Hi,
On Sat, 19 Oct 2024 at 19:20, Torbjörn SVENSSON
<torbjorn.svens...@foss.st.com> wrote:
>
> With r15-1618-g9f168b412f4, I get the following asm generated for the test
> case:
>
> .align 1
> .align 2
> .global test5
> .syntax unified
> .thumb
> .thumb_func
> .type test5, %function
> test5:
> @ args = 4, pretend = 0, frame = 0
> @ frame_needed = 0, uses_anonymous_args = 0
> push {r4, r5, r6, lr}
> ldr r4, [sp, #16]
> cmp r4, #0
> ble .L37
> sub ip, r4, #16
> adds r6, r2, r4
> adds r5, r1, r4
> add r0, r0, r4
> dlstp.8 lr, r4
> .L39:
> subs r2, r5, r4
> subs r1, r0, r4
> vldrb.8 q3, [r1]
> vldrb.8 q2, [r2]
> subs r2, r6, r4
> mov r4, ip
> sub ip, ip, #16
> vadd.i8 q3, q3, q2
> vstrb.8 q3, [r2]
> vstrb.8 q3, [r3]
> letp lr, .L39
> .L37:
> pop {r4, r5, r6, pc}
> .size test5, .-test5
>
> ...
>
> .align 1
> .align 2
> .global test8
> .syntax unified
> .thumb
> .thumb_func
> .type test8, %function
> test8:
> @ args = 4, pretend = 0, frame = 0
> @ frame_needed = 0, uses_anonymous_args = 0
> push {r4, lr}
> ldr r4, [sp, #8]
> cmp r3, #0
> ble .L59
> dlstp.32 lr, r3
> .L61:
> vldrw.32 q3, [r0], #16
> vctp.32 r4
> vpst
> vldrwt.32 q2, [r1], #16
> adds r4, r4, #1
> vadd.i32 q3, q3, q2
> vstrw.32 q3, [r2], #16
> letp lr, .L61
> .L59:
> pop {r4, pc}
> .size test8, .-test8
>
>
>
>
> With r15-1619-g3b9b8d6cfdf, I instead get:
>
> .align 1
> .align 2
> .global test5
> .syntax unified
> .thumb
> .thumb_func
> .type test5, %function
> test5:
> @ args = 4, pretend = 0, frame = 0
> @ frame_needed = 0, uses_anonymous_args = 0
> push {r4, r5, r6, lr}
> ldr ip, [sp, #16]
> cmp ip, #0
> ble .L37
> mov r6, r3
> sub r3, ip, #16
> add r5, r2, ip
> add r4, r1, ip
> add r0, r0, ip
> dlstp.8 lr, ip
> .L39:
> sub r2, r4, ip
> sub r1, r0, ip
> vldrb.8 q3, [r1]
> vldrb.8 q2, [r2]
> sub r2, r5, ip
> mov ip, r3
> subs r3, r3, #16
> vadd.i8 q3, q3, q2
> vstrb.8 q3, [r2]
> vstrb.8 q3, [r6]
> letp lr, .L39
> .L37:
> pop {r4, r5, r6, pc}
> .size test5, .-test5
>
> ...
>
> .align 1
> .align 2
> .global test8
> .syntax unified
> .thumb
> .thumb_func
> .type test8, %function
> test8:
> @ args = 4, pretend = 0, frame = 0
> @ frame_needed = 0, uses_anonymous_args = 0
> push {lr}
> ldr ip, [sp, #4]
> cmp r3, #0
> ble .L59
> dlstp.32 lr, r3
> .L61:
> vldrw.32 q3, [r0], #16
> vctp.32 ip
> vpst
> vldrwt.32 q2, [r1], #16
> add ip, ip, #1
> vadd.i32 q3, q3, q2
> vstrw.32 q3, [r2], #16
> letp lr, .L61
> .L59:
> ldr pc, [sp], #4
> .size test8, .-test8
>
>
>
> As can be seen, with r15-1619-g3b9b8d6cfdf, it now uses ip in ways that it did
> not before. I think this part is fine.
> It also, for some reason, decides to move r3 into r6 in test5 and then use
> that later for the vstrb.8. While I suppose it does work, it will consume one
> extra mov, so it's slightly bigger.
>
> With below patch, I no longer see any failure reported for arm-none-eabi.
>
> Even with the slight size increase for test5, is it ok for trunk?
>
> --
>
> Since r15-1619-g3b9b8d6cfdf, test5 and test8 fails due to that "ip"
> might be used and r3 might be moved to another register for later
> dereference.
>
> gcc/testsuite/ChangeLog:
>
> PR testsuite/116623
> * gcc.target/arm/mve/dlstp-compile-asm-2.c: Align test5 and
> test8 with changes in r15-1619-g3b9b8d6cfdf.
>
Thanks for looking into this. That commit (r15-1619-g3b9b8d6cfdf)
caused several regressions, including this one.
LGTM.
Christophe
> Signed-off-by: Torbjörn SVENSSON <torbjorn.svens...@foss.st.com>
> ---
> gcc/testsuite/gcc.target/arm/mve/dlstp-compile-asm-2.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/gcc/testsuite/gcc.target/arm/mve/dlstp-compile-asm-2.c
> b/gcc/testsuite/gcc.target/arm/mve/dlstp-compile-asm-2.c
> index 84f4a2fc4f9..c62f592a60d 100644
> --- a/gcc/testsuite/gcc.target/arm/mve/dlstp-compile-asm-2.c
> +++ b/gcc/testsuite/gcc.target/arm/mve/dlstp-compile-asm-2.c
> @@ -147,15 +147,17 @@ void test5 (uint8_t *a, uint8_t *b, uint8_t *c,
> uint8_t *d, int n)
> /*
> ** test5:
> **...
> -** dlstp.8 lr, r[0-9]+
> +** (?:mov (r[0-9]+), r3)?
> +**...
> +** dlstp.8 lr, (?:r[0-9]+|ip)
> **...
> ** vldrb.8 q[0-9]+, \[r1\]
> ** vldrb.8 q[0-9]+, \[r2\]
> **...
> ** vadd.i8 (q[0-9]+), q[0-9]+, q[0-9]+
> **...
> -** vstrb.8 \1, \[r2\]
> -** vstrb.8 \1, \[r3\]
> +** vstrb.8 \2, \[r2\]
> +** vstrb.8 \2, \[(r3|\1)\]
> ** letp lr, .*
> **...
> */
> @@ -247,7 +249,7 @@ void test8 (int32_t *a, int32_t *b, int32_t *c, int n,
> int g)
> **...
> ** dlstp.32 lr, r3
> ** vldrw.32 q[0-9]+, \[r0\], #16
> -** vctp.32 r4
> +** vctp.32 (?:r4|ip)
> ** vpst
> ** vldrwt.32 q[0-9]+, \[r1\], #16
> **...
> --
> 2.25.1
>
