On 10/11/21 15:49, Martin Liška wrote:
Let me update the documentation bits.
There's the updated patch.
May I install the patch now?
Thanks,
Martin
From fdeb81a960faa19f75316e279a79c231da212f99 Mon Sep 17 00:00:00 2001
From: Martin Liska <mli...@suse.cz>
Date: Thu, 9 Sep 2021 13:02:24 +0200
Subject: [PATCH] gcov: make profile merging smarter
Support merging of profiles that are built from a different .o files
but belong to the same source file. Moreover, a checksum is verified
during profile merging and so we can safely combine such profile.
PR gcov-profile/90364
gcc/ChangeLog:
* coverage.c (build_info): Emit checksum to the global variable.
(build_info_type): Add new field for checksum.
(coverage_obj_finish): Pass object_checksum.
(coverage_init): Use 0 as checksum for .gcno files.
* gcov-dump.c (dump_gcov_file): Dump also new checksum field.
* gcov.c (read_graph_file): Read also checksum.
* doc/invoke.texi: Document the behaviour change.
libgcc/ChangeLog:
* libgcov-driver.c (merge_one_data): Skip timestamp and verify
checksums.
(write_one_data): Write also checksum.
* libgcov-util.c (read_gcda_file): Read also checksum field.
* libgcov.h (struct gcov_info): Add new field.
diff --git a/gcc/coverage.c b/gcc/coverage.c
index 10d7f8366cb..4467f1eaa5c 100644
--- a/gcc/coverage.c
+++ b/gcc/coverage.c
@@ -129,16 +129,7 @@ static const char *const ctr_names[GCOV_COUNTERS] = {
#undef DEF_GCOV_COUNTER
/* Forward declarations. */
-static void read_counts_file (void);
static tree build_var (tree, tree, int);
-static void build_fn_info_type (tree, unsigned, tree);
-static void build_info_type (tree, tree);
-static tree build_fn_info (const struct coverage_data *, tree, tree);
-static tree build_info (tree, tree);
-static bool coverage_obj_init (void);
-static vec<constructor_elt, va_gc> *coverage_obj_fn
-(vec<constructor_elt, va_gc> *, tree, struct coverage_data const *);
-static void coverage_obj_finish (vec<constructor_elt, va_gc> *);
/* Return the type node for gcov_type. */
@@ -218,6 +209,9 @@ read_counts_file (void)
tag = gcov_read_unsigned ();
bbg_file_stamp = crc32_unsigned (bbg_file_stamp, tag);
+ /* Read checksum. */
+ gcov_read_unsigned ();
+
counts_hash = new hash_table<counts_entry> (10);
while ((tag = gcov_read_unsigned ()))
{
@@ -935,6 +929,12 @@ build_info_type (tree type, tree fn_info_ptr_type)
DECL_CHAIN (field) = fields;
fields = field;
+ /* Checksum. */
+ field = build_decl (BUILTINS_LOCATION, FIELD_DECL, NULL_TREE,
+ get_gcov_unsigned_t ());
+ DECL_CHAIN (field) = fields;
+ fields = field;
+
/* Filename */
field = build_decl (BUILTINS_LOCATION, FIELD_DECL, NULL_TREE,
build_pointer_type (build_qualified_type
@@ -977,7 +977,7 @@ build_info_type (tree type, tree fn_info_ptr_type)
function info objects. */
static tree
-build_info (tree info_type, tree fn_ary)
+build_info (tree info_type, tree fn_ary, unsigned object_checksum)
{
tree info_fields = TYPE_FIELDS (info_type);
tree merge_fn_type, n_funcs;
@@ -996,13 +996,19 @@ build_info (tree info_type, tree fn_ary)
/* next -- NULL */
CONSTRUCTOR_APPEND_ELT (v1, info_fields, null_pointer_node);
info_fields = DECL_CHAIN (info_fields);
-
+
/* stamp */
CONSTRUCTOR_APPEND_ELT (v1, info_fields,
build_int_cstu (TREE_TYPE (info_fields),
bbg_file_stamp));
info_fields = DECL_CHAIN (info_fields);
+ /* Checksum. */
+ CONSTRUCTOR_APPEND_ELT (v1, info_fields,
+ build_int_cstu (TREE_TYPE (info_fields),
+ object_checksum));
+ info_fields = DECL_CHAIN (info_fields);
+
/* Filename */
da_file_name_len = strlen (da_file_name);
filename_string = build_string (da_file_name_len + 1, da_file_name);
@@ -1214,7 +1220,8 @@ coverage_obj_fn (vec<constructor_elt, va_gc> *ctor, tree fn,
function objects from CTOR. Generate the gcov_info initializer. */
static void
-coverage_obj_finish (vec<constructor_elt, va_gc> *ctor)
+coverage_obj_finish (vec<constructor_elt, va_gc> *ctor,
+ unsigned object_checksum)
{
unsigned n_functions = vec_safe_length (ctor);
tree fn_info_ary_type = build_array_type
@@ -1231,7 +1238,7 @@ coverage_obj_finish (vec<constructor_elt, va_gc> *ctor)
varpool_node::finalize_decl (fn_info_ary);
DECL_INITIAL (gcov_info_var)
- = build_info (TREE_TYPE (gcov_info_var), fn_info_ary);
+ = build_info (TREE_TYPE (gcov_info_var), fn_info_ary, object_checksum);
varpool_node::finalize_decl (gcov_info_var);
}
@@ -1300,7 +1307,6 @@ coverage_init (const char *filename)
strcpy (da_file_name + prefix_len + len, GCOV_DATA_SUFFIX);
bbg_file_stamp = local_tick;
-
if (flag_auto_profile)
read_autofdo_file ();
else if (flag_branch_probabilities)
@@ -1328,6 +1334,8 @@ coverage_init (const char *filename)
gcov_write_unsigned (GCOV_NOTE_MAGIC);
gcov_write_unsigned (GCOV_VERSION);
gcov_write_unsigned (bbg_file_stamp);
+ /* Use an arbitrary checksum */
+ gcov_write_unsigned (0);
gcov_write_string (getpwd ());
/* Do not support has_unexecuted_blocks for Ada. */
@@ -1353,14 +1361,24 @@ coverage_finish (void)
cannot uniquely stamp it. If we can stamp it, libgcov will DTRT. */
unlink (da_file_name);
+ /* Global GCDA checksum that aggregates all functions. */
+ unsigned object_checksum = 0;
+
if (coverage_obj_init ())
{
vec<constructor_elt, va_gc> *fn_ctor = NULL;
struct coverage_data *fn;
for (fn = functions_head; fn; fn = fn->next)
- fn_ctor = coverage_obj_fn (fn_ctor, fn->fn_decl, fn);
- coverage_obj_finish (fn_ctor);
+ {
+ fn_ctor = coverage_obj_fn (fn_ctor, fn->fn_decl, fn);
+
+ object_checksum = crc32_unsigned (object_checksum, fn->ident);
+ object_checksum = crc32_unsigned (object_checksum,
+ fn->lineno_checksum);
+ object_checksum = crc32_unsigned (object_checksum, fn->cfg_checksum);
+ }
+ coverage_obj_finish (fn_ctor, object_checksum);
}
XDELETEVEC (da_file_name);
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 8b3ebcfbc4f..c37a320ba4f 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -14882,6 +14882,10 @@ supports locking, the data files will be correctly updated. Unless
a strict ISO C dialect option is in effect, @code{fork} calls are
detected and correctly handled without double counting.
+Moreover, an object file can be recompiled multiple times
+and the corresponding @file{.gcda} file merges as long as
+the source file and the compiler options are unchanged.
+
@item
For profile-directed optimizations, compile the source files again with
the same optimization and code generation options plus
diff --git a/gcc/gcov-dump.c b/gcc/gcov-dump.c
index f1489fe0214..bfaf735d2ff 100644
--- a/gcc/gcov-dump.c
+++ b/gcc/gcov-dump.c
@@ -206,11 +206,12 @@ dump_gcov_file (const char *filename)
}
/* stamp */
- {
- unsigned stamp = gcov_read_unsigned ();
+ unsigned stamp = gcov_read_unsigned ();
+ printf ("%s:stamp %lu\n", filename, (unsigned long)stamp);
- printf ("%s:stamp %lu\n", filename, (unsigned long)stamp);
- }
+ /* Checksum */
+ unsigned checksum = gcov_read_unsigned ();
+ printf ("%s:checksum %lu\n", filename, (unsigned long)checksum);
if (!is_data_type)
{
diff --git a/gcc/gcov.c b/gcc/gcov.c
index cf0a49d8c30..829e955a63b 100644
--- a/gcc/gcov.c
+++ b/gcc/gcov.c
@@ -1814,6 +1814,8 @@ read_graph_file (void)
bbg_file_name, v, e);
}
bbg_stamp = gcov_read_unsigned ();
+ /* Read checksum. */
+ gcov_read_unsigned ();
bbg_cwd = xstrdup (gcov_read_string ());
bbg_supports_has_unexecuted_blocks = gcov_read_unsigned ();
@@ -2031,6 +2033,9 @@ read_count_file (void)
goto cleanup;
}
+ /* Read checksum. */
+ gcov_read_unsigned ();
+
while ((tag = gcov_read_unsigned ()))
{
unsigned length = gcov_read_unsigned ();
diff --git a/libgcc/libgcov-driver.c b/libgcc/libgcov-driver.c
index 087f71e0107..7aa97bbb06a 100644
--- a/libgcc/libgcov-driver.c
+++ b/libgcc/libgcov-driver.c
@@ -260,12 +260,15 @@ merge_one_data (const char *filename,
if (!gcov_version (gi_ptr, length, filename))
return -1;
+ /* Skip timestamp. */
+ gcov_read_unsigned ();
+
length = gcov_read_unsigned ();
- if (length != gi_ptr->stamp)
+ if (length != gi_ptr->checksum)
{
/* Read from a different compilation. Overwrite the file. */
gcov_error (GCOV_PROF_PREFIX "overwriting an existing profile data "
- "with a different timestamp\n", filename);
+ "with a different checksum\n", filename);
return 0;
}
@@ -495,6 +498,7 @@ write_one_data (const struct gcov_info *gi_ptr,
dump_unsigned (GCOV_DATA_MAGIC, dump_fn, arg);
dump_unsigned (GCOV_VERSION, dump_fn, arg);
dump_unsigned (gi_ptr->stamp, dump_fn, arg);
+ dump_unsigned (gi_ptr->checksum, dump_fn, arg);
#ifdef NEED_L_GCOV
/* Generate whole program statistics. */
diff --git a/libgcc/libgcov-util.c b/libgcc/libgcov-util.c
index bc7416d99bf..766ca3559c4 100644
--- a/libgcc/libgcov-util.c
+++ b/libgcc/libgcov-util.c
@@ -310,6 +310,9 @@ read_gcda_file (const char *filename)
/* Read stamp. */
obj_info->stamp = gcov_read_unsigned ();
+ /* Read checksum. */
+ obj_info->checksum = gcov_read_unsigned ();
+
while (1)
{
gcov_position_t base;
diff --git a/libgcc/libgcov.h b/libgcc/libgcov.h
index f6354a7a070..2a365c95759 100644
--- a/libgcc/libgcov.h
+++ b/libgcc/libgcov.h
@@ -230,6 +230,7 @@ struct gcov_info
struct gcov_info *next; /* link to next, used by libgcov */
gcov_unsigned_t stamp; /* uniquifying time stamp */
+ gcov_unsigned_t checksum; /* unique object checksum */
const char *filename; /* output file name */
gcov_merge_fn merge[GCOV_COUNTERS]; /* merge functions (null for
--
2.33.0
