On 7/16/19 8:53 AM, luoxhu wrote:
> Currently get_most_common_single_value could only return the max hist
> <value, count>, add qsort to enable this function return nth value.
> Rename it to get_nth_most_common_value.
>
> v3 Changes:
> 1. Move sort to profile.c after loading values from disk. Simplify
> get_nth_most_common_value.
> 2. Make qsort stable with value check if count is same.
> 3. Other comments from v2.
Hi.
Thank you for the updated patch. But you are probably using a line wrapping
in your email client and I can't apply the patch.
>
> gcc/ChangeLog:
>
> 2019-07-15 Xiong Hu Luo <luo...@linux.ibm.com>
>
> * ipa-profile.c (get_most_common_single_value): Use
> get_nth_most_common_value.
> * profile.c (struct value_count_t): New struct.
> (cmp_counts): New function.
> (sort_hist_value): New function.
> (compute_value_histograms): Call sort_hist_value to sort the
> values after loading from disk.
> * value-prof.c (get_most_common_single_value): Rename to ...
> get_nth_most_common_value. Add input params n, return
> the n_th value and count.
> (gimple_divmod_fixed_value_transform): Use
> get_nth_most_common_value.
> (gimple_ic_transform): Likewise.
> (gimple_stringops_transform): Likewise.
> * value-prof.h (get_most_common_single_value): Add input params
> n, default to 0.
> ---
> gcc/ipa-profile.c | 4 +--
> gcc/profile.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++
> gcc/value-prof.c | 53 +++++++++++++++------------------
> gcc/value-prof.h | 9 +++---
> 4 files changed, 103 insertions(+), 37 deletions(-)
>
> diff --git a/gcc/ipa-profile.c b/gcc/ipa-profile.c
> index 1fb939b73d0..970dba39c80 100644
> --- a/gcc/ipa-profile.c
> +++ b/gcc/ipa-profile.c
> @@ -192,8 +192,8 @@ ipa_profile_generate_summary (void)
> if (h)
> {
> gcov_type val, count, all;
> - if (get_most_common_single_value (NULL, "indirect call",
> - h, &val, &count, &all))
> + if (get_nth_most_common_value (NULL, "indirect call", h,
> + &val, &count, &all))
> {
> struct cgraph_edge * e = node->get_edge (stmt);
> if (e && !e->indirect_unknown_callee)
> diff --git a/gcc/profile.c b/gcc/profile.c
> index 441cb8eb183..54780b44859 100644
> --- a/gcc/profile.c
> +++ b/gcc/profile.c
> @@ -743,6 +743,74 @@ compute_branch_probabilities (unsigned cfg_checksum,
> unsigned lineno_checksum)
> free_aux_for_blocks ();
> }
>
> +struct value_count_t
> +{
> + gcov_type value;
> + gcov_type count;
> +};
> +
Please make a brief comment here.
> +static int
> +cmp_counts (const void *v1, const void *v2)
> +{
> + const value_count_t *h1 = (const value_count_t *) v1;
> + const value_count_t *h2 = (const value_count_t *) v2;
> + if (h1->count < h2->count)
> + return 1;
> + if (h1->count > h2->count)
> + return -1;
> + if (h1->count == h2->count)
> + {
> + if (h1->value < h2->value)
> + return 1;
> + if (h1->value > h2->value)
> + return -1;
> + }
What about something easier like:
return (h1->count != h2->count ? h2->count - h1->count : h2->value - h1->value)
?
> + /* There may be two entries with same count as well as value very unlikely
> + in a multi-threaded instrumentation. But the memory layout of the
> {value,
> + count} tuple can be different. The function will return K-th most
> + common value. */
> + return 0;
> +}
> +
> +/* Sort the histogram value and count for TOPN and INDIR_CALL type. */
> +
> +static bool
> +sort_hist_value (histogram_value hist)
> +{
> + auto_vec<struct value_count_t, GCOV_TOPN_VALUES> value_vec;
> + struct value_count_t temp;
> + unsigned i;
> +
> + if (hist->hvalue.counters[2] == -1)
> + return false;
> +
> + gcc_assert (hist->type == HIST_TYPE_TOPN_VALUES
> + || hist->type == HIST_TYPE_INDIR_CALL);
> +
> + gcc_assert (hist->n_counters == GCOV_TOPN_VALUES_COUNTERS);
> +
> + for (i = 0; i < GCOV_TOPN_VALUES; i++)
> + {
> + gcov_type v = hist->hvalue.counters[2 * i + 1];
> + gcov_type c = hist->hvalue.counters[2 * i + 2];
> +
> + temp.value = v;
> + temp.count = c;
> +
> + value_vec.safe_push (temp);
> + }
> +
> + value_vec.qsort (cmp_counts);
> +
> + gcc_assert (value_vec.length () == GCOV_TOPN_VALUES);
> +
> + for (i = 0; i < GCOV_TOPN_VALUES; i++)
> + {
> + hist->hvalue.counters[2 * i + 1] = value_vec[i].value;
> + hist->hvalue.counters[2 * i + 2] = value_vec[i].count;
> + }
> + return true;
> +}
Well, to be honest I don't like so much manipulation for sorting of 4 values.
Please implement a simple bubble sort which will do sorting in place and
will finish as soon as the sequence is sorted. Using qsort is overkill
in my opinion.
Thanks,
Martin
> /* Load value histograms values whose description is stored in VALUES array
> from .gcda file.
>
> @@ -808,6 +876,12 @@ compute_value_histograms (histogram_values values,
> unsigned cfg_checksum,
> else
> hist->hvalue.counters[j] = 0;
>
> + if (hist->type == HIST_TYPE_TOPN_VALUES
> + || hist->type == HIST_TYPE_INDIR_CALL)
> + {
> + sort_hist_value (hist);
> + }
> +
> /* Time profiler counter is not related to any statement,
> so that we have to read the counter and set the value to
> the corresponding call graph node. */
> diff --git a/gcc/value-prof.c b/gcc/value-prof.c
> index 32e6ddd8165..97e4ae18ba3 100644
> --- a/gcc/value-prof.c
> +++ b/gcc/value-prof.c
> @@ -713,45 +713,38 @@ gimple_divmod_fixed_value (gassign *stmt, tree value,
> profile_probability prob,
> return tmp2;
> }
>
> -/* Return most common value of TOPN_VALUE histogram. If
> - there's a unique value, return true and set VALUE and COUNT
> +/* Return the n-th value count of TOPN_VALUE histogram. If
> + there's a value, return true and set VALUE and COUNT
> arguments. */
>
> bool
> -get_most_common_single_value (gimple *stmt, const char *counter_type,
> - histogram_value hist,
> - gcov_type *value, gcov_type *count,
> - gcov_type *all)
> +get_nth_most_common_value (gimple *stmt, const char *counter_type,
> + histogram_value hist, gcov_type *value,
> + gcov_type *count, gcov_type *all, unsigned n)
> {
> if (hist->hvalue.counters[2] == -1)
> return false;
>
> + gcc_assert (n < GCOV_TOPN_VALUES);
> +
> *count = 0;
> *value = 0;
>
> gcov_type read_all = hist->hvalue.counters[0];
>
> - for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
> - {
> - gcov_type v = hist->hvalue.counters[2 * i + 1];
> - gcov_type c = hist->hvalue.counters[2 * i + 2];
> -
> - /* Indirect calls can't be vereified. */
> - if (stmt && check_counter (stmt, counter_type, &c, &read_all,
> - gimple_bb (stmt)->count))
> - return false;
> + gcov_type v = hist->hvalue.counters[2 * n + 1];
> + gcov_type c = hist->hvalue.counters[2 * n + 2];
>
> - *all = read_all;
> + /* Indirect calls can't be vereified. */
> + if (stmt
> + && check_counter (stmt, counter_type, &c, &read_all,
> + gimple_bb (stmt)->count))
> + return false;
>
> - if (c > *count)
> - {
> - *value = v;
> - *count = c;
> - }
> - else if (c == *count && v > *value)
> - *value = v;
> - }
> + *all = read_all;
>
> + *value = v;
> + *count = c;
> return true;
> }
>
> @@ -784,8 +777,8 @@ gimple_divmod_fixed_value_transform (gimple_stmt_iterator
> *si)
> if (!histogram)
> return false;
>
> - if (!get_most_common_single_value (stmt, "divmod", histogram, &val, &count,
> - &all))
> + if (!get_nth_most_common_value (stmt, "divmod", histogram, &val, &count,
> + &all))
> return false;
>
> value = histogram->hvalue.value;
> @@ -1439,8 +1432,8 @@ gimple_ic_transform (gimple_stmt_iterator *gsi)
> if (!histogram)
> return false;
>
> - if (!get_most_common_single_value (NULL, "indirect call", histogram, &val,
> - &count, &all))
> + if (!get_nth_most_common_value (NULL, "indirect call", histogram, &val,
> + &count, &all))
> return false;
>
> if (4 * count <= 3 * all)
> @@ -1658,8 +1651,8 @@ gimple_stringops_transform (gimple_stmt_iterator *gsi)
> if (!histogram)
> return false;
>
> - if (!get_most_common_single_value (stmt, "stringops", histogram, &val,
> - &count, &all))
> + if (!get_nth_most_common_value (stmt, "stringops", histogram, &val, &count,
> + &all))
> return false;
>
> gimple_remove_histogram_value (cfun, stmt, histogram);
> diff --git a/gcc/value-prof.h b/gcc/value-prof.h
> index ca846d08cbd..1078722163b 100644
> --- a/gcc/value-prof.h
> +++ b/gcc/value-prof.h
> @@ -89,11 +89,10 @@ void free_histograms (function *);
> void stringop_block_profile (gimple *, unsigned int *, HOST_WIDE_INT *);
> gcall *gimple_ic (gcall *, struct cgraph_node *, profile_probability);
> bool check_ic_target (gcall *, struct cgraph_node *);
> -bool get_most_common_single_value (gimple *stmt, const char *counter_type,
> - histogram_value hist,
> - gcov_type *value, gcov_type *count,
> - gcov_type *all);
> -
> +bool get_nth_most_common_value (gimple *stmt, const char *counter_type,
> + histogram_value hist, gcov_type *value,
> + gcov_type *count, gcov_type *all,
> + unsigned n = 0);
>
> /* In tree-profile.c. */
> extern void gimple_init_gcov_profiler (void);
