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[AArch64] Add Neon implementation of ScaleRowDown2_16_NEON

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The auto-vectorized implementation unrolls to process 32 elements per
iteration, so unroll the new Neon implementation to match and avoid a
performance regression on little cores.

Performance relative to the auto-vectorized C implementation compiled
with LLVM 19:

 Cortex-A55: -35.8%
Cortex-A510: -20.4%
Cortex-A520: -22.1%
 Cortex-A76: -54.8%
Cortex-A710: -44.5%
Cortex-A715: -31.1%
Cortex-A720: -31.4%
  Cortex-X1: -48.5%
  Cortex-X2: -47.8%
  Cortex-X3: -47.6%
  Cortex-X4: -51.1%
Cortex-X925: -14.6%

Bug: b/42280942
Change-Id: Ib4e89ba230d554f2717052e934ca0e8a109ccc42
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/6040153
Reviewed-by: Justin Green <greenjustin@google.com>
Reviewed-by: Frank Barchard <fbarchard@chromium.org>
This commit is contained in:
George Steed 2024-11-15 14:36:12 +00:00 committed by Frank Barchard
parent 952d6a282f
commit 11c57f4f12
3 changed files with 52 additions and 2 deletions
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4
include/libyuv/scale_row.h
View File

@ -1428,6 +1428,10 @@ void ScaleRowDown2_NEON(const uint8_t* src_ptr,
ptrdiff_t src_stride,
uint8_t* dst,
int dst_width);
void ScaleRowDown2_16_NEON(const uint16_t* src_ptr,
ptrdiff_t src_stride,
uint16_t* dst,
int dst_width);
void ScaleRowDown2_SME(const uint8_t* src_ptr,
ptrdiff_t src_stride,
uint8_t* dst,

5
source/scale.cc
View File

@ -187,8 +187,9 @@ static void ScalePlaneDown2_16(int src_width,
}
#if defined(HAS_SCALEROWDOWN2_16_NEON)
if (TestCpuFlag(kCpuHasNEON) && IS_ALIGNED(dst_width, 16) && filtering) {
ScaleRowDown2 = ScaleRowDown2Box_16_NEON;
if (TestCpuFlag(kCpuHasNEON) && IS_ALIGNED(dst_width, 16)) {
ScaleRowDown2 =
filtering ? ScaleRowDown2Box_16_NEON : ScaleRowDown2_16_NEON;
}
#endif
#if defined(HAS_SCALEROWDOWN2_16_SSE2)

45
source/scale_neon64.cc
View File

@ -1354,6 +1354,51 @@ void ScaleARGBFilterCols_NEON(uint8_t* dst_argb,
#undef SCALE_ARGB_FILTER_COLS_STEP_ADDR
void ScaleRowDown2_16_NEON(const uint16_t* src_ptr,
ptrdiff_t src_stride,
uint16_t* dst,
int dst_width) {
(void)src_stride;
asm volatile(
"subs %w[dst_width], %w[dst_width], #32 \n"
"b.lt 2f \n"
"1: \n"
"ldp q0, q1, [%[src_ptr]] \n"
"ldp q2, q3, [%[src_ptr], #32] \n"
"ldp q4, q5, [%[src_ptr], #64] \n"
"ldp q6, q7, [%[src_ptr], #96] \n"
"add %[src_ptr], %[src_ptr], #128 \n"
"uzp2 v0.8h, v0.8h, v1.8h \n"
"uzp2 v1.8h, v2.8h, v3.8h \n"
"uzp2 v2.8h, v4.8h, v5.8h \n"
"uzp2 v3.8h, v6.8h, v7.8h \n"
"subs %w[dst_width], %w[dst_width], #32 \n" // 32 elems per iteration.
"stp q0, q1, [%[dst_ptr]] \n"
"stp q2, q3, [%[dst_ptr], #32] \n"
"add %[dst_ptr], %[dst_ptr], #64 \n"
"b.ge 1b \n"
"2: \n"
"adds %w[dst_width], %w[dst_width], #32 \n"
"b.eq 99f \n"
"ldp q0, q1, [%[src_ptr]] \n"
"ldp q2, q3, [%[src_ptr], #32] \n"
"add %[src_ptr], %[src_ptr], #64 \n"
"uzp2 v0.8h, v0.8h, v1.8h \n"
"uzp2 v1.8h, v2.8h, v3.8h \n"
"stp q0, q1, [%[dst_ptr]], #32 \n"
"99: \n"
: [src_ptr]"+r"(src_ptr),
[dst_ptr]"+r"(dst),
[dst_width]"+r"(dst_width)
:
: "cc", "memory", "v0", "v1", "v2", "v3", "v4", "v5", "v6", "v7");
}
// Read 16x2 average down and write 8x1.
void ScaleRowDown2Box_16_NEON(const uint16_t* src_ptr,
ptrdiff_t src_stride,