[gcc(refs/users/ppalka/heads/libstdcxx-constrained-algos)] Smart relaxation of TOP N counter.
Patrick Palka
ppalka@gcc.gnu.org
Sat Jan 25 22:51:00 GMT 2020
https://gcc.gnu.org/g:5f32f9cf13f99f6295591927950aaf98aa8dba91
commit 5f32f9cf13f99f6295591927950aaf98aa8dba91
Author: Martin Liska <mliska@suse.cz>
Date: Wed Jan 22 12:08:11 2020 +0100
Smart relaxation of TOP N counter.
PR tree-optimization/92924
* profile.c (compute_value_histograms): Divide
all counter values.
PR tree-optimization/92924
* libgcov-driver.c (prune_topn_counter): New.
(prune_counters): Likewise.
(dump_one_gcov): Prune a run-time counter.
* libgcov-profiler.c (__gcov_topn_values_profiler_body):
For a known value, add GCOV_TOPN_VALUES to value.
Otherwise, decrement all counters by one.
Diff:
---
gcc/ChangeLog | 6 ++++++
gcc/profile.c | 10 ++++++++-
libgcc/ChangeLog | 10 +++++++++
libgcc/libgcov-driver.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++-
libgcc/libgcov-profiler.c | 30 ++++++++++++--------------
5 files changed, 92 insertions(+), 18 deletions(-)
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d3a7bc2..f672e93 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-01-22 Martin Liska <mliska@suse.cz>
+
+ PR tree-optimization/92924
+ * profile.c (compute_value_histograms): Divide
+ all counter values.
+
2020-01-22 Jakub Jelinek <jakub@redhat.com>
PR target/91298
diff --git a/gcc/profile.c b/gcc/profile.c
index 6a2de21..cd754c4 100644
--- a/gcc/profile.c
+++ b/gcc/profile.c
@@ -863,7 +863,15 @@ compute_value_histograms (histogram_values values, unsigned cfg_checksum,
if (hist->type == HIST_TYPE_TOPN_VALUES
|| hist->type == HIST_TYPE_INDIR_CALL)
- sort_hist_values (hist);
+ {
+ /* Each count value is multiplied by GCOV_TOPN_VALUES. */
+ if (hist->hvalue.counters[2] != -1)
+ for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
+ hist->hvalue.counters[2 * i + 2]
+ = RDIV (hist->hvalue.counters[2 * i + 2], GCOV_TOPN_VALUES);
+
+ sort_hist_values (hist);
+ }
/* Time profiler counter is not related to any statement,
so that we have to read the counter and set the value to
diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index 5e8b506..441c8f0 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,13 @@
+2020-01-22 Martin Liska <mliska@suse.cz>
+
+ PR tree-optimization/92924
+ * libgcov-driver.c (prune_topn_counter): New.
+ (prune_counters): Likewise.
+ (dump_one_gcov): Prune a run-time counter.
+ * libgcov-profiler.c (__gcov_topn_values_profiler_body):
+ For a known value, add GCOV_TOPN_VALUES to value.
+ Otherwise, decrement all counters by one.
+
2020-01-18 Hans-Peter Nilsson <hp@axis.com>
* config/cris/arit.c (DS): Apply attribute __fallthrough__.
diff --git a/libgcc/libgcov-driver.c b/libgcc/libgcov-driver.c
index 1c07761..cdb611d 100644
--- a/libgcc/libgcov-driver.c
+++ b/libgcc/libgcov-driver.c
@@ -213,6 +213,56 @@ static struct gcov_fn_buffer *fn_buffer;
/* Including system dependent components. */
#include "libgcov-driver-system.c"
+/* Prune TOP N value COUNTERS. It's needed in order to preserve
+ reproducibility of builds. */
+
+static void
+prune_topn_counter (gcov_type *counters, gcov_type all)
+{
+ if (counters[1] == -1)
+ return;
+
+ for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
+ {
+ if (counters[2 * i + 1] < all)
+ {
+ counters[2 * i] = 0;
+ counters[2 * i + 1] = 0;
+ }
+ }
+}
+
+/* Prune counters so that they are ready to store or merge. */
+
+static void
+prune_counters (struct gcov_info *gi)
+{
+ for (unsigned i = 0; i < gi->n_functions; i++)
+ {
+ const struct gcov_fn_info *gfi = gi->functions[i];
+ const struct gcov_ctr_info *ci = gfi->ctrs;
+
+ for (unsigned j = 0; j < GCOV_COUNTERS; j++)
+ {
+ if (gi->merge[j] == NULL)
+ continue;
+
+ if (gi->merge[j] == __gcov_merge_topn)
+ {
+ gcc_assert (!(ci->num % GCOV_TOPN_VALUES_COUNTERS));
+ for (unsigned k = 0; k < (ci->num / GCOV_TOPN_VALUES_COUNTERS);
+ k++)
+ {
+ gcov_type *counters
+ = ci->values + (k * GCOV_TOPN_VALUES_COUNTERS);
+ prune_topn_counter (counters + 1, *counters);
+ }
+ }
+ ci++;
+ }
+ }
+}
+
/* This function merges counters in GI_PTR to an existing gcda file.
Return 0 on success.
Return -1 on error. In this case, caller will goto read_fatal. */
@@ -429,9 +479,11 @@ dump_one_gcov (struct gcov_info *gi_ptr, struct gcov_filename *gf,
struct gcov_summary summary = {};
int error;
gcov_unsigned_t tag;
-
fn_buffer = 0;
+ /* Prune current counters before we merge them. */
+ prune_counters (gi_ptr);
+
error = gcov_exit_open_gcda_file (gi_ptr, gf);
if (error == -1)
return;
diff --git a/libgcc/libgcov-profiler.c b/libgcc/libgcov-profiler.c
index 9417904..f45ef49 100644
--- a/libgcc/libgcov-profiler.c
+++ b/libgcc/libgcov-profiler.c
@@ -119,37 +119,35 @@ __gcov_topn_values_profiler_body (gcov_type *counters, gcov_type value,
++counters;
- /* We have GCOV_TOPN_VALUES as we can keep multiple values
- next to each other. */
- unsigned sindex = 0;
-
for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
{
if (value == counters[2 * i])
{
if (use_atomic)
- __atomic_fetch_add (&counters[2 * i + 1], 1, __ATOMIC_RELAXED);
+ __atomic_fetch_add (&counters[2 * i + 1], GCOV_TOPN_VALUES,
+ __ATOMIC_RELAXED);
else
- counters[2 * i + 1]++;
+ counters[2 * i + 1] += GCOV_TOPN_VALUES;
return;
}
- else if (counters[2 * i + 1] == 0)
+ else if (counters[2 * i + 1] <= 0)
{
/* We found an empty slot. */
counters[2 * i] = value;
- counters[2 * i + 1] = 1;
+ counters[2 * i + 1] = GCOV_TOPN_VALUES;
return;
}
-
- if (counters[2 * i + 1] < counters[2 * sindex + 1])
- sindex = i;
}
- /* We haven't found an empty slot, then decrement the smallest. */
- if (use_atomic)
- __atomic_fetch_sub (&counters[2 * sindex + 1], 1, __ATOMIC_RELAXED);
- else
- counters[2 * sindex + 1]--;
+ /* We haven't found an empty slot, then decrement all
+ counter values by one. */
+ for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
+ {
+ if (use_atomic)
+ __atomic_fetch_sub (&counters[2 * i + 1], 1, __ATOMIC_RELAXED);
+ else
+ counters[2 * i + 1]--;
+ }
}
#ifdef L_gcov_topn_values_profiler
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