On Mon, 2021-03-22 at 22:55 +0000, Richard Sandiford wrote: > Ilya Leoshkevich <i...@linux.ibm.com> writes: > > On Mon, 2021-03-22 at 18:23 +0000, Richard Sandiford wrote: > > > Ilya Leoshkevich <i...@linux.ibm.com> writes: > > > > [...] > > > > > > Do you still want me to add single_nondebug_use() for > > > > completeness > > > > in > > > > this patch, or would it be better to add it later when it's > > > > actually > > > > needed? > > > > > > I was thinking that the fwprop.c code would use > > > def->single_nondebug_use () instead of > > > def->single_nondebug_insn_use () && !def->has_phi_uses (). > > > > But these two are not equivalent, are they? single_nondebug_use() > > that you proposed explicitly allows phis: > > > > // If there is exactly one nondebug use of the set's result, > > // return that use, otherwise return null. The use might be in > > // instruction or a phi node. > > use_info *single_nondebug_use () const; > > > > but I don't think we want to propagate into phis here. > > Or should the check be a bit bigger, like the following? > > But we're in the process of substituting the definition into an > insn use. So we know that an insn use exists. I think the > question we're trying to answer is: is this insn use the only > nondebug use? I'd rather test that with a single accessor rather > than break it down into individual data structure tests.
Ah, you are absolutely right - now I get it. Please ignore the v2 then, I will send a v3.
