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predict.c (tree_estimate_probability): Add new parameter for estimate_bb_frequencies.

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2013-10-10  Teresa Johnson  <tejohnson@google.com>

	* predict.c (tree_estimate_probability): Add new parameter
	for estimate_bb_frequencies.
	(estimate_bb_frequencies): Add new parameter to force estimation.
	(rebuild_frequencies): When max frequency in function is small,
	recompute counts from frequencies.
	* predict.h (estimate_bb_frequencies): New parameter.

From-SVN: r203395
This commit is contained in:
Teresa Johnson 2013-10-10 20:30:08 +00:00 • committed by Teresa Johnson
parent 58b2a35853
commit 67fa788072
3 changed files with 37 additions and 10 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2013-10-10 Teresa Johnson <tejohnson@google.com>
* predict.c (tree_estimate_probability): Add new parameter
for estimate_bb_frequencies.
(estimate_bb_frequencies): Add new parameter to force estimation.
(rebuild_frequencies): When max frequency in function is small,
recompute counts from frequencies.
* predict.h (estimate_bb_frequencies): New parameter.
2013-10-10 David Malcolm <dmalcolm@redhat.com>
* ipa-inline.c (ipa_inline): Fix leak of "order" when

36
gcc/predict.c
View file

@ -2389,7 +2389,7 @@ tree_estimate_probability (void)
pointer_map_destroy (bb_predictions);
bb_predictions = NULL;
estimate_bb_frequencies ();
estimate_bb_frequencies (false);
free_dominance_info (CDI_POST_DOMINATORS);
remove_fake_exit_edges ();
}
@ -2692,7 +2692,7 @@ propagate_freq (basic_block head, bitmap tovisit)
}
}
/* 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)
@ -2801,15 +2801,17 @@ expensive_function_p (int threshold)
return false;
}
/* Estimate basic blocks frequency by given branch probabilities. */
/* 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 (void)
estimate_bb_frequencies (bool force)
{
basic_block bb;
sreal freq_max;
if (profile_status != PROFILE_READ || !counts_to_freqs ())
if (force || profile_status != PROFILE_READ || !counts_to_freqs ())
{
static int real_values_initialized = 0;
@ -2846,8 +2848,8 @@ estimate_bb_frequencies (void)
}
}
/* 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));
@ -3028,13 +3030,29 @@ void
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. */
gcov_type count_max = 0;
basic_block bb;
FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
count_max = MAX (bb->count, count_max);
if (profile_status == PROFILE_GUESSED
|| (profile_status == 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 ();
}

2
gcc/predict.h
View file

@ -37,7 +37,7 @@ enum prediction
extern void predict_insn_def (rtx, enum br_predictor, enum prediction);
extern int counts_to_freqs (void);
extern void estimate_bb_frequencies (void);
extern void estimate_bb_frequencies (bool);
extern const char *predictor_name (enum br_predictor);
extern tree build_predict_expr (enum br_predictor, enum prediction);
extern void tree_estimate_probability (void);