On 1/13/25 1:41 AM, Jin Ma wrote:
Thank you very much for your professional reply. I am trying to solve the
problem
using the "spec_restriction" way. But unfortunately, I have a new problem. As
pattern below, how can I enable "r" and disable "K" when XTheadVector? "rK"
already
seems to be the smallest unit and not able to be
controlled separately using spec_restriction?
(define_insn "@pred_madc<mode>"
[(set (match_operand:<VM> 0 "register_operand" "=vr, &vr, &vr")
(unspec:<VM>
[(plus:VI
(match_operand:VI 1 "register_operand" " %0, vr, vr")
(match_operand:VI 2 "vector_arith_operand" "vrvi, vr, vi"))
(match_operand:<VM> 3 "register_operand" " vm, vm, vm")
(unspec:<VM>
[(match_operand 4 "vector_length_operand" " rK, rK, rK")
(match_operand 5 "const_int_operand" " i, i, i")
(reg:SI VL_REGNUM)
(reg:SI VTYPE_REGNUM)] UNSPEC_VPREDICATE)] UNSPEC_VMADC))]
"TARGET_VECTOR"
"vmadc.v%o2m\t%0,%1,%v2,%3"
[(set_attr "type" "vicalu")
(set_attr "mode" "<MODE>")
(set_attr "vl_op_idx" "4")
(set (attr "avl_type_idx") (const_int 5))
(set_attr "spec_restriction" "thv,none,none")])
"rK" can be split up further into "r" and "K" so I'd say you
need to adjust (and split) the alternatives accordingly. The new "r"
alternative would have spec_restriction "none" and the "K" alternative "rvv".
Yes. This will solve the problem, but it will lead to very large-scale changes
(splitting each rK, adding 1 column constraint), and make the pattern more
complex
and more difficult to maintain. In contrast, how about replacing "rK" with a new
constrain in the way jeff mentioned? For example, "Vvl".
Jeff: We could also create a new constraint that mostly behaves like rK, but
rejects (const_int 1) when thead-vector is enabled and use that in the
vsetvl pattern instead of rK. (
https://gcc.gnu.org/pipermail/gcc-patches/2024-December/671836.html )
I think both roughly end up being the same amount of work. I'm not too
worried about the extra alternatives and such, risc-v is pretty
reasonable in that regard if you compare it to some other ports.
Both ultimately end up forcing us to adjust the constraints on every
affected pattern. I think that's unavoidable.
jeff
