bbs[i]->index); free (bbs); - propagate_freq (loop); + propagate_freq (loop, tovisit); } } -/* Convert counts measured by profile driven feedback to frequencies. */ +/* Convert counts measured by profile driven feedback to frequencies. + Return nonzero iff there was any nonzero execution count. */ -static void +int counts_to_freqs (void) { - gcov_type count_max = 1; + gcov_type count_max, true_count_max = 0; basic_block bb; FOR_EACH_BB (bb) - count_max = MAX (bb->count, count_max); + true_count_max = MAX (bb->count, true_count_max); + count_max = MAX (true_count_max, 1); FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max; + return true_count_max; } /* Return true if function is likely to be expensive, so there is no point to @@ -1090,8 +1771,7 @@ expensive_function_p (int threshold) /* We can not compute accurately for large thresholds due to scaled frequencies. */ - if (threshold > BB_FREQ_MAX) - abort (); + gcc_assert (threshold <= BB_FREQ_MAX); /* Frequencies are out of range. This either means that function contains internal loop executing more than BB_FREQ_MAX times or profile feedback @@ -1105,7 +1785,7 @@ expensive_function_p (int threshold) { 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)) { @@ -1126,11 +1806,10 @@ estimate_bb_frequencies (struct loops *loops) basic_block bb; sreal freq_max; - if (flag_branch_probabilities) - counts_to_freqs (); - else + if (!flag_branch_probabilities || !counts_to_freqs ()) { static int real_values_initialized = 0; + bitmap tovisit; if (!real_values_initialized) { @@ -1145,43 +1824,19 @@ estimate_bb_frequencies (struct loops *loops) } mark_dfs_back_edges (); - /* Fill in the probability values in flowgraph based on the REG_BR_PROB - notes. */ - FOR_EACH_BB (bb) - { - rtx last_insn = bb->end; - - if (!can_predict_insn_p (last_insn)) - { - /* We can predict only conditional jumps at the moment. - Expect each edge to be equally probable. - ?? In the future we want to make abnormal edges improbable. */ - int nedges = 0; - edge e; - - for (e = bb->succ; e; e = e->succ_next) - { - nedges++; - if (e->probability != 0) - break; - } - if (!e) - for (e = bb->succ; e; e = e->succ_next) - e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges; - } - } - ENTRY_BLOCK_PTR->succ->probability = REG_BR_PROB_BASE; + single_succ_edge (ENTRY_BLOCK_PTR)->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) { edge e; + edge_iterator ei; - BLOCK_INFO (bb)->tovisit = 0; - for (e = bb->succ; e; e = e->succ_next) + FOR_EACH_EDGE (e, ei, bb->succs) { sreal_init (&EDGE_INFO (e)->back_edge_prob, e->probability, 0); sreal_mul (&EDGE_INFO (e)->back_edge_prob, @@ -1192,7 +1847,7 @@ estimate_bb_frequencies (struct loops *loops) /* First compute probabilities locally for each loop from innermost to outermost to examine probabilities for back edges. */ - estimate_loops_at_level (loops->tree_root); + estimate_loops_at_level (loops->tree_root, tovisit); memcpy (&freq_max, &real_zero, sizeof (real_zero)); FOR_EACH_BB (bb) @@ -1211,6 +1866,7 @@ estimate_bb_frequencies (struct loops *loops) free_aux_for_blocks (); free_aux_for_edges (); + BITMAP_FREE (tovisit); } compute_function_frequency (); if (flag_reorder_functions) @@ -1250,6 +1906,13 @@ choose_function_section (void) 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. */ + + 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); @@ -1258,3 +1921,26 @@ choose_function_section (void) build_string (strlen (UNLIKELY_EXECUTED_TEXT_SECTION_NAME), UNLIKELY_EXECUTED_TEXT_SECTION_NAME); } + +static bool +gate_estimate_probability (void) +{ + return flag_guess_branch_prob; +} + +struct tree_opt_pass pass_profile = +{ + "profile", /* name */ + gate_estimate_probability, /* 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 */ +};