@@ -801,6 +801,14 @@ as well as handlers registered with @code{atexit}.
If an executable loads a dynamic shared object via dlopen functionality,
@option{-Wl,--dynamic-list-data} is needed to dump all profile data.
+Profiling run-time library reports various errors related to profile
+manipulation and profile saving. Errors are printed into standard error output
+or @samp{GCOV_ERROR_FILE} file, if environment variable is used.
+In order to terminate immediately after an errors occurs
+set @samp{GCOV_EXIT_AT_ERROR} environment variable.
+That can help users to find profile clashing which leads
+to a misleading profile.
+
@c man end
@node Gcov Data Files
@@ -62,8 +62,16 @@ gcov_error (const char *fmt, ...)
va_list argp;
va_start (argp, fmt);
- ret = vfprintf (get_gcov_error_file (), fmt, argp);
+ FILE *f = get_gcov_error_file ();
+ ret = vfprintf (f, fmt, argp);
va_end (argp);
+
+ if (getenv ("GCOV_EXIT_AT_ERROR"))
+ {
+ fprintf (f, "profiling:exiting after an error\n");
+ exit (1);
+ }
+
return ret;
}
@@ -372,8 +372,12 @@ merge_one_data (const char *filename,
length = gcov_read_unsigned ();
if (length != gi_ptr->stamp)
- /* Read from a different compilation. Overwrite the file. */
- return 0;
+ {
+ /* Read from a different compilation. Overwrite the file. */
+ gcov_error ("profiling:%s:overwriting an existing profile data "
+ "with a different timestamp\n", filename);
+ return 0;
+ }
/* Look for program summary. */
for (f_ix = 0;;)
Hi. As showed twice in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85759 it's quite problematic when a profile data file is overwritten for a different compilation unit. I believe it's not intentional in most cases and it deserves an error message in libgcov. Moreover, to be really sure we don't break a profile, users should use GCOV_EXIT_AT_ERROR. Tested on gcov.exp on x86_64-linux-gnu. Ready to install after proper bootstrap? Thanks, Martin gcc/ChangeLog: 2018-05-29 Martin Liska <mliska@suse.cz> PR gcov-profile/85759 * doc/gcov.texi: Document GCOV_ERROR_FILE and GCOV_EXIT_AT_ERROR env variables. libgcc/ChangeLog: 2018-05-29 Martin Liska <mliska@suse.cz> PR gcov-profile/85759 * libgcov-driver-system.c (gcov_error): Introduce usage of GCOV_EXIT_AT_ERROR env. variable. * libgcov-driver.c (merge_one_data): Print error that we overwrite a gcov file with a different timestamp. --- gcc/doc/gcov.texi | 8 ++++++++ libgcc/libgcov-driver-system.c | 10 +++++++++- libgcc/libgcov-driver.c | 8 ++++++-- 3 files changed, 23 insertions(+), 3 deletions(-)