[Bug tree-optimization/101267] [12 Regression] ICE in vect_is_simple_use when building 521.wrf_r with -Ofast -march=znver2

["rsandifo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101267

--- Comment #5 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #4)
> So we're having
> 
> (gdb) p debug (slp_node)
> t.f90:1:21: note: node 0x39fbbc0 (max_nunits=2, refcnt=1)
> t.f90:1:21: note: op template: _144 = .MASK_LOAD (_143, 32B, _142);
> t.f90:1:21: note:       stmt 0 _144 = .MASK_LOAD (_143, 32B, _142);
> t.f90:1:21: note:       stmt 1 _146 = .MASK_LOAD (_145, 32B, _142);
> t.f90:1:21: note:       children 0x39fbc48
> 
> where vectorizable_load invokes
> 
> 8500              if (!vect_check_scalar_mask (vinfo, stmt_info, mask,
> &mask_dt,
> 8501                                           &mask_vectype))
> 8502                return false;
> 
> but the SLP child is
> 
> (gdb) p debug ((slp_tree)0x39fbc48)
> t.f90:1:21: note: node (external) 0x39fbc48 (max_nunits=1, refcnt=1)
> t.f90:1:21: note:       { _142, _142 }
> 
> so it won't have a vector type set.  In fact vect_check_scalar_mask doesn't
> seem to be prepared for SLP at all - we're lucky it "works" but then most
> definitely it won't for externals.  You'll note that the SLP variant for
> vect_is_simple_use won't be applicable here since we only have SLP
> representations for the mask operand which isn't even the first one.
Seems like we should have a way of representing this kind of situation
though.  It doesn't seem unreasonable to have some operands (and especially
call arguments) that don't need to be vectorised.

Maybe a “fix” for now might be to pass separate SLP and non-SLP operand
numbers to vect_is_simple_use.