On Sun, Apr 18, 2021 at 12:03:39PM -0500, Segher Boessenkool wrote: > On Sun, Apr 18, 2021 at 05:24:50PM +0200, Jakub Jelinek wrote: > > On Sun, Apr 18, 2021 at 03:03:07PM +0000, Segher Boessenkool wrote: > > > If the register named in an existing REG_UNUSED note dies somewhere > > > between where the note used to be and I3, we should just drop it.
> > And, shouldn't the > > record_value_for_reg (XEXP (note, 0), NULL, NULL_RTX); > > be called in some cases? > > I don't see why? We don't remove any clobber or set, just the REG_UNUSED > note? > > > To me it would make more sense to add the if (reg_set_between_p (...)) > > break; > > to the individual cases later, so before > > if (! (REG_P (XEXP (note, 0)) > > ? find_regno_note (i3, REG_UNUSED, REGNO (XEXP (note, > > 0))) > > : find_reg_note (i3, REG_UNUSED, XEXP (note, 0)))) > > place = i3; > > and before > > PUT_REG_NOTE_KIND (note, REG_DEAD); > > place = i3; > > and into the > > if (from_insn != i3 && i2 && INSN_P (i2) > > && reg_referenced_p (XEXP (note, 0), PATTERN (i2))) > > but there just checking if it isn't set in between from_insn and i2 > > But the REG_UNUSED note should just be dropped in all these cases, so it > is much simpler code to do it like this. Or am I missing something? I have now tested this on kernel builds on all supported archs (and variations; 31 builds, mostly defconfigs, some bigger). The patch changed generated code in no single place, so we're good probably :-) Segher
