https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119702
--- Comment #20 from Avinash Jayakar <avinashd at linux dot ibm.com> --- (In reply to Segher Boessenkool from comment #19) > If it does something that does make sense here, it is a good addition. For > other archs as well (although Gimple-level optimisations are so ver far away > from the eventual machine code that it is hard to talk about the machine code > there at all: you are transforming some bit of Gimple code to some nicer > piece > of Gimple code!) In that case, I will update the vectorization of multiplication as well, and send a patch. > dead_or_set_p perhaps. It all depends on context. You can use all of DF as > well of course. > Peepholes make no sense ever, hehe. Sometimes they are the most convenient > solution though. > > You are thinking about peep2_reg_dead_p? Yeah, and why peephole, is because it looks at a window of instructions and tries to rewrite it in a machine dependent way. > There are better, more modern, solutions almost always :-) Text-based > peepholes have been eradicated from most places, now peephole2 should go the > way of the dodo :-) Other way is to use the combine pass, which is machine independent and not the right choice in this case I think. I am not sure just if the "define_insn" that produces assembly, can look at 2 instructions and replace it with one. Can it?
