http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58602
Bug ID: 58602
Summary: .gcno files not truncated at gcov_close
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: gcov-profile
Assignee: unassigned at gcc dot gnu.org
Reporter: laurent.alfonsi at st dot com
Created attachment 30950
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30950&action=edit
script to reproduce
Gcc doesnot clean the .gcno file before writing in. Thus, it might contain
garbage at the end.
At one point, it was truncated, but this has been removed.
http://gcc.gnu.org/ml/gcc-patches/2004-07/msg02541.html
Test case :
$ rm test.gcno
$ gcc -ftest-coverage -fprofile-arcs test.c -O3
$ ls -la test.gcno
-rw-r--r-- 1 alfonsi gnbcomp 688 Oct 3 11:57 test.gcno
$ gcc -ftest-coverage -fprofile-arcs test.c -O0
$ ls -la test.gcno
-rw-r--r-- 1 alfonsi gnbcomp 908 Oct 3 11:57 test.gcno
$ gcc -ftest-coverage -fprofile-arcs test.c -O3
$ ls -la test.gcno
-rw-r--r-- 1 alfonsi gnbcomp 908 Oct 3 11:58 test.gcno
As you may see, the last 220 bytes are garbage from the preceding O0
compilation.
I enclosed a small script that expose the problem.
This has been trackeddown from a kernel issue on lcov:
http://sourceforge.net/p/ltp/mailman/message/31141937/
