On Fri, Aug 2, 2024 at 6:15 PM Mariam Arutunian
<mariamarutun...@gmail.com> wrote:
>
> After the loop exit an internal function call (CRC, CRC_REV) is added,
> and its result is assigned to the output CRC variable (the variable where the
> calculated CRC is stored after the loop execution).
> The removal of the loop is left to CFG cleanup and DCE.
>
> gcc/
>
> * gimple-crc-optimization.cc (get_data): New function.
> (optimize_crc_loop): Likewise.
> (build_polynomial_without_1): Likewise.
> (execute): Add optimize_crc_loop function call.
+ /* If we have the data, use it. */
+ if (m_phi_for_data)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file,
+ "Data and CRC are xor-ed in the for loop. Initializing data "
+ "with its value.\n");
+ tree data_arg = PHI_ARG_DEF (m_phi_for_data, 1);
how do you know statically that it's the second PHI arg def? That
seems fragile.
I suppose you are looking for a latch definition?
+ if (TYPE_PRECISION (TREE_TYPE (data_arg)) == data_size)
+ return data_arg;
+ else
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file,
+ "Loop iteration number and data's size differ.\n");
+ return nullptr;
that seems to be oddly placed in the transform rather than the analysis phase?
+ gcc_assert (m_phi_for_crc);
+
+ tree crc_arg = PHI_ARG_DEF (m_phi_for_crc, 1);
same issue here - I think you want to use PHI_ARG_DEF_FROM_EDGE?
+ /* We don't support the case where data is larger than the CRC. */
+ if (TYPE_PRECISION (TREE_TYPE (crc_arg))
+ < TYPE_PRECISION (TREE_TYPE (data_arg)))
+ return false;
you can check that before building any stuff?
+ gimple_stmt_iterator si = gsi_start_bb (output_crc->bb);
+ gsi_insert_before (&si, call, GSI_SAME_STMT);
you want gsi_after_labels (gimple_bb (output_crc))
+ /* Remove phi statement, which was holding CRC result. */
+ gimple_stmt_iterator tmp_gsi = gsi_for_stmt (output_crc);
+ gsi_remove (&tmp_gsi, true);
Please use remove_phi_node (&tmp_gsi, false).
otherwise looks fine.
Richard.
> Signed-off-by: Mariam Arutunian <mariamarutun...@gmail.com>
