On Tue, Apr 27, 2021 at 3:14 AM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> Change a while loop in op_by_pieces_d::run to a do-while loop to prepare
> for offset adjusted operation for the remaining bytes on the last piece
> operation of a memory region.
OK.
Thanks,
Richard.
> PR middl-end/90773
> * expr.c (op_by_pieces_d::get_usable_mode): New member function.
> (op_by_pieces_d::run): Cange a while loop to a do-while loop.
> ---
> gcc/expr.c | 76 +++++++++++++++++++++++++++++++++++++-----------------
> 1 file changed, 53 insertions(+), 23 deletions(-)
>
> diff --git a/gcc/expr.c b/gcc/expr.c
> index a0e19465965..07cb64427c9 100644
> --- a/gcc/expr.c
> +++ b/gcc/expr.c
> @@ -1041,6 +1041,9 @@ pieces_addr::maybe_postinc (HOST_WIDE_INT size)
>
> class op_by_pieces_d
> {
> + private:
> + scalar_int_mode get_usable_mode (scalar_int_mode mode, unsigned int);
> +
> protected:
> pieces_addr m_to, m_from;
> unsigned HOST_WIDE_INT m_len;
> @@ -1108,6 +1111,25 @@ op_by_pieces_d::op_by_pieces_d (rtx to, bool to_load,
> m_align = align;
> }
>
> +/* This function returns the largest usable integer mode for LEN bytes
> + whose size is no bigger than size of MODE. */
> +
> +scalar_int_mode
> +op_by_pieces_d::get_usable_mode (scalar_int_mode mode, unsigned int len)
> +{
> + unsigned int size;
> + do
> + {
> + size = GET_MODE_SIZE (mode);
> + if (len >= size && prepare_mode (mode, m_align))
> + break;
> + /* NB: widest_int_mode_for_size checks SIZE > 1. */
> + mode = widest_int_mode_for_size (size);
> + }
> + while (1);
> + return mode;
> +}
> +
> /* This function contains the main loop used for expanding a block
> operation. First move what we can in the largest integer mode,
> then go to successively smaller modes. For every access, call
> @@ -1116,42 +1138,50 @@ op_by_pieces_d::op_by_pieces_d (rtx to, bool to_load,
> void
> op_by_pieces_d::run ()
> {
> - while (m_max_size > 1 && m_len > 0)
> + if (m_len == 0)
> + return;
> +
> + /* NB: widest_int_mode_for_size checks M_MAX_SIZE > 1. */
> + scalar_int_mode mode = widest_int_mode_for_size (m_max_size);
> + mode = get_usable_mode (mode, m_len);
> +
> + do
> {
> - scalar_int_mode mode = widest_int_mode_for_size (m_max_size);
> + unsigned int size = GET_MODE_SIZE (mode);
> + rtx to1 = NULL_RTX, from1;
>
> - if (prepare_mode (mode, m_align))
> + while (m_len >= size)
> {
> - unsigned int size = GET_MODE_SIZE (mode);
> - rtx to1 = NULL_RTX, from1;
> + if (m_reverse)
> + m_offset -= size;
>
> - while (m_len >= size)
> - {
> - if (m_reverse)
> - m_offset -= size;
> + to1 = m_to.adjust (mode, m_offset);
> + from1 = m_from.adjust (mode, m_offset);
>
> - to1 = m_to.adjust (mode, m_offset);
> - from1 = m_from.adjust (mode, m_offset);
> + m_to.maybe_predec (-(HOST_WIDE_INT)size);
> + m_from.maybe_predec (-(HOST_WIDE_INT)size);
>
> - m_to.maybe_predec (-(HOST_WIDE_INT)size);
> - m_from.maybe_predec (-(HOST_WIDE_INT)size);
> + generate (to1, from1, mode);
>
> - generate (to1, from1, mode);
> + m_to.maybe_postinc (size);
> + m_from.maybe_postinc (size);
>
> - m_to.maybe_postinc (size);
> - m_from.maybe_postinc (size);
> + if (!m_reverse)
> + m_offset += size;
>
> - if (!m_reverse)
> - m_offset += size;
> + m_len -= size;
> + }
>
> - m_len -= size;
> - }
> + finish_mode (mode);
>
> - finish_mode (mode);
> - }
> + if (m_len == 0)
> + return;
>
> - m_max_size = GET_MODE_SIZE (mode);
> + /* NB: widest_int_mode_for_size checks SIZE > 1. */
> + mode = widest_int_mode_for_size (size);
> + mode = get_usable_mode (mode, m_len);
> }
> + while (1);
>
> /* The code above should have handled everything. */
> gcc_assert (!m_len);
> --
> 2.31.1
>
