Hi Eric,
Thanks for the review.
> +/* Return true if X is a sign_extract or zero_extract from the least
> + significant bit. */
> +
> +static bool
> +lsb_bitfield_op_p (rtx x)
> +{
> + if (GET_RTX_CLASS (GET_CODE (x)) == RTX_BITFIELD_OPS)
> + {
> + enum machine_mode mode = GET_MODE(x);
> + unsigned HOST_WIDE_INT len = INTVAL (XEXP (x, 1));
> + HOST_WIDE_INT pos = INTVAL (XEXP (x, 2));
> +
> + return (pos == (BITS_BIG_ENDIAN ? GET_MODE_PRECISION (mode) - len :
> 0));
>
> It seems strange to use the destination mode to decide whether this is the LSB
> of the source.
Indeed, I think it has to be the mode of loc, but I just wonder if it
is not always the same, as in the doc it is written that mode m is the
same as the mode that would be used for loc if it were a register.
> +/* Return true if X is a shifting operation. */
> +
> +static bool
> +shift_code_p (rtx x)
> +{
> + return (GET_CODE (x) == ASHIFT
> + || GET_CODE (x) == ASHIFTRT
> + || GET_CODE (x) == LSHIFTRT
> + || GET_CODE (x) == ROTATE
> + || GET_CODE (x) == ROTATERT);
> +}
>
> ROTATE and ROTATERT aren't really shifting operations though, so are they
> really needed here?
According to gcc internals, ROTATE and ROTATERT are similar to the
shifting operations, but to be more accurate maybe we can rename
shif_code_p in shift_and _rotate_code_p rotation are used in arm
address calculation, and thus need to be handle in must_be_index_p
and set_address_index
Thanks,
Yvan
