Re: [PATCH 2/3] tcg: Fold deposit with zero to and

[Philippe Mathieu-Daudé]

On 16/8/23 16:55, Richard Henderson wrote:
> Inserting a zero into a value, or inserting a value
> into zero at offset 0 my be implemented with AND.

Typo "may".

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   tcg/optimize.c | 35 +++++++++++++++++++++++++++++++++++
>   1 file changed, 35 insertions(+)
>
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index d2156367a3..956114b631 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -1279,6 +1279,8 @@ static bool fold_ctpop(OptContext *ctx, TCGOp *op)
>   
>   static bool fold_deposit(OptContext *ctx, TCGOp *op)
>   {
> +    TCGOpcode and_opc;
> +
>       if (arg_is_const(op->args[1]) && arg_is_const(op->args[2])) {
>           uint64_t t1 = arg_info(op->args[1])->val;
>           uint64_t t2 = arg_info(op->args[2])->val;
> @@ -1287,6 +1289,39 @@ static bool fold_deposit(OptContext *ctx, TCGOp *op)
>           return tcg_opt_gen_movi(ctx, op, op->args[0], t1);
>       }
>   
> +    switch (ctx->type) {
> +    case TCG_TYPE_I32:
> +        and_opc = INDEX_op_and_i32;
> +        break;
> +    case TCG_TYPE_I64:
> +        and_opc = INDEX_op_and_i64;
> +        break;
> +    default:
> +        g_assert_not_reached();
> +    }
> +
> +    if (arg_is_const(op->args[1])
> +        && arg_info(op->args[1])->val == 0
> +        && op->args[3] == 0) {

           /* Inserting a value into zero at offset 0. */

> +        uint64_t mask = MAKE_64BIT_MASK(0, op->args[4]);
> +
> +        op->opc = and_opc;
> +        op->args[1] = op->args[2];
> +        op->args[2] = temp_arg(tcg_constant_internal(ctx->type, mask));
> +        ctx->z_mask = mask & arg_info(op->args[1])->z_mask;
> +        return false;
> +    }
> +
> +    if (arg_is_const(op->args[2])
> +        && arg_info(op->args[2])->val == 0) {

           /* Inserting a zero into a value. */

> +        uint64_t mask = deposit64(-1, op->args[3], op->args[4], 0);
> +
> +        op->opc = and_opc;
> +        op->args[2] = temp_arg(tcg_constant_internal(ctx->type, mask));
> +        ctx->z_mask = mask & arg_info(op->args[1])->z_mask;
> +        return false;
> +    }

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>