Re: [PATCH] LoongArch: Improve memory ops

From: Xi Ruoyao
Date: Mon Apr 10 2023 - 08:54:04 EST


On Mon, 2023-04-10 at 19:57 +0800, WANG rui wrote:
> We use a jump table to dispatch cases for short data lengths, and for long data
> lengths, we use unaligned memory access instruction to process the first and
> last 8 bytes. The data in the middle is processed at an aligned destination
> address.

Regarding these functions: we have -ffreestanding which is preventing
the compiler from optimizing for e.g. "memcpy(a, b, 8);" into a simple
ld.d/st.d pair. A explicit compiler built-in usage like

#define memcpy(a, b, c) __builtin_memcpy(a, b, c)

would allow the compiler to do such kind of optimization. Will this
improve the performance?

>
> We have tested micro-bench[1] on a Loongson-3C5000 16-core machine (2.2GHz):
>
> 1. memset
>
> > length | src offset | dst offset | speed before | speed after |
> > %       |
> > --------|------------|------------|--------------|-------------|----
> > -----|
> > 8      | 0          | 0          | 696.191      | 1518.785    |
> > 118.16% |
> > 8      | 0          | 1          | 696.325      | 1518.937    |
> > 118.14% |
> > 50     | 0          | 0          | 969.976      | 8053.902    |
> > 730.32% |
> > 50     | 0          | 1          | 970.034      | 8058.475    |
> > 730.74% |
> > 300    | 0          | 0          | 5876.612     | 16544.703   |
> > 181.53% |
> > 300    | 0          | 1          | 5030.849     | 16549.011   |
> > 228.95% |
> > 1200   | 0          | 0          | 11797.077    | 16752.137   |
> > 42.00%  |
> > 1200   | 0          | 1          | 5687.141     | 16645.233   |
> > 192.68% |
> > 4000   | 0          | 0          | 15723.27     | 16761.557   |
> > 6.60%   |
> > 4000   | 0          | 1          | 5906.114     | 16732.316   |
> > 183.30% |
> > 8000   | 0          | 0          | 16751.403    | 16770.002   |
> > 0.11%   |
> > 8000   | 0          | 1          | 5995.449     | 16754.07    |
> > 179.45% |
>
> 2. memcpy
>
> > length | src offset | dst offset | speed before | speed after |
> > %       |
> > --------|------------|------------|--------------|-------------|----
> > -----|
> > 8      | 0          | 0          | 696.2        | 1670.605    |
> > 139.96% |
> > 8      | 0          | 1          | 696.325      | 1671.138    |
> > 139.99% |
> > 50     | 0          | 0          | 969.974      | 8724.999    |
> > 799.51% |
> > 50     | 0          | 1          | 970.032      | 8730.138    |
> > 799.98% |
> > 300    | 0          | 0          | 5564.662     | 16272.652   |
> > 192.43% |
> > 300    | 0          | 1          | 4670.436     | 14972.842   |
> > 220.59% |
> > 1200   | 0          | 0          | 10740.23     | 16751.728   |
> > 55.97%  |
> > 1200   | 0          | 1          | 5027.741     | 14874.564   |
> > 195.85% |
> > 4000   | 0          | 0          | 15122.367    | 16737.642   |
> > 10.68%  |
> > 4000   | 0          | 1          | 5536.918     | 14890.397   |
> > 168.93% |
> > 8000   | 0          | 0          | 16505.453    | 16553.543   |
> > 0.29%   |
> > 8000   | 0          | 1          | 5821.619     | 14841.804   |
> > 154.94% |
>
> 3. memmove
>
> > length | src offset | dst offset | speed before | speed after |
> > %       |
> > --------|------------|------------|--------------|-------------|----
> > -----|
> > 8      | 0          | 0          | 982.693      | 1670.568    |
> > 70.00%  |
> > 8      | 0          | 1          | 983.023      | 1671.174    |
> > 70.00%  |
> > 50     | 0          | 0          | 1230.87      | 8727.625    |
> > 609.06% |
> > 50     | 0          | 1          | 1232.515     | 8730.138    |
> > 608.32% |
> > 300    | 0          | 0          | 6490.375     | 16296.993   |
> > 151.09% |
> > 300    | 0          | 1          | 4282.687     | 14972.842   |
> > 249.61% |
> > 1200   | 0          | 0          | 11742.755    | 16752.546   |
> > 42.66%  |
> > 1200   | 0          | 1          | 5039.338     | 14872.951   |
> > 195.14% |
> > 4000   | 0          | 0          | 15467.786    | 16737.09    |
> > 8.21%   |
> > 4000   | 0          | 1          | 5009.905     | 14890.542   |
> > 197.22% |
> > 8000   | 0          | 0          | 16489.664    | 16553.273   |
> > 0.39%   |
> > 8000   | 0          | 1          | 5823.786     | 14858.646   |
> > 155.14% |
>
> * speed: MB/s
> * length: byte
>
> [1] https://github.com/heiher/mem-bench
>
> Signed-off-by: WANG rui <wangrui@xxxxxxxxxxx>
> ---
>  arch/loongarch/lib/clear_user.S | 137 +++++++++++++++--
>  arch/loongarch/lib/copy_user.S  | 251 +++++++++++++++++++++++++------
> -
>  arch/loongarch/lib/memcpy.S     | 147 +++++++++++++++----
>  arch/loongarch/lib/memmove.S    | 120 ++++++++-------
>  arch/loongarch/lib/memset.S     | 117 ++++++++++++---
>  5 files changed, 605 insertions(+), 167 deletions(-)
>
> diff --git a/arch/loongarch/lib/clear_user.S
> b/arch/loongarch/lib/clear_user.S
> index 2dc48e61a2c8..02f112b265cd 100644
> --- a/arch/loongarch/lib/clear_user.S
> +++ b/arch/loongarch/lib/clear_user.S
> @@ -13,7 +13,14 @@
>  
>  .irp to, 0, 1, 2, 3, 4, 5, 6, 7
>  .L_fixup_handle_\to\():
> -       addi.d  a0, a1, (\to) * (-8)
> +       sub.d   a0, a2, a0
> +       addi.d  a0, a0, (\to) * (-8)
> +       jr      ra
> +.endr
> +
> +.irp to, 0, 2, 4
> +.L_fixup_handle_s\to\():
> +       addi.d  a0, a1, -\to
>         jr      ra
>  .endr
>  
> @@ -44,7 +51,7 @@ SYM_FUNC_START(__clear_user_generic)
>  2:     move    a0, a1
>         jr      ra
>  
> -       _asm_extable 1b, .L_fixup_handle_0
> +       _asm_extable 1b, .L_fixup_handle_s0
>  SYM_FUNC_END(__clear_user_generic)
>  
>  /*
> @@ -54,12 +61,22 @@ SYM_FUNC_END(__clear_user_generic)
>   * a1: size
>   */
>  SYM_FUNC_START(__clear_user_fast)
> -       beqz    a1, 10f
> +       sltui   t0, a1, 9
> +       bnez    t0, .Lsmall
>  
> -       ori     a2, zero, 64
> -       blt     a1, a2, 9f
> +       add.d   a2, a0, a1
> +0:     st.d    zero, a0, 0
> +
> +       /* align up address */
> +       andi    t1, a0, 7
> +       sub.d   a0, a0, t1
> +       addi.d  a0, a0, 8
> +
> +       addi.d  a3, a2, -64
> +       bgeu    a0, a3, .Llt64
>  
>         /* set 64 bytes at a time */
> +.Lloop64:
>  1:     st.d    zero, a0, 0
>  2:     st.d    zero, a0, 8
>  3:     st.d    zero, a0, 16
> @@ -68,24 +85,95 @@ SYM_FUNC_START(__clear_user_fast)
>  6:     st.d    zero, a0, 40
>  7:     st.d    zero, a0, 48
>  8:     st.d    zero, a0, 56
> -
>         addi.d  a0, a0, 64
> -       addi.d  a1, a1, -64
> -       bge     a1, a2, 1b
> -
> -       beqz    a1, 10f
> +       bltu    a0, a3, .Lloop64
>  
>         /* set the remaining bytes */
> -9:     st.b    zero, a0, 0
> -       addi.d  a0, a0, 1
> -       addi.d  a1, a1, -1
> -       bgt     a1, zero, 9b
> +.Llt64:
> +       addi.d  a3, a2, -32
> +       bgeu    a0, a3, .Llt32
> +9:     st.d    zero, a0, 0
> +10:    st.d    zero, a0, 8
> +11:    st.d    zero, a0, 16
> +12:    st.d    zero, a0, 24
> +       addi.d  a0, a0, 32
> +
> +.Llt32:
> +       addi.d  a3, a2, -16
> +       bgeu    a0, a3, .Llt16
> +13:    st.d    zero, a0, 0
> +14:    st.d    zero, a0, 8
> +       addi.d  a0, a0, 16
> +
> +.Llt16:
> +       addi.d  a3, a2, -8
> +       bgeu    a0, a3, .Llt8
> +15:    st.d    zero, a0, 0
> +
> +.Llt8:
> +16:    st.d    zero, a2, -8
>  
>         /* return */
> -10:    move    a0, a1
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  4
> +.Lsmall:
> +       pcaddi  t0, 4
> +       slli.d  a2, a1, 4
> +       add.d   t0, t0, a2
> +       jr      t0
> +
> +       .align  4
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  4
> +17:    st.b    zero, a0, 0
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  4
> +18:    st.h    zero, a0, 0
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  4
> +19:    st.h    zero, a0, 0
> +20:    st.b    zero, a0, 2
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  4
> +21:    st.w    zero, a0, 0
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  4
> +22:    st.w    zero, a0, 0
> +23:    st.b    zero, a0, 4
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  4
> +24:    st.w    zero, a0, 0
> +25:    st.h    zero, a0, 4
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  4
> +26:    st.w    zero, a0, 0
> +27:    st.w    zero, a0, 3
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  4
> +28:    st.d    zero, a0, 0
> +       move    a0, zero
>         jr      ra
>  
>         /* fixup and ex_table */
> +       _asm_extable 0b, .L_fixup_handle_0
>         _asm_extable 1b, .L_fixup_handle_0
>         _asm_extable 2b, .L_fixup_handle_1
>         _asm_extable 3b, .L_fixup_handle_2
> @@ -95,4 +183,23 @@ SYM_FUNC_START(__clear_user_fast)
>         _asm_extable 7b, .L_fixup_handle_6
>         _asm_extable 8b, .L_fixup_handle_7
>         _asm_extable 9b, .L_fixup_handle_0
> +       _asm_extable 10b, .L_fixup_handle_1
> +       _asm_extable 11b, .L_fixup_handle_2
> +       _asm_extable 12b, .L_fixup_handle_3
> +       _asm_extable 13b, .L_fixup_handle_0
> +       _asm_extable 14b, .L_fixup_handle_1
> +       _asm_extable 15b, .L_fixup_handle_0
> +       _asm_extable 16b, .L_fixup_handle_1
> +       _asm_extable 17b, .L_fixup_handle_s0
> +       _asm_extable 18b, .L_fixup_handle_s0
> +       _asm_extable 19b, .L_fixup_handle_s0
> +       _asm_extable 20b, .L_fixup_handle_s2
> +       _asm_extable 21b, .L_fixup_handle_s0
> +       _asm_extable 22b, .L_fixup_handle_s0
> +       _asm_extable 23b, .L_fixup_handle_s4
> +       _asm_extable 24b, .L_fixup_handle_s0
> +       _asm_extable 25b, .L_fixup_handle_s4
> +       _asm_extable 26b, .L_fixup_handle_s0
> +       _asm_extable 27b, .L_fixup_handle_s4
> +       _asm_extable 28b, .L_fixup_handle_s0
>  SYM_FUNC_END(__clear_user_fast)
> diff --git a/arch/loongarch/lib/copy_user.S
> b/arch/loongarch/lib/copy_user.S
> index 55ac6020a1ad..b21f6d5d38f5 100644
> --- a/arch/loongarch/lib/copy_user.S
> +++ b/arch/loongarch/lib/copy_user.S
> @@ -13,7 +13,14 @@
>  
>  .irp to, 0, 1, 2, 3, 4, 5, 6, 7
>  .L_fixup_handle_\to\():
> -       addi.d  a0, a2, (\to) * (-8)
> +       sub.d   a0, a2, a0
> +       addi.d  a0, a0, (\to) * (-8)
> +       jr      ra
> +.endr
> +
> +.irp to, 0, 2, 4
> +.L_fixup_handle_s\to\():
> +       addi.d  a0, a2, -\to
>         jr      ra
>  .endr
>  
> @@ -47,8 +54,8 @@ SYM_FUNC_START(__copy_user_generic)
>  3:     move    a0, a2
>         jr      ra
>  
> -       _asm_extable 1b, .L_fixup_handle_0
> -       _asm_extable 2b, .L_fixup_handle_0
> +       _asm_extable 1b, .L_fixup_handle_s0
> +       _asm_extable 2b, .L_fixup_handle_s0
>  SYM_FUNC_END(__copy_user_generic)
>  
>  /*
> @@ -59,65 +66,209 @@ SYM_FUNC_END(__copy_user_generic)
>   * a2: n
>   */
>  SYM_FUNC_START(__copy_user_fast)
> -       beqz    a2, 19f
> +       sltui   t0, a2, 9
> +       bnez    t0, .Lsmall
>  
> -       ori     a3, zero, 64
> -       blt     a2, a3, 17f
> +       add.d   a3, a1, a2
> +       add.d   a2, a0, a2
> +0:     ld.d    t0, a1, 0
> +1:     st.d    t0, a0, 0
>  
> -       /* copy 64 bytes at a time */
> -1:     ld.d    t0, a1, 0
> -2:     ld.d    t1, a1, 8
> -3:     ld.d    t2, a1, 16
> -4:     ld.d    t3, a1, 24
> -5:     ld.d    t4, a1, 32
> -6:     ld.d    t5, a1, 40
> -7:     ld.d    t6, a1, 48
> -8:     ld.d    t7, a1, 56
> -9:     st.d    t0, a0, 0
> -10:    st.d    t1, a0, 8
> -11:    st.d    t2, a0, 16
> -12:    st.d    t3, a0, 24
> -13:    st.d    t4, a0, 32
> -14:    st.d    t5, a0, 40
> -15:    st.d    t6, a0, 48
> -16:    st.d    t7, a0, 56
> +       /* align up destination address */
> +       andi    t1, a0, 7
> +       sub.d   t0, zero, t1
> +       addi.d  t0, t0, 8
> +       add.d   a1, a1, t0
> +       add.d   a0, a0, t0
>  
> -       addi.d  a0, a0, 64
> -       addi.d  a1, a1, 64
> -       addi.d  a2, a2, -64
> -       bge     a2, a3, 1b
> +       addi.d  a4, a3, -64
> +       bgeu    a1, a4, .Llt64
>  
> -       beqz    a2, 19f
> +       /* copy 64 bytes at a time */
> +.Lloop64:
> +2:     ld.d    t0, a1, 0
> +3:     ld.d    t1, a1, 8
> +4:     ld.d    t2, a1, 16
> +5:     ld.d    t3, a1, 24
> +6:     ld.d    t4, a1, 32
> +7:     ld.d    t5, a1, 40
> +8:     ld.d    t6, a1, 48
> +9:     ld.d    t7, a1, 56
> +       addi.d  a1, a1, 64
> +10:    st.d    t0, a0, 0
> +11:    st.d    t1, a0, 8
> +12:    st.d    t2, a0, 16
> +13:    st.d    t3, a0, 24
> +14:    st.d    t4, a0, 32
> +15:    st.d    t5, a0, 40
> +16:    st.d    t6, a0, 48
> +17:    st.d    t7, a0, 56
> +       addi.d  a0, a0, 64
> +       bltu    a1, a4, .Lloop64
>  
>         /* copy the remaining bytes */
> -17:    ld.b    t0, a1, 0
> -18:    st.b    t0, a0, 0
> -       addi.d  a0, a0, 1
> -       addi.d  a1, a1, 1
> -       addi.d  a2, a2, -1
> -       bgt     a2, zero, 17b
> +.Llt64:
> +       addi.d  a4, a3, -32
> +       bgeu    a1, a4, .Llt32
> +18:    ld.d    t0, a1, 0
> +19:    ld.d    t1, a1, 8
> +20:    ld.d    t2, a1, 16
> +21:    ld.d    t3, a1, 24
> +       addi.d  a1, a1, 32
> +22:    st.d    t0, a0, 0
> +23:    st.d    t1, a0, 8
> +24:    st.d    t2, a0, 16
> +25:    st.d    t3, a0, 24
> +       addi.d  a0, a0, 32
> +
> +.Llt32:
> +       addi.d  a4, a3, -16
> +       bgeu    a1, a4, .Llt16
> +26:    ld.d    t0, a1, 0
> +27:    ld.d    t1, a1, 8
> +       addi.d  a1, a1, 16
> +28:    st.d    t0, a0, 0
> +29:    st.d    t1, a0, 8
> +       addi.d  a0, a0, 16
> +
> +.Llt16:
> +       addi.d  a4, a3, -8
> +       bgeu    a1, a4, .Llt8
> +30:    ld.d    t0, a1, 0
> +31:    st.d    t0, a0, 0
> +
> +.Llt8:
> +32:    ld.d    t0, a3, -8
> +33:    st.d    t0, a2, -8
>  
>         /* return */
> -19:    move    a0, a2
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  5
> +.Lsmall:
> +       pcaddi  t0, 8
> +       slli.d  a3, a2, 5
> +       add.d   t0, t0, a3
> +       jr      t0
> +
> +       .align  5
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  5
> +34:    ld.b    t0, a1, 0
> +35:    st.b    t0, a0, 0
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  5
> +36:    ld.h    t0, a1, 0
> +37:    st.h    t0, a0, 0
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  5
> +38:    ld.h    t0, a1, 0
> +39:    ld.b    t1, a1, 2
> +40:    st.h    t0, a0, 0
> +41:    st.b    t1, a0, 2
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  5
> +42:    ld.w    t0, a1, 0
> +43:    st.w    t0, a0, 0
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  5
> +44:    ld.w    t0, a1, 0
> +45:    ld.b    t1, a1, 4
> +46:    st.w    t0, a0, 0
> +47:    st.b    t1, a0, 4
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  5
> +48:    ld.w    t0, a1, 0
> +49:    ld.h    t1, a1, 4
> +50:    st.w    t0, a0, 0
> +51:    st.h    t1, a0, 4
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  5
> +52:    ld.w    t0, a1, 0
> +53:    ld.w    t1, a1, 3
> +54:    st.w    t0, a0, 0
> +55:    st.w    t1, a0, 3
> +       move    a0, zero
> +       jr      ra
> +
> +       .align  5
> +56:    ld.d    t0, a1, 0
> +57:    st.d    t0, a0, 0
> +       move    a0, zero
>         jr      ra
>  
>         /* fixup and ex_table */
> +       _asm_extable 0b, .L_fixup_handle_0
>         _asm_extable 1b, .L_fixup_handle_0
> -       _asm_extable 2b, .L_fixup_handle_1
> -       _asm_extable 3b, .L_fixup_handle_2
> -       _asm_extable 4b, .L_fixup_handle_3
> -       _asm_extable 5b, .L_fixup_handle_4
> -       _asm_extable 6b, .L_fixup_handle_5
> -       _asm_extable 7b, .L_fixup_handle_6
> -       _asm_extable 8b, .L_fixup_handle_7
> +       _asm_extable 2b, .L_fixup_handle_0
> +       _asm_extable 3b, .L_fixup_handle_0
> +       _asm_extable 4b, .L_fixup_handle_0
> +       _asm_extable 5b, .L_fixup_handle_0
> +       _asm_extable 6b, .L_fixup_handle_0
> +       _asm_extable 7b, .L_fixup_handle_0
> +       _asm_extable 8b, .L_fixup_handle_0
>         _asm_extable 9b, .L_fixup_handle_0
> -       _asm_extable 10b, .L_fixup_handle_1
> -       _asm_extable 11b, .L_fixup_handle_2
> -       _asm_extable 12b, .L_fixup_handle_3
> -       _asm_extable 13b, .L_fixup_handle_4
> -       _asm_extable 14b, .L_fixup_handle_5
> -       _asm_extable 15b, .L_fixup_handle_6
> -       _asm_extable 16b, .L_fixup_handle_7
> -       _asm_extable 17b, .L_fixup_handle_0
> +       _asm_extable 10b, .L_fixup_handle_0
> +       _asm_extable 11b, .L_fixup_handle_1
> +       _asm_extable 12b, .L_fixup_handle_2
> +       _asm_extable 13b, .L_fixup_handle_3
> +       _asm_extable 14b, .L_fixup_handle_4
> +       _asm_extable 15b, .L_fixup_handle_5
> +       _asm_extable 16b, .L_fixup_handle_6
> +       _asm_extable 17b, .L_fixup_handle_7
>         _asm_extable 18b, .L_fixup_handle_0
> +       _asm_extable 19b, .L_fixup_handle_0
> +       _asm_extable 20b, .L_fixup_handle_0
> +       _asm_extable 21b, .L_fixup_handle_0
> +       _asm_extable 22b, .L_fixup_handle_0
> +       _asm_extable 23b, .L_fixup_handle_1
> +       _asm_extable 24b, .L_fixup_handle_2
> +       _asm_extable 25b, .L_fixup_handle_3
> +       _asm_extable 26b, .L_fixup_handle_0
> +       _asm_extable 27b, .L_fixup_handle_0
> +       _asm_extable 28b, .L_fixup_handle_0
> +       _asm_extable 29b, .L_fixup_handle_1
> +       _asm_extable 30b, .L_fixup_handle_0
> +       _asm_extable 31b, .L_fixup_handle_0
> +       _asm_extable 32b, .L_fixup_handle_0
> +       _asm_extable 33b, .L_fixup_handle_1
> +       _asm_extable 34b, .L_fixup_handle_s0
> +       _asm_extable 35b, .L_fixup_handle_s0
> +       _asm_extable 36b, .L_fixup_handle_s0
> +       _asm_extable 37b, .L_fixup_handle_s0
> +       _asm_extable 38b, .L_fixup_handle_s0
> +       _asm_extable 39b, .L_fixup_handle_s0
> +       _asm_extable 40b, .L_fixup_handle_s0
> +       _asm_extable 41b, .L_fixup_handle_s2
> +       _asm_extable 42b, .L_fixup_handle_s0
> +       _asm_extable 43b, .L_fixup_handle_s0
> +       _asm_extable 44b, .L_fixup_handle_s0
> +       _asm_extable 45b, .L_fixup_handle_s0
> +       _asm_extable 46b, .L_fixup_handle_s0
> +       _asm_extable 47b, .L_fixup_handle_s4
> +       _asm_extable 48b, .L_fixup_handle_s0
> +       _asm_extable 49b, .L_fixup_handle_s0
> +       _asm_extable 50b, .L_fixup_handle_s0
> +       _asm_extable 51b, .L_fixup_handle_s4
> +       _asm_extable 52b, .L_fixup_handle_s0
> +       _asm_extable 53b, .L_fixup_handle_s0
> +       _asm_extable 54b, .L_fixup_handle_s0
> +       _asm_extable 55b, .L_fixup_handle_s4
> +       _asm_extable 56b, .L_fixup_handle_s0
> +       _asm_extable 57b, .L_fixup_handle_s0
>  SYM_FUNC_END(__copy_user_fast)
> diff --git a/arch/loongarch/lib/memcpy.S b/arch/loongarch/lib/memcpy.S
> index 3b7e1dec7109..39ce6621c704 100644
> --- a/arch/loongarch/lib/memcpy.S
> +++ b/arch/loongarch/lib/memcpy.S
> @@ -44,6 +44,66 @@ SYM_FUNC_START(__memcpy_generic)
>  SYM_FUNC_END(__memcpy_generic)
>  _ASM_NOKPROBE(__memcpy_generic)
>  
> +       .align  5
> +SYM_FUNC_START_NOALIGN(__memcpy_small)
> +       pcaddi  t0, 8
> +       slli.d  a2, a2, 5
> +       add.d   t0, t0, a2
> +       jr      t0
> +
> +       .align  5
> +0:     jr      ra
> +
> +       .align  5
> +1:     ld.b    t0, a1, 0
> +       st.b    t0, a0, 0
> +       jr      ra
> +
> +       .align  5
> +2:     ld.h    t0, a1, 0
> +       st.h    t0, a0, 0
> +       jr      ra
> +
> +       .align  5
> +3:     ld.h    t0, a1, 0
> +       ld.b    t1, a1, 2
> +       st.h    t0, a0, 0
> +       st.b    t1, a0, 2
> +       jr      ra
> +
> +       .align  5
> +4:     ld.w    t0, a1, 0
> +       st.w    t0, a0, 0
> +       jr      ra
> +
> +       .align  5
> +5:     ld.w    t0, a1, 0
> +       ld.b    t1, a1, 4
> +       st.w    t0, a0, 0
> +       st.b    t1, a0, 4
> +       jr      ra
> +
> +       .align  5
> +6:     ld.w    t0, a1, 0
> +       ld.h    t1, a1, 4
> +       st.w    t0, a0, 0
> +       st.h    t1, a0, 4
> +       jr      ra
> +
> +       .align  5
> +7:     ld.w    t0, a1, 0
> +       ld.w    t1, a1, 3
> +       st.w    t0, a0, 0
> +       st.w    t1, a0, 3
> +       jr      ra
> +
> +       .align  5
> +8:     ld.d    t0, a1, 0
> +       st.d    t0, a0, 0
> +       jr      ra
> +SYM_FUNC_END(__memcpy_small)
> +_ASM_NOKPROBE(__memcpy_small)
> +
>  /*
>   * void *__memcpy_fast(void *dst, const void *src, size_t n)
>   *
> @@ -52,14 +112,27 @@ _ASM_NOKPROBE(__memcpy_generic)
>   * a2: n
>   */
>  SYM_FUNC_START(__memcpy_fast)
> -       move    a3, a0
> -       beqz    a2, 3f
> +       sltui   t0, a2, 9
> +       bnez    t0, __memcpy_small
> +
> +       add.d   a3, a1, a2
> +       add.d   a2, a0, a2
> +       ld.d    a6, a1, 0
> +       ld.d    a7, a3, -8
> +
> +       /* align up destination address */
> +       andi    t1, a0, 7
> +       sub.d   t0, zero, t1
> +       addi.d  t0, t0, 8
> +       add.d   a1, a1, t0
> +       add.d   a5, a0, t0
>  
> -       ori     a4, zero, 64
> -       blt     a2, a4, 2f
> +       addi.d  a4, a3, -64
> +       bgeu    a1, a4, .Llt64
>  
>         /* copy 64 bytes at a time */
> -1:     ld.d    t0, a1, 0
> +.Lloop64:
> +       ld.d    t0, a1, 0
>         ld.d    t1, a1, 8
>         ld.d    t2, a1, 16
>         ld.d    t3, a1, 24
> @@ -67,32 +140,54 @@ SYM_FUNC_START(__memcpy_fast)
>         ld.d    t5, a1, 40
>         ld.d    t6, a1, 48
>         ld.d    t7, a1, 56
> -       st.d    t0, a0, 0
> -       st.d    t1, a0, 8
> -       st.d    t2, a0, 16
> -       st.d    t3, a0, 24
> -       st.d    t4, a0, 32
> -       st.d    t5, a0, 40
> -       st.d    t6, a0, 48
> -       st.d    t7, a0, 56
> -
> -       addi.d  a0, a0, 64
>         addi.d  a1, a1, 64
> -       addi.d  a2, a2, -64
> -       bge     a2, a4, 1b
> -
> -       beqz    a2, 3f
> +       st.d    t0, a5, 0
> +       st.d    t1, a5, 8
> +       st.d    t2, a5, 16
> +       st.d    t3, a5, 24
> +       st.d    t4, a5, 32
> +       st.d    t5, a5, 40
> +       st.d    t6, a5, 48
> +       st.d    t7, a5, 56
> +       addi.d  a5, a5, 64
> +       bltu    a1, a4, .Lloop64
>  
>         /* copy the remaining bytes */
> -2:     ld.b    t0, a1, 0
> -       st.b    t0, a0, 0
> -       addi.d  a0, a0, 1
> -       addi.d  a1, a1, 1
> -       addi.d  a2, a2, -1
> -       bgt     a2, zero, 2b
> +.Llt64:
> +       addi.d  a4, a3, -32
> +       bgeu    a1, a4, .Llt32
> +       ld.d    t0, a1, 0
> +       ld.d    t1, a1, 8
> +       ld.d    t2, a1, 16
> +       ld.d    t3, a1, 24
> +       addi.d  a1, a1, 32
> +       st.d    t0, a5, 0
> +       st.d    t1, a5, 8
> +       st.d    t2, a5, 16
> +       st.d    t3, a5, 24
> +       addi.d  a5, a5, 32
> +
> +.Llt32:
> +       addi.d  a4, a3, -16
> +       bgeu    a1, a4, .Llt16
> +       ld.d    t0, a1, 0
> +       ld.d    t1, a1, 8
> +       addi.d  a1, a1, 16
> +       st.d    t0, a5, 0
> +       st.d    t1, a5, 8
> +       addi.d  a5, a5, 16
> +
> +.Llt16:
> +       addi.d  a4, a3, -8
> +       bgeu    a1, a4, .Llt8
> +       ld.d    t0, a1, 0
> +       st.d    t0, a5, 0
> +
> +.Llt8:
> +       st.d    a6, a0, 0
> +       st.d    a7, a2, -8
>  
>         /* return */
> -3:     move    a0, a3
>         jr      ra
>  SYM_FUNC_END(__memcpy_fast)
>  _ASM_NOKPROBE(__memcpy_fast)
> diff --git a/arch/loongarch/lib/memmove.S
> b/arch/loongarch/lib/memmove.S
> index b796c3d6da05..45b725ba7867 100644
> --- a/arch/loongarch/lib/memmove.S
> +++ b/arch/loongarch/lib/memmove.S
> @@ -11,23 +11,9 @@
>  #include <asm/regdef.h>
>  
>  SYM_FUNC_START(memmove)
> -       blt     a0, a1, 1f      /* dst < src, memcpy */
> -       blt     a1, a0, 3f      /* src < dst, rmemcpy */
> +       blt     a0, a1, memcpy  /* dst < src, memcpy */
> +       blt     a1, a0, rmemcpy /* src < dst, rmemcpy */
>         jr      ra              /* dst == src, return */
> -
> -       /* if (src - dst) < 64, copy 1 byte at a time */
> -1:     ori     a3, zero, 64
> -       sub.d   t0, a1, a0
> -       blt     t0, a3, 2f
> -       b       memcpy
> -2:     b       __memcpy_generic
> -
> -       /* if (dst - src) < 64, copy 1 byte at a time */
> -3:     ori     a3, zero, 64
> -       sub.d   t0, a0, a1
> -       blt     t0, a3, 4f
> -       b       rmemcpy
> -4:     b       __rmemcpy_generic
>  SYM_FUNC_END(memmove)
>  _ASM_NOKPROBE(memmove)
>  
> @@ -76,50 +62,80 @@ _ASM_NOKPROBE(__rmemcpy_generic)
>   * a2: n
>   */
>  SYM_FUNC_START(__rmemcpy_fast)
> -       move    a3, a0
> -       beqz    a2, 3f
> +       sltui   t0, a2, 9
> +       bnez    t0, __memcpy_small
>  
> -       add.d   a0, a0, a2
> -       add.d   a1, a1, a2
> +       add.d   a3, a1, a2
> +       add.d   a2, a0, a2
> +       ld.d    a6, a1, 0
> +       ld.d    a7, a3, -8
> +
> +       /* align up destination address */
> +       andi    t1, a2, 7
> +       sub.d   a3, a3, t1
> +       sub.d   a5, a2, t1
>  
> -       ori     a4, zero, 64
> -       blt     a2, a4, 2f
> +       addi.d  a4, a1, 64
> +       bgeu    a4, a3, .Llt64
>  
>         /* copy 64 bytes at a time */
> -1:     ld.d    t0, a1, -8
> -       ld.d    t1, a1, -16
> -       ld.d    t2, a1, -24
> -       ld.d    t3, a1, -32
> -       ld.d    t4, a1, -40
> -       ld.d    t5, a1, -48
> -       ld.d    t6, a1, -56
> -       ld.d    t7, a1, -64
> -       st.d    t0, a0, -8
> -       st.d    t1, a0, -16
> -       st.d    t2, a0, -24
> -       st.d    t3, a0, -32
> -       st.d    t4, a0, -40
> -       st.d    t5, a0, -48
> -       st.d    t6, a0, -56
> -       st.d    t7, a0, -64
> -
> -       addi.d  a0, a0, -64
> -       addi.d  a1, a1, -64
> -       addi.d  a2, a2, -64
> -       bge     a2, a4, 1b
> -
> -       beqz    a2, 3f
> +.Lloop64:
> +       ld.d    t0, a3, -8
> +       ld.d    t1, a3, -16
> +       ld.d    t2, a3, -24
> +       ld.d    t3, a3, -32
> +       ld.d    t4, a3, -40
> +       ld.d    t5, a3, -48
> +       ld.d    t6, a3, -56
> +       ld.d    t7, a3, -64
> +       addi.d  a3, a3, -64
> +       st.d    t0, a5, -8
> +       st.d    t1, a5, -16
> +       st.d    t2, a5, -24
> +       st.d    t3, a5, -32
> +       st.d    t4, a5, -40
> +       st.d    t5, a5, -48
> +       st.d    t6, a5, -56
> +       st.d    t7, a5, -64
> +       addi.d  a5, a5, -64
> +       bltu    a4, a3, .Lloop64
>  
>         /* copy the remaining bytes */
> -2:     ld.b    t0, a1, -1
> -       st.b    t0, a0, -1
> -       addi.d  a0, a0, -1
> -       addi.d  a1, a1, -1
> -       addi.d  a2, a2, -1
> -       bgt     a2, zero, 2b
> +.Llt64:
> +       addi.d  a4, a1, 32
> +       bgeu    a4, a3, .Llt32
> +       ld.d    t0, a3, -8
> +       ld.d    t1, a3, -16
> +       ld.d    t2, a3, -24
> +       ld.d    t3, a3, -32
> +       addi.d  a3, a3, -32
> +       st.d    t0, a5, -8
> +       st.d    t1, a5, -16
> +       st.d    t2, a5, -24
> +       st.d    t3, a5, -32
> +       addi.d  a5, a5, -32
> +
> +.Llt32:
> +       addi.d  a4, a1, 16
> +       bgeu    a4, a3, .Llt16
> +       ld.d    t0, a3, -8
> +       ld.d    t1, a3, -16
> +       addi.d  a3, a3, -16
> +       st.d    t0, a5, -8
> +       st.d    t1, a5, -16
> +       addi.d  a5, a5, -16
> +
> +.Llt16:
> +       addi.d  a4, a1, 8
> +       bgeu    a4, a3, .Llt8
> +       ld.d    t0, a3, -8
> +       st.d    t0, a5, -8
> +
> +.Llt8:
> +       st.d    a6, a0, 0
> +       st.d    a7, a2, -8
>  
>         /* return */
> -3:     move    a0, a3
>         jr      ra
>  SYM_FUNC_END(__rmemcpy_fast)
>  _ASM_NOKPROBE(__rmemcpy_fast)
> diff --git a/arch/loongarch/lib/memset.S b/arch/loongarch/lib/memset.S
> index a9eb732ab2ad..c5836d916736 100644
> --- a/arch/loongarch/lib/memset.S
> +++ b/arch/loongarch/lib/memset.S
> @@ -56,39 +56,108 @@ _ASM_NOKPROBE(__memset_generic)
>   * a2: n
>   */
>  SYM_FUNC_START(__memset_fast)
> -       move    a3, a0
> -       beqz    a2, 3f
> -
> -       ori     a4, zero, 64
> -       blt     a2, a4, 2f
> -
>         /* fill a1 to 64 bits */
>         fill_to_64 a1
>  
> -       /* set 64 bytes at a time */
> -1:     st.d    a1, a0, 0
> -       st.d    a1, a0, 8
> -       st.d    a1, a0, 16
> -       st.d    a1, a0, 24
> -       st.d    a1, a0, 32
> -       st.d    a1, a0, 40
> -       st.d    a1, a0, 48
> -       st.d    a1, a0, 56
> +       sltui   t0, a2, 9
> +       bnez    t0, .Lsmall
>  
> -       addi.d  a0, a0, 64
> -       addi.d  a2, a2, -64
> -       bge     a2, a4, 1b
> +       add.d   a2, a0, a2
> +       st.d    a1, a0, 0
>  
> -       beqz    a2, 3f
> +       /* align up address */
> +       andi    t1, a0, 7
> +       sub.d   a3, a0, t1
> +       addi.d  a3, a3, 8
> +
> +       addi.d  a4, a2, -64
> +       bgeu    a3, a4, .Llt64
> +
> +       /* set 64 bytes at a time */
> +.Lloop64:
> +       st.d    a1, a3, 0
> +       st.d    a1, a3, 8
> +       st.d    a1, a3, 16
> +       st.d    a1, a3, 24
> +       st.d    a1, a3, 32
> +       st.d    a1, a3, 40
> +       st.d    a1, a3, 48
> +       st.d    a1, a3, 56
> +       addi.d  a3, a3, 64
> +       bltu    a3, a4, .Lloop64
>  
>         /* set the remaining bytes */
> -2:     st.b    a1, a0, 0
> -       addi.d  a0, a0, 1
> -       addi.d  a2, a2, -1
> -       bgt     a2, zero, 2b
> +.Llt64:
> +       addi.d  a4, a2, -32
> +       bgeu    a3, a4, .Llt32
> +       st.d    a1, a3, 0
> +       st.d    a1, a3, 8
> +       st.d    a1, a3, 16
> +       st.d    a1, a3, 24
> +       addi.d  a3, a3, 32
> +
> +.Llt32:
> +       addi.d  a4, a2, -16
> +       bgeu    a3, a4, .Llt16
> +       st.d    a1, a3, 0
> +       st.d    a1, a3, 8
> +       addi.d  a3, a3, 16
> +
> +.Llt16:
> +       addi.d  a4, a2, -8
> +       bgeu    a3, a4, .Llt8
> +       st.d    a1, a3, 0
> +
> +.Llt8:
> +       st.d    a1, a2, -8
>  
>         /* return */
> -3:     move    a0, a3
> +       jr      ra
> +
> +       .align  4
> +.Lsmall:
> +       pcaddi  t0, 4
> +       slli.d  a2, a2, 4
> +       add.d   t0, t0, a2
> +       jr      t0
> +
> +       .align  4
> +0:     jr      ra
> +
> +       .align  4
> +1:     st.b    a1, a0, 0
> +       jr      ra
> +
> +       .align  4
> +2:     st.h    a1, a0, 0
> +       jr      ra
> +
> +       .align  4
> +3:     st.h    a1, a0, 0
> +       st.b    a1, a0, 2
> +       jr      ra
> +
> +       .align  4
> +4:     st.w    a1, a0, 0
> +       jr      ra
> +
> +       .align  4
> +5:     st.w    a1, a0, 0
> +       st.b    a1, a0, 4
> +       jr      ra
> +
> +       .align  4
> +6:     st.w    a1, a0, 0
> +       st.h    a1, a0, 4
> +       jr      ra
> +
> +       .align  4
> +7:     st.w    a1, a0, 0
> +       st.w    a1, a0, 3
> +       jr      ra
> +
> +       .align  4
> +8:     st.d    a1, a0, 0
>         jr      ra
>  SYM_FUNC_END(__memset_fast)
>  _ASM_NOKPROBE(__memset_fast)

--
Xi Ruoyao <xry111@xxxxxxxxxxx>
School of Aerospace Science and Technology, Xidian University