Re: [PATCH 5/7] riscv: Use by-pieces to do overlapping accesses in block_move_straight

[Jeff Law <jeffreyalaw@gmail.com>]

On 11/13/22 16:05, Christoph Muellner wrote:
> From: Christoph Müllner <christoph.muellner@vrull.eu>
>
> The current implementation of riscv_block_move_straight() emits a couple
> of load-store pairs with maximum width (e.g. 8-byte for RV64).
> The remainder is handed over to move_by_pieces(), which emits code based
> target settings like slow_unaligned_access and overlap_op_by_pieces.
>
> move_by_pieces() will emit overlapping memory accesses with maximum
> width only if the given length exceeds the size of one access
> (e.g. 15-bytes for 8-byte accesses).
>
> This patch changes the implementation of riscv_block_move_straight()
> such, that it preserves a remainder within the interval
> [delta..2*delta) instead of [0..delta), so that overlapping memory
> access may be emitted (if the requirements for them are given).
>
> gcc/ChangeLog:
>
> 	* config/riscv/riscv-string.c (riscv_block_move_straight):
> 	  Adjust range for emitted load/store pairs.

The change to riscv_expand_block_move isn't noted in the ChangeLog.  OK 
with that fixed (I'm assuming you want to attempt to use overlapping 
word ops for that case).


jeff