/* Branch prediction routines for the GNU compiler.
- Copyright (C) 2000-2014 Free Software Foundation, Inc.
+ Copyright (C) 2000-2016 Free Software Foundation, Inc.
This file is part of GCC.
#include "config.h"
#include "system.h"
#include "coretypes.h"
-#include "tm.h"
-#include "tree.h"
-#include "calls.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 "function.h"
-#include "except.h"
-#include "diagnostic-core.h"
-#include "recog.h"
-#include "expr.h"
-#include "predict.h"
+#include "tree.h"
+#include "gimple.h"
+#include "cfghooks.h"
+#include "tree-pass.h"
+#include "ssa.h"
+#include "emit-rtl.h"
+#include "cgraph.h"
#include "coverage.h"
+#include "diagnostic-core.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 "pointer-set.h"
-#include "tree-ssa-alias.h"
-#include "internal-fn.h"
-#include "gimple-expr.h"
-#include "is-a.h"
-#include "gimple.h"
#include "gimple-iterator.h"
-#include "gimple-ssa.h"
-#include "cgraph.h"
#include "tree-cfg.h"
-#include "tree-phinodes.h"
-#include "ssa-iterators.h"
#include "tree-ssa-loop-niter.h"
#include "tree-ssa-loop.h"
-#include "tree-pass.h"
#include "tree-scalar-evolution.h"
-#include "cfgloop.h"
+#include "ipa-utils.h"
+#include "gimple-pretty-print.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;
-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. */
static inline bool
maybe_hot_frequency_p (struct function *fun, int freq)
{
- struct cgraph_node *node = cgraph_get_node (fun->decl);
- if (!profile_info || !flag_branch_probabilities)
+ struct cgraph_node *node = cgraph_node::get (fun->decl);
+ if (!profile_info
+ || !opt_for_fn (fun->decl, flag_branch_probabilities))
{
if (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED)
return false;
return false;
if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0)
return false;
- if (freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency
- / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION)))
+ if (freq * PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION)
+ < ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency)
return false;
return true;
}
/* Return TRUE if frequency FREQ is considered to be hot. */
-static inline bool
+bool
maybe_hot_count_p (struct function *fun, gcov_type count)
{
if (fun && profile_status_for_fn (fun) != PROFILE_READ)
return maybe_hot_frequency_p (fun, 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
- && !maybe_hot_count_p (NULL,
- edge->count))
- return false;
- if (edge->caller->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED
- || (edge->callee
- && edge->callee->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED))
- return false;
- if (edge->caller->frequency > NODE_FREQUENCY_UNLIKELY_EXECUTED
- && (edge->callee
- && 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)
- {
- if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0
- || edge->frequency <= (CGRAPH_FREQ_BASE
- / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION)))
- return false;
- }
- return true;
-}
-
/* Return true in case BB can be CPU intensive and should be optimized
for maximal performance. */
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. */
gcov_type count, int frequency)
{
gcc_checking_assert (fun);
- if (profile_status_for_fn (cfun) == PROFILE_READ)
+ if (profile_status_for_fn (fun) == PROFILE_READ)
{
int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION);
if (count * unlikely_count_fraction >= profile_info->runs)
return false;
if (!frequency)
return true;
- if (!ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency)
+ if (!ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency)
return false;
- if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count)
+ if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count)
{
gcov_type computed_count;
/* Check for possibility of overflow, in which case entry bb count
is large enough to do the division first without losing much
precision. */
- if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count < REG_BR_PROB_BASE *
+ if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count < REG_BR_PROB_BASE *
REG_BR_PROB_BASE)
{
gcov_type scaled_count
- = frequency * ENTRY_BLOCK_PTR_FOR_FN (cfun)->count *
+ = frequency * ENTRY_BLOCK_PTR_FOR_FN (fun)->count *
unlikely_count_fraction;
computed_count = RDIV (scaled_count,
- ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency);
+ ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency);
}
else
{
- computed_count = RDIV (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count,
- ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency);
+ computed_count = RDIV (ENTRY_BLOCK_PTR_FOR_FN (fun)->count,
+ ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency);
computed_count *= frequency * unlikely_count_fraction;
}
if (computed_count >= profile_info->runs)
}
return true;
}
- if ((!profile_info || !flag_branch_probabilities)
- && (cgraph_get_node (fun->decl)->frequency
+ if ((!profile_info || !(opt_for_fn (fun->decl, flag_branch_probabilities)))
+ && (cgraph_node::get (fun->decl)->frequency
== NODE_FREQUENCY_UNLIKELY_EXECUTED))
return true;
return false;
return probably_never_executed (fun, e->count, EDGE_FREQUENCY (e));
}
-/* Return true if NODE should be optimized for size. */
-
-bool
-cgraph_optimize_for_size_p (struct cgraph_node *node)
-{
- if (optimize_size)
- return true;
- if (node && (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED))
- return true;
- else
- return false;
-}
-
/* Return true when current function should always be optimized for size. */
bool
optimize_function_for_size_p (struct function *fun)
{
- if (optimize_size)
- return true;
if (!fun || !fun->decl)
- return false;
- return cgraph_optimize_for_size_p (cgraph_get_node (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. */
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 (cfun, bb);
+ return (optimize_function_for_size_p (cfun)
+ || (bb && !maybe_hot_bb_p (cfun, bb)));
}
/* Return TRUE when BB should be optimized for speed. */
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
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 {
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. */
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 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)
+{
+ 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;
+}
+
/* Return true when the probability of edge is reliable.
The profile guessing code is good at predicting branch outcome (ie.
}
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)
/* 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;
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
void
gimple_predict_edge (edge e, enum br_predictor predictor, int probability)
{
- gcc_assert (profile_status_for_fn (cfun) != PROFILE_GUESSED);
- if ((e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun) && 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);
+ edge_prediction *&preds = bb_predictions->get_or_insert (e->src);
- i->ep_next = (struct edge_prediction *) *preds;
- *preds = i;
+ i->ep_next = preds;
+ preds = i;
i->ep_probability = probability;
i->ep_predictor = predictor;
i->ep_edge = e;
}
}
-/* Remove all predictions on given basic block that are attached
- to edge E. */
+/* Filter edge predictions PREDS by a function FILTER. DATA are passed
+ to the filter function. */
+
void
-remove_predictions_associated_with_edge (edge e)
+filter_predictions (edge_prediction **preds,
+ bool (*filter) (edge_prediction *, void *), void *data)
{
- 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 **prediction = preds;
struct edge_prediction *next;
while (*prediction)
{
- if ((*prediction)->ep_edge == e)
+ if ((*filter) (*prediction, data))
+ prediction = &((*prediction)->ep_next);
+ else
{
next = (*prediction)->ep_next;
free (*prediction);
*prediction = next;
}
- else
- prediction = &((*prediction)->ep_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)
+{
+ if (!bb_predictions)
+ return;
+
+ edge_prediction **preds = bb_predictions->get (e->src);
+ filter_predictions (preds, equal_edge_p, e);
+}
+
/* Clears the list of predictions stored for BB. */
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);
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)
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;
+ if (e == NULL)
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if (! (e->flags & EDGE_FALLTHRU))
+ break;
- fprintf (file, " %s heuristics%s: %.1f%%",
+ 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);
+ edge_info_str, reason_messages[reason],
+ probability * 100.0 / REG_BR_PROB_BASE);
if (bb->count)
{
- fprintf (file, " exec %"PRId64, bb->count);
+ fprintf (file, " exec %" PRId64, bb->count);
if (e)
{
- fprintf (file, " hit %"PRId64, e->count);
+ fprintf (file, " hit %" PRId64, e->count);
fprintf (file, " (%.1f%%)", e->count * 100.0 / bb->count);
}
}
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;
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
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)
{
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
single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
}
+/* 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;
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)))
this later. */
if (nedges != 2)
{
- if (!bb->count)
+ if (!bb->count && !dry_run)
set_even_probabilities (bb);
clear_bb_predictions (bb);
if (dump_file)
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;
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;
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;
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)
{
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 && !dry_run)
{
first->probability = combined_probability;
second->probability = REG_BR_PROB_BASE - combined_probability;
Otherwise return false and set LOOP_INVAIANT to NULL. */
static bool
-is_comparison_with_loop_invariant_p (gimple stmt, struct loop *loop,
+is_comparison_with_loop_invariant_p (gcond *stmt, struct loop *loop,
tree *loop_invariant,
enum tree_code *compare_code,
tree *loop_step,
static bool
expr_coherent_p (tree t1, tree t2)
{
- gimple stmt;
+ gimple *stmt;
tree ssa_name_1 = NULL;
tree ssa_name_2 = NULL;
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.
enum tree_code loop_bound_code,
int loop_bound_step)
{
- gimple stmt;
+ 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_p (bb, PRED_LOOP_ITERATIONS_GUESSED)
- || predicted_by_p (bb, PRED_LOOP_ITERATIONS)
- || predicted_by_p (bb, PRED_LOOP_EXIT))
+ 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 (stmt, loop, &compare_var,
+ if (!is_comparison_with_loop_invariant_p (as_a <gcond *> (stmt),
+ loop, &compare_var,
&compare_code,
&compare_step_var,
&compare_base))
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);
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_EXIT. */
+ 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 phi_stmt;
+ gimple *lhs_def_stmt;
+ gphi *phi_stmt;
tree cmp_rhs, cmp_lhs;
- gimple cmp_stmt = last_stmt (exit_edge->src);
+ gimple *last;
+ gcond *cmp_stmt;
- if (!cmp_stmt || gimple_code (cmp_stmt) != GIMPLE_COND)
+ 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)
^ (gimple_cond_code (cmp_stmt) == EQ_EXPR))
^ ((exit_edge->flags & EDGE_TRUE_VALUE) != 0));
- phi_stmt = SSA_NAME_DEF_STMT (cmp_lhs);
- if (!phi_stmt || gimple_code (phi_stmt) != GIMPLE_PHI)
+ 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++)
continue;
if (EDGE_COUNT (e->src->succs) != 1)
{
- predict_paths_leading_to_edge (e, PRED_LOOP_EXIT, NOT_TAKEN);
+ 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_EXIT, NOT_TAKEN);
+ predict_paths_leading_to_edge (e1, PRED_LOOP_EXTRA_EXIT, NOT_TAKEN);
}
}
+
/* Predict edge probabilities by exploiting loop structure. */
static void
predict_loops (void)
{
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 (loop, 0)
+ FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
{
basic_block bb, *bbs;
- unsigned j, n_exits;
+ unsigned j, n_exits = 0;
vec<edge> exits;
struct tree_niter_desc niter_desc;
edge ex;
tree loop_bound_step = NULL;
tree loop_bound_var = NULL;
tree loop_iv_base = NULL;
- gimple stmt = NULL;
+ gcond *stmt = NULL;
+ bool recursion = with_recursion.contains (loop);
exits = get_loop_exit_edges (loop);
- n_exits = exits.length ();
+ FOR_EACH_VEC_ELT (exits, j, ex)
+ if (!(ex->flags & (EDGE_EH | EDGE_ABNORMAL_CALL | EDGE_FAKE)))
+ 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;
int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS);
int probability;
enum br_predictor predictor;
+ widest_int nit;
+ if (ex->flags & (EDGE_EH | EDGE_ABNORMAL_CALL | EDGE_FAKE))
+ 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 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_stmt_executions_int (loop);
- 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
- continue;
+ {
+ 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);
}
exits.release ();
if (nb_iter->stmt
&& gimple_code (nb_iter->stmt) == GIMPLE_COND)
{
- stmt = nb_iter->stmt;
+ stmt = as_a <gcond *> (nb_iter->stmt);
break;
}
if (!stmt && last_stmt (loop->header)
&& gimple_code (last_stmt (loop->header)) == GIMPLE_COND)
- stmt = last_stmt (loop->header);
+ stmt = as_a <gcond *> (last_stmt (loop->header));
if (stmt)
is_comparison_with_loop_invariant_p (stmt, loop,
&loop_bound_var,
for (j = 0; j < loop->num_nodes; j++)
{
- int header_found = 0;
edge e;
edge_iterator ei;
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
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,
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_code (call_stmt) == GIMPLE_CALL
+ && gimple_call_internal_p (call_stmt)
+ && gimple_call_internal_fn (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));
+ }
+ }
+
/* Free basic blocks from get_loop_body. */
free (bbs);
}
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))
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;
return val;
if (predictor)
{
- *predictor = PRED_BUILTIN_EXPECT;
tree val2 = gimple_call_arg (def, 2);
gcc_assert (TREE_CODE (val2) == INTEGER_CST
&& tree_fits_uhwi_p (val2)
if (predictor)
*predictor = PRED_COMPARE_AND_SWAP;
return boolean_true_node;
+ default:
+ break;
}
}
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;
predict_edge (then_edge, PRED_BUILTIN_EXPECT, HITRATE (percent));
}
else
- predict_edge (then_edge, predictor,
- integer_zerop (val) ? NOT_TAKEN : TAKEN);
+ predict_edge_def (then_edge, predictor,
+ integer_zerop (val) ? NOT_TAKEN : TAKEN);
}
/* Try "pointer heuristic."
A comparison ptr == 0 is predicted as false.
if (TREE_CONSTANT (val)
&& (!integer_zerop (val) && !integer_onep (val)))
{
- *prediction = TAKEN;
+ *prediction = NOT_TAKEN;
return PRED_CONST_RETURN;
}
}
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;
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;
|| !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);
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))
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)
{
}
}
-#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. */
{
edge e;
edge_iterator ei;
- gimple last;
+ gimple *last;
FOR_EACH_EDGE (e, ei, bb->succs)
{
gimple_stmt_iterator gi;
for (gi = gsi_start_bb (e->dest); !gsi_end_p (gi); gsi_next (&gi))
{
- gimple stmt = gsi_stmt (gi);
+ glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gi));
tree decl;
- if (gimple_code (stmt) != GIMPLE_LABEL)
+ if (!label_stmt)
break;
- decl = gimple_label_label (stmt);
+ decl = gimple_label_label (label_stmt);
if (DECL_ARTIFICIAL (decl))
continue;
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 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;
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 ();
tree_estimate_probability_bb (bb);
FOR_EACH_BB_FN (bb, cfun)
- combine_predictions_for_bb (bb);
+ combine_predictions_for_bb (bb, dry_run);
-#ifdef ENABLE_CHECKING
- pointer_map_traverse (bb_predictions, assert_is_empty, NULL);
-#endif
- pointer_map_destroy (bb_predictions);
+ if (flag_checking)
+ bb_predictions->traverse<void *, assert_is_empty> (NULL);
+
+ delete bb_predictions;
bb_predictions = NULL;
- estimate_bb_frequencies (false);
+ if (!dry_run)
+ estimate_bb_frequencies (false);
free_dominance_info (CDI_POST_DOMINATORS);
remove_fake_exit_edges ();
}
predict_paths_for_bb (basic_block cur, basic_block bb,
enum br_predictor pred,
enum prediction taken,
- bitmap visited)
+ 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)
gcc_assert (bb == cur || dominated_by_p (CDI_POST_DOMINATORS, cur, bb));
/* See if there is an edge from e->src that is not abnormal
- and does not lead to BB. */
+ 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))
+ && !dominated_by_p (CDI_POST_DOMINATORS, e2->dest, bb)
+ && (!in_loop || !loop_exit_edge_p (in_loop, e2)))
{
found = true;
break;
regions that are only reachable by abnormal edges. We simply
prevent visiting given BB twice. */
if (found)
- predict_edge_def (e, 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);
+ 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, visited);
+ predict_paths_for_bb (son, bb, pred, taken, visited, in_loop);
}
/* Sets branch probabilities according to PREDiction and
static void
predict_paths_leading_to (basic_block bb, enum br_predictor pred,
- enum prediction taken)
+ enum prediction taken, struct loop *in_loop)
{
bitmap visited = BITMAP_ALLOC (NULL);
- predict_paths_for_bb (bb, bb, pred, taken, visited);
+ predict_paths_for_bb (bb, bb, pred, taken, visited, in_loop);
BITMAP_FREE (visited);
}
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;
if (!has_nonloop_edge)
{
bitmap visited = BITMAP_ALLOC (NULL);
- predict_paths_for_bb (bb, bb, pred, taken, visited);
+ predict_paths_for_bb (bb, bb, pred, taken, visited, in_loop);
BITMAP_FREE (visited);
}
else
/* 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;
/* 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
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
bb->count = 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;
/* 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;
+ 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;
}
}
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;
+ tmp *= BLOCK_INFO (bb)->frequency;
+ EDGE_INFO (e)->back_edge_prob = tmp * real_inv_br_prob_base;
}
/* Propagate to successor blocks. */
/* 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)
+ if (!flag_auto_profile && !ENTRY_BLOCK_PTR_FOR_FN (cfun)->count)
return 0;
FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb)
limit = ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency * threshold;
FOR_EACH_BB_FN (bb, cfun)
{
- rtx insn;
+ rtx_insn *insn;
FOR_BB_INSNS (bb, insn)
if (active_insn_p (insn))
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 ();
REG_BR_PROB_BASE;
/* Set up block info for each basic block. */
- alloc_aux_for_blocks (sizeof (struct block_info_def));
- alloc_aux_for_edges (sizeof (struct edge_info_def));
+ 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;
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;
+ EDGE_INFO (e)->back_edge_prob *= real_inv_br_prob_base;
}
}
to outermost to examine frequencies for back edges. */
estimate_loops ();
- memcpy (&freq_max, &real_zero, sizeof (real_zero));
+ freq_max = 0;
FOR_EACH_BB_FN (bb, cfun)
- if (sreal_compare (&freq_max, &BLOCK_INFO (bb)->frequency) < 0)
- memcpy (&freq_max, &BLOCK_INFO (bb)->frequency, sizeof (freq_max));
+ if (freq_max < BLOCK_INFO (bb)->frequency)
+ freq_max = BLOCK_INFO (bb)->frequency;
- sreal_div (&freq_max, &real_bb_freq_max, &freq_max);
+ 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 ();
compute_function_frequency (void)
{
basic_block bb;
- struct cgraph_node *node = cgraph_get_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)))
GIMPLE_PASS, /* type */
"profile_estimate", /* name */
OPTGROUP_NONE, /* optinfo_flags */
- true, /* has_execute */
TV_BRANCH_PROB, /* tv_id */
PROP_cfg, /* properties_required */
0, /* properties_provided */
{
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);
if (nb_loops > 1)
scev_initialize ();
- tree_estimate_probability ();
+ tree_estimate_probability (false);
if (nb_loops > 1)
scev_finalize ();
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;
}
GIMPLE_PASS, /* type */
"*strip_predict_hints", /* name */
OPTGROUP_NONE, /* optinfo_flags */
- true, /* has_execute */
TV_BRANCH_PROB, /* tv_id */
PROP_cfg, /* properties_required */
0, /* properties_provided */
pass_strip_predict_hints::execute (function *fun)
{
basic_block bb;
- gimple ass_stmt;
+ 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);
+ gimple *stmt = gsi_stmt (bi);
if (gimple_code (stmt) == GIMPLE_PREDICT)
{
gsi_remove (&bi, true);
+ changed = true;
continue;
}
else if (is_gimple_call (stmt))
&& gimple_call_internal_fn (stmt) == IFN_BUILTIN_EXPECT))
{
var = gimple_call_lhs (stmt);
+ changed = true;
if (var)
{
ass_stmt
gsi_next (&bi);
}
}
- return 0;
+ return changed ? TODO_cleanup_cfg : 0;
}
} // anon namespace
count_max = MAX (bb->count, count_max);
if (profile_status_for_fn (cfun) == PROFILE_GUESSED
- || (profile_status_for_fn (cfun) == PROFILE_READ && count_max < REG_BR_PROB_BASE/10))
+ || (!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 ();
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)
+{
+ gcov_type count_sum = 0;
+ int prob_sum = 0;
+ edge_iterator ei;
+ edge e2;
+ gcov_type old_count = e->count;
+ int old_probability = e->probability;
+ gcov_type gcov_scale = REG_BR_PROB_BASE;
+ int prob_scale = REG_BR_PROB_BASE;
+
+ /* If edge is already improbably or cold, just return. */
+ if (e->probability <= impossible ? PROB_VERY_UNLIKELY : 0
+ && (!impossible || !e->count))
+ return;
+ FOR_EACH_EDGE (e2, ei, e->src->succs)
+ if (e2 != e)
+ {
+ count_sum += e2->count;
+ prob_sum += e2->probability;
+ }
+
+ /* If there are other edges out of e->src, redistribute probabilitity
+ there. */
+ if (prob_sum)
+ {
+ e->probability
+ = MIN (e->probability, impossible ? 0 : PROB_VERY_UNLIKELY);
+ if (old_probability)
+ e->count = RDIV (e->count * e->probability, old_probability);
+ else
+ e->count = MIN (e->count, impossible ? 0 : 1);
+
+ if (count_sum)
+ gcov_scale = RDIV ((count_sum + old_count - e->count) * REG_BR_PROB_BASE,
+ count_sum);
+ prob_scale = RDIV ((REG_BR_PROB_BASE - e->probability) * REG_BR_PROB_BASE,
+ prob_sum);
+ 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->count = RDIV (e2->count * gcov_scale, REG_BR_PROB_BASE);
+ e2->probability = RDIV (e2->probability * prob_scale,
+ REG_BR_PROB_BASE);
+ }
+ }
+ /* If all edges out of e->src are unlikely, the basic block itself
+ is unlikely. */
+ else
+ {
+ e->probability = REG_BR_PROB_BASE;
+
+ /* 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 && !count_sum && 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);
+ e->src->count = e->count = RDIV (e->src->count * 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");
+ }
+}
projects / platform / upstream / gcc.git / blobdiff