https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109465
--- Comment #2 from CVS Commits ---
The master branch has been updated by Xi Ruoyao :
https://gcc.gnu.org/g:6d7e0bcfa49e4ddc84dabe520bba8a023bc52692
commit r14-70-g6d7e0bcfa49e4ddc84dabe520bba8a023bc52692
Author: Xi Ruoyao
Date: Wed Apr 12 11:45:48 2023 +
LoongArch: Improve cpymemsi expansion [PR109465]
We'd been generating really bad block move sequences which is recently
complained by kernel developers who tried __builtin_memcpy. To improve
it:
1. Take the advantage of -mno-strict-align. When it is set, set mode
size to UNITS_PER_WORD regardless of the alignment.
2. Half the mode size when (block size) % (mode size) != 0, instead of
falling back to ld.bu/st.b at once.
3. Limit the length of block move sequence considering the number of
instructions, not the size of block. When -mstrict-align is set and
the block is not aligned, the old size limit for straight-line
implementation (64 bytes) was definitely too large (we don't have 64
registers anyway).
Change since v1: add a comment about the calculation of num_reg.
gcc/ChangeLog:
PR target/109465
* config/loongarch/loongarch-protos.h
(loongarch_expand_block_move): Add a parameter as alignment RTX.
* config/loongarch/loongarch.h:
(LARCH_MAX_MOVE_BYTES_PER_LOOP_ITER): Remove.
(LARCH_MAX_MOVE_BYTES_STRAIGHT): Remove.
(LARCH_MAX_MOVE_OPS_PER_LOOP_ITER): Define.
(LARCH_MAX_MOVE_OPS_STRAIGHT): Define.
(MOVE_RATIO): Use LARCH_MAX_MOVE_OPS_PER_LOOP_ITER instead of
LARCH_MAX_MOVE_BYTES_PER_LOOP_ITER.
* config/loongarch/loongarch.cc (loongarch_expand_block_move):
Take the alignment from the parameter, but set it to
UNITS_PER_WORD if !TARGET_STRICT_ALIGN. Limit the length of
straight-line implementation with LARCH_MAX_MOVE_OPS_STRAIGHT
instead of LARCH_MAX_MOVE_BYTES_STRAIGHT.
(loongarch_block_move_straight): When there are left-over bytes,
half the mode size instead of falling back to byte mode at once.
(loongarch_block_move_loop): Limit the length of loop body with
LARCH_MAX_MOVE_OPS_PER_LOOP_ITER instead of
LARCH_MAX_MOVE_BYTES_PER_LOOP_ITER.
* config/loongarch/loongarch.md (cpymemsi): Pass the alignment
to loongarch_expand_block_move.
gcc/testsuite/ChangeLog:
PR target/109465
* gcc.target/loongarch/pr109465-1.c: New test.
* gcc.target/loongarch/pr109465-2.c: New test.
* gcc.target/loongarch/pr109465-3.c: New test.
