On Thu, Jul 23, 2020 at 2:01 PM Roger Sayle <ro...@nextmovesoftware.com> wrote:
>
>
> On Thu, Jul 23, 2020 at 10:02 Richard Biener wrote:
> > Likewise for the existing
> >
> >+/* popcount(X) == 0 is X == 0, and related (in)equalities. */ (for
> >+(for popcount (POPCOUNT)
> > (for cmp (le eq ne gt)
> > rep (eq eq ne ne)
> > (simplify
> > (cmp (popcount @0) integer_zerop)
> > (rep @0 { build_zero_cst (TREE_TYPE (@0)); }))))
> >
> > you can elide the (for ...)
>
> Unfortunately, I tried that myself when preparing this patch:
>
> Attempt #1:
>
> (for cmp (le eq ne gt)
> rep (eq eq ne ne)
> (simplify
> (cmp (POPCOUNT @0) integer_zerop)
> (rep @0 { build_zero_cst (TREE_TYPE (@0)); }))))
>
> results in:
> build/genmatch --gimple ../../patcha3/gcc/match.pd \
> > tmp-gimple-match.c
> ../../patcha3/gcc/match.pd:5977:11 error: operator-list POPCOUNT cannot be
> expanded inside 'for'
> (cmp (POPCOUNT @0) integer_zerop)
> ^
> Attempt #2:
>
> (for popcount (POPCOUNT)
> cmp (le eq ne gt)
> rep (eq eq ne ne)
> (simplify
> (cmp (popcount @0) integer_zerop)
> (rep @0 { build_zero_cst (TREE_TYPE (@0)); })))
>
> results in:
> > tmp-gimple-match.c
> ../../patcha3/gcc/match.pd:5975:22 error: All user-defined identifiers must
> have a multiple number of operator substitutions of the smallest number of
> substitutions
> cmp (le eq ne gt)
> ^
Oh yeah - I failed to spot the outer (for ..), indeed it doesn't work
then. We're not magically
creating a nest from the first vairant which we could make work - I
erred on the side of
"too much implicitness" caution here.
> I'll leave it the way it is with the nested FORs, and investigate your other
> suggestions.
Yeah, fine.
> > OK with those changes.
> >
> > Richard.
>
>
> Roger
> --
>
>
