On Mon, Apr 10, 2017 at 06:38:07PM +0100, Richard Sandiford wrote: > Segher Boessenkool <seg...@kernel.crashing.org> writes: > > On Fri, Apr 07, 2017 at 10:39:03AM +0200, Eric Botcazou wrote: > >> > Or we could just change "blockage" and wait for the next bug report. > >> > >> That's my suggestion, yes. > >> > >> > Alternatively, we can arrange for the bypass functions to not ICE. We > >> > can do that specific to these rs6000 pipeline descriptions, by having > >> > our own version of store_data_bypass_p; or we can make that function > >> > work for all insns (its definition works fine for insn pairs where > >> > not both the producer and consumer are SETs). That's what Kelvin's > >> > patch does. What is the value in ICEing here? > >> > >> Telling the back-end writer that something may be wrong somewhere instead > >> of > >> silently accepting nonsense? > > > > Why is it nonsense? The predicate gives the answer to the question > > "given these insns A and B, does A feed data that B stores in memory". > > That is a perfectly valid question to ask of any two insns. > > Agreed FWIW, but for: > > @@ -3701,7 +3704,8 @@ store_data_bypass_p (rtx_insn *out_insn, rtx_insn > if (GET_CODE (out_exp) == CLOBBER) > continue; > > - gcc_assert (GET_CODE (out_exp) == SET); > + if (GET_CODE (out_exp) != SET) > + return false; > > if (reg_mentioned_p (SET_DEST (out_exp), SET_DEST (in_set))) > return false; > > how about instead changing the CLOBBER check so that we continue > when it isn't a SET? That would allow things like UNSPECs and > USEs as well.
Yeah that sounds good. Kelvin, could you try that please? Segher