Richard Sandiford <[EMAIL PROTECTED]> writes: > I realise no-one else has spoken out in support of me, so perhaps > I'm in a minority of one here. But it does seem to me that in the > Tree-SSA world, it makes less sense to duplicate standard optabs > in the backend purely for the reason of keeping DImode arithmetic > around as DImode arithmetic for longer.
The main issue I know of is the RTL level loop optimizers (combine and CSE can mostly work off of REG_EQUAL notes). If you define_expand adddi3, they won't be able to handle loops using long long types. Whether this matters in practice for real code, I don't know. Certainly adddi3 and friends should not be straight define_insns, as they used to be for MIPS. With the lower-subreg pass, they should be either define_expand to individual insns or define_insn_and_split with an unconditional split before reload. Ian
