https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111770
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- As said X + 0. -> X is an invalid transform with FP unless there are no signed zeros (maybe also problematic with sign-dependent rounding). I think we agree to define .MASK_LOAD to zero masked elements. When we need something else we need to add an explicit ELSE value. That needs documenting of course and also possibly testsuite coverage - I _think_ you should be able to do a GIMPLE frontend testcase for this. Note this behavior would extend to .MASK_GATHER_LOAD as well as the load-lanes and -len variants. Unfortunately we do not have _any_ internals manual documentation for internal functions - but you can backtrack to the optabs documentation where this would need documenting. Now, if-conversion could indeed elide the .COND_ADD for integers. It's problematic there only because of signed overflow undefinedness, so you shouldn't see it for 'unsigned' already, and adding zero is safe. if-conversion would need to have an idea of all the ranges involved here so it might be a bit sophisticated to get it right.
