The code coverage support uses counters to determine which edges in the control
flow graph were executed. If a counter overflows, then the code coverage
information is invalid. Therefore the counter type should be a 64-bit integer.
In multi-threaded applications, it is important that the counter increments are
atomic. This is not the case by default. The user can enable atomic counter
increments through the -fprofile-update=atomic and
-fprofile-update=prefer-atomic options.
If the target supports 64-bit atomic operations, then everything is fine. If
not and -fprofile-update=prefer-atomic was chosen by the user, then non-atomic
counter increments will be used. However, if the target does not support the
required atomic operations and -fprofile-atomic=update was chosen by the user,
then a warning was issued and as a forced fallback to non-atomic operations was
done. This is probably not what a user wants. There is still hardware on the
market which does not have atomic operations and is used for multi-threaded
applications. A user which selects -fprofile-update=atomic wants consistent
code coverage data and not random data.
This patch removes the fallback to non-atomic operations for
-fprofile-update=atomic the target platform supports libatomic. To
mitigate potential performance issues an optimization for systems which
only support 32-bit atomic operations is provided. Here, the edge
counter increments are done like this:
low = __atomic_add_fetch_4 (&counter.low, 1, MEMMODEL_RELAXED);
high_inc = low == 0 ? 1 : 0;
__atomic_add_fetch_4 (&counter.high, high_inc, MEMMODEL_RELAXED);
In gimple_gen_time_profiler() this split operation cannot be used, since the
updated counter value is also required. Here, a library call is emitted. This
is not a performance issue since the update is only done if counters[0] == 0.
gcc/c-family/ChangeLog:
* c-cppbuiltin.cc (c_cpp_builtins): Define
__LIBGCC_HAVE_LIBATOMIC for libgcov.
gcc/ChangeLog:
* doc/invoke.texi (-fprofile-update): Clarify default method. Document
the atomic method behaviour.
* tree-profile.cc (enum counter_update_method): New.
(counter_update): Likewise.
(gen_counter_update): Use counter_update_method. Split the
atomic counter update in two 32-bit atomic operations if
necessary.
(tree_profiling): Select counter_update_method.
libgcc/ChangeLog:
* libgcov.h (GCOV_SUPPORTS_ATOMIC): Always define it.
Set it also to 1, if __LIBGCC_HAVE_LIBATOMIC is defined.
gcov_info::n_functions type is initialized by generated
code in build_info_type:
/* n_functions */
field = build_decl (BUILTINS_LOCATION, FIELD_DECL, NULL_TREE,
get_gcov_unsigned_t ());
It uses gcov_unsigned_t, but the struct definition in libgcov.h uses
unsigned type. That brings troubled on 16-bit targets.
PR gcov-profile/105535
libgcc/ChangeLog:
* libgcov.h (struct gcov_info): Use gcov_unsigned_t for
n_functions.
Co-Authored-By: Hans-Peter Helfert <peter-helfert@t-online.de>
This function is only used by gcov_write_length() in the gcov-io.cc file.
gcc/
* gcov-io.cc (gcov_seek): Make it static.
* gcov-io.h (struct gcov_summary): Do not mention gcov_seek().
libgcc/
* libgcov.h (gcov_seek): Remove define and declaration.
gcc/
* gcov-io.cc (gcov_open): Always use the mode parameter.
* gcov-io.h (gcov_open): Declare it unconditionally.
libgcc/
* libgcov-driver-system.c (gcov_exit_open_gcda_file): Open file for
reading and writing.
* libgcov-util.c (read_gcda_file): Open file for reading.
* libgcov.h (gcov_open): Delete declaration.
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.
If -fprofile-update=atomic is used, then the target must provide atomic
operations for the counters of the type returned by get_gcov_type().
This is a 64-bit type for targets which have a 64-bit long long type.
On 32-bit targets this could be an issue since they may not provide
64-bit atomic operations. Allow targets to override the default type
size with the new TARGET_GCOV_TYPE_SIZE target hook.
If a 32-bit gcov type size is used, then there is currently a warning in
libgcov-driver.c in a dead code block due to
sizeof (counter) == sizeof (gcov_unsigned_t):
libgcc/libgcov-driver.c: In function 'dump_counter':
libgcc/libgcov-driver.c:401:46: warning: right shift count >= width of type [-Wshift-count-overflow]
401 | dump_unsigned ((gcov_unsigned_t)(counter >> 32), dump_fn, arg);
| ^~
gcc/c-family/
* c-cppbuiltin.c (c_cpp_builtins): Define
__LIBGCC_GCOV_TYPE_SIZE if flag_building_libgcc is true.
gcc/
* config/sparc/rtemself.h (SPARC_GCOV_TYPE_SIZE): Define.
* config/sparc/sparc.c (sparc_gcov_type_size): New.
(TARGET_GCOV_TYPE_SIZE): Redefine if SPARC_GCOV_TYPE_SIZE is defined.
* coverage.c (get_gcov_type): Use targetm.gcov_type_size().
* doc/tm.texi (TARGET_GCOV_TYPE_SIZE): Add hook under "Misc".
* doc/tm.texi.in: Regenerate.
* target.def (gcov_type_size): New target hook.
* targhooks.c (default_gcov_type_size): New.
* targhooks.h (default_gcov_type_size): Declare.
* tree-profile.c (gimple_gen_edge_profiler): Use precision of
gcov_type_node.
(gimple_gen_time_profiler): Likewise.
libgcc/
* libgcov.h (gcov_type): Define using __LIBGCC_GCOV_TYPE_SIZE.
(gcov_type_unsigned): Likewise.
Add __gcov_info_to_gcda() to libgcov to get the gcda data for a gcda info in a
freestanding environment. It is intended to be used with the
-fprofile-info-section option. A crude test program which doesn't use a linker
script is (use "gcc -coverage -fprofile-info-section -lgcov test.c" to compile
it):
#include <gcov.h>
#include <stdio.h>
#include <stdlib.h>
extern const struct gcov_info *my_info;
static void
filename (const char *f, void *arg)
{
printf("filename: %s\n", f);
}
static void
dump (const void *d, unsigned n, void *arg)
{
const unsigned char *c = d;
for (unsigned i = 0; i < n; ++i)
printf ("%02x", c[i]);
}
static void *
allocate (unsigned length, void *arg)
{
return malloc (length);
}
int main()
{
__asm__ volatile (".set my_info, .LPBX2");
__gcov_info_to_gcda (my_info, filename, dump, allocate, NULL);
return 0;
}
With this patch, <stdint.h> is included in libgcov-driver.c even if
inhibit_libc is defined. This header file should be also available for
freestanding environments. If this is not the case, then we have to define
intptr_t somehow.
The patch removes one use of memset() which makes the <string.h> include
superfluous.
gcc/
* gcov-io.h (gcov_write): Declare.
* gcov-io.c (gcov_write): New.
(gcov_write_counter): Remove.
(gcov_write_tag_length): Likewise.
(gcov_write_summary): Replace gcov_write_tag_length() with calls to
gcov_write_unsigned().
* doc/invoke.texi (fprofile-info-section): Mention
__gcov_info_to_gdca().
gcc/testsuite/
* gcc.dg/gcov-info-to-gcda.c: New test.
libgcc/
* Makefile.in (LIBGCOV_DRIVER): Add _gcov_info_to_gcda.
* gcov.h (gcov_info): Declare.
(__gcov_info_to_gdca): Likewise.
* libgcov.h (gcov_write_counter): Remove.
(gcov_write_tag_length): Likewise.
* libgcov-driver.c (#include <stdint.h>): New.
(#include <string.h>): Remove.
(NEED_L_GCOV): Conditionally define.
(NEED_L_GCOV_INFO_TO_GCDA): Likewise.
(are_all_counters_zero): New.
(gcov_dump_handler): Likewise.
(gcov_allocate_handler): Likewise.
(dump_unsigned): Likewise.
(dump_counter): Likewise.
(write_topn_counters): Add dump_fn, allocate_fn, and arg parameters.
Use dump_unsigned() and dump_counter().
(write_one_data): Add dump_fn, allocate_fn, and arg parameters. Use
dump_unsigned(), dump_counter(), and are_all_counters_zero().
(__gcov_info_to_gcda): New.
If you attempt a profiled bootstrap on the MinGW platforms with -jN, N > 1,
it miserably fails because of profile mismatches all over the place, the
reason being that gcov has no support for parallelism on these platforms.
libgcc/
* libgcov.h: For the target, define GCOV_LOCKED_WITH_LOCKING
if __MSVCRT__ and, for the host, define it if HOST_HAS_LK_LOCK.
* libgcov-driver.c: Add directives if GCOV_LOCKED_WITH_LOCKING.
gcc/
* configure.ac: Check for the presence of sys/locking.h header and
for whether _LK_LOCK is supported by _locking.
* configure: Regenerate.
* config.in: Likewise.
* gcov-io.h: Define GCOV_LOCKED_WITH_LOCKING if HOST_HAS_LK_LOCK.
* gcov-io.c (gcov_open): Add support for GCOV_LOCKED_WITH_LOCKING.
* system.h: Include <sys/locking.h> if HAVE_SYS_LOCKING_H.
As reported, bootstrap currently fails on older Darwin because MAP_ANONYMOUS
is not defined.
The following is what gcc/system.h does, so I think it should work for
libgcov.
2021-03-06 Jakub Jelinek <jakub@redhat.com>
PR gcov-profile/99406
* libgcov.h (MAP_FAILED, MAP_ANONYMOUS): If HAVE_SYS_MMAN_H is
defined, define these macros if not defined already.
libgcc/ChangeLog:
PR gcov-profile/99105
* libgcov-driver.c (write_top_counters): Rename to ...
(write_topn_counters): ... this.
(write_one_data): Pre-allocate buffer for number of items
in the corresponding linked lists.
* libgcov.h (malloc_mmap): New function.
(allocate_gcov_kvp): Use it.
gcc/testsuite/ChangeLog:
PR gcov-profile/99105
* gcc.dg/tree-prof/indir-call-prof-malloc.c: Use profile
correction as the wrapped malloc is called one more time
from libgcov.
* gcc.dg/tree-prof/pr97461.c: Likewise.
libgcc/ChangeLog:
PR gcov-profile/98739
* libgcov.h (gcov_topn_add_value): Do not train when
we have a merged profile with a negative number of total
value.
gcc/ChangeLog:
PR gcov-profile/97461
* gcov-io.h (GCOV_PREALLOCATED_KVP): Pre-allocate 64
static counters.
libgcc/ChangeLog:
PR gcov-profile/97461
* libgcov.h (gcov_counter_add): Use first static counters
as it should help to have malloc wrappers set up.
gcc/testsuite/ChangeLog:
PR gcov-profile/97461
* gcc.dg/tree-prof/pr97461.c: New test.
libgcc/ChangeLog:
* libgcov-driver.c (merge_summary): Remove function as its name
is misleading and doing something different.
(dump_one_gcov): Add ATTRIBUTE_UNUSED for 2 args. Take read summary
in gcov-tool.
* libgcov-util.c (curr_object_summary): Remove.
(read_gcda_file): Remove unused curr_object_summary.
(gcov_merge): Merge summaries.
* libgcov.h: Add summary argument for gcov_info struct.
libgcc/ChangeLog:
* libgcov-util.c (read_gcda_finalize): Remove const operator.
(merge_wrapper): Add both counts and use them properly.
(topn_to_memory_representation): New function.
(gcov_merge): Covert on disk representation to in memory
representation.
* libgcov.h: Remove const operator.
The patch fixes tree-prof.exp tests on solaris11 and i686-linux-gnu,
problem was that sizeof of a pointer is different from sizeof gcov_type.
I'm going to install it if there are no objections.
Thanks,
Martin
libgcc/ChangeLog:
PR gcov-profile/95494
* libgcov-driver.c (write_top_counters): Cast first to
intptr_t as sizeof(*) != sizeof(gcov_type).
* libgcov.h (gcov_counter_set_if_null): Remove.
(gcov_topn_add_value): Cast first to intptr_t and update
linked list directly.
We must guard used atomic builtins with GCOV_SUPPORTS_ATOMIC.
The patch is tested on AIX and I'm going to push it.
libgcc/ChangeLog:
PR gcov-profile/95480
* libgcov-profiler.c (GCOV_SUPPORTS_ATOMIC): Move to...
* libgcov.h (GCOV_SUPPORTS_ATOMIC): ...here.
(gcov_counter_add): Use GCOV_SUPPORTS_ATOMIC guard.
(gcov_counter_set_if_null): Likewise.
The calloc was in the original tested version of the patch
and I made accidental last minute change.
Installed to master as obvious.
libgcc/ChangeLog:
* libgcov.h (gcov_topn_add_value): Use xcalloc instead
of xmalloc.
gcc/ChangeLog:
* coverage.c (get_coverage_counts): Skip sanity check for TOP N counters
as they have variable number of counters.
* gcov-dump.c (main): Add new option -r.
(print_usage): Likewise.
(tag_counters): All new raw format.
* gcov-io.h (struct gcov_kvp): New.
(GCOV_TOPN_VALUES): Remove.
(GCOV_TOPN_VALUES_COUNTERS): Likewise.
(GCOV_TOPN_MEM_COUNTERS): New.
(GCOV_TOPN_DISK_COUNTERS): Likewise.
(GCOV_TOPN_MAXIMUM_TRACKED_VALUES): Likewise.
* ipa-profile.c (ipa_profile_generate_summary): Use
GCOV_TOPN_MAXIMUM_TRACKED_VALUES.
(ipa_profile_write_edge_summary): Likewise.
(ipa_profile_read_edge_summary): Likewise.
(ipa_profile): Remove usage of GCOV_TOPN_VALUES.
* profile.c (sort_hist_values): Sort variable number
of counters.
(compute_value_histograms): Special case for TOP N counters
that have dynamic number of key-value pairs.
* value-prof.c (dump_histogram_value): Dump variable number
of key-value pairs.
(stream_in_histogram_value): Stream in variable number
of key-value pairs for TOP N counter.
(get_nth_most_common_value): Deal with variable number
of key-value pairs.
(dump_ic_profile): Use GCOV_TOPN_MAXIMUM_TRACKED_VALUES
for loop iteration.
(gimple_find_values_to_profile): Set GCOV_TOPN_MEM_COUNTERS
to n_counters.
* doc/gcov-dump.texi: Document new -r option.
libgcc/ChangeLog:
* libgcov-driver.c (prune_topn_counter): Remove.
(prune_counters): Likewise.
(merge_one_data): Special case TOP N counters
as they have variable length.
(write_top_counters): New.
(write_one_data): Special case TOP N.
(dump_one_gcov): Do not prune TOP N counters.
* libgcov-merge.c (merge_topn_values_set): Remove.
(__gcov_merge_topn): Use gcov_topn_add_value.
* libgcov-profiler.c (__gcov_topn_values_profiler_body):
Likewise here.
* libgcov.h (gcov_counter_add): New.
(gcov_counter_set_if_null): Likewise.
(gcov_topn_add_value): New.
2018-10-04 Martin Liska <mliska@suse.cz>
PR gcov-profile/84107
* tree-profile.c (init_ic_make_global_vars):
Remove ic_void_ptr_var and ic_gcov_type_ptr_var.
Come up with new ic_tuple* variables. Emit
__gcov_indirect_call{,_topn} variables.
(gimple_gen_ic_profiler): Access the variable
and emit gimple.
(gimple_gen_ic_func_profiler): Access
__gcov_indirect_call.callee field.
(gimple_init_gcov_profiler): Use ptr_type_node.
* value-prof.c (gimple_ic): Use ptr_type_node.
2018-10-04 Martin Liska <mliska@suse.cz>
PR gcov-profile/84107
* libgcov-profiler.c (__gcov_indirect_call):
Change type to indirect_call_tuple.
(struct indirect_call_tuple): New struct.
(__gcov_indirect_call_topn_profiler): Change type.
(__gcov_indirect_call_profiler_v2): Use the new
variables.
* libgcov.h (struct indirect_call_tuple): New struct
definition.
From-SVN: r264840
2017-06-21 Richard Biener <rguenther@suse.de>
PR gcov-profile/81080
* configure.ac: Add AC_SYS_LARGEFILE.
* libgcov.h: Include auto-target.h before tsystem.h to pick
up _FILE_OFFSET_BITS which might differ for multilibs.
* config.in: Regenerate.
* configure: Likewise.
From-SVN: r249435
2017-04-19 Martin Liska <mliska@suse.cz>
PR gcov-profile/80435
* Makefile.in: Install gcov.h.
* gcov.h: New file.
* libgcov.h: Use the header and make __gcov_flush publicly
visible.
From-SVN: r246990
PR gcov-profile/7970
PR gcov-profile/16855
PR gcov-profile/44779
* g++.dg/gcov/pr16855.C: New test.
* coverage.c (build_gcov_exit_decl): New function.
(coverage_obj_init): Call the function and generate __gcov_exit
destructor.
* doc/gcov.texi: Document when __gcov_exit function is called.
* libgcov-driver.c (__gcov_init): Do not register a atexit
handler.
(__gcov_exit): Rename from gcov_exit.
* libgcov.h (__gcov_exit): Declare.
From-SVN: r240529
* Makefile.in: Remove __gcov_indirect_call_profiler.
* libgcov-profiler.c (__gcov_indirect_call_profiler): Remove
function.
* libgcov.h: And the declaration of the function.
From-SVN: r239306
