Thanks Robin.
> As we're not recursively traversing, does something like
>
> FOR_EACH_SUBRTX (...)
> if (GET_CODE (*iter) == VEC_DUPLICATE)
>
> help, regardless of the actual operation?
I see, in fact we don't care about the ops but the vec_dup of subrtx.
I will try to refactor that first and then rebase this series based on that.
Pan
-----Original Message-----
From: Robin Dapp <rdapp....@gmail.com>
Sent: Monday, August 4, 2025 3:28 PM
To: Li, Pan2 <pan2...@intel.com>; gcc-patches@gcc.gnu.org
Cc: juzhe.zh...@rivai.ai; kito.ch...@gmail.com; jeffreya...@gmail.com;
rdapp....@gmail.com; Chen, Ken <ken.c...@intel.com>; Liu, Hongtao
<hongtao....@intel.com>
Subject: Re: [PATCH v1 1/2] RISC-V: Combine vec_duplicate + vmerge.vv to
vmerge.vx on GR2VR cost
> @@ -3971,15 +3971,20 @@ get_vector_binary_rtx_cost (rtx x, int
> scalar2vr_cost)
> rtx op_0;
> rtx op_1;
>
> - if (GET_CODE (x) == UNSPEC)
> - {
> - op_0 = XVECEXP (x, 0, 0);
> - op_1 = XVECEXP (x, 0, 1);
> - }
> - else
> + switch (GET_CODE (x))
> {
> - op_0 = XEXP (x, 0);
> - op_1 = XEXP (x, 1);
> + case REG:
> + return COSTS_N_INSNS (1);
> + case VEC_DUPLICATE:
> + return (scalar2vr_cost + 1) * COSTS_N_INSNS (1);
> + case UNSPEC:
> + op_0 = XVECEXP (x, 0, 0);
> + op_1 = XVECEXP (x, 0, 1);
> + break;
> + default:
> + op_0 = XEXP (x, 0);
> + op_1 = XEXP (x, 1);
> + break;
Generally, the patch looks reasonable to me but costing gets more confusing by
the day :)
Originally we used get_vector_binary_rtx_cost just for binary ops but now it
also takes regs, vec_duplicates etc.? And merge is not really a binary op
either, is it?
The whole idea of rtx costing is to use the recursive properties and build a
"cost tree". Generally, isn't it sufficient to find a (vec_duplicate: scalar)
anywhere and then be done? The only distinction we need is whether we're
costing a real vmv.v.x or any other instruction.
As we're not recursively traversing, does something like
FOR_EACH_SUBRTX (...)
if (GET_CODE (*iter) == VEC_DUPLICATE)
help, regardless of the actual operation?
--
Regards
Robin
