Re: [PATCH v2 1/6] tcg/optimize: Lower unsupported deposit during optimize

[Jim MacArthur <jim.macarthur@linaro.org>]

On Wed, Feb 04, 2026 at 03:24:51PM +1000, Richard Henderson wrote:
> The expansions that we chose in tcg-op.c may be less than optimial.
> Delay lowering until optimize, so that we have propagated constants
> and have computed known zero/one masks.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> +        /* Lower invalid deposit into zero as AND + SHL or SHL + AND. */
> +        if (!valid) {
> +            if (TCG_TARGET_extract_valid(ctx->type, 0, ofs + len) &&
> +                !TCG_TARGET_extract_valid(ctx->type, 0, len)) {
> +                op2 = opt_insert_before(ctx, op, INDEX_op_shl, 3);
> +                op2->args[0] = ret;
> +                op2->args[1] = arg2;
> +                op2->args[2] = arg_new_constant(ctx, ofs);
> +
> +                op->opc = INDEX_op_extract;
> +                op->args[1] = ret;
> +                op->args[2] = 0;
> +                op->args[3] = ofs + len;
> +                goto done;
> +            }

I also had questions about extract vs shift/and here. You've explained this on patch 6, but a comment here about it might help future developers.

Nonetheless,

Reviewed-by: Jim MacArthur <jim.macarthur@linaro.org>