[Mesa-dev] [PATCH v3 17/43] i965/fs: Enable rounding mode on f2f16 ops

[Jason Ekstrand]

On Thu, Oct 12, 2017 at 11:38 AM, Jose Maria Casanova Crespo <
jmcasanova at igalia.com> wrote:

> From: Alejandro Piñeiro <apinheiro at igalia.com>
>
> By default we don't set the rounding mode. We only set
> round-to-near-even or round-to-zero mode if explicitly set from nir.
>
> v2: Use a single SHADER_OPCODE_RND_MODE opcode taking an immediate
>     with the rounding mode (Curro)
>
> Signed-off-by: Jose Maria Casanova Crespo <jmcasanova at igalia.com>
> Signed-off-by: Alejandro Piñeiro <apinheiro at igalia.com>
> ---
>  src/intel/compiler/brw_fs_nir.cpp | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/src/intel/compiler/brw_fs_nir.cpp
> b/src/intel/compiler/brw_fs_nir.cpp
> index 6908c7ea02..b356836e80 100644
> --- a/src/intel/compiler/brw_fs_nir.cpp
> +++ b/src/intel/compiler/brw_fs_nir.cpp
> @@ -693,6 +693,14 @@ fs_visitor::nir_emit_alu(const fs_builder &bld,
> nir_alu_instr *instr)
>        inst->saturate = instr->dest.saturate;
>        break;
>
> +   case nir_op_f2f16_rtne:
> +   case nir_op_f2f16_rtz:
> +      if (instr->op == nir_op_f2f16_rtz)
> +         bld.emit(SHADER_OPCODE_RND_MODE, bld.null_reg_ud(),
> brw_imm_d(BRW_RND_MODE_RTZ));
> +      else if (instr->op == nir_op_f2f16_rtne)
> +         bld.emit(SHADER_OPCODE_RND_MODE, bld.null_reg_ud(),
> brw_imm_d(BRW_RND_MODE_RTNE));
> +      /* fallthrough */
>

It might look a little nicer (though it's more lines of code) to have a
little brw_from_nir_rounding_mode helper and then we could have just the
one emit call.  I don't care too much though.


> +
>        /* In theory, it would be better to use BRW_OPCODE_F32TO16.
> Depending
>         * on the HW gen, it is a special hw opcode or just a MOV, and
>         * brw_F32TO16 (at brw_eu_emit) would do the work to chose.
> --
> 2.13.6
>
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