Ok, after personal discussion with Honza that I had,
we should be more conservative and prune only
a run-time TOP N counters before we merge them.
The patch does that. Can you please Honza test me the patch of Firefox?
Thanks,
Martin
>From 7fe1e6a59139ae00cefd1f5edf082d428952203e Mon Sep 17 00:00:00 2001
From: Martin Liska <mli...@suse.cz>
Date: Wed, 15 Jan 2020 15:39:55 +0100
Subject: [PATCH] Smart relaxation of TOP N counter.
---
gcc/profile.c | 9 +++++-
libgcc/libgcov-driver.c | 58 ++++++++++++++++++++++++++++++++++++++-
libgcc/libgcov-profiler.c | 27 ++++++++----------
3 files changed, 77 insertions(+), 17 deletions(-)
diff --git a/gcc/profile.c b/gcc/profile.c
index 6a2de21c3bd..1a6caf75a61 100644
--- a/gcc/profile.c
+++ b/gcc/profile.c
@@ -863,7 +863,14 @@ 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] /= 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/libgcov-driver.c b/libgcc/libgcov-driver.c
index 1c07761b7f1..b71b0e3edac 100644
--- a/libgcc/libgcov-driver.c
+++ b/libgcc/libgcov-driver.c
@@ -213,6 +213,60 @@ static struct gcov_fn_buffer *fn_buffer;
/* Including system dependent components. */
#include "libgcov-driver-system.c"
+/* Prune TOP N value COUNTERS. */
+
+static void
+prune_topn_counter (gcov_type *counters, gcov_type all)
+{
+ if (counters[1] == -1)
+ return;
+
+ // TODO
+#if 0
+ fprintf (stderr, "prune_topn_counter for all=%d\n", all);
+ for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
+ fprintf (stderr, "%d:%d:%d\n", i, counters[2 * i], counters[2 * i + 1]);
+#endif
+
+ 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 +483,11 @@ 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 9417904d462..39e3c523250 100644
--- a/libgcc/libgcov-profiler.c
+++ b/libgcc/libgcov-profiler.c
@@ -119,37 +119,34 @@ __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)
{
/* 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
--
2.24.1
