On 02/07/2025 18:59, David Malcolm wrote:
...
Brainstorming some ideas on other possible approaches on making our
tests less brittle; for context I did some investigation back in 2018
about implementing "optimizations remarks" like clang does: diagnostics
about optimization decisions, so you could have a dg directive like
this on a particular line:
foo (); /* { dg-remark "inlined call to 'foo' into 'bar'" } */
I like the idea. However, it seems unlikely that we can make a
clean switchover in this decade, unless you find one or more
corporate sponsors.
We probably always want dump files without a rigid structure, because
it makes it easier to add debug output when you flesh out a new pass
or a change to an existing one. We can make the calls that generate
the json output also emit output in the dump file, so we won't carry
a doubled maintenance burden; however, this means the current ad-hoc
messages would become more unified; thus the testsuite will have to
be adjusted.
FWIW, even you you were to get rid of the current dump files (which
I think would be stifling for GCC development for the above
reasons), you would have to adjust the testsuite.
So, we could use the json framework for new dump output that is
contributed before or along with the parts of the testsuite that
scan for it, but for any legacy dump output that is scanned for
in the testsuite, that requires to adjust the testsuite. More
than 26K dejagnu scan-*-dump* directives in the gcc15 testsuite.
And you'll have a bit flag day, or a ton of small ones. Plus
all the friction that this will create with porting patches up
and down gcc versions.
That is a lot of thankless work, which I can't imagine doing as a
hobby. And condifering people at the start of their career who
might think of doing some unpaid drudge work in hope of getting
recognition that'll get them some paid work, with paying work
for GCC drying up, they would more likely do something for LLVM,
which also seems to better align with the skills of recent
graduates.
So, unless/until you have (a) corporate sponsor(s) to pay for
the work on the existing testsuite - and that work is
successfully concluded - we will have to find a way to
make the scans of the dump files more maintainable.
In fact, if we can solve the maintenance hassle of having
multiple in a test by making the scan patterns more specific,
so we don't have to split the tests up, that will put us in
better position if/when the transition to a more organized
optimization records system is made.
