Mercurial > hg > CbC > CbC_gcc
diff gcc/predict.c @ 111:04ced10e8804
gcc 7
| author | kono |
|---|---|
| date | Fri, 27 Oct 2017 22:46:09 +0900 |
| parents | f6334be47118 |
| children | 84e7813d76e9 |
line wrap: on
line diff
--- a/gcc/predict.c Sun Aug 21 07:07:55 2011 +0900 +++ b/gcc/predict.c Fri Oct 27 22:46:09 2017 +0900 @@ -1,6 +1,5 @@ /* Branch prediction routines for the GNU compiler. - Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010 - Free Software Foundation, Inc. + Copyright (C) 2000-2017 Free Software Foundation, Inc. This file is part of GCC. @@ -31,54 +30,68 @@ #include "config.h" #include "system.h" #include "coretypes.h" -#include "tm.h" -#include "tree.h" +#include "backend.h" #include "rtl.h" -#include "tm_p.h" -#include "hard-reg-set.h" -#include "basic-block.h" -#include "insn-config.h" -#include "regs.h" -#include "flags.h" -#include "output.h" -#include "function.h" -#include "except.h" +#include "tree.h" +#include "gimple.h" +#include "cfghooks.h" +#include "tree-pass.h" +#include "ssa.h" +#include "memmodel.h" +#include "emit-rtl.h" +#include "cgraph.h" +#include "coverage.h" #include "diagnostic-core.h" -#include "recog.h" -#include "expr.h" -#include "predict.h" -#include "coverage.h" +#include "gimple-predict.h" +#include "fold-const.h" +#include "calls.h" +#include "cfganal.h" +#include "profile.h" #include "sreal.h" #include "params.h" -#include "target.h" #include "cfgloop.h" -#include "tree-flow.h" -#include "ggc.h" -#include "tree-dump.h" -#include "tree-pass.h" -#include "timevar.h" +#include "gimple-iterator.h" +#include "tree-cfg.h" +#include "tree-ssa-loop-niter.h" +#include "tree-ssa-loop.h" #include "tree-scalar-evolution.h" -#include "cfgloop.h" -#include "pointer-set.h" +#include "ipa-utils.h" +#include "gimple-pretty-print.h" +#include "selftest.h" +#include "cfgrtl.h" +#include "stringpool.h" +#include "attribs.h" + +/* Enum with reasons why a predictor is ignored. */ + +enum predictor_reason +{ + REASON_NONE, + REASON_IGNORED, + REASON_SINGLE_EDGE_DUPLICATE, + REASON_EDGE_PAIR_DUPLICATE +}; + +/* String messages for the aforementioned enum. */ + +static const char *reason_messages[] = {"", " (ignored)", + " (single edge duplicate)", " (edge pair duplicate)"}; /* 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, +static sreal real_almost_one, real_br_prob_base, real_inv_br_prob_base, real_one_half, real_bb_freq_max; -/* Random guesstimation given names. - PROV_VERY_UNLIKELY should be small enough so basic block predicted - by it gets bellow HOT_BB_FREQUENCY_FRANCTION. */ -#define PROB_VERY_UNLIKELY (REG_BR_PROB_BASE / 2000 - 1) -#define PROB_EVEN (REG_BR_PROB_BASE / 2) -#define PROB_VERY_LIKELY (REG_BR_PROB_BASE - PROB_VERY_UNLIKELY) -#define PROB_ALWAYS (REG_BR_PROB_BASE) - -static void combine_predictions_for_insn (rtx, basic_block); -static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int); -static void predict_paths_leading_to (basic_block, enum br_predictor, enum prediction); -static void predict_paths_leading_to_edge (edge, enum br_predictor, enum prediction); -static bool can_predict_insn_p (const_rtx); +static void combine_predictions_for_insn (rtx_insn *, basic_block); +static void dump_prediction (FILE *, enum br_predictor, int, basic_block, + enum predictor_reason, edge); +static void predict_paths_leading_to (basic_block, enum br_predictor, + enum prediction, + struct loop *in_loop = NULL); +static void predict_paths_leading_to_edge (edge, enum br_predictor, + enum prediction, + struct loop *in_loop = NULL); +static bool can_predict_insn_p (const rtx_insn *); /* Information we hold about each branch predictor. Filled using information from predict.def. */ @@ -111,78 +124,77 @@ /* Return TRUE if frequency FREQ is considered to be hot. */ static inline bool -maybe_hot_frequency_p (int freq) +maybe_hot_frequency_p (struct function *fun, int freq) { - struct cgraph_node *node = cgraph_node (current_function_decl); - if (!profile_info || !flag_branch_probabilities) + struct cgraph_node *node = cgraph_node::get (fun->decl); + if (!profile_info || profile_status_for_fn (fun) != PROFILE_READ) { if (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED) return false; if (node->frequency == NODE_FREQUENCY_HOT) return true; } - if (profile_status == PROFILE_ABSENT) + if (profile_status_for_fn (fun) == PROFILE_ABSENT) return true; if (node->frequency == NODE_FREQUENCY_EXECUTED_ONCE - && freq <= (ENTRY_BLOCK_PTR->frequency * 2 / 3)) + && freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency * 2 / 3)) return false; - if (freq < ENTRY_BLOCK_PTR->frequency / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION)) + if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0) + return false; + if (freq * PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) + < ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency) return false; return true; } +static gcov_type min_count = -1; + +/* Determine the threshold for hot BB counts. */ + +gcov_type +get_hot_bb_threshold () +{ + gcov_working_set_t *ws; + if (min_count == -1) + { + ws = find_working_set (PARAM_VALUE (HOT_BB_COUNT_WS_PERMILLE)); + gcc_assert (ws); + min_count = ws->min_counter; + } + return min_count; +} + +/* Set the threshold for hot BB counts. */ + +void +set_hot_bb_threshold (gcov_type min) +{ + min_count = min; +} + /* Return TRUE if frequency FREQ is considered to be hot. */ -static inline bool -maybe_hot_count_p (gcov_type count) +bool +maybe_hot_count_p (struct function *, profile_count count) { - if (profile_status != PROFILE_READ) + if (!count.initialized_p ()) return true; /* Code executed at most once is not hot. */ - if (profile_info->runs >= count) + if (count <= MAX (profile_info ? profile_info->runs : 1, 1)) return false; - return (count - > profile_info->sum_max / PARAM_VALUE (HOT_BB_COUNT_FRACTION)); + return (count.to_gcov_type () >= get_hot_bb_threshold ()); } /* Return true in case BB can be CPU intensive and should be optimized for maximal performance. */ bool -maybe_hot_bb_p (const_basic_block bb) +maybe_hot_bb_p (struct function *fun, const_basic_block bb) { - if (profile_status == PROFILE_READ) - return maybe_hot_count_p (bb->count); - return maybe_hot_frequency_p (bb->frequency); -} - -/* Return true if the call can be hot. */ - -bool -cgraph_maybe_hot_edge_p (struct cgraph_edge *edge) -{ - if (profile_info && flag_branch_probabilities - && (edge->count - <= profile_info->sum_max / PARAM_VALUE (HOT_BB_COUNT_FRACTION))) + gcc_checking_assert (fun); + if (!maybe_hot_count_p (fun, bb->count)) return false; - if (edge->caller->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED - || edge->callee->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED) - return false; - if (edge->caller->frequency > NODE_FREQUENCY_UNLIKELY_EXECUTED - && edge->callee->frequency <= NODE_FREQUENCY_EXECUTED_ONCE) - return false; - if (optimize_size) - return false; - if (edge->caller->frequency == NODE_FREQUENCY_HOT) - return true; - if (edge->caller->frequency == NODE_FREQUENCY_EXECUTED_ONCE - && edge->frequency < CGRAPH_FREQ_BASE * 3 / 2) - return false; - if (flag_guess_branch_prob - && edge->frequency <= (CGRAPH_FREQ_BASE - / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))) - return false; - return true; + return maybe_hot_frequency_p (fun, bb->frequency); } /* Return true in case BB can be CPU intensive and should be optimized @@ -191,21 +203,63 @@ bool maybe_hot_edge_p (edge e) { - if (profile_status == PROFILE_READ) - return maybe_hot_count_p (e->count); - return maybe_hot_frequency_p (EDGE_FREQUENCY (e)); + if (!maybe_hot_count_p (cfun, e->count ())) + return false; + return maybe_hot_frequency_p (cfun, EDGE_FREQUENCY (e)); } +/* Return true if profile COUNT and FREQUENCY, or function FUN static + node frequency reflects never being executed. */ + +static bool +probably_never_executed (struct function *fun, + profile_count count, int) +{ + gcc_checking_assert (fun); + if (count == profile_count::zero ()) + return true; + if (count.initialized_p () && profile_status_for_fn (fun) == PROFILE_READ) + { + int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); + if (count.apply_scale (unlikely_count_fraction, 1) >= profile_info->runs) + return false; + return true; + } + if ((!profile_info || profile_status_for_fn (fun) != PROFILE_READ) + && (cgraph_node::get (fun->decl)->frequency + == NODE_FREQUENCY_UNLIKELY_EXECUTED)) + return true; + return false; +} + + /* Return true in case BB is probably never executed. */ + bool -probably_never_executed_bb_p (const_basic_block bb) +probably_never_executed_bb_p (struct function *fun, const_basic_block bb) +{ + return probably_never_executed (fun, bb->count, bb->frequency); +} + + +/* Return true if E is unlikely executed for obvious reasons. */ + +static bool +unlikely_executed_edge_p (edge e) { - if (profile_info && flag_branch_probabilities) - return ((bb->count + profile_info->runs / 2) / profile_info->runs) == 0; - if ((!profile_info || !flag_branch_probabilities) - && cgraph_node (current_function_decl)->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED) + return (e->count () == profile_count::zero () + || e->probability == profile_probability::never ()) + || (e->flags & (EDGE_EH | EDGE_FAKE)); +} + +/* Return true in case edge E is probably never executed. */ + +bool +probably_never_executed_edge_p (struct function *fun, edge e) +{ + if (unlikely_executed_edge_p (e)) return true; - return false; + return probably_never_executed (fun, e->count (), EDGE_FREQUENCY (e)); } /* Return true when current function should always be optimized for size. */ @@ -213,10 +267,10 @@ bool optimize_function_for_size_p (struct function *fun) { - return (optimize_size - || (fun && fun->decl - && (cgraph_node (fun->decl)->frequency - == NODE_FREQUENCY_UNLIKELY_EXECUTED))); + if (!fun || !fun->decl) + return optimize_size; + cgraph_node *n = cgraph_node::get (fun->decl); + return n && n->optimize_for_size_p (); } /* Return true when current function should always be optimized for speed. */ @@ -227,12 +281,23 @@ return !optimize_function_for_size_p (fun); } +/* Return the optimization type that should be used for the function FUN. */ + +optimization_type +function_optimization_type (struct function *fun) +{ + return (optimize_function_for_speed_p (fun) + ? OPTIMIZE_FOR_SPEED + : OPTIMIZE_FOR_SIZE); +} + /* Return TRUE when BB should be optimized for size. */ bool optimize_bb_for_size_p (const_basic_block bb) { - return optimize_function_for_size_p (cfun) || !maybe_hot_bb_p (bb); + return (optimize_function_for_size_p (cfun) + || (bb && !maybe_hot_bb_p (cfun, bb))); } /* Return TRUE when BB should be optimized for speed. */ @@ -243,6 +308,16 @@ return !optimize_bb_for_size_p (bb); } +/* Return the optimization type that should be used for block BB. */ + +optimization_type +bb_optimization_type (const_basic_block bb) +{ + return (optimize_bb_for_speed_p (bb) + ? OPTIMIZE_FOR_SPEED + : OPTIMIZE_FOR_SIZE); +} + /* Return TRUE when BB should be optimized for size. */ bool @@ -333,11 +408,11 @@ bool predictable_edge_p (edge e) { - if (profile_status == PROFILE_ABSENT) + if (!e->probability.initialized_p ()) return false; - if ((e->probability + if ((e->probability.to_reg_br_prob_base () <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100) - || (REG_BR_PROB_BASE - e->probability + || (REG_BR_PROB_BASE - e->probability.to_reg_br_prob_base () <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100)) return true; return false; @@ -349,7 +424,7 @@ void rtl_profile_for_bb (basic_block bb) { - crtl->maybe_hot_insn_p = maybe_hot_bb_p (bb); + crtl->maybe_hot_insn_p = maybe_hot_bb_p (cfun, bb); } /* Set RTL expansion for edge profile. */ @@ -383,11 +458,6 @@ return false; } -/* This map contains for a basic block the list of predictions for the - outgoing edges. */ - -static struct pointer_map_t *bb_predictions; - /* Structure representing predictions in tree level. */ struct edge_prediction { @@ -397,6 +467,11 @@ int ep_probability; }; +/* This map contains for a basic block the list of predictions for the + outgoing edges. */ + +static hash_map<const_basic_block, edge_prediction *> *bb_predictions; + /* Return true if the one of outgoing edges is already predicted by PREDICTOR. */ @@ -404,46 +479,47 @@ gimple_predicted_by_p (const_basic_block bb, enum br_predictor predictor) { struct edge_prediction *i; - void **preds = pointer_map_contains (bb_predictions, bb); + edge_prediction **preds = bb_predictions->get (bb); if (!preds) return false; - for (i = (struct edge_prediction *) *preds; i; i = i->ep_next) + for (i = *preds; i; i = i->ep_next) if (i->ep_predictor == predictor) return true; return false; } -/* Return true when the probability of edge is reliable. - - The profile guessing code is good at predicting branch outcome (ie. - taken/not taken), that is predicted right slightly over 75% of time. - It is however notoriously poor on predicting the probability itself. - In general the profile appear a lot flatter (with probabilities closer - to 50%) than the reality so it is bad idea to use it to drive optimization - such as those disabling dynamic branch prediction for well predictable - branches. - - There are two exceptions - edges leading to noreturn edges and edges - predicted by number of iterations heuristics are predicted well. This macro - should be able to distinguish those, but at the moment it simply check for - noreturn heuristic that is only one giving probability over 99% or bellow - 1%. In future we might want to propagate reliability information across the - CFG if we find this information useful on multiple places. */ -static bool -probability_reliable_p (int prob) +/* Return true if the one of outgoing edges is already predicted by + PREDICTOR for edge E predicted as TAKEN. */ + +bool +edge_predicted_by_p (edge e, enum br_predictor predictor, bool taken) { - return (profile_status == PROFILE_READ - || (profile_status == PROFILE_GUESSED - && (prob <= HITRATE (1) || prob >= HITRATE (99)))); + struct edge_prediction *i; + basic_block bb = e->src; + edge_prediction **preds = bb_predictions->get (bb); + if (!preds) + return false; + + int probability = predictor_info[(int) predictor].hitrate; + + if (taken != TAKEN) + probability = REG_BR_PROB_BASE - probability; + + for (i = *preds; i; i = i->ep_next) + if (i->ep_predictor == predictor + && i->ep_edge == e + && i->ep_probability == probability) + return true; + return false; } /* Same predicate as above, working on edges. */ bool edge_probability_reliable_p (const_edge e) { - return probability_reliable_p (e->probability); + return e->probability.probably_reliable_p (); } /* Same predicate as edge_probability_reliable_p, working on notes. */ @@ -451,11 +527,12 @@ br_prob_note_reliable_p (const_rtx note) { gcc_assert (REG_NOTE_KIND (note) == REG_BR_PROB); - return probability_reliable_p (INTVAL (XEXP (note, 0))); + return profile_probability::from_reg_br_prob_note + (XINT (note, 0)).probably_reliable_p (); } static void -predict_insn (rtx insn, enum br_predictor predictor, int probability) +predict_insn (rtx_insn *insn, enum br_predictor predictor, int probability) { gcc_assert (any_condjump_p (insn)); if (!flag_guess_branch_prob) @@ -470,7 +547,7 @@ /* Predict insn by given predictor. */ void -predict_insn_def (rtx insn, enum br_predictor predictor, +predict_insn_def (rtx_insn *insn, enum br_predictor predictor, enum prediction taken) { int probability = predictor_info[(int) predictor].hitrate; @@ -486,7 +563,7 @@ void rtl_predict_edge (edge e, enum br_predictor predictor, int probability) { - rtx last_insn; + rtx_insn *last_insn; last_insn = BB_END (e->src); /* We can store the branch prediction information only about @@ -505,50 +582,70 @@ void gimple_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) + if (e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun) + && EDGE_COUNT (e->src->succs) > 1 + && flag_guess_branch_prob + && optimize) { struct edge_prediction *i = XNEW (struct edge_prediction); - void **preds = pointer_map_insert (bb_predictions, e->src); - - i->ep_next = (struct edge_prediction *) *preds; - *preds = i; + edge_prediction *&preds = bb_predictions->get_or_insert (e->src); + + i->ep_next = preds; + preds = i; i->ep_probability = probability; i->ep_predictor = predictor; i->ep_edge = e; } } +/* Filter edge predictions PREDS by a function FILTER. DATA are passed + to the filter function. */ + +void +filter_predictions (edge_prediction **preds, + bool (*filter) (edge_prediction *, void *), void *data) +{ + if (!bb_predictions) + return; + + if (preds) + { + struct edge_prediction **prediction = preds; + struct edge_prediction *next; + + while (*prediction) + { + if ((*filter) (*prediction, data)) + prediction = &((*prediction)->ep_next); + else + { + next = (*prediction)->ep_next; + free (*prediction); + *prediction = next; + } + } + } +} + +/* Filter function predicate that returns true for a edge predicate P + if its edge is equal to DATA. */ + +bool +equal_edge_p (edge_prediction *p, void *data) +{ + return p->ep_edge == (edge)data; +} + /* Remove all predictions on given basic block that are attached to edge E. */ void remove_predictions_associated_with_edge (edge e) { - void **preds; - if (!bb_predictions) return; - preds = pointer_map_contains (bb_predictions, e->src); - - if (preds) - { - struct edge_prediction **prediction = (struct edge_prediction **) preds; - struct edge_prediction *next; - - while (*prediction) - { - if ((*prediction)->ep_edge == e) - { - next = (*prediction)->ep_next; - free (*prediction); - *prediction = next; - } - else - prediction = &((*prediction)->ep_next); - } - } + edge_prediction **preds = bb_predictions->get (e->src); + filter_predictions (preds, equal_edge_p, e); } /* Clears the list of predictions stored for BB. */ @@ -556,13 +653,13 @@ static void clear_bb_predictions (basic_block bb) { - void **preds = pointer_map_contains (bb_predictions, bb); + edge_prediction **preds = bb_predictions->get (bb); struct edge_prediction *pred, *next; if (!preds) return; - for (pred = (struct edge_prediction *) *preds; pred; pred = next) + for (pred = *preds; pred; pred = next) { next = pred->ep_next; free (pred); @@ -574,7 +671,7 @@ At the moment we represent predictions only on conditional jumps, not at computed jump or other complicated cases. */ static bool -can_predict_insn_p (const_rtx insn) +can_predict_insn_p (const rtx_insn *insn) { return (JUMP_P (insn) && any_condjump_p (insn) @@ -605,7 +702,8 @@ 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))); + XINT (note, 0) = profile_probability::from_reg_br_prob_note + (XINT (note, 0)).invert ().to_reg_br_prob_note (); 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))); @@ -615,61 +713,167 @@ static void dump_prediction (FILE *file, enum br_predictor predictor, int probability, - basic_block bb, int used) + basic_block bb, enum predictor_reason reason = REASON_NONE, + edge ep_edge = NULL) { - edge e; + edge e = ep_edge; edge_iterator ei; if (!file) return; - FOR_EACH_EDGE (e, ei, bb->succs) - if (! (e->flags & EDGE_FALLTHRU)) - break; - - fprintf (file, " %s heuristics%s: %.1f%%", + if (e == NULL) + FOR_EACH_EDGE (e, ei, bb->succs) + if (! (e->flags & EDGE_FALLTHRU)) + break; + + char edge_info_str[128]; + if (ep_edge) + sprintf (edge_info_str, " of edge %d->%d", ep_edge->src->index, + ep_edge->dest->index); + else + edge_info_str[0] = '\0'; + + fprintf (file, " %s heuristics%s%s: %.1f%%", predictor_info[predictor].name, - used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE); - - if (bb->count) + edge_info_str, reason_messages[reason], + probability * 100.0 / REG_BR_PROB_BASE); + + if (bb->count.initialized_p ()) { fprintf (file, " exec "); - fprintf (file, HOST_WIDEST_INT_PRINT_DEC, bb->count); + bb->count.dump (file); if (e) { fprintf (file, " hit "); - fprintf (file, HOST_WIDEST_INT_PRINT_DEC, e->count); - fprintf (file, " (%.1f%%)", e->count * 100.0 / bb->count); + e->count ().dump (file); + fprintf (file, " (%.1f%%)", e->count ().to_gcov_type() * 100.0 + / bb->count.to_gcov_type ()); } } fprintf (file, "\n"); } +/* Return true if STMT is known to be unlikely executed. */ + +static bool +unlikely_executed_stmt_p (gimple *stmt) +{ + if (!is_gimple_call (stmt)) + return false; + /* NORETURN attribute alone is not strong enough: exit() may be quite + likely executed once during program run. */ + if (gimple_call_fntype (stmt) + && lookup_attribute ("cold", + TYPE_ATTRIBUTES (gimple_call_fntype (stmt))) + && !lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl))) + return true; + tree decl = gimple_call_fndecl (stmt); + if (!decl) + return false; + if (lookup_attribute ("cold", DECL_ATTRIBUTES (decl)) + && !lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl))) + return true; + + cgraph_node *n = cgraph_node::get (decl); + if (!n) + return false; + + availability avail; + n = n->ultimate_alias_target (&avail); + if (avail < AVAIL_AVAILABLE) + return false; + if (!n->analyzed + || n->decl == current_function_decl) + return false; + return n->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED; +} + +/* Return true if BB is unlikely executed. */ + +static bool +unlikely_executed_bb_p (basic_block bb) +{ + if (bb->count == profile_count::zero ()) + return true; + if (bb == ENTRY_BLOCK_PTR_FOR_FN (cfun) || bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) + return false; + for (gimple_stmt_iterator gsi = gsi_start_bb (bb); + !gsi_end_p (gsi); gsi_next (&gsi)) + { + if (unlikely_executed_stmt_p (gsi_stmt (gsi))) + return true; + if (stmt_can_terminate_bb_p (gsi_stmt (gsi))) + return false; + } + return false; +} + /* We can not predict the probabilities of outgoing edges of bb. Set them - evenly and hope for the best. */ + evenly and hope for the best. If UNLIKELY_EDGES is not null, distribute + even probability for all edges not mentioned in the set. These edges + are given PROB_VERY_UNLIKELY probability. */ + static void -set_even_probabilities (basic_block bb) +set_even_probabilities (basic_block bb, + hash_set<edge> *unlikely_edges = NULL) { - int nedges = 0; - edge e; + unsigned nedges = 0, unlikely_count = 0; + edge e = NULL; edge_iterator ei; + profile_probability all = profile_probability::always (); FOR_EACH_EDGE (e, ei, bb->succs) - if (!(e->flags & (EDGE_EH | EDGE_FAKE))) - nedges ++; + if (e->probability.initialized_p ()) + all -= e->probability; + else if (!unlikely_executed_edge_p (e)) + { + nedges ++; + if (unlikely_edges != NULL && unlikely_edges->contains (e)) + { + all -= profile_probability::very_unlikely (); + unlikely_count++; + } + } + + /* Make the distribution even if all edges are unlikely. */ + if (unlikely_count == nedges) + { + unlikely_edges = NULL; + unlikely_count = 0; + } + + unsigned c = nedges - unlikely_count; + FOR_EACH_EDGE (e, ei, bb->succs) - if (!(e->flags & (EDGE_EH | EDGE_FAKE))) - e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges; + if (e->probability.initialized_p ()) + ; + else if (!unlikely_executed_edge_p (e)) + { + if (unlikely_edges != NULL && unlikely_edges->contains (e)) + e->probability = profile_probability::very_unlikely (); + else + e->probability = all.apply_scale (1, c).guessed (); + } else - e->probability = 0; + e->probability = profile_probability::never (); +} + +/* Add REG_BR_PROB note to JUMP with PROB. */ + +void +add_reg_br_prob_note (rtx_insn *jump, profile_probability prob) +{ + gcc_checking_assert (JUMP_P (jump) && !find_reg_note (jump, REG_BR_PROB, 0)); + add_int_reg_note (jump, REG_BR_PROB, prob.to_reg_br_prob_note ()); } /* Combine all REG_BR_PRED notes into single probability and attach REG_BR_PROB note if not already present. Remove now useless REG_BR_PRED notes. */ static void -combine_predictions_for_insn (rtx insn, basic_block bb) +combine_predictions_for_insn (rtx_insn *insn, basic_block bb) { rtx prob_note; rtx *pnote; @@ -703,7 +907,8 @@ int probability = INTVAL (XEXP (XEXP (note, 0), 1)); found = true; - if (best_predictor > predictor) + if (best_predictor > predictor + && predictor_info[predictor].flags & PRED_FLAG_FIRST_MATCH) best_probability = probability, best_predictor = predictor; d = (combined_probability * probability @@ -723,23 +928,25 @@ 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) + if (best_predictor != END_PREDICTORS) first_match = true; if (!found) dump_prediction (dump_file, PRED_NO_PREDICTION, - combined_probability, bb, true); + combined_probability, bb); 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) + dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, + bb, !first_match ? REASON_NONE : REASON_IGNORED); + else + dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, + bb, first_match ? REASON_NONE : REASON_IGNORED); } if (first_match) combined_probability = best_probability; - dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); + dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb); while (*pnote) { @@ -750,7 +957,8 @@ int probability = INTVAL (XEXP (XEXP (*pnote, 0), 1)); dump_prediction (dump_file, predictor, probability, bb, - !first_match || best_predictor == predictor); + (!first_match || best_predictor == predictor) + ? REASON_NONE : REASON_IGNORED); *pnote = XEXP (*pnote, 1); } else @@ -759,33 +967,152 @@ if (!prob_note) { - add_reg_note (insn, REG_BR_PROB, GEN_INT (combined_probability)); + profile_probability p + = profile_probability::from_reg_br_prob_base (combined_probability); + add_reg_br_prob_note (insn, p); /* Save the prediction into CFG in case we are seeing non-degenerated conditional jump. */ if (!single_succ_p (bb)) { - BRANCH_EDGE (bb)->probability = combined_probability; + BRANCH_EDGE (bb)->probability = p; FALLTHRU_EDGE (bb)->probability - = REG_BR_PROB_BASE - combined_probability; + = BRANCH_EDGE (bb)->probability.invert (); } } else if (!single_succ_p (bb)) { - int prob = INTVAL (XEXP (prob_note, 0)); + profile_probability prob = profile_probability::from_reg_br_prob_note + (XINT (prob_note, 0)); BRANCH_EDGE (bb)->probability = prob; - FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - prob; + FALLTHRU_EDGE (bb)->probability = prob.invert (); } else - single_succ_edge (bb)->probability = REG_BR_PROB_BASE; + single_succ_edge (bb)->probability = profile_probability::always (); +} + +/* Edge prediction hash traits. */ + +struct predictor_hash: pointer_hash <edge_prediction> +{ + + static inline hashval_t hash (const edge_prediction *); + static inline bool equal (const edge_prediction *, const edge_prediction *); +}; + +/* Calculate hash value of an edge prediction P based on predictor and + normalized probability. */ + +inline hashval_t +predictor_hash::hash (const edge_prediction *p) +{ + inchash::hash hstate; + hstate.add_int (p->ep_predictor); + + int prob = p->ep_probability; + if (prob > REG_BR_PROB_BASE / 2) + prob = REG_BR_PROB_BASE - prob; + + hstate.add_int (prob); + + return hstate.end (); +} + +/* Return true whether edge predictions P1 and P2 use the same predictor and + have equal (or opposed probability). */ + +inline bool +predictor_hash::equal (const edge_prediction *p1, const edge_prediction *p2) +{ + return (p1->ep_predictor == p2->ep_predictor + && (p1->ep_probability == p2->ep_probability + || p1->ep_probability == REG_BR_PROB_BASE - p2->ep_probability)); +} + +struct predictor_hash_traits: predictor_hash, + typed_noop_remove <edge_prediction *> {}; + +/* Return true if edge prediction P is not in DATA hash set. */ + +static bool +not_removed_prediction_p (edge_prediction *p, void *data) +{ + hash_set<edge_prediction *> *remove = (hash_set<edge_prediction *> *) data; + return !remove->contains (p); +} + +/* Prune predictions for a basic block BB. Currently we do following + clean-up steps: + + 1) remove duplicate prediction that is guessed with the same probability + (different than 1/2) to both edge + 2) remove duplicates for a prediction that belongs with the same probability + to a single edge + + */ + +static void +prune_predictions_for_bb (basic_block bb) +{ + edge_prediction **preds = bb_predictions->get (bb); + + if (preds) + { + hash_table <predictor_hash_traits> s (13); + hash_set <edge_prediction *> remove; + + /* Step 1: identify predictors that should be removed. */ + for (edge_prediction *pred = *preds; pred; pred = pred->ep_next) + { + edge_prediction *existing = s.find (pred); + if (existing) + { + if (pred->ep_edge == existing->ep_edge + && pred->ep_probability == existing->ep_probability) + { + /* Remove a duplicate predictor. */ + dump_prediction (dump_file, pred->ep_predictor, + pred->ep_probability, bb, + REASON_SINGLE_EDGE_DUPLICATE, pred->ep_edge); + + remove.add (pred); + } + else if (pred->ep_edge != existing->ep_edge + && pred->ep_probability == existing->ep_probability + && pred->ep_probability != REG_BR_PROB_BASE / 2) + { + /* Remove both predictors as they predict the same + for both edges. */ + dump_prediction (dump_file, existing->ep_predictor, + pred->ep_probability, bb, + REASON_EDGE_PAIR_DUPLICATE, + existing->ep_edge); + dump_prediction (dump_file, pred->ep_predictor, + pred->ep_probability, bb, + REASON_EDGE_PAIR_DUPLICATE, + pred->ep_edge); + + remove.add (existing); + remove.add (pred); + } + } + + edge_prediction **slot2 = s.find_slot (pred, INSERT); + *slot2 = pred; + } + + /* Step 2: Remove predictors. */ + filter_predictions (preds, not_removed_prediction_p, &remove); + } } /* Combine predictions into single probability and store them into CFG. - Remove now useless prediction entries. */ + Remove now useless prediction entries. + If DRY_RUN is set, only produce dumps and do not modify profile. */ static void -combine_predictions_for_bb (basic_block bb) +combine_predictions_for_bb (basic_block bb, bool dry_run) { int best_probability = PROB_EVEN; enum br_predictor best_predictor = END_PREDICTORS; @@ -797,10 +1124,9 @@ int nedges = 0; edge e, first = NULL, second = NULL; edge_iterator ei; - void **preds; FOR_EACH_EDGE (e, ei, bb->succs) - if (!(e->flags & (EDGE_EH | EDGE_FAKE))) + if (!unlikely_executed_edge_p (e)) { nedges ++; if (first && !second) @@ -808,33 +1134,71 @@ if (!first) first = e; } + else if (!e->probability.initialized_p ()) + e->probability = profile_probability::never (); /* 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. */ + When we have a basic block with more than 2 successors, the situation + is more complicated as DS theory cannot be used literally. + More precisely, let's assume we predicted edge e1 with probability p1, + thus: m1({b1}) = p1. As we're going to combine more than 2 edges, we + need to find probability of e.g. m1({b2}), which we don't know. + The only approximation is to equally distribute 1-p1 to all edges + different from b1. + + According to numbers we've got from SPEC2006 benchark, there's only + one interesting reliable predictor (noreturn call), which can be + handled with a bit easier approach. */ if (nedges != 2) { - if (!bb->count) - set_even_probabilities (bb); + hash_set<edge> unlikely_edges (4); + + /* Identify all edges that have a probability close to very unlikely. + Doing the approach for very unlikely doesn't worth for doing as + there's no such probability in SPEC2006 benchmark. */ + edge_prediction **preds = bb_predictions->get (bb); + if (preds) + for (pred = *preds; pred; pred = pred->ep_next) + if (pred->ep_probability <= PROB_VERY_UNLIKELY) + unlikely_edges.add (pred->ep_edge); + + if (!dry_run) + set_even_probabilities (bb, &unlikely_edges); clear_bb_predictions (bb); if (dump_file) - fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n", - nedges, bb->index); + { + fprintf (dump_file, "Predictions for bb %i\n", bb->index); + if (unlikely_edges.elements () == 0) + fprintf (dump_file, + "%i edges in bb %i predicted to even probabilities\n", + nedges, bb->index); + else + { + fprintf (dump_file, + "%i edges in bb %i predicted with some unlikely edges\n", + nedges, bb->index); + FOR_EACH_EDGE (e, ei, bb->succs) + if (!unlikely_executed_edge_p (e)) + dump_prediction (dump_file, PRED_COMBINED, + e->probability.to_reg_br_prob_base (), bb, REASON_NONE, e); + } + } return; } if (dump_file) fprintf (dump_file, "Predictions for bb %i\n", bb->index); - preds = pointer_map_contains (bb_predictions, bb); + prune_predictions_for_bb (bb); + + edge_prediction **preds = bb_predictions->get (bb); + if (preds) { /* We implement "first match" heuristics and use probability guessed by predictor with smallest index. */ - for (pred = (struct edge_prediction *) *preds; pred; pred = pred->ep_next) + for (pred = *preds; pred; pred = pred->ep_next) { enum br_predictor predictor = pred->ep_predictor; int probability = pred->ep_probability; @@ -845,15 +1209,17 @@ found = true; /* First match heuristics would be widly confused if we predicted both directions. */ - if (best_predictor > predictor) + if (best_predictor > predictor + && predictor_info[predictor].flags & PRED_FLAG_FIRST_MATCH) { struct edge_prediction *pred2; int prob = probability; - for (pred2 = (struct edge_prediction *) *preds; pred2; pred2 = pred2->ep_next) + for (pred2 = (struct edge_prediction *) *preds; + pred2; pred2 = pred2->ep_next) if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor) { - int probability2 = pred->ep_probability; + int probability2 = pred2->ep_probability; if (pred2->ep_edge != first) probability2 = REG_BR_PROB_BASE - probability2; @@ -890,22 +1256,24 @@ 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) + if (best_predictor != END_PREDICTORS) first_match = true; if (!found) - dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true); + dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb); 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) + dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb, + !first_match ? REASON_NONE : REASON_IGNORED); + else + dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb, + first_match ? REASON_NONE : REASON_IGNORED); } if (first_match) combined_probability = best_probability; - dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); + dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb); if (preds) { @@ -914,60 +1282,624 @@ enum br_predictor 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); + (!first_match || best_predictor == predictor) + ? REASON_NONE : REASON_IGNORED, pred->ep_edge); } } clear_bb_predictions (bb); - if (!bb->count) + if (!bb->count.initialized_p () && !dry_run) { - first->probability = combined_probability; - second->probability = REG_BR_PROB_BASE - combined_probability; + first->probability + = profile_probability::from_reg_br_prob_base (combined_probability); + second->probability = first->probability.invert (); + } +} + +/* Check if T1 and T2 satisfy the IV_COMPARE condition. + Return the SSA_NAME if the condition satisfies, NULL otherwise. + + T1 and T2 should be one of the following cases: + 1. T1 is SSA_NAME, T2 is NULL + 2. T1 is SSA_NAME, T2 is INTEGER_CST between [-4, 4] + 3. T2 is SSA_NAME, T1 is INTEGER_CST between [-4, 4] */ + +static tree +strips_small_constant (tree t1, tree t2) +{ + tree ret = NULL; + int value = 0; + + if (!t1) + return NULL; + else if (TREE_CODE (t1) == SSA_NAME) + ret = t1; + else if (tree_fits_shwi_p (t1)) + value = tree_to_shwi (t1); + else + return NULL; + + if (!t2) + return ret; + else if (tree_fits_shwi_p (t2)) + value = tree_to_shwi (t2); + else if (TREE_CODE (t2) == SSA_NAME) + { + if (ret) + return NULL; + else + ret = t2; + } + + if (value <= 4 && value >= -4) + return ret; + else + return NULL; +} + +/* Return the SSA_NAME in T or T's operands. + Return NULL if SSA_NAME cannot be found. */ + +static tree +get_base_value (tree t) +{ + if (TREE_CODE (t) == SSA_NAME) + return t; + + if (!BINARY_CLASS_P (t)) + return NULL; + + switch (TREE_OPERAND_LENGTH (t)) + { + case 1: + return strips_small_constant (TREE_OPERAND (t, 0), NULL); + case 2: + return strips_small_constant (TREE_OPERAND (t, 0), + TREE_OPERAND (t, 1)); + default: + return NULL; } } +/* Check the compare STMT in LOOP. If it compares an induction + variable to a loop invariant, return true, and save + LOOP_INVARIANT, COMPARE_CODE and LOOP_STEP. + Otherwise return false and set LOOP_INVAIANT to NULL. */ + +static bool +is_comparison_with_loop_invariant_p (gcond *stmt, struct loop *loop, + tree *loop_invariant, + enum tree_code *compare_code, + tree *loop_step, + tree *loop_iv_base) +{ + tree op0, op1, bound, base; + affine_iv iv0, iv1; + enum tree_code code; + tree step; + + code = gimple_cond_code (stmt); + *loop_invariant = NULL; + + switch (code) + { + case GT_EXPR: + case GE_EXPR: + case NE_EXPR: + case LT_EXPR: + case LE_EXPR: + case EQ_EXPR: + break; + + default: + return false; + } + + op0 = gimple_cond_lhs (stmt); + op1 = gimple_cond_rhs (stmt); + + if ((TREE_CODE (op0) != SSA_NAME && TREE_CODE (op0) != INTEGER_CST) + || (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op1) != INTEGER_CST)) + return false; + if (!simple_iv (loop, loop_containing_stmt (stmt), op0, &iv0, true)) + return false; + if (!simple_iv (loop, loop_containing_stmt (stmt), op1, &iv1, true)) + return false; + if (TREE_CODE (iv0.step) != INTEGER_CST + || TREE_CODE (iv1.step) != INTEGER_CST) + return false; + if ((integer_zerop (iv0.step) && integer_zerop (iv1.step)) + || (!integer_zerop (iv0.step) && !integer_zerop (iv1.step))) + return false; + + if (integer_zerop (iv0.step)) + { + if (code != NE_EXPR && code != EQ_EXPR) + code = invert_tree_comparison (code, false); + bound = iv0.base; + base = iv1.base; + if (tree_fits_shwi_p (iv1.step)) + step = iv1.step; + else + return false; + } + else + { + bound = iv1.base; + base = iv0.base; + if (tree_fits_shwi_p (iv0.step)) + step = iv0.step; + else + return false; + } + + if (TREE_CODE (bound) != INTEGER_CST) + bound = get_base_value (bound); + if (!bound) + return false; + if (TREE_CODE (base) != INTEGER_CST) + base = get_base_value (base); + if (!base) + return false; + + *loop_invariant = bound; + *compare_code = code; + *loop_step = step; + *loop_iv_base = base; + return true; +} + +/* Compare two SSA_NAMEs: returns TRUE if T1 and T2 are value coherent. */ + +static bool +expr_coherent_p (tree t1, tree t2) +{ + gimple *stmt; + tree ssa_name_1 = NULL; + tree ssa_name_2 = NULL; + + gcc_assert (TREE_CODE (t1) == SSA_NAME || TREE_CODE (t1) == INTEGER_CST); + gcc_assert (TREE_CODE (t2) == SSA_NAME || TREE_CODE (t2) == INTEGER_CST); + + if (t1 == t2) + return true; + + if (TREE_CODE (t1) == INTEGER_CST && TREE_CODE (t2) == INTEGER_CST) + return true; + if (TREE_CODE (t1) == INTEGER_CST || TREE_CODE (t2) == INTEGER_CST) + return false; + + /* Check to see if t1 is expressed/defined with t2. */ + stmt = SSA_NAME_DEF_STMT (t1); + gcc_assert (stmt != NULL); + if (is_gimple_assign (stmt)) + { + ssa_name_1 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); + if (ssa_name_1 && ssa_name_1 == t2) + return true; + } + + /* Check to see if t2 is expressed/defined with t1. */ + stmt = SSA_NAME_DEF_STMT (t2); + gcc_assert (stmt != NULL); + if (is_gimple_assign (stmt)) + { + ssa_name_2 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); + if (ssa_name_2 && ssa_name_2 == t1) + return true; + } + + /* Compare if t1 and t2's def_stmts are identical. */ + if (ssa_name_2 != NULL && ssa_name_1 == ssa_name_2) + return true; + else + return false; +} + +/* Return true if E is predicted by one of loop heuristics. */ + +static bool +predicted_by_loop_heuristics_p (basic_block bb) +{ + struct edge_prediction *i; + edge_prediction **preds = bb_predictions->get (bb); + + if (!preds) + return false; + + for (i = *preds; i; i = i->ep_next) + if (i->ep_predictor == PRED_LOOP_ITERATIONS_GUESSED + || i->ep_predictor == PRED_LOOP_ITERATIONS_MAX + || i->ep_predictor == PRED_LOOP_ITERATIONS + || i->ep_predictor == PRED_LOOP_EXIT + || i->ep_predictor == PRED_LOOP_EXIT_WITH_RECURSION + || i->ep_predictor == PRED_LOOP_EXTRA_EXIT) + return true; + return false; +} + +/* Predict branch probability of BB when BB contains a branch that compares + an induction variable in LOOP with LOOP_IV_BASE_VAR to LOOP_BOUND_VAR. The + loop exit is compared using LOOP_BOUND_CODE, with step of LOOP_BOUND_STEP. + + E.g. + for (int i = 0; i < bound; i++) { + if (i < bound - 2) + computation_1(); + else + computation_2(); + } + + In this loop, we will predict the branch inside the loop to be taken. */ + +static void +predict_iv_comparison (struct loop *loop, basic_block bb, + tree loop_bound_var, + tree loop_iv_base_var, + enum tree_code loop_bound_code, + int loop_bound_step) +{ + gimple *stmt; + tree compare_var, compare_base; + enum tree_code compare_code; + tree compare_step_var; + edge then_edge; + edge_iterator ei; + + if (predicted_by_loop_heuristics_p (bb)) + return; + + stmt = last_stmt (bb); + if (!stmt || gimple_code (stmt) != GIMPLE_COND) + return; + if (!is_comparison_with_loop_invariant_p (as_a <gcond *> (stmt), + loop, &compare_var, + &compare_code, + &compare_step_var, + &compare_base)) + return; + + /* Find the taken edge. */ + FOR_EACH_EDGE (then_edge, ei, bb->succs) + if (then_edge->flags & EDGE_TRUE_VALUE) + break; + + /* When comparing an IV to a loop invariant, NE is more likely to be + taken while EQ is more likely to be not-taken. */ + if (compare_code == NE_EXPR) + { + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); + return; + } + else if (compare_code == EQ_EXPR) + { + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); + return; + } + + if (!expr_coherent_p (loop_iv_base_var, compare_base)) + return; + + /* If loop bound, base and compare bound are all constants, we can + calculate the probability directly. */ + if (tree_fits_shwi_p (loop_bound_var) + && tree_fits_shwi_p (compare_var) + && tree_fits_shwi_p (compare_base)) + { + int probability; + bool overflow, overall_overflow = false; + widest_int compare_count, tem; + + /* (loop_bound - base) / compare_step */ + tem = wi::sub (wi::to_widest (loop_bound_var), + wi::to_widest (compare_base), SIGNED, &overflow); + overall_overflow |= overflow; + widest_int loop_count = wi::div_trunc (tem, + wi::to_widest (compare_step_var), + SIGNED, &overflow); + overall_overflow |= overflow; + + if (!wi::neg_p (wi::to_widest (compare_step_var)) + ^ (compare_code == LT_EXPR || compare_code == LE_EXPR)) + { + /* (loop_bound - compare_bound) / compare_step */ + tem = wi::sub (wi::to_widest (loop_bound_var), + wi::to_widest (compare_var), SIGNED, &overflow); + overall_overflow |= overflow; + compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), + SIGNED, &overflow); + overall_overflow |= overflow; + } + else + { + /* (compare_bound - base) / compare_step */ + tem = wi::sub (wi::to_widest (compare_var), + wi::to_widest (compare_base), SIGNED, &overflow); + overall_overflow |= overflow; + compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), + SIGNED, &overflow); + overall_overflow |= overflow; + } + if (compare_code == LE_EXPR || compare_code == GE_EXPR) + ++compare_count; + if (loop_bound_code == LE_EXPR || loop_bound_code == GE_EXPR) + ++loop_count; + if (wi::neg_p (compare_count)) + compare_count = 0; + if (wi::neg_p (loop_count)) + loop_count = 0; + if (loop_count == 0) + probability = 0; + else if (wi::cmps (compare_count, loop_count) == 1) + probability = REG_BR_PROB_BASE; + else + { + tem = compare_count * REG_BR_PROB_BASE; + tem = wi::udiv_trunc (tem, loop_count); + probability = tem.to_uhwi (); + } + + /* FIXME: The branch prediction seems broken. It has only 20% hitrate. */ + if (!overall_overflow) + predict_edge (then_edge, PRED_LOOP_IV_COMPARE, probability); + + return; + } + + if (expr_coherent_p (loop_bound_var, compare_var)) + { + if ((loop_bound_code == LT_EXPR || loop_bound_code == LE_EXPR) + && (compare_code == LT_EXPR || compare_code == LE_EXPR)) + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); + else if ((loop_bound_code == GT_EXPR || loop_bound_code == GE_EXPR) + && (compare_code == GT_EXPR || compare_code == GE_EXPR)) + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); + else if (loop_bound_code == NE_EXPR) + { + /* If the loop backedge condition is "(i != bound)", we do + the comparison based on the step of IV: + * step < 0 : backedge condition is like (i > bound) + * step > 0 : backedge condition is like (i < bound) */ + gcc_assert (loop_bound_step != 0); + if (loop_bound_step > 0 + && (compare_code == LT_EXPR + || compare_code == LE_EXPR)) + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); + else if (loop_bound_step < 0 + && (compare_code == GT_EXPR + || compare_code == GE_EXPR)) + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); + else + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); + } + else + /* The branch is predicted not-taken if loop_bound_code is + opposite with compare_code. */ + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); + } + else if (expr_coherent_p (loop_iv_base_var, compare_var)) + { + /* For cases like: + for (i = s; i < h; i++) + if (i > s + 2) .... + The branch should be predicted taken. */ + if (loop_bound_step > 0 + && (compare_code == GT_EXPR || compare_code == GE_EXPR)) + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); + else if (loop_bound_step < 0 + && (compare_code == LT_EXPR || compare_code == LE_EXPR)) + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); + else + predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); + } +} + +/* Predict for extra loop exits that will lead to EXIT_EDGE. The extra loop + exits are resulted from short-circuit conditions that will generate an + if_tmp. E.g.: + + if (foo() || global > 10) + break; + + This will be translated into: + + BB3: + loop header... + BB4: + if foo() goto BB6 else goto BB5 + BB5: + if global > 10 goto BB6 else goto BB7 + BB6: + goto BB7 + BB7: + iftmp = (PHI 0(BB5), 1(BB6)) + if iftmp == 1 goto BB8 else goto BB3 + BB8: + outside of the loop... + + The edge BB7->BB8 is loop exit because BB8 is outside of the loop. + From the dataflow, we can infer that BB4->BB6 and BB5->BB6 are also loop + exits. This function takes BB7->BB8 as input, and finds out the extra loop + exits to predict them using PRED_LOOP_EXTRA_EXIT. */ + +static void +predict_extra_loop_exits (edge exit_edge) +{ + unsigned i; + bool check_value_one; + gimple *lhs_def_stmt; + gphi *phi_stmt; + tree cmp_rhs, cmp_lhs; + gimple *last; + gcond *cmp_stmt; + + last = last_stmt (exit_edge->src); + if (!last) + return; + cmp_stmt = dyn_cast <gcond *> (last); + if (!cmp_stmt) + return; + + cmp_rhs = gimple_cond_rhs (cmp_stmt); + cmp_lhs = gimple_cond_lhs (cmp_stmt); + if (!TREE_CONSTANT (cmp_rhs) + || !(integer_zerop (cmp_rhs) || integer_onep (cmp_rhs))) + return; + if (TREE_CODE (cmp_lhs) != SSA_NAME) + return; + + /* If check_value_one is true, only the phi_args with value '1' will lead + to loop exit. Otherwise, only the phi_args with value '0' will lead to + loop exit. */ + check_value_one = (((integer_onep (cmp_rhs)) + ^ (gimple_cond_code (cmp_stmt) == EQ_EXPR)) + ^ ((exit_edge->flags & EDGE_TRUE_VALUE) != 0)); + + lhs_def_stmt = SSA_NAME_DEF_STMT (cmp_lhs); + if (!lhs_def_stmt) + return; + + phi_stmt = dyn_cast <gphi *> (lhs_def_stmt); + if (!phi_stmt) + return; + + for (i = 0; i < gimple_phi_num_args (phi_stmt); i++) + { + edge e1; + edge_iterator ei; + tree val = gimple_phi_arg_def (phi_stmt, i); + edge e = gimple_phi_arg_edge (phi_stmt, i); + + if (!TREE_CONSTANT (val) || !(integer_zerop (val) || integer_onep (val))) + continue; + if ((check_value_one ^ integer_onep (val)) == 1) + continue; + if (EDGE_COUNT (e->src->succs) != 1) + { + predict_paths_leading_to_edge (e, PRED_LOOP_EXTRA_EXIT, NOT_TAKEN); + continue; + } + + FOR_EACH_EDGE (e1, ei, e->src->preds) + predict_paths_leading_to_edge (e1, PRED_LOOP_EXTRA_EXIT, NOT_TAKEN); + } +} + + /* Predict edge probabilities by exploiting loop structure. */ static void predict_loops (void) { - loop_iterator li; struct loop *loop; + basic_block bb; + hash_set <struct loop *> with_recursion(10); + + FOR_EACH_BB_FN (bb, cfun) + { + gimple_stmt_iterator gsi; + tree decl; + + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + if (is_gimple_call (gsi_stmt (gsi)) + && (decl = gimple_call_fndecl (gsi_stmt (gsi))) != NULL + && recursive_call_p (current_function_decl, decl)) + { + loop = bb->loop_father; + while (loop && !with_recursion.add (loop)) + loop = loop_outer (loop); + } + } /* Try to predict out blocks in a loop that are not part of a natural loop. */ - FOR_EACH_LOOP (li, loop, 0) + FOR_EACH_LOOP (loop, LI_FROM_INNERMOST) { basic_block bb, *bbs; - unsigned j, n_exits; - VEC (edge, heap) *exits; + unsigned j, n_exits = 0; + vec<edge> exits; struct tree_niter_desc niter_desc; edge ex; + struct nb_iter_bound *nb_iter; + enum tree_code loop_bound_code = ERROR_MARK; + tree loop_bound_step = NULL; + tree loop_bound_var = NULL; + tree loop_iv_base = NULL; + gcond *stmt = NULL; + bool recursion = with_recursion.contains (loop); exits = get_loop_exit_edges (loop); - n_exits = VEC_length (edge, exits); - - FOR_EACH_VEC_ELT (edge, exits, j, ex) + FOR_EACH_VEC_ELT (exits, j, ex) + if (!unlikely_executed_edge_p (ex) && !(ex->flags & EDGE_ABNORMAL_CALL)) + n_exits ++; + if (!n_exits) + { + exits.release (); + continue; + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Predicting loop %i%s with %i exits.\n", + loop->num, recursion ? " (with recursion)":"", n_exits); + if (dump_file && (dump_flags & TDF_DETAILS) + && max_loop_iterations_int (loop) >= 0) + { + fprintf (dump_file, + "Loop %d iterates at most %i times.\n", loop->num, + (int)max_loop_iterations_int (loop)); + } + if (dump_file && (dump_flags & TDF_DETAILS) + && likely_max_loop_iterations_int (loop) >= 0) + { + fprintf (dump_file, "Loop %d likely iterates at most %i times.\n", + loop->num, (int)likely_max_loop_iterations_int (loop)); + } + + FOR_EACH_VEC_ELT (exits, j, ex) { tree niter = NULL; HOST_WIDE_INT nitercst; int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS); int probability; enum br_predictor predictor; - - if (number_of_iterations_exit (loop, ex, &niter_desc, false)) + widest_int nit; + + if (unlikely_executed_edge_p (ex) + || (ex->flags & EDGE_ABNORMAL_CALL)) + continue; + /* Loop heuristics do not expect exit conditional to be inside + inner loop. We predict from innermost to outermost loop. */ + if (predicted_by_loop_heuristics_p (ex->src)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Skipping exit %i->%i because " + "it is already predicted.\n", + ex->src->index, ex->dest->index); + continue; + } + predict_extra_loop_exits (ex); + + if (number_of_iterations_exit (loop, ex, &niter_desc, false, false)) niter = niter_desc.niter; if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST) niter = loop_niter_by_eval (loop, ex); + if (dump_file && (dump_flags & TDF_DETAILS) + && TREE_CODE (niter) == INTEGER_CST) + { + fprintf (dump_file, "Exit %i->%i %d iterates ", + ex->src->index, ex->dest->index, + loop->num); + print_generic_expr (dump_file, niter, TDF_SLIM); + fprintf (dump_file, " times.\n"); + } if (TREE_CODE (niter) == INTEGER_CST) { - if (host_integerp (niter, 1) - && compare_tree_int (niter, max-1) == -1) - nitercst = tree_low_cst (niter, 1) + 1; + if (tree_fits_uhwi_p (niter) + && max + && compare_tree_int (niter, max - 1) == -1) + nitercst = tree_to_uhwi (niter) + 1; else nitercst = max; predictor = PRED_LOOP_ITERATIONS; @@ -975,29 +1907,75 @@ /* If we have just one exit and we can derive some information about the number of iterations of the loop from the statements inside the loop, use it to predict this exit. */ - else if (n_exits == 1) + else if (n_exits == 1 + && estimated_stmt_executions (loop, &nit)) { - nitercst = estimated_loop_iterations_int (loop, false); - if (nitercst < 0) - continue; - if (nitercst > max) + if (wi::gtu_p (nit, max)) nitercst = max; - + else + nitercst = nit.to_shwi (); predictor = PRED_LOOP_ITERATIONS_GUESSED; } + /* If we have likely upper bound, trust it for very small iteration + counts. Such loops would otherwise get mispredicted by standard + LOOP_EXIT heuristics. */ + else if (n_exits == 1 + && likely_max_stmt_executions (loop, &nit) + && wi::ltu_p (nit, + RDIV (REG_BR_PROB_BASE, + REG_BR_PROB_BASE + - predictor_info + [recursion + ? PRED_LOOP_EXIT_WITH_RECURSION + : PRED_LOOP_EXIT].hitrate))) + { + nitercst = nit.to_shwi (); + predictor = PRED_LOOP_ITERATIONS_MAX; + } else + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Nothing known about exit %i->%i.\n", + ex->src->index, ex->dest->index); + continue; + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Recording prediction to %i iterations by %s.\n", + (int)nitercst, predictor_info[predictor].name); + /* If the prediction for number of iterations is zero, do not + predict the exit edges. */ + if (nitercst == 0) continue; - probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst); + probability = RDIV (REG_BR_PROB_BASE, nitercst); predict_edge (ex, predictor, probability); } - VEC_free (edge, heap, exits); + exits.release (); + + /* Find information about loop bound variables. */ + for (nb_iter = loop->bounds; nb_iter; + nb_iter = nb_iter->next) + if (nb_iter->stmt + && gimple_code (nb_iter->stmt) == GIMPLE_COND) + { + stmt = as_a <gcond *> (nb_iter->stmt); + break; + } + if (!stmt && last_stmt (loop->header) + && gimple_code (last_stmt (loop->header)) == GIMPLE_COND) + stmt = as_a <gcond *> (last_stmt (loop->header)); + if (stmt) + is_comparison_with_loop_invariant_p (stmt, loop, + &loop_bound_var, + &loop_bound_code, + &loop_bound_step, + &loop_iv_base); bbs = get_loop_body (loop); for (j = 0; j < loop->num_nodes; j++) { - int header_found = 0; edge e; edge_iterator ei; @@ -1008,27 +1986,16 @@ in the source language and are better to be handled separately. */ if (predicted_by_p (bb, PRED_CONTINUE)) - continue; - - /* Loop branch heuristics - predict an edge back to a - loop's head as taken. */ - if (bb == loop->latch) { - e = find_edge (loop->latch, loop->header); - if (e) - { - header_found = 1; - predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN); - } + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "BB %i predicted by continue.\n", + bb->index); + continue; } - /* Loop exit heuristics - predict an edge exiting the loop if the - conditional has no loop header successors as not taken. */ - if (!header_found - /* If we already used more reliable loop exit predictors, do not - bother with PRED_LOOP_EXIT. */ - && !predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) - && !predicted_by_p (bb, PRED_LOOP_ITERATIONS)) + /* If we already used more reliable loop exit predictors, do not + bother with PRED_LOOP_EXIT. */ + if (!predicted_by_loop_heuristics_p (bb)) { /* For loop with many exits we don't want to predict all exits with the pretty large probability, because if all exits are @@ -1045,14 +2012,99 @@ a wide loop. */ int probability = ((REG_BR_PROB_BASE - - predictor_info [(int) PRED_LOOP_EXIT].hitrate) + - predictor_info + [recursion + ? PRED_LOOP_EXIT_WITH_RECURSION + : PRED_LOOP_EXIT].hitrate) / n_exits); if (probability < HITRATE (2)) probability = HITRATE (2); 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, probability); + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, + "Predicting exit %i->%i with prob %i.\n", + e->src->index, e->dest->index, probability); + predict_edge (e, + recursion ? PRED_LOOP_EXIT_WITH_RECURSION + : PRED_LOOP_EXIT, probability); + } + } + if (loop_bound_var) + predict_iv_comparison (loop, bb, loop_bound_var, loop_iv_base, + loop_bound_code, + tree_to_shwi (loop_bound_step)); + } + + /* In the following code + for (loop1) + if (cond) + for (loop2) + body; + guess that cond is unlikely. */ + if (loop_outer (loop)->num) + { + basic_block bb = NULL; + edge preheader_edge = loop_preheader_edge (loop); + + if (single_pred_p (preheader_edge->src) + && single_succ_p (preheader_edge->src)) + preheader_edge = single_pred_edge (preheader_edge->src); + + gimple *stmt = last_stmt (preheader_edge->src); + /* Pattern match fortran loop preheader: + _16 = BUILTIN_EXPECT (_15, 1, PRED_FORTRAN_LOOP_PREHEADER); + _17 = (logical(kind=4)) _16; + if (_17 != 0) + goto <bb 11>; + else + goto <bb 13>; + + Loop guard branch prediction says nothing about duplicated loop + headers produced by fortran frontend and in this case we want + to predict paths leading to this preheader. */ + + if (stmt + && gimple_code (stmt) == GIMPLE_COND + && gimple_cond_code (stmt) == NE_EXPR + && TREE_CODE (gimple_cond_lhs (stmt)) == SSA_NAME + && integer_zerop (gimple_cond_rhs (stmt))) + { + gimple *call_stmt = SSA_NAME_DEF_STMT (gimple_cond_lhs (stmt)); + if (gimple_code (call_stmt) == GIMPLE_ASSIGN + && gimple_expr_code (call_stmt) == NOP_EXPR + && TREE_CODE (gimple_assign_rhs1 (call_stmt)) == SSA_NAME) + call_stmt = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (call_stmt)); + if (gimple_call_internal_p (call_stmt, IFN_BUILTIN_EXPECT) + && TREE_CODE (gimple_call_arg (call_stmt, 2)) == INTEGER_CST + && tree_fits_uhwi_p (gimple_call_arg (call_stmt, 2)) + && tree_to_uhwi (gimple_call_arg (call_stmt, 2)) + == PRED_FORTRAN_LOOP_PREHEADER) + bb = preheader_edge->src; + } + if (!bb) + { + if (!dominated_by_p (CDI_DOMINATORS, + loop_outer (loop)->latch, loop->header)) + predict_paths_leading_to_edge (loop_preheader_edge (loop), + recursion + ? PRED_LOOP_GUARD_WITH_RECURSION + : PRED_LOOP_GUARD, + NOT_TAKEN, + loop_outer (loop)); + } + else + { + if (!dominated_by_p (CDI_DOMINATORS, + loop_outer (loop)->latch, bb)) + predict_paths_leading_to (bb, + recursion + ? PRED_LOOP_GUARD_WITH_RECURSION + : PRED_LOOP_GUARD, + NOT_TAKEN, + loop_outer (loop)); } } @@ -1066,7 +2118,7 @@ static void bb_estimate_probability_locally (basic_block bb) { - rtx last_insn = BB_END (bb); + rtx_insn *last_insn = BB_END (bb); rtx cond; if (! can_predict_insn_p (last_insn)) @@ -1168,20 +2220,43 @@ combine_predictions_for_insn (BB_END (bb), bb); } -static tree expr_expected_value (tree, bitmap); +static tree expr_expected_value (tree, bitmap, enum br_predictor *predictor); /* Helper function for expr_expected_value. */ static tree -expr_expected_value_1 (tree type, tree op0, enum tree_code code, tree op1, bitmap visited) +expr_expected_value_1 (tree type, tree op0, enum tree_code code, + tree op1, bitmap visited, enum br_predictor *predictor) { - gimple def; + gimple *def; + + if (predictor) + *predictor = PRED_UNCONDITIONAL; if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS) { if (TREE_CONSTANT (op0)) return op0; + if (code == IMAGPART_EXPR) + { + if (TREE_CODE (TREE_OPERAND (op0, 0)) == SSA_NAME) + { + def = SSA_NAME_DEF_STMT (TREE_OPERAND (op0, 0)); + if (is_gimple_call (def) + && gimple_call_internal_p (def) + && (gimple_call_internal_fn (def) + == IFN_ATOMIC_COMPARE_EXCHANGE)) + { + /* Assume that any given atomic operation has low contention, + and thus the compare-and-swap operation succeeds. */ + if (predictor) + *predictor = PRED_COMPARE_AND_SWAP; + return build_one_cst (TREE_TYPE (op0)); + } + } + } + if (code != SSA_NAME) return NULL_TREE; @@ -1201,6 +2276,7 @@ for (i = 0; i < n; i++) { tree arg = PHI_ARG_DEF (def, i); + enum br_predictor predictor2; /* If this PHI has itself as an argument, we cannot determine the string length of this argument. However, @@ -1211,7 +2287,12 @@ if (arg == PHI_RESULT (def)) continue; - new_val = expr_expected_value (arg, visited); + new_val = expr_expected_value (arg, visited, &predictor2); + + /* It is difficult to combine value predictors. Simply assume + that later predictor is weaker and take its prediction. */ + if (predictor && *predictor < predictor2) + *predictor = predictor2; if (!new_val) return NULL; if (!val) @@ -1230,25 +2311,69 @@ gimple_assign_rhs1 (def), gimple_assign_rhs_code (def), gimple_assign_rhs2 (def), - visited); + visited, predictor); } if (is_gimple_call (def)) { tree decl = gimple_call_fndecl (def); if (!decl) - return NULL; - if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL - && DECL_FUNCTION_CODE (decl) == BUILT_IN_EXPECT) { - tree val; - - if (gimple_call_num_args (def) != 2) - return NULL; - val = gimple_call_arg (def, 0); - if (TREE_CONSTANT (val)) - return val; - return gimple_call_arg (def, 1); + if (gimple_call_internal_p (def) + && gimple_call_internal_fn (def) == IFN_BUILTIN_EXPECT) + { + gcc_assert (gimple_call_num_args (def) == 3); + tree val = gimple_call_arg (def, 0); + if (TREE_CONSTANT (val)) + return val; + if (predictor) + { + tree val2 = gimple_call_arg (def, 2); + gcc_assert (TREE_CODE (val2) == INTEGER_CST + && tree_fits_uhwi_p (val2) + && tree_to_uhwi (val2) < END_PREDICTORS); + *predictor = (enum br_predictor) tree_to_uhwi (val2); + } + return gimple_call_arg (def, 1); + } + return NULL; + } + if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL) + switch (DECL_FUNCTION_CODE (decl)) + { + case BUILT_IN_EXPECT: + { + tree val; + if (gimple_call_num_args (def) != 2) + return NULL; + val = gimple_call_arg (def, 0); + if (TREE_CONSTANT (val)) + return val; + if (predictor) + *predictor = PRED_BUILTIN_EXPECT; + return gimple_call_arg (def, 1); + } + + case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_N: + case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1: + case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2: + case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4: + case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8: + case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16: + case BUILT_IN_ATOMIC_COMPARE_EXCHANGE: + case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_N: + case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1: + case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2: + case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4: + case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8: + case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16: + /* Assume that any given atomic operation has low contention, + and thus the compare-and-swap operation succeeds. */ + if (predictor) + *predictor = PRED_COMPARE_AND_SWAP; + return boolean_true_node; + default: + break; } } @@ -1258,10 +2383,13 @@ if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS) { tree res; - op0 = expr_expected_value (op0, visited); + enum br_predictor predictor2; + op0 = expr_expected_value (op0, visited, predictor); if (!op0) return NULL; - op1 = expr_expected_value (op1, visited); + op1 = expr_expected_value (op1, visited, &predictor2); + if (predictor && *predictor < predictor2) + *predictor = predictor2; if (!op1) return NULL; res = fold_build2 (code, type, op0, op1); @@ -1272,7 +2400,7 @@ if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS) { tree res; - op0 = expr_expected_value (op0, visited); + op0 = expr_expected_value (op0, visited, predictor); if (!op0) return NULL; res = fold_build1 (code, type, op0); @@ -1292,82 +2420,36 @@ implementation. */ static tree -expr_expected_value (tree expr, bitmap visited) +expr_expected_value (tree expr, bitmap visited, + enum br_predictor *predictor) { enum tree_code code; tree op0, op1; if (TREE_CONSTANT (expr)) - return expr; + { + if (predictor) + *predictor = PRED_UNCONDITIONAL; + return expr; + } extract_ops_from_tree (expr, &code, &op0, &op1); return expr_expected_value_1 (TREE_TYPE (expr), - op0, code, op1, visited); -} - - -/* Get rid of all builtin_expect calls and GIMPLE_PREDICT statements - we no longer need. */ -static unsigned int -strip_predict_hints (void) -{ - basic_block bb; - gimple ass_stmt; - tree var; - - FOR_EACH_BB (bb) - { - gimple_stmt_iterator bi; - for (bi = gsi_start_bb (bb); !gsi_end_p (bi);) - { - gimple stmt = gsi_stmt (bi); - - if (gimple_code (stmt) == GIMPLE_PREDICT) - { - gsi_remove (&bi, true); - continue; - } - else if (gimple_code (stmt) == GIMPLE_CALL) - { - tree fndecl = gimple_call_fndecl (stmt); - - if (fndecl - && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL - && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT - && gimple_call_num_args (stmt) == 2) - { - var = gimple_call_lhs (stmt); - if (var) - { - ass_stmt - = gimple_build_assign (var, gimple_call_arg (stmt, 0)); - gsi_replace (&bi, ass_stmt, true); - } - else - { - gsi_remove (&bi, true); - continue; - } - } - } - gsi_next (&bi); - } - } - return 0; + op0, code, op1, visited, predictor); } /* Predict using opcode of the last statement in basic block. */ static void tree_predict_by_opcode (basic_block bb) { - gimple stmt = last_stmt (bb); + gimple *stmt = last_stmt (bb); edge then_edge; tree op0, op1; tree type; tree val; enum tree_code cmp; - bitmap visited; edge_iterator ei; + enum br_predictor predictor; if (!stmt || gimple_code (stmt) != GIMPLE_COND) return; @@ -1378,16 +2460,22 @@ op1 = gimple_cond_rhs (stmt); cmp = gimple_cond_code (stmt); type = TREE_TYPE (op0); - visited = BITMAP_ALLOC (NULL); - val = expr_expected_value_1 (boolean_type_node, op0, cmp, op1, visited); - BITMAP_FREE (visited); - if (val) + val = expr_expected_value_1 (boolean_type_node, op0, cmp, op1, auto_bitmap (), + &predictor); + if (val && TREE_CODE (val) == INTEGER_CST) { - if (integer_zerop (val)) - predict_edge_def (then_edge, PRED_BUILTIN_EXPECT, NOT_TAKEN); + if (predictor == PRED_BUILTIN_EXPECT) + { + int percent = PARAM_VALUE (BUILTIN_EXPECT_PROBABILITY); + + gcc_assert (percent >= 0 && percent <= 100); + if (integer_zerop (val)) + percent = 100 - percent; + predict_edge (then_edge, PRED_BUILTIN_EXPECT, HITRATE (percent)); + } else - predict_edge_def (then_edge, PRED_BUILTIN_EXPECT, TAKEN); - return; + predict_edge_def (then_edge, predictor, + integer_zerop (val) ? NOT_TAKEN : TAKEN); } /* Try "pointer heuristic." A comparison ptr == 0 is predicted as false. @@ -1473,6 +2561,21 @@ } } +/* Returns TRUE if the STMT is exit(0) like statement. */ + +static bool +is_exit_with_zero_arg (const gimple *stmt) +{ + /* This is not exit, _exit or _Exit. */ + if (!gimple_call_builtin_p (stmt, BUILT_IN_EXIT) + && !gimple_call_builtin_p (stmt, BUILT_IN__EXIT) + && !gimple_call_builtin_p (stmt, BUILT_IN__EXIT2)) + return false; + + /* Argument is an interger zero. */ + return integer_zerop (gimple_call_arg (stmt, 0)); +} + /* Try to guess whether the value of return means error code. */ static enum br_predictor @@ -1507,7 +2610,7 @@ if (TREE_CONSTANT (val) && (!integer_zerop (val) && !integer_onep (val))) { - *prediction = TAKEN; + *prediction = NOT_TAKEN; return PRED_CONST_RETURN; } } @@ -1519,21 +2622,24 @@ static void apply_return_prediction (void) { - gimple return_stmt = NULL; + greturn *return_stmt = NULL; tree return_val; edge e; - gimple phi; + gphi *phi; int phi_num_args, i; enum br_predictor pred; enum prediction direction; edge_iterator ei; - FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) + FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) { - return_stmt = last_stmt (e->src); - if (return_stmt - && gimple_code (return_stmt) == GIMPLE_RETURN) - break; + gimple *last = last_stmt (e->src); + if (last + && gimple_code (last) == GIMPLE_RETURN) + { + return_stmt = as_a <greturn *> (last); + break; + } } if (!e) return; @@ -1544,7 +2650,7 @@ || !SSA_NAME_DEF_STMT (return_val) || gimple_code (SSA_NAME_DEF_STMT (return_val)) != GIMPLE_PHI) return; - phi = SSA_NAME_DEF_STMT (return_val); + phi = as_a <gphi *> (SSA_NAME_DEF_STMT (return_val)); phi_num_args = gimple_phi_num_args (phi); pred = return_prediction (PHI_ARG_DEF (phi, 0), &direction); @@ -1576,8 +2682,8 @@ edge e; edge_iterator ei; - FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) - if (!(e->flags & (EDGE_ABNORMAL | EDGE_FAKE | EDGE_EH))) + FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) + if (!unlikely_executed_edge_p (e) && !(e->flags & EDGE_ABNORMAL_CALL)) { has_return_edges = true; break; @@ -1585,19 +2691,20 @@ apply_return_prediction (); - FOR_EACH_BB (bb) + FOR_EACH_BB_FN (bb, cfun) { gimple_stmt_iterator gsi; for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { - gimple stmt = gsi_stmt (gsi); + gimple *stmt = gsi_stmt (gsi); tree decl; if (is_gimple_call (stmt)) { - if ((gimple_call_flags (stmt) & ECF_NORETURN) - && has_return_edges) + if (gimple_call_noreturn_p (stmt) + && has_return_edges + && !is_exit_with_zero_arg (stmt)) predict_paths_leading_to (bb, PRED_NORETURN, NOT_TAKEN); decl = gimple_call_fndecl (stmt); @@ -1606,6 +2713,9 @@ DECL_ATTRIBUTES (decl))) predict_paths_leading_to (bb, PRED_COLD_FUNCTION, NOT_TAKEN); + if (decl && recursive_call_p (current_function_decl, decl)) + predict_paths_leading_to (bb, PRED_RECURSIVE_CALL, + NOT_TAKEN); } else if (gimple_code (stmt) == GIMPLE_PREDICT) { @@ -1618,74 +2728,32 @@ } } -#ifdef ENABLE_CHECKING - -/* Callback for pointer_map_traverse, asserts that the pointer map is +/* Callback for hash_map::traverse, asserts that the pointer map is empty. */ -static bool -assert_is_empty (const void *key ATTRIBUTE_UNUSED, void **value, - void *data ATTRIBUTE_UNUSED) +bool +assert_is_empty (const_basic_block const &, edge_prediction *const &value, + void *) { - gcc_assert (!*value); + gcc_assert (!value); return false; } -#endif - -/* Predict branch probabilities and estimate profile for basic block BB. */ + +/* Predict branch probabilities and estimate profile for basic block BB. + When LOCAL_ONLY is set do not use any global properties of CFG. */ static void -tree_estimate_probability_bb (basic_block bb) +tree_estimate_probability_bb (basic_block bb, bool local_only) { edge e; edge_iterator ei; - gimple last; 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 through function. - - Since we've already removed the return statements, we are - looking for CFG like: - - if (conditional) - { - .. - goto return_block - } - some other blocks - return_block: - return_stmt. */ - if (e->dest != bb->next_bb - && e->dest != EXIT_BLOCK_PTR - && single_succ_p (e->dest) - && single_succ_edge (e->dest)->dest == EXIT_BLOCK_PTR - && (last = last_stmt (e->dest)) != NULL - && gimple_code (last) == GIMPLE_RETURN) - { - edge e1; - edge_iterator ei1; - - if (single_succ_p (bb)) - { - 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)) - predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN); - } - else - if (!predicted_by_p (e->src, PRED_NULL_RETURN) - && !predicted_by_p (e->src, PRED_CONST_RETURN) - && !predicted_by_p (e->src, PRED_NEGATIVE_RETURN)) - predict_edge_def (e, PRED_TREE_EARLY_RETURN, NOT_TAKEN); - } - /* Look for block we are guarding (ie we dominate it, but it doesn't postdominate us). */ - if (e->dest != EXIT_BLOCK_PTR && e->dest != bb + if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) && e->dest != bb + && !local_only && dominated_by_p (CDI_DOMINATORS, e->dest, e->src) && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest)) { @@ -1698,13 +2766,19 @@ for (bi = gsi_start_bb (e->dest); !gsi_end_p (bi); gsi_next (&bi)) { - gimple stmt = gsi_stmt (bi); + gimple *stmt = gsi_stmt (bi); if (is_gimple_call (stmt) + && !gimple_inexpensive_call_p (as_a <gcall *> (stmt)) /* Constant and pure calls are hardly used to signalize something exceptional. */ && gimple_has_side_effects (stmt)) { - predict_edge_def (e, PRED_CALL, NOT_TAKEN); + if (gimple_call_fndecl (stmt)) + predict_edge_def (e, PRED_CALL, NOT_TAKEN); + else if (virtual_method_call_p (gimple_call_fn (stmt))) + predict_edge_def (e, PRED_POLYMORPHIC_CALL, NOT_TAKEN); + else + predict_edge_def (e, PRED_INDIR_CALL, TAKEN); break; } } @@ -1715,10 +2789,11 @@ /* Predict branch probabilities and estimate profile of the tree CFG. This function can be called from the loop optimizers to recompute - the profile information. */ + the profile information. + If DRY_RUN is set, do not modify CFG and only produce dump files. */ void -tree_estimate_probability (void) +tree_estimate_probability (bool dry_run) { basic_block bb; @@ -1729,59 +2804,42 @@ create_preheaders (CP_SIMPLE_PREHEADERS); calculate_dominance_info (CDI_POST_DOMINATORS); - bb_predictions = pointer_map_create (); + bb_predictions = new hash_map<const_basic_block, edge_prediction *>; tree_bb_level_predictions (); record_loop_exits (); - if (number_of_loops () > 1) + if (number_of_loops (cfun) > 1) predict_loops (); - FOR_EACH_BB (bb) - tree_estimate_probability_bb (bb); - - FOR_EACH_BB (bb) - combine_predictions_for_bb (bb); - -#ifdef ENABLE_CHECKING - pointer_map_traverse (bb_predictions, assert_is_empty, NULL); -#endif - pointer_map_destroy (bb_predictions); + FOR_EACH_BB_FN (bb, cfun) + tree_estimate_probability_bb (bb, false); + + FOR_EACH_BB_FN (bb, cfun) + combine_predictions_for_bb (bb, dry_run); + + if (flag_checking) + bb_predictions->traverse<void *, assert_is_empty> (NULL); + + delete bb_predictions; bb_predictions = NULL; - estimate_bb_frequencies (); + if (!dry_run) + estimate_bb_frequencies (false); free_dominance_info (CDI_POST_DOMINATORS); remove_fake_exit_edges (); } -/* Predict branch probabilities and estimate profile of the tree CFG. - This is the driver function for PASS_PROFILE. */ - -static unsigned int -tree_estimate_probability_driver (void) +/* Set edge->probability for each successor edge of BB. */ +void +tree_guess_outgoing_edge_probabilities (basic_block bb) { - unsigned nb_loops; - - loop_optimizer_init (0); - if (dump_file && (dump_flags & TDF_DETAILS)) - flow_loops_dump (dump_file, NULL, 0); - - mark_irreducible_loops (); - - nb_loops = number_of_loops (); - if (nb_loops > 1) - scev_initialize (); - - tree_estimate_probability (); - - if (nb_loops > 1) - scev_finalize (); - - loop_optimizer_finalize (); - if (dump_file && (dump_flags & TDF_DETAILS)) - gimple_dump_cfg (dump_file, dump_flags); - if (profile_status == PROFILE_ABSENT) - profile_status = PROFILE_GUESSED; - return 0; + bb_predictions = new hash_map<const_basic_block, edge_prediction *>; + tree_estimate_probability_bb (bb, true); + combine_predictions_for_bb (bb, false); + if (flag_checking) + bb_predictions->traverse<void *, assert_is_empty> (NULL); + delete bb_predictions; + bb_predictions = NULL; } /* Predict edges to successors of CUR whose sources are not postdominated by @@ -1790,12 +2848,20 @@ static void predict_paths_for_bb (basic_block cur, basic_block bb, enum br_predictor pred, - enum prediction taken) + enum prediction taken, + bitmap visited, struct loop *in_loop = NULL) { edge e; edge_iterator ei; basic_block son; + /* If we exited the loop or CUR is unconditional in the loop, there is + nothing to do. */ + if (in_loop + && (!flow_bb_inside_loop_p (in_loop, cur) + || dominated_by_p (CDI_DOMINATORS, in_loop->latch, cur))) + return; + /* We are looking for all edges forming edge cut induced by set of all blocks postdominated by BB. */ FOR_EACH_EDGE (e, ei, cur->preds) @@ -1807,16 +2873,17 @@ bool found = false; /* Ignore fake edges and eh, we predict them as not taken anyway. */ - if (e->flags & (EDGE_EH | EDGE_FAKE)) + if (unlikely_executed_edge_p (e)) continue; gcc_assert (bb == cur || dominated_by_p (CDI_POST_DOMINATORS, cur, bb)); - /* See if there is how many edge from e->src that is not abnormal - and does not lead to BB. */ + /* See if there is an edge from e->src that is not abnormal + and does not lead to BB and does not exit the loop. */ FOR_EACH_EDGE (e2, ei2, e->src->succs) if (e2 != e - && !(e2->flags & (EDGE_EH | EDGE_FAKE)) - && !dominated_by_p (CDI_POST_DOMINATORS, e2->dest, bb)) + && !unlikely_executed_edge_p (e2) + && !dominated_by_p (CDI_POST_DOMINATORS, e2->dest, bb) + && (!in_loop || !loop_exit_edge_p (in_loop, e2))) { found = true; break; @@ -1824,16 +2891,23 @@ /* If there is non-abnormal path leaving e->src, predict edge using predictor. Otherwise we need to look for paths - leading to e->src. */ + leading to e->src. + + The second may lead to infinite loop in the case we are predicitng + regions that are only reachable by abnormal edges. We simply + prevent visiting given BB twice. */ if (found) - predict_edge_def (e, pred, taken); - else - predict_paths_for_bb (e->src, e->src, pred, taken); + { + if (!edge_predicted_by_p (e, pred, taken)) + predict_edge_def (e, pred, taken); + } + else if (bitmap_set_bit (visited, e->src->index)) + predict_paths_for_bb (e->src, e->src, pred, taken, visited, in_loop); } for (son = first_dom_son (CDI_POST_DOMINATORS, cur); son; son = next_dom_son (CDI_POST_DOMINATORS, son)) - predict_paths_for_bb (son, bb, pred, taken); + predict_paths_for_bb (son, bb, pred, taken, visited, in_loop); } /* Sets branch probabilities according to PREDiction and @@ -1841,16 +2915,16 @@ static void predict_paths_leading_to (basic_block bb, enum br_predictor pred, - enum prediction taken) + enum prediction taken, struct loop *in_loop) { - predict_paths_for_bb (bb, bb, pred, taken); + predict_paths_for_bb (bb, bb, pred, taken, auto_bitmap (), in_loop); } /* Like predict_paths_leading_to but take edge instead of basic block. */ static void predict_paths_leading_to_edge (edge e, enum br_predictor pred, - enum prediction taken) + enum prediction taken, struct loop *in_loop) { bool has_nonloop_edge = false; edge_iterator ei; @@ -1859,14 +2933,16 @@ basic_block bb = e->src; FOR_EACH_EDGE (e2, ei, bb->succs) if (e2->dest != e->src && e2->dest != e->dest - && !(e->flags & (EDGE_EH | EDGE_FAKE)) + && !unlikely_executed_edge_p (e) && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e2->dest)) { has_nonloop_edge = true; break; } if (!has_nonloop_edge) - predict_paths_for_bb (bb, bb, pred, taken); + { + predict_paths_for_bb (bb, bb, pred, taken, auto_bitmap (), in_loop); + } else predict_edge_def (e, pred, taken); } @@ -1874,7 +2950,7 @@ /* 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 +struct block_info { /* Estimated frequency of execution of basic_block. */ sreal frequency; @@ -1884,10 +2960,10 @@ /* Number of predecessors we need to visit first. */ int npredecessors; -} *block_info; +}; /* Similar information for edges. */ -typedef struct edge_info_def +struct edge_prob_info { /* 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 @@ -1895,10 +2971,11 @@ sreal back_edge_prob; /* 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) -#define EDGE_INFO(E) ((edge_info) (E)->aux) +}; + +#define BLOCK_INFO(B) ((block_info *) (B)->aux) +#undef EDGE_INFO +#define EDGE_INFO(E) ((edge_prob_info *) (E)->aux) /* Helper function for estimate_bb_frequencies. Propagate the frequencies in blocks marked in @@ -1921,7 +2998,7 @@ edge_iterator ei; int count = 0; - bb = BASIC_BLOCK (i); + bb = BASIC_BLOCK_FOR_FN (cfun, i); FOR_EACH_EDGE (e, ei, bb->preds) { @@ -1936,19 +3013,20 @@ } BLOCK_INFO (bb)->npredecessors = count; /* When function never returns, we will never process exit block. */ - if (!count && bb == EXIT_BLOCK_PTR) - bb->count = bb->frequency = 0; + if (!count && bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) + { + bb->count = profile_count::zero (); + bb->frequency = 0; + } } - memcpy (&BLOCK_INFO (head)->frequency, &real_one, sizeof (real_one)); + BLOCK_INFO (head)->frequency = 1; last = head; for (bb = head; bb; bb = nextbb) { edge_iterator ei; - sreal cyclic_probability, frequency; - - memcpy (&cyclic_probability, &real_zero, sizeof (real_zero)); - memcpy (&frequency, &real_zero, sizeof (real_zero)); + sreal cyclic_probability = 0; + sreal frequency = 0; nextbb = BLOCK_INFO (bb)->next; BLOCK_INFO (bb)->next = NULL; @@ -1956,51 +3034,42 @@ /* Compute frequency of basic block. */ if (bb != head) { -#ifdef ENABLE_CHECKING - FOR_EACH_EDGE (e, ei, bb->preds) - gcc_assert (!bitmap_bit_p (tovisit, e->src->index) - || (e->flags & EDGE_DFS_BACK)); -#endif + if (flag_checking) + FOR_EACH_EDGE (e, ei, bb->preds) + gcc_assert (!bitmap_bit_p (tovisit, e->src->index) + || (e->flags & EDGE_DFS_BACK)); FOR_EACH_EDGE (e, ei, bb->preds) if (EDGE_INFO (e)->back_edge) { - sreal_add (&cyclic_probability, &cyclic_probability, - &EDGE_INFO (e)->back_edge_prob); + cyclic_probability += EDGE_INFO (e)->back_edge_prob; } else if (!(e->flags & EDGE_DFS_BACK)) { - sreal tmp; - /* frequency += (e->probability * BLOCK_INFO (e->src)->frequency / REG_BR_PROB_BASE); */ - sreal_init (&tmp, e->probability, 0); - sreal_mul (&tmp, &tmp, &BLOCK_INFO (e->src)->frequency); - sreal_mul (&tmp, &tmp, &real_inv_br_prob_base); - sreal_add (&frequency, &frequency, &tmp); + sreal tmp = e->probability.to_reg_br_prob_base (); + tmp *= BLOCK_INFO (e->src)->frequency; + tmp *= real_inv_br_prob_base; + frequency += tmp; } - if (sreal_compare (&cyclic_probability, &real_zero) == 0) + if (cyclic_probability == 0) { - memcpy (&BLOCK_INFO (bb)->frequency, &frequency, - sizeof (frequency)); + BLOCK_INFO (bb)->frequency = frequency; } else { - if (sreal_compare (&cyclic_probability, &real_almost_one) > 0) - { - memcpy (&cyclic_probability, &real_almost_one, - sizeof (real_almost_one)); - } + if (cyclic_probability > real_almost_one) + cyclic_probability = 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); + cyclic_probability = sreal (1) - cyclic_probability; + BLOCK_INFO (bb)->frequency = frequency / cyclic_probability; } } @@ -2009,16 +3078,13 @@ 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); + sreal tmp = e->probability.to_reg_br_prob_base (); + tmp *= BLOCK_INFO (bb)->frequency; + EDGE_INFO (e)->back_edge_prob = tmp * real_inv_br_prob_base; } /* Propagate to successor blocks. */ @@ -2040,7 +3106,7 @@ } } -/* Estimate probabilities of loopback edges in loops at same nest level. */ +/* Estimate frequencies in loops at same nest level. */ static void estimate_loops_at_level (struct loop *first_loop) @@ -2052,7 +3118,7 @@ edge e; basic_block *bbs; unsigned i; - bitmap tovisit = BITMAP_ALLOC (NULL); + auto_bitmap tovisit; estimate_loops_at_level (loop->inner); @@ -2065,7 +3131,6 @@ bitmap_set_bit (tovisit, bbs[i]->index); free (bbs); propagate_freq (loop->header, tovisit); - BITMAP_FREE (tovisit); } } @@ -2074,39 +3139,194 @@ static void estimate_loops (void) { - bitmap tovisit = BITMAP_ALLOC (NULL); + auto_bitmap tovisit; basic_block bb; /* Start by estimating the frequencies in the loops. */ - if (number_of_loops () > 1) + if (number_of_loops (cfun) > 1) estimate_loops_at_level (current_loops->tree_root->inner); /* Now propagate the frequencies through all the blocks. */ - FOR_ALL_BB (bb) + FOR_ALL_BB_FN (bb, cfun) { bitmap_set_bit (tovisit, bb->index); } - propagate_freq (ENTRY_BLOCK_PTR, tovisit); - BITMAP_FREE (tovisit); + propagate_freq (ENTRY_BLOCK_PTR_FOR_FN (cfun), tovisit); +} + +/* Drop the profile for NODE to guessed, and update its frequency based on + whether it is expected to be hot given the CALL_COUNT. */ + +static void +drop_profile (struct cgraph_node *node, profile_count call_count) +{ + struct function *fn = DECL_STRUCT_FUNCTION (node->decl); + /* In the case where this was called by another function with a + dropped profile, call_count will be 0. Since there are no + non-zero call counts to this function, we don't know for sure + whether it is hot, and therefore it will be marked normal below. */ + bool hot = maybe_hot_count_p (NULL, call_count); + + if (dump_file) + fprintf (dump_file, + "Dropping 0 profile for %s. %s based on calls.\n", + node->dump_name (), + hot ? "Function is hot" : "Function is normal"); + /* We only expect to miss profiles for functions that are reached + via non-zero call edges in cases where the function may have + been linked from another module or library (COMDATs and extern + templates). See the comments below for handle_missing_profiles. + Also, only warn in cases where the missing counts exceed the + number of training runs. In certain cases with an execv followed + by a no-return call the profile for the no-return call is not + dumped and there can be a mismatch. */ + if (!DECL_COMDAT (node->decl) && !DECL_EXTERNAL (node->decl) + && call_count > profile_info->runs) + { + if (flag_profile_correction) + { + if (dump_file) + fprintf (dump_file, + "Missing counts for called function %s\n", + node->dump_name ()); + } + else + warning (0, "Missing counts for called function %s", + node->dump_name ()); + } + + basic_block bb; + FOR_ALL_BB_FN (bb, fn) + { + bb->count = profile_count::uninitialized (); + } + + struct cgraph_edge *e; + for (e = node->callees; e; e = e->next_caller) + { + e->frequency = compute_call_stmt_bb_frequency (e->caller->decl, + gimple_bb (e->call_stmt)); + } + + profile_status_for_fn (fn) + = (flag_guess_branch_prob ? PROFILE_GUESSED : PROFILE_ABSENT); + node->frequency + = hot ? NODE_FREQUENCY_HOT : NODE_FREQUENCY_NORMAL; +} + +/* In the case of COMDAT routines, multiple object files will contain the same + function and the linker will select one for the binary. In that case + all the other copies from the profile instrument binary will be missing + profile counts. Look for cases where this happened, due to non-zero + call counts going to 0-count functions, and drop the profile to guessed + so that we can use the estimated probabilities and avoid optimizing only + for size. + + The other case where the profile may be missing is when the routine + is not going to be emitted to the object file, e.g. for "extern template" + class methods. Those will be marked DECL_EXTERNAL. Emit a warning in + all other cases of non-zero calls to 0-count functions. */ + +void +handle_missing_profiles (void) +{ + struct cgraph_node *node; + int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); + auto_vec<struct cgraph_node *, 64> worklist; + + /* See if 0 count function has non-0 count callers. In this case we + lost some profile. Drop its function profile to PROFILE_GUESSED. */ + FOR_EACH_DEFINED_FUNCTION (node) + { + struct cgraph_edge *e; + profile_count call_count = profile_count::zero (); + gcov_type max_tp_first_run = 0; + struct function *fn = DECL_STRUCT_FUNCTION (node->decl); + + if (!(node->count == profile_count::zero ())) + continue; + for (e = node->callers; e; e = e->next_caller) + if (e->count.initialized_p () && e->count > 0) + { + call_count = call_count + e->count; + + if (e->caller->tp_first_run > max_tp_first_run) + max_tp_first_run = e->caller->tp_first_run; + } + + /* If time profile is missing, let assign the maximum that comes from + caller functions. */ + if (!node->tp_first_run && max_tp_first_run) + node->tp_first_run = max_tp_first_run + 1; + + if (call_count > 0 + && fn && fn->cfg + && (call_count.apply_scale (unlikely_count_fraction, 1) + >= profile_info->runs)) + { + drop_profile (node, call_count); + worklist.safe_push (node); + } + } + + /* Propagate the profile dropping to other 0-count COMDATs that are + potentially called by COMDATs we already dropped the profile on. */ + while (worklist.length () > 0) + { + struct cgraph_edge *e; + + node = worklist.pop (); + for (e = node->callees; e; e = e->next_caller) + { + struct cgraph_node *callee = e->callee; + struct function *fn = DECL_STRUCT_FUNCTION (callee->decl); + + if (callee->count > 0) + continue; + if ((DECL_COMDAT (callee->decl) || DECL_EXTERNAL (callee->decl)) + && fn && fn->cfg + && profile_status_for_fn (fn) == PROFILE_READ) + { + drop_profile (node, profile_count::zero ()); + worklist.safe_push (callee); + } + } + } } /* Convert counts measured by profile driven feedback to frequencies. Return nonzero iff there was any nonzero execution count. */ -int +bool counts_to_freqs (void) { - gcov_type count_max, true_count_max = 0; + gcov_type count_max; + profile_count true_count_max = profile_count::zero (); basic_block bb; - FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) - true_count_max = MAX (bb->count, true_count_max); - - count_max = MAX (true_count_max, 1); - FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) - bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max; - - return true_count_max; + /* Don't overwrite the estimated frequencies when the profile for + the function is missing. We may drop this function PROFILE_GUESSED + later in drop_profile (). */ + if (!ENTRY_BLOCK_PTR_FOR_FN (cfun)->count.initialized_p () + || ENTRY_BLOCK_PTR_FOR_FN (cfun)->count == profile_count::zero ()) + return false; + + FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) + if (bb->count > true_count_max) + true_count_max = bb->count; + + /* If we have no counts to base frequencies on, keep those that are + already there. */ + if (!(true_count_max > 0)) + return false; + + count_max = true_count_max.to_gcov_type (); + + FOR_ALL_BB_FN (bb, cfun) + if (bb->count.initialized_p ()) + bb->frequency = RDIV (bb->count.to_gcov_type () * BB_FREQ_MAX, count_max); + + return true; } /* Return true if function is likely to be expensive, so there is no point to @@ -2128,17 +3348,16 @@ /* Frequencies are out of range. This either means that function contains internal loop executing more than BB_FREQ_MAX times or profile feedback is available and function has not been executed at all. */ - if (ENTRY_BLOCK_PTR->frequency == 0) + if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency == 0) return true; /* Maximally BB_FREQ_MAX^2 so overflow won't happen. */ - limit = ENTRY_BLOCK_PTR->frequency * threshold; - FOR_EACH_BB (bb) + limit = ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency * threshold; + FOR_EACH_BB_FN (bb, cfun) { - rtx insn; - - for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb)); - insn = NEXT_INSN (insn)) + rtx_insn *insn; + + FOR_BB_INSNS (bb, insn) if (active_insn_p (insn)) { sum += bb->frequency; @@ -2150,68 +3369,211 @@ return false; } -/* Estimate basic blocks frequency by given branch probabilities. */ +/* All basic blocks that are reachable only from unlikely basic blocks are + unlikely. */ void -estimate_bb_frequencies (void) +propagate_unlikely_bbs_forward (void) +{ + auto_vec<basic_block, 64> worklist; + basic_block bb; + edge_iterator ei; + edge e; + + if (!(ENTRY_BLOCK_PTR_FOR_FN (cfun)->count == profile_count::zero ())) + { + ENTRY_BLOCK_PTR_FOR_FN (cfun)->aux = (void *)(size_t) 1; + worklist.safe_push (ENTRY_BLOCK_PTR_FOR_FN (cfun)); + + while (worklist.length () > 0) + { + bb = worklist.pop (); + FOR_EACH_EDGE (e, ei, bb->succs) + if (!(e->count () == profile_count::zero ()) + && !(e->dest->count == profile_count::zero ()) + && !e->dest->aux) + { + e->dest->aux = (void *)(size_t) 1; + worklist.safe_push (e->dest); + } + } + } + + FOR_ALL_BB_FN (bb, cfun) + { + if (!bb->aux) + { + if (!(bb->count == profile_count::zero ()) + && (dump_file && (dump_flags & TDF_DETAILS))) + fprintf (dump_file, + "Basic block %i is marked unlikely by forward prop\n", + bb->index); + bb->count = profile_count::zero (); + bb->frequency = 0; + } + else + bb->aux = NULL; + } +} + +/* Determine basic blocks/edges that are known to be unlikely executed and set + their counters to zero. + This is done with first identifying obviously unlikely BBs/edges and then + propagating in both directions. */ + +static void +determine_unlikely_bbs () +{ + basic_block bb; + auto_vec<basic_block, 64> worklist; + edge_iterator ei; + edge e; + + FOR_EACH_BB_FN (bb, cfun) + { + if (!(bb->count == profile_count::zero ()) + && unlikely_executed_bb_p (bb)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Basic block %i is locally unlikely\n", + bb->index); + bb->count = profile_count::zero (); + } + + if (bb->count == profile_count::zero ()) + bb->frequency = 0; + + FOR_EACH_EDGE (e, ei, bb->succs) + if (!(e->probability == profile_probability::never ()) + && unlikely_executed_edge_p (e)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Edge %i->%i is locally unlikely\n", + bb->index, e->dest->index); + e->probability = profile_probability::never (); + } + + gcc_checking_assert (!bb->aux); + } + + auto_vec<int, 64> nsuccs; + nsuccs.safe_grow_cleared (last_basic_block_for_fn (cfun)); + FOR_ALL_BB_FN (bb, cfun) + if (!(bb->count == profile_count::zero ()) + && bb != EXIT_BLOCK_PTR_FOR_FN (cfun)) + { + nsuccs[bb->index] = 0; + FOR_EACH_EDGE (e, ei, bb->succs) + if (!(e->probability == profile_probability::never ()) + && !(e->dest->count == profile_count::zero ())) + nsuccs[bb->index]++; + if (!nsuccs[bb->index]) + worklist.safe_push (bb); + } + while (worklist.length () > 0) + { + bb = worklist.pop (); + if (bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)) + { + bool found = false; + for (gimple_stmt_iterator gsi = gsi_start_bb (bb); + !gsi_end_p (gsi); gsi_next (&gsi)) + if (stmt_can_terminate_bb_p (gsi_stmt (gsi)) + /* stmt_can_terminate_bb_p special cases noreturns because it + assumes that fake edges are created. We want to know that + noreturn alone does not imply BB to be unlikely. */ + || (is_gimple_call (gsi_stmt (gsi)) + && (gimple_call_flags (gsi_stmt (gsi)) & ECF_NORETURN))) + { + found = true; + break; + } + if (found) + continue; + } + if (!(bb->count == profile_count::zero ()) + && (dump_file && (dump_flags & TDF_DETAILS))) + fprintf (dump_file, + "Basic block %i is marked unlikely by backward prop\n", + bb->index); + bb->count = profile_count::zero (); + bb->frequency = 0; + FOR_EACH_EDGE (e, ei, bb->preds) + if (!(e->probability == profile_probability::never ())) + { + e->probability = profile_probability::never (); + if (!(e->src->count == profile_count::zero ())) + { + nsuccs[e->src->index]--; + if (!nsuccs[e->src->index]) + worklist.safe_push (e->src); + } + } + } +} + +/* Estimate and propagate basic block frequencies using the given branch + probabilities. If FORCE is true, the frequencies are used to estimate + the counts even when there are already non-zero profile counts. */ + +void +estimate_bb_frequencies (bool force) { basic_block bb; sreal freq_max; - if (profile_status != PROFILE_READ || !counts_to_freqs ()) + determine_unlikely_bbs (); + + if (force || profile_status_for_fn (cfun) != PROFILE_READ + || !counts_to_freqs ()) { static int real_values_initialized = 0; if (!real_values_initialized) { real_values_initialized = 1; - sreal_init (&real_zero, 0, 0); - sreal_init (&real_one, 1, 0); - sreal_init (&real_br_prob_base, REG_BR_PROB_BASE, 0); - sreal_init (&real_bb_freq_max, BB_FREQ_MAX, 0); - sreal_init (&real_one_half, 1, -1); - sreal_div (&real_inv_br_prob_base, &real_one, &real_br_prob_base); - sreal_sub (&real_almost_one, &real_one, &real_inv_br_prob_base); + real_br_prob_base = REG_BR_PROB_BASE; + real_bb_freq_max = BB_FREQ_MAX; + real_one_half = sreal (1, -1); + real_inv_br_prob_base = sreal (1) / real_br_prob_base; + real_almost_one = sreal (1) - real_inv_br_prob_base; } mark_dfs_back_edges (); - single_succ_edge (ENTRY_BLOCK_PTR)->probability = REG_BR_PROB_BASE; + single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))->probability = + profile_probability::always (); /* 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) + alloc_aux_for_blocks (sizeof (block_info)); + alloc_aux_for_edges (sizeof (edge_prob_info)); + FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) { edge e; edge_iterator ei; 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, - &EDGE_INFO (e)->back_edge_prob, - &real_inv_br_prob_base); + EDGE_INFO (e)->back_edge_prob + = e->probability.to_reg_br_prob_base (); + EDGE_INFO (e)->back_edge_prob *= real_inv_br_prob_base; } } - /* First compute probabilities locally for each loop from innermost - to outermost to examine probabilities for back edges. */ + /* First compute frequencies locally for each loop from innermost + to outermost to examine frequencies for back edges. */ estimate_loops (); - 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) + freq_max = 0; + FOR_EACH_BB_FN (bb, cfun) + if (freq_max < BLOCK_INFO (bb)->frequency) + freq_max = BLOCK_INFO (bb)->frequency; + + freq_max = real_bb_freq_max / freq_max; + FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) { - sreal tmp; - - sreal_mul (&tmp, &BLOCK_INFO (bb)->frequency, &freq_max); - sreal_add (&tmp, &tmp, &real_one_half); - bb->frequency = sreal_to_int (&tmp); + sreal tmp = BLOCK_INFO (bb)->frequency * freq_max + real_one_half; + bb->frequency = tmp.to_int (); } free_aux_for_blocks (); @@ -2225,19 +3587,24 @@ compute_function_frequency (void) { basic_block bb; - struct cgraph_node *node = cgraph_node (current_function_decl); + struct cgraph_node *node = cgraph_node::get (current_function_decl); + if (DECL_STATIC_CONSTRUCTOR (current_function_decl) || MAIN_NAME_P (DECL_NAME (current_function_decl))) node->only_called_at_startup = true; if (DECL_STATIC_DESTRUCTOR (current_function_decl)) node->only_called_at_exit = true; - if (!profile_info || !flag_branch_probabilities) + if (profile_status_for_fn (cfun) != PROFILE_READ) { int flags = flags_from_decl_or_type (current_function_decl); - if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) - != NULL) - node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; + if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count == profile_count::zero () + || lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) + != NULL) + { + node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; + warn_function_cold (current_function_decl); + } else if (lookup_attribute ("hot", DECL_ATTRIBUTES (current_function_decl)) != NULL) node->frequency = NODE_FREQUENCY_HOT; @@ -2250,31 +3617,34 @@ node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; return; } - node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; - FOR_EACH_BB (bb) + + /* Only first time try to drop function into unlikely executed. + After inlining the roundoff errors may confuse us. + Ipa-profile pass will drop functions only called from unlikely + functions to unlikely and that is most of what we care about. */ + if (!cfun->after_inlining) { - if (maybe_hot_bb_p (bb)) + node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; + warn_function_cold (current_function_decl); + } + FOR_EACH_BB_FN (bb, cfun) + { + if (maybe_hot_bb_p (cfun, bb)) { node->frequency = NODE_FREQUENCY_HOT; return; } - if (!probably_never_executed_bb_p (bb)) + if (!probably_never_executed_bb_p (cfun, bb)) node->frequency = NODE_FREQUENCY_NORMAL; } } -static bool -gate_estimate_probability (void) -{ - return flag_guess_branch_prob; -} - /* Build PREDICT_EXPR. */ tree build_predict_expr (enum br_predictor predictor, enum prediction taken) { tree t = build1 (PREDICT_EXPR, void_type_node, - build_int_cst (NULL, predictor)); + build_int_cst (integer_type_node, predictor)); SET_PREDICT_EXPR_OUTCOME (t, taken); return t; } @@ -2285,44 +3655,175 @@ return predictor_info[predictor].name; } -struct gimple_opt_pass pass_profile = +/* Predict branch probabilities and estimate profile of the tree CFG. */ + +namespace { + +const pass_data pass_data_profile = { - { - GIMPLE_PASS, - "profile", /* name */ - gate_estimate_probability, /* gate */ - tree_estimate_probability_driver, /* 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 */ - } + GIMPLE_PASS, /* type */ + "profile_estimate", /* name */ + OPTGROUP_NONE, /* optinfo_flags */ + TV_BRANCH_PROB, /* tv_id */ + PROP_cfg, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + 0, /* todo_flags_finish */ }; -struct gimple_opt_pass pass_strip_predict_hints = +class pass_profile : public gimple_opt_pass +{ +public: + pass_profile (gcc::context *ctxt) + : gimple_opt_pass (pass_data_profile, ctxt) + {} + + /* opt_pass methods: */ + virtual bool gate (function *) { return flag_guess_branch_prob; } + virtual unsigned int execute (function *); + +}; // class pass_profile + +unsigned int +pass_profile::execute (function *fun) +{ + unsigned nb_loops; + + if (profile_status_for_fn (cfun) == PROFILE_GUESSED) + return 0; + + loop_optimizer_init (LOOPS_NORMAL); + if (dump_file && (dump_flags & TDF_DETAILS)) + flow_loops_dump (dump_file, NULL, 0); + + mark_irreducible_loops (); + + nb_loops = number_of_loops (fun); + if (nb_loops > 1) + scev_initialize (); + + tree_estimate_probability (false); + + if (nb_loops > 1) + scev_finalize (); + + loop_optimizer_finalize (); + if (dump_file && (dump_flags & TDF_DETAILS)) + gimple_dump_cfg (dump_file, dump_flags); + if (profile_status_for_fn (fun) == PROFILE_ABSENT) + profile_status_for_fn (fun) = PROFILE_GUESSED; + if (dump_file && (dump_flags & TDF_DETAILS)) + { + struct loop *loop; + FOR_EACH_LOOP (loop, LI_FROM_INNERMOST) + if (loop->header->frequency) + fprintf (dump_file, "Loop got predicted %d to iterate %i times.\n", + loop->num, + (int)expected_loop_iterations_unbounded (loop)); + } + return 0; +} + +} // anon namespace + +gimple_opt_pass * +make_pass_profile (gcc::context *ctxt) +{ + return new pass_profile (ctxt); +} + +namespace { + +const pass_data pass_data_strip_predict_hints = { - { - GIMPLE_PASS, - "*strip_predict_hints", /* name */ - NULL, /* gate */ - strip_predict_hints, /* 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 */ - } + GIMPLE_PASS, /* type */ + "*strip_predict_hints", /* name */ + OPTGROUP_NONE, /* optinfo_flags */ + TV_BRANCH_PROB, /* tv_id */ + PROP_cfg, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + 0, /* todo_flags_finish */ }; +class pass_strip_predict_hints : public gimple_opt_pass +{ +public: + pass_strip_predict_hints (gcc::context *ctxt) + : gimple_opt_pass (pass_data_strip_predict_hints, ctxt) + {} + + /* opt_pass methods: */ + opt_pass * clone () { return new pass_strip_predict_hints (m_ctxt); } + virtual unsigned int execute (function *); + +}; // class pass_strip_predict_hints + +/* Get rid of all builtin_expect calls and GIMPLE_PREDICT statements + we no longer need. */ +unsigned int +pass_strip_predict_hints::execute (function *fun) +{ + basic_block bb; + gimple *ass_stmt; + tree var; + bool changed = false; + + FOR_EACH_BB_FN (bb, fun) + { + gimple_stmt_iterator bi; + for (bi = gsi_start_bb (bb); !gsi_end_p (bi);) + { + gimple *stmt = gsi_stmt (bi); + + if (gimple_code (stmt) == GIMPLE_PREDICT) + { + gsi_remove (&bi, true); + changed = true; + continue; + } + else if (is_gimple_call (stmt)) + { + tree fndecl = gimple_call_fndecl (stmt); + + if ((fndecl + && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL + && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT + && gimple_call_num_args (stmt) == 2) + || (gimple_call_internal_p (stmt) + && gimple_call_internal_fn (stmt) == IFN_BUILTIN_EXPECT)) + { + var = gimple_call_lhs (stmt); + changed = true; + if (var) + { + ass_stmt + = gimple_build_assign (var, gimple_call_arg (stmt, 0)); + gsi_replace (&bi, ass_stmt, true); + } + else + { + gsi_remove (&bi, true); + continue; + } + } + } + gsi_next (&bi); + } + } + return changed ? TODO_cleanup_cfg : 0; +} + +} // anon namespace + +gimple_opt_pass * +make_pass_strip_predict_hints (gcc::context *ctxt) +{ + return new pass_strip_predict_hints (ctxt); +} + /* Rebuild function frequencies. Passes are in general expected to maintain profile by hand, however in some cases this is not possible: for example when inlining several functions with loops freuqencies might run @@ -2332,19 +3833,250 @@ rebuild_frequencies (void) { timevar_push (TV_REBUILD_FREQUENCIES); - if (profile_status == PROFILE_GUESSED) + + /* When the max bb count in the function is small, there is a higher + chance that there were truncation errors in the integer scaling + of counts by inlining and other optimizations. This could lead + to incorrect classification of code as being cold when it isn't. + In that case, force the estimation of bb counts/frequencies from the + branch probabilities, rather than computing frequencies from counts, + which may also lead to frequencies incorrectly reduced to 0. There + is less precision in the probabilities, so we only do this for small + max counts. */ + profile_count count_max = profile_count::zero (); + basic_block bb; + FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) + if (bb->count > count_max) + count_max = bb->count; + + if (profile_status_for_fn (cfun) == PROFILE_GUESSED + || (!flag_auto_profile && profile_status_for_fn (cfun) == PROFILE_READ + && count_max < REG_BR_PROB_BASE / 10)) { loop_optimizer_init (0); add_noreturn_fake_exit_edges (); mark_irreducible_loops (); connect_infinite_loops_to_exit (); - estimate_bb_frequencies (); + estimate_bb_frequencies (true); remove_fake_exit_edges (); loop_optimizer_finalize (); } - else if (profile_status == PROFILE_READ) + else if (profile_status_for_fn (cfun) == PROFILE_READ) counts_to_freqs (); else gcc_unreachable (); timevar_pop (TV_REBUILD_FREQUENCIES); } + +/* Perform a dry run of the branch prediction pass and report comparsion of + the predicted and real profile into the dump file. */ + +void +report_predictor_hitrates (void) +{ + unsigned nb_loops; + + loop_optimizer_init (LOOPS_NORMAL); + if (dump_file && (dump_flags & TDF_DETAILS)) + flow_loops_dump (dump_file, NULL, 0); + + mark_irreducible_loops (); + + nb_loops = number_of_loops (cfun); + if (nb_loops > 1) + scev_initialize (); + + tree_estimate_probability (true); + + if (nb_loops > 1) + scev_finalize (); + + loop_optimizer_finalize (); +} + +/* Force edge E to be cold. + If IMPOSSIBLE is true, for edge to have count and probability 0 otherwise + keep low probability to represent possible error in a guess. This is used + i.e. in case we predict loop to likely iterate given number of times but + we are not 100% sure. + + This function locally updates profile without attempt to keep global + consistency which can not be reached in full generality without full profile + rebuild from probabilities alone. Doing so is not necessarily a good idea + because frequencies and counts may be more realistic then probabilities. + + In some cases (such as for elimination of early exits during full loop + unrolling) the caller can ensure that profile will get consistent + afterwards. */ + +void +force_edge_cold (edge e, bool impossible) +{ + profile_count count_sum = profile_count::zero (); + profile_probability prob_sum = profile_probability::never (); + edge_iterator ei; + edge e2; + bool uninitialized_exit = false; + + profile_probability goal = (impossible ? profile_probability::never () + : profile_probability::very_unlikely ()); + + /* If edge is already improbably or cold, just return. */ + if (e->probability <= goal + && (!impossible || e->count () == profile_count::zero ())) + return; + FOR_EACH_EDGE (e2, ei, e->src->succs) + if (e2 != e) + { + if (e2->count ().initialized_p ()) + count_sum += e2->count (); + else + uninitialized_exit = true; + if (e2->probability.initialized_p ()) + prob_sum += e2->probability; + } + + /* If there are other edges out of e->src, redistribute probabilitity + there. */ + if (prob_sum > profile_probability::never ()) + { + if (!(e->probability < goal)) + e->probability = goal; + + profile_probability prob_comp = prob_sum / e->probability.invert (); + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Making edge %i->%i %s by redistributing " + "probability to other edges.\n", + e->src->index, e->dest->index, + impossible ? "impossible" : "cold"); + FOR_EACH_EDGE (e2, ei, e->src->succs) + if (e2 != e) + { + e2->probability /= prob_comp; + } + if (current_ir_type () != IR_GIMPLE + && e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun)) + update_br_prob_note (e->src); + } + /* If all edges out of e->src are unlikely, the basic block itself + is unlikely. */ + else + { + if (prob_sum == profile_probability::never ()) + e->probability = profile_probability::always (); + else + { + if (impossible) + e->probability = profile_probability::never (); + /* If BB has some edges out that are not impossible, we can not + assume that BB itself is. */ + impossible = false; + } + if (current_ir_type () != IR_GIMPLE + && e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun)) + update_br_prob_note (e->src); + if (e->src->count == profile_count::zero ()) + return; + if (count_sum == profile_count::zero () && !uninitialized_exit + && impossible) + { + bool found = false; + if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun)) + ; + else if (current_ir_type () == IR_GIMPLE) + for (gimple_stmt_iterator gsi = gsi_start_bb (e->src); + !gsi_end_p (gsi); gsi_next (&gsi)) + { + if (stmt_can_terminate_bb_p (gsi_stmt (gsi))) + { + found = true; + break; + } + } + /* FIXME: Implement RTL path. */ + else + found = true; + if (!found) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, + "Making bb %i impossible and dropping count to 0.\n", + e->src->index); + e->src->count = profile_count::zero (); + FOR_EACH_EDGE (e2, ei, e->src->preds) + force_edge_cold (e2, impossible); + return; + } + } + + /* If we did not adjusting, the source basic block has no likely edeges + leaving other direction. In that case force that bb cold, too. + This in general is difficult task to do, but handle special case when + BB has only one predecestor. This is common case when we are updating + after loop transforms. */ + if (!(prob_sum > profile_probability::never ()) + && count_sum == profile_count::zero () + && single_pred_p (e->src) && e->src->frequency > (impossible ? 0 : 1)) + { + int old_frequency = e->src->frequency; + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Making bb %i %s.\n", e->src->index, + impossible ? "impossible" : "cold"); + e->src->frequency = MIN (e->src->frequency, impossible ? 0 : 1); + if (impossible) + e->src->count = profile_count::zero (); + else + e->src->count = e->count ().apply_scale (e->src->frequency, + old_frequency); + force_edge_cold (single_pred_edge (e->src), impossible); + } + else if (dump_file && (dump_flags & TDF_DETAILS) + && maybe_hot_bb_p (cfun, e->src)) + fprintf (dump_file, "Giving up on making bb %i %s.\n", e->src->index, + impossible ? "impossible" : "cold"); + } +} + +#if CHECKING_P + +namespace selftest { + +/* Test that value range of predictor values defined in predict.def is + within range (50, 100]. */ + +struct branch_predictor +{ + const char *name; + unsigned probability; +}; + +#define DEF_PREDICTOR(ENUM, NAME, HITRATE, FLAGS) { NAME, HITRATE }, + +static void +test_prediction_value_range () +{ + branch_predictor predictors[] = { +#include "predict.def" + {NULL, -1U} + }; + + for (unsigned i = 0; predictors[i].name != NULL; i++) + { + unsigned p = 100 * predictors[i].probability / REG_BR_PROB_BASE; + ASSERT_TRUE (p > 50 && p <= 100); + } +} + +#undef DEF_PREDICTOR + +/* Run all of the selfests within this file. */ + +void +predict_c_tests () +{ + test_prediction_value_range (); +} + +} // namespace selftest +#endif /* CHECKING_P. */