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.