* [FFmpeg-devel] [PATCH] avutil/aarch64/tx_float_neon.S: clean up FFT4_X2
@ 2025-02-25 20:45 Krzysztof Pyrkosz via ffmpeg-devel
2025-02-28 12:43 ` Lynne
0 siblings, 1 reply; 2+ messages in thread
From: Krzysztof Pyrkosz via ffmpeg-devel @ 2025-02-25 20:45 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: Krzysztof Pyrkosz
---
This patch rids the code from two tbl instructions and the shuffle
table. There's no fneg v0.s[3] instruction unfortunately, so I negate
the whole vector and copy the last element only.
It's tricky to benchmark this little change but on average it seems to
be beneficial.
Krzysztof
libavutil/aarch64/tx_float_neon.S | 32 ++++++++-----------------------
1 file changed, 8 insertions(+), 24 deletions(-)
diff --git a/libavutil/aarch64/tx_float_neon.S b/libavutil/aarch64/tx_float_neon.S
index 78e4876d6c..d00b3f9684 100644
--- a/libavutil/aarch64/tx_float_neon.S
+++ b/libavutil/aarch64/tx_float_neon.S
@@ -119,13 +119,6 @@ endconst
.endif
.endm
-const shuf_4pt_x2, align=4
- .byte 24, 25, 26, 27 // reg2, 3
- .byte 12, 13, 14, 15 // reg1, 4
- .byte 8, 9, 10, 11 // reg1, 3
- .byte 28, 29, 30, 31 // reg2, 4
-endconst
-
// Identical to FFT4, but does 2 transforms in parallel, with no deinterleaving
.macro FFT4_X2 e0, o0, e1, o1, \
t0=v16, t1=v17, t2=v18, t3=v19, t4=v20, t5=v21, t6=v22
@@ -135,18 +128,17 @@ endconst
fsub \e0\().4s, \e0\().4s, \o0\().4s // t1234
fsub \e1\().4s, \e1\().4s, \o1\().4s // t1234
- movrel x5, shuf_4pt_x2
-
rev64 \t4\().4s, \e0\().4s
rev64 \t5\().4s, \e1\().4s
- zip2 \o0\().2d, \t0\().2d, \e0\().2d // t3,4 r3,4
- zip2 \o1\().2d, \t2\().2d, \e1\().2d // t3,4 r3,4
+ zip2 \o0\().2d, \t0\().2d, \t4\().2d // t3,4 r3,4
+ zip2 \o1\().2d, \t2\().2d, \t5\().2d // t3,4 r3,4
- ld1 { \t6\().16b }, [x5]
+ fneg \t3\().4s, \t4\().4s
+ fneg \t4\().4s, \t5\().4s
- mov \o0\().d[1], \t4\().d[1]
- mov \o1\().d[1], \t5\().d[1]
+ mov \o0\().s[3], \t3\().s[3]
+ mov \o1\().s[3], \t4\().s[3]
zip1 \t1\().2d, \t0\().2d, \e0\().2d // t1,2 r1,2
zip1 \t3\().2d, \t2\().2d, \e1\().2d // t1,2 r1,2
@@ -156,18 +148,10 @@ endconst
fsub \t2\().4s, \t3\().4s, \o1\().4s // a34 b32
fadd \t3\().4s, \t3\().4s, \o1\().4s // a12 b14
- // TODO: experiment with movs instead of tables here
- tbl \o0\().16b, { \t4\().16b, \t5\().16b }, \t6\().16b // b1234
- tbl \o1\().16b, { \t2\().16b, \t3\().16b }, \t6\().16b // b1234
-
zip1 \e0\().2d, \t5\().2d, \t4\().2d // a1234
-// zip2 \o0\().2d, \t5\().2d, \t4\().2d // b1432
+ zip2 \o0\().2d, \t5\().2d, \t4\().2d // b1432
zip1 \e1\().2d, \t3\().2d, \t2\().2d // a1234
-// zip2 \o1\().2d, \t3\().2d, \t2\().2d // b1432
-// rev64 \o0\().4s, \o0\().4s // b4123
-// rev64 \o1\().4s, \o1\().4s // b4123
-// ext \o0\().16b, \o0\().16b, \o0\().16b, #4 // b1234
-// ext \o1\().16b, \o1\().16b, \o1\().16b, #4 // b1234
+ zip2 \o1\().2d, \t3\().2d, \t2\().2d // b1432
.endm
const tab_8pt, align=4
--
2.47.2
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* Re: [FFmpeg-devel] [PATCH] avutil/aarch64/tx_float_neon.S: clean up FFT4_X2
2025-02-25 20:45 [FFmpeg-devel] [PATCH] avutil/aarch64/tx_float_neon.S: clean up FFT4_X2 Krzysztof Pyrkosz via ffmpeg-devel
@ 2025-02-28 12:43 ` Lynne
0 siblings, 0 replies; 2+ messages in thread
From: Lynne @ 2025-02-28 12:43 UTC (permalink / raw)
To: ffmpeg-devel
[-- Attachment #1.1.1.1: Type: text/plain, Size: 3973 bytes --]
On 25/02/2025 21:45, Krzysztof Pyrkosz via ffmpeg-devel wrote:
> ---
> This patch rids the code from two tbl instructions and the shuffle
> table. There's no fneg v0.s[3] instruction unfortunately, so I negate
> the whole vector and copy the last element only.
>
> It's tricky to benchmark this little change but on average it seems to
> be beneficial.
>
> Krzysztof
>
> libavutil/aarch64/tx_float_neon.S | 32 ++++++++-----------------------
> 1 file changed, 8 insertions(+), 24 deletions(-)
>
> diff --git a/libavutil/aarch64/tx_float_neon.S b/libavutil/aarch64/tx_float_neon.S
> index 78e4876d6c..d00b3f9684 100644
> --- a/libavutil/aarch64/tx_float_neon.S
> +++ b/libavutil/aarch64/tx_float_neon.S
> @@ -119,13 +119,6 @@ endconst
> .endif
> .endm
>
> -const shuf_4pt_x2, align=4
> - .byte 24, 25, 26, 27 // reg2, 3
> - .byte 12, 13, 14, 15 // reg1, 4
> - .byte 8, 9, 10, 11 // reg1, 3
> - .byte 28, 29, 30, 31 // reg2, 4
> -endconst
> -
> // Identical to FFT4, but does 2 transforms in parallel, with no deinterleaving
> .macro FFT4_X2 e0, o0, e1, o1, \
> t0=v16, t1=v17, t2=v18, t3=v19, t4=v20, t5=v21, t6=v22
> @@ -135,18 +128,17 @@ endconst
> fsub \e0\().4s, \e0\().4s, \o0\().4s // t1234
> fsub \e1\().4s, \e1\().4s, \o1\().4s // t1234
>
> - movrel x5, shuf_4pt_x2
> -
> rev64 \t4\().4s, \e0\().4s
> rev64 \t5\().4s, \e1\().4s
>
> - zip2 \o0\().2d, \t0\().2d, \e0\().2d // t3,4 r3,4
> - zip2 \o1\().2d, \t2\().2d, \e1\().2d // t3,4 r3,4
> + zip2 \o0\().2d, \t0\().2d, \t4\().2d // t3,4 r3,4
> + zip2 \o1\().2d, \t2\().2d, \t5\().2d // t3,4 r3,4
>
> - ld1 { \t6\().16b }, [x5]
> + fneg \t3\().4s, \t4\().4s
> + fneg \t4\().4s, \t5\().4s
>
> - mov \o0\().d[1], \t4\().d[1]
> - mov \o1\().d[1], \t5\().d[1]
> + mov \o0\().s[3], \t3\().s[3]
> + mov \o1\().s[3], \t4\().s[3]
>
> zip1 \t1\().2d, \t0\().2d, \e0\().2d // t1,2 r1,2
> zip1 \t3\().2d, \t2\().2d, \e1\().2d // t1,2 r1,2
> @@ -156,18 +148,10 @@ endconst
> fsub \t2\().4s, \t3\().4s, \o1\().4s // a34 b32
> fadd \t3\().4s, \t3\().4s, \o1\().4s // a12 b14
>
> - // TODO: experiment with movs instead of tables here
> - tbl \o0\().16b, { \t4\().16b, \t5\().16b }, \t6\().16b // b1234
> - tbl \o1\().16b, { \t2\().16b, \t3\().16b }, \t6\().16b // b1234
> -
> zip1 \e0\().2d, \t5\().2d, \t4\().2d // a1234
> -// zip2 \o0\().2d, \t5\().2d, \t4\().2d // b1432
> + zip2 \o0\().2d, \t5\().2d, \t4\().2d // b1432
> zip1 \e1\().2d, \t3\().2d, \t2\().2d // a1234
> -// zip2 \o1\().2d, \t3\().2d, \t2\().2d // b1432
> -// rev64 \o0\().4s, \o0\().4s // b4123
> -// rev64 \o1\().4s, \o1\().4s // b4123
> -// ext \o0\().16b, \o0\().16b, \o0\().16b, #4 // b1234
> -// ext \o1\().16b, \o1\().16b, \o1\().16b, #4 // b1234
> + zip2 \o1\().2d, \t3\().2d, \t2\().2d // b1432
> .endm
>
> const tab_8pt, align=4
Thanks, pushed.
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2025-02-25 20:45 [FFmpeg-devel] [PATCH] avutil/aarch64/tx_float_neon.S: clean up FFT4_X2 Krzysztof Pyrkosz via ffmpeg-devel
2025-02-28 12:43 ` Lynne
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