https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68785
--- Comment #7 from rguenther at suse dot de <rguenther at suse dot de> --- On Wed, 9 Dec 2015, jakub at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68785 > > --- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> --- > (In reply to rguent...@suse.de from comment #5) > > Err, no - the only option would be to _not_ fold if elen < size. As > > said, SCCVN aggressively folds reads from initializers (even if > > in differing types). I invented the "offset" parameter for this. > > But that is what will happen, if there aren't enough bytes in the buffer for > a value you want native_interpret_*, then it returns NULL_TREE. > Look at all the native_interpret_* functions, they start with checking if > there > are enough bytes in the buffer for what they want. Sure, but SCCVN explicitely tells it the buffer is large enough (because it ensured this for the cases it handles). If the read is out-of-bounds SCCVN doesn't care (and I don't see why we should preserve the original undefined behavior here, just for the sake of valgrind). Yes, SCCVN _could_ pass the return value from native_encode_expr to native_interpret_expr.
