https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108787
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Created attachment 54460 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54460&action=edit gcc13-pr108787.patch Patch that kills maddditi4 in addition to fixing umaddditi4. As mentioned above, in the umaddditi4 case if we later on e.g. during combine find out that the high half of the last operand is zero, it will be nicely optimized to the optimal sequence. Unfortunately, with maddditi4 it is really hard to find out at expansion time if the last operand is sign extended from DImode or narrower, there is no SSA_NAME on the pseudo to check say for value ranges, and looking at earlier already emitted instructions checking for one subreg of it set to something and the other to copies of its sign bit would be a total mess. And at combine time I'm afraid we'd need 5 instruction combination. So if we want to be able to optimize qux above, I'm afraid we'd need to add a new optab.
