[Mesa-dev] [PATCH] ac/nir: use llvm fma intrinsic if nir instruction is exact.

[Marek Olšák]

FYI, if we switch radeonsi to NIR, we are going to disable fma
completely, exact or not.

Marek

On Wed, Oct 4, 2017 at 10:04 PM, Dave Airlie <airlied at gmail.com> wrote:
> From: Dave Airlie <airlied at redhat.com>
>
> As pointed out by Connor we still need to use fma if nir wants
> exact (precise) behaviour.
>
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
>  src/amd/common/ac_nir_to_llvm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
> index 11ba487..38a2bbe 100644
> --- a/src/amd/common/ac_nir_to_llvm.c
> +++ b/src/amd/common/ac_nir_to_llvm.c
> @@ -1707,7 +1707,7 @@ static void visit_alu(struct ac_nir_context *ctx, const nir_alu_instr *instr)
>                                                       result);
>                 break;
>         case nir_op_ffma:
> -               result = emit_intrin_3f_param(&ctx->ac, "llvm.fmuladd",
> +               result = emit_intrin_3f_param(&ctx->ac, instr->exact ? "llvm.fma" : "llvm.fmuladd",
>                                               ac_to_float_type(&ctx->ac, def_type), src[0], src[1], src[2]);
>                 break;
>         case nir_op_ibitfield_extract:
> --
> 2.9.5
>
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