[Bug gcov-profile/44779] The gcov library does not adequately handle functions with constructor/destructor attributes
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44779 Martin Liška changed: What|Removed |Added Status|REOPENED|RESOLVED Resolution|--- |FIXED --- Comment #9 from Martin Liška --- Fixed on trunk.
[Bug gcov-profile/44779] The gcov library does not adequately handle functions with constructor/destructor attributes
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44779 --- Comment #8 from Martin Liška --- Author: marxin Date: Tue Sep 27 11:07:11 2016 New Revision: 240529 URL: https://gcc.gnu.org/viewcvs?rev=240529=gcc=rev Log: gcov: dump in a static dtor instead of in an atexit handler 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. Added: trunk/gcc/testsuite/g++.dg/gcov/pr16855.C Modified: trunk/gcc/ChangeLog trunk/gcc/coverage.c trunk/gcc/doc/gcov.texi trunk/gcc/testsuite/ChangeLog trunk/libgcc/ChangeLog trunk/libgcc/libgcov-driver.c trunk/libgcc/libgcov.h
[Bug gcov-profile/44779] The gcov library does not adequately handle functions with constructor/destructor attributes
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44779 Martin Liška changed: What|Removed |Added Status|RESOLVED|REOPENED Resolution|INVALID |--- Assignee|unassigned at gcc dot gnu.org |marxin at gcc dot gnu.org --- Comment #7 from Martin Liška --- Looks I've got working solution for situation 2).
[Bug gcov-profile/44779] The gcov library does not adequately handle functions with constructor/destructor attributes
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44779
Martin Liška changed:
What|Removed |Added
Status|WAITING |RESOLVED
CC||marxin at gcc dot gnu.org
Resolution|--- |INVALID
--- Comment #6 from Martin Liška ---
(In reply to Jay Vaughan from comment #0)
> I am developing a software system which has the requirement (as it is
> safety-critical), that we report full coverage of our modules as part of the
> validation process.
>
> One aspect of this software system is the inclusion of a library - lets call
> it libguardian - which is wrapped around all applications being run on our
> custom system, using LD_PRELOAD. The purpose of libguardian is to obtain
> valid conditions for continued launch prior to the execution of main() by
> the runtime in the wrapped application. To this end, libguardian defines a
> constructor and destructor pair of functions that obtain the valid
> conditions required for continued launch, and clean up/report on exit of the
> application.
>
> This libguardian, and associated applications, works perfectly fine.
> However, it is not possible to capture coverage information for these
> functions due to limits in gcov.
>
> The constructor/destructor methods are defined thus:
>
>
> #define GUARDIAN_CONSTRUCTOR_DESTRUCTOR_PRIORITY 65535
> /* NOTE: this priority can also be 101! */
>
> void guardian_constructor(void) __attribute__
> ((constructor(GUARDIAN_CONSTRUCTOR_DESTRUCTOR_PRIORITY)));
>
> void guardian_destructor(void) __attribute__
> ((destructor(GUARDIAN_CONSTRUCTOR_DESTRUCTOR_PRIORITY)));
>
>
> If the guardian_constructor() finds conditions unsavory for continued
> execution in our environment, it exit()'s immediately. In this circumstance,
> coverage is lost (or not provided) by gcov's atexit/destructor methods, as
> it appears that *priority* of known constructors is not accounted for in the
> gcov library, nor is there an atexit() handler that can adequately sort
> these priorities.
Well, there are two scenarios that happen for your test-case:
1) guardian_constructor exits: as the function is called via LD_PRELOAD,
libgcov is not yet registered and cannot produce any *.gcda files. It's
unrelated to priorities of dtors/atexit handlers
2) _SHOULD_CONSTRUCTOR_DIE_ is undefined: all works fine except
guardian_exiter:
LD_PRELOAD=./testlib.so ./testapp
++ GUARDIAN CONSTRUCTOR STAGE: [15226]
This is a number between 1 and 10: 1
This is a number between 1 and 10: 2
This is a number between 1 and 10: 3
This is a number between 1 and 10: 4
This is a number between 1 and 10: 5
This is a number between 1 and 10: 6
This is a number between 1 and 10: 7
This is a number between 1 and 10: 8
This is a number between 1 and 10: 9
This is a number between 1 and 10: 10
**
gcov init is called
gcov init is called
^^ That was the constructor ^^
This is main() in the testapp()
By now, the testlib should have reported
its own progress in counting 1 to 10.
Next comes the destructor :::
gcov_exit is called
-- GUARDIAN DESTRUCTOR STAGE:
**
gcov_exit is called
!! GUARDIAN EXIT HANDLER REACHED !!
gcov testlib.c
File 'testlib.c'
Lines executed:78.57% of 14
Creating 'testlib.c.gcov'
gcov testapp.c
File 'testapp.c'
Lines executed:100.00% of 3
Creating 'testapp.c.gcov'
As you can see, I added dumping of gcov_init/gcov_exit. The only functions
which is not seen by coverage is:
#: 16:static void guardian_exiter(void)
-: 17:{
#: 18:fprintf(stderr, "!! GUARDIAN EXIT HANDLER REACHED
!!\n");
#: 19:}
That's kind of expected behavior because atexit handlers are executed in
reverse order to how they were registered.
I would recommend to not utilize atexit handler and do the necessary work in
guardian_destructor.
Due to aforementioned explanation, I'm closing the PR as invalid.
[Bug gcov-profile/44779] The gcov library does not adequately handle functions with constructor/destructor attributes
--- Comment #1 from rguenth at gcc dot gnu dot org 2010-07-02 09:16 --- Can you provide a testcase that when executed shows the issue? -- rguenth at gcc dot gnu dot org changed: What|Removed |Added Status|UNCONFIRMED |WAITING http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44779
[Bug gcov-profile/44779] The gcov library does not adequately handle functions with constructor/destructor attributes
--- Comment #2 from jay dot vaughan at thalesgroup dot com 2010-07-02 11:29 --- Created an attachment (id=21066) -- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21066action=view) Makefile for testcase. This the Makefile for a testunit that will demonstrate this behaviour. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44779
[Bug gcov-profile/44779] The gcov library does not adequately handle functions with constructor/destructor attributes
--- Comment #3 from jay dot vaughan at thalesgroup dot com 2010-07-02 11:30 --- Created an attachment (id=21067) -- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21067action=view) This is the test application program sources for the testunit. This file is the test application, to be wrapped by the test library, to demonstrate the behaviour of this bug. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44779
[Bug gcov-profile/44779] The gcov library does not adequately handle functions with constructor/destructor attributes
--- Comment #4 from jay dot vaughan at thalesgroup dot com 2010-07-02 11:31 --- Created an attachment (id=21068) -- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21068action=view) This is the test library sources for the testunit. This file is the test library, which is wrapped around the application, to demonstrate the behaviour of this bug. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44779
[Bug gcov-profile/44779] The gcov library does not adequately handle functions with constructor/destructor attributes
--- Comment #5 from jay dot vaughan at thalesgroup dot com 2010-07-02 11:32 --- To use the sources provided as a test unit: 1. First, 'make clean'. 2. Then, 'make test.app' - notice the coverage of the constructor/destructor functions. 3. Then, 'make test.lib' - notice coverage. -- jay dot vaughan at thalesgroup dot com changed: What|Removed |Added CC||jay dot vaughan at ||thalesgroup dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44779
