Hi.
So I'm sending first version of the relaxation patch and a demonstration
source file that can demonstrate how me merge profile for indirect
functions provided on input. There are some demonstrations:
1) rm indir-call.gcda -f ; ./a.out ABCD && gcov-dump -l indir-call.gcda | grep
-A2 'indirect_call 9'
indir-call.gcda: 01a90000: 18:COUNTERS indirect_call 9 counts
indir-call.gcda: 0: 4 51084318 4 1042717606 4 1451412899 4
1149064406
indir-call.gcda: 8: 4
All 4 values will fit in the counter (note that profile read code will divide
all values by 4).
2) rm indir-call.gcda -f ; ./a.out AAABB && ./a.out B && ./a.out C && gcov-dump
-l indir-call.gcda | grep -A2 'indirect_call 9'
indir-call.gcda: 01a90000: 18:COUNTERS indirect_call 9 counts
indir-call.gcda: 0: 7 51084318 12 1042717606 12 0 0 0
indir-call.gcda: 8: 0
Here A, B, C have frequency < 5/4.
3) rm indir-call.gcda -f ; ./a.out AABCDE && gcov-dump -l indir-call.gcda |
grep -A2 'indirect_call 9'
indir-call.gcda: 01a90000: 18:COUNTERS indirect_call 9 counts
indir-call.gcda: 0: 6 51084318 7 0 0 0 0 0
indir-call.gcda: 8: 0
Here only A survives (2 * 4 - 1).
4) rm indir-call.gcda -f ; ./a.out AAABB && ./a.out B && gcov-dump -l
indir-call.gcda | grep -A2 'indirect_call 9'
indir-call.gcda: 01a90000: 18:COUNTERS indirect_call 9 counts
indir-call.gcda: 0: 6 51084318 12 1042717606 12 0 0 0
indir-call.gcda: 8: 0
Merging works in between runs properly
5) rm indir-call.gcda -f ; ./a.out AAABB && ./a.out B && ./a.out C && gcov-dump
-l indir-call.gcda | grep -A2 'indirect_call 9'
indir-call.gcda: 01a90000: 18:COUNTERS indirect_call 9 counts
indir-call.gcda: 0: 7 51084318 12 1042717606 12 0 0 0
indir-call.gcda: 8: 0
Same here, where C is discarded due to small count.
Can you please Honza take a look and provide a feedback? About the new option:
I would like not to invent a bigger complexity. Even now, the merging is quite
complex.
Martin
>From 0965602cd24d29e6d4442a0e530794e70650328e Mon Sep 17 00:00:00 2001
From: Martin Liska <[email protected]>
Date: Wed, 15 Jan 2020 15:39:55 +0100
Subject: [PATCH] Smart relaxation of TOP N counter.
---
gcc/gcov-io.c | 25 +++++++++++++++++
gcc/gcov-io.h | 1 +
gcc/profile.c | 9 ++++++-
libgcc/libgcov-driver.c | 33 ++++++++++++++++++++++-
libgcc/libgcov-merge.c | 57 ++++++++++++++++++++++++---------------
libgcc/libgcov-profiler.c | 27 +++++++++----------
6 files changed, 113 insertions(+), 39 deletions(-)
diff --git a/gcc/gcov-io.c b/gcc/gcov-io.c
index 213c413b3a0..0bdc49bc108 100644
--- a/gcc/gcov-io.c
+++ b/gcc/gcov-io.c
@@ -587,6 +587,31 @@ mangle_path (char const *base)
return buffer;
}
+/* Prune TOP N value COUNTERS. */
+
+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;
+ }
+ }
+}
+
/* We need to expose the below function when compiling for gcov-tool. */
#if !IN_LIBGCOV || defined (IN_GCOV_TOOL)
diff --git a/gcc/gcov-io.h b/gcc/gcov-io.h
index d21a43c4c31..61bb7def23b 100644
--- a/gcc/gcov-io.h
+++ b/gcc/gcov-io.h
@@ -338,6 +338,7 @@ GCOV_LINKAGE const char *gcov_read_string (void);
GCOV_LINKAGE void gcov_sync (gcov_position_t /*base*/,
gcov_unsigned_t /*length */);
char *mangle_path (char const *base);
+void prune_topn_counter (gcov_type *counters, gcov_type all);
#if !IN_GCOV
/* Available outside gcov */
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..de5e2eea29b 100644
--- a/libgcc/libgcov-driver.c
+++ b/libgcc/libgcov-driver.c
@@ -213,6 +213,35 @@ static struct gcov_fn_buffer *fn_buffer;
/* Including system dependent components. */
#include "libgcov-driver-system.c"
+/* 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 +458,11 @@ 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-merge.c b/libgcc/libgcov-merge.c
index b658aec46c6..d2898f67a5a 100644
--- a/libgcc/libgcov-merge.c
+++ b/libgcc/libgcov-merge.c
@@ -92,10 +92,11 @@ merge_topn_values_set (gcov_type *counters)
/* First value is number of total executions of the profiler. */
gcov_type all = gcov_get_counter_ignore_scaling (-1);
counters[0] += all;
+ all = counters[0];
++counters;
- /* Read all part values. */
- gcov_type read_counters[2 * GCOV_TOPN_VALUES];
+ /* Read all part values. Make the buffer twice bigger. */
+ gcov_type read_counters[2 * 2 * GCOV_TOPN_VALUES] = {};
for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
{
@@ -109,32 +110,44 @@ merge_topn_values_set (gcov_type *counters)
return;
}
+ /* Merge both couters into read_counter which has sufficient size. */
for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
+ for (unsigned j = 0; j < GCOV_TOPN_VALUES; j++)
+ {
+ if (read_counters[2 * j] == counters[2 * i])
+ {
+ read_counters[2 * j + 1] += counters[2 * i + 1];
+ break;
+ }
+ else if (read_counters[2 * j + 1] == 0)
+ {
+ read_counters[2 * j] += counters[2 * i];
+ read_counters[2 * j + 1] += counters[2 * i + 1];
+ break;
+ }
+ }
+
+ /* Prune both halves of the read_counters. */
+ prune_topn_counter (read_counters, all);
+ prune_topn_counter (read_counters + 2 * GCOV_TOPN_VALUES, all);
+
+ /* Copy back merged values. */
+ memset (counters, 0, GCOV_TOPN_VALUES_COUNTERS * sizeof (counters[0]));
+ unsigned index = 0;
+ for (unsigned i = 0; i < 2 * GCOV_TOPN_VALUES; i++)
{
- if (read_counters[2 * i + 1] == 0)
- return;
-
- unsigned j;
- for (j = 0; j < GCOV_TOPN_VALUES; j++)
+ if (read_counters[2 * i + 1] > 0)
{
- if (counters[2 * j] == read_counters[2 * i])
- {
- counters[2 * j + 1] += read_counters[2 * i + 1];
- break;
- }
- else if (counters[2 * j + 1] == 0)
+ /* We haven't found an empty slot, bail out. */
+ if (index == GCOV_TOPN_VALUES)
{
- counters[2 * j] += read_counters[2 * i];
- counters[2 * j + 1] += read_counters[2 * i + 1];
- break;
+ counters[1] = -1;
+ return;
}
- }
- /* We haven't found a slot, bail out. */
- if (j == GCOV_TOPN_VALUES)
- {
- counters[1] = -1;
- return;
+ counters[2 * index] = read_counters[2 * i];
+ counters[2 * index + 1] = read_counters[2 * i + 1];
+ index++;
}
}
}
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
/* { dg-options "-O2 -fdump-tree-optimized -fdump-ipa-profile-optimized -fdump-ipa-afdo" } */
static int a (void)
{
return 10;
}
static int b (void)
{
return 0;
}
static int c (void)
{
return 2;
}
static int d (void)
{
return 22;
}
static int e (void)
{
return 222;
}
static int f (void)
{
return 2222;
}
typedef int (*tp) (void);
static tp fns[] = {a, b, c, d, e, f};
void setp (int (**ptr) (void), char c)
{
*ptr = fns[c - 'A'];
}
int
main (int argc, char **argv)
{
if (argc != 2)
return 1;
char *str = argv[1];
int (*p) (void);
int i;
for (int i = 0; i < __builtin_strlen (str); i ++)
{
setp (&p, str[i]);
p ();
}
return 0;
}
/* { dg-final-use-not-autofdo { scan-ipa-dump "Indirect call -> direct call.* a1 transformation on insn" "profile"} } */
/* { dg-final-use-autofdo { scan-ipa-dump "Indirect call -> direct call.* a1 transformation on insn" "afdo"} } */
/* { dg-final-use { scan-tree-dump-not "Invalid sum" "optimized"} } */
