From 724dc202806a34995694f734ea20fc92c365ef6a Mon Sep 17 00:00:00 2001
From: Lynne <dev@lynne.ee>
Date: Thu, 1 Sep 2022 23:26:29 +0200
Subject: [PATCH] x86/tx_float: implement inverse MDCT AVX2 assembly
This commit implements an iMDCT in pure assembly.
This is capable of processing any mod-8 transforms, rather than just
power of two, but since power of two is all we have assembly for
currently, that's what's supported.
It would really benefit if we could somehow use the C code to decide
which function to jump into, but exposing function labels from assebly
into C is anything but easy.
The post-transform loop could probably be improved.
This was somewhat annoying to write, as we must support arbitrary
strides during runtime. There's a fast branch for stride == 4 bytes
and a slower one which uses vgatherdps.
Benchmarks for stride == 4 for old (av_imdct_half) vs new (av_tx):
128pt:
2791 decicycles in av_tx (imdct),16775675 runs, 1541 skips
3024 decicycles in av_imdct_half,16776779 runs, 437 skips
256pt:
5055 decicycles in av_tx (imdct), 2096602 runs, 550 skips
5324 decicycles in av_imdct_half, 2097046 runs, 106 skips
512pt:
9922 decicycles in av_tx (imdct), 2096983 runs, 169 skips
10390 decicycles in av_imdct_half, 2097002 runs, 150 skips
1024pt:
20482 decicycles in av_tx (imdct), 2097089 runs, 63 skips
20662 decicycles in av_imdct_half, 2097115 runs, 37 skips
---
libavutil/tx.c | 19 ++--
libavutil/tx_priv.h | 8 +-
libavutil/x86/tx_float.asm | 168 +++++++++++++++++++++++++++++++++-
libavutil/x86/tx_float_init.c | 29 +++++-
4 files changed, 209 insertions(+), 15 deletions(-)
@@ -206,23 +206,24 @@ static void parity_revtab_generator(int *revtab, int n, int inv, int offset,
1, 1, len >> 1, basis, dual_stride, inv_lookup);
}
-int ff_tx_gen_split_radix_parity_revtab(AVTXContext *s, int invert_lookup,
- int basis, int dual_stride)
+int ff_tx_gen_split_radix_parity_revtab(AVTXContext *s, int len, int inv,
+ int inv_lookup, int basis, int dual_stride)
{
- int len = s->len;
- int inv = s->inv;
-
- if (!(s->map = av_mallocz(len*sizeof(*s->map))))
- return AVERROR(ENOMEM);
-
basis >>= 1;
if (len < basis)
return AVERROR(EINVAL);
+ if (!(s->map = av_mallocz((inv_lookup == -1 ? 2 : 1)*len*sizeof(*s->map))))
+ return AVERROR(ENOMEM);
+
av_assert0(!dual_stride || !(dual_stride & (dual_stride - 1)));
av_assert0(dual_stride <= basis);
+
parity_revtab_generator(s->map, len, inv, 0, 0, 0, len,
- basis, dual_stride, invert_lookup);
+ basis, dual_stride, inv_lookup != 0);
+ if (inv_lookup == -1)
+ parity_revtab_generator(s->map + len, len, inv, 0, 0, 0, len,
+ basis, dual_stride, 0);
return 0;
}
@@ -287,9 +287,13 @@ int ff_tx_gen_ptwo_inplace_revtab_idx(AVTXContext *s);
* functions in AVX mode.
*
* If length is smaller than basis/2 this function will not do anything.
+ *
+ * If inv_lookup is set to 1, it will flip the lookup from out[map[i]] = src[i]
+ * to out[i] = src[map[i]]. If set to -1, will generate 2 maps, the first one
+ * flipped, the second one regular.
*/
-int ff_tx_gen_split_radix_parity_revtab(AVTXContext *s, int invert_lookup,
- int basis, int dual_stride);
+int ff_tx_gen_split_radix_parity_revtab(AVTXContext *s, int len, int inv,
+ int inv_lookup, int basis, int dual_stride);
/* Typed init function to initialize shared tables. Will initialize all tables
* for all factors of a length. */
@@ -925,9 +925,9 @@ ALIGN 16
%macro FFT_SPLIT_RADIX_FN 3
INIT_YMM %1
-cglobal fft_sr_ %+ %2, 4, 8, 16, 272, lut, out, in, len, tmp, itab, rtab, tgt
- movsxd lenq, dword [lutq + AVTXContext.len]
- mov lutq, [lutq + AVTXContext.map]
+cglobal fft_sr_ %+ %2, 4, 9, 16, 272, ctx, out, in, tmp, len, lut, itab, rtab, tgt
+ movsxd lenq, dword [ctxq + AVTXContext.len]
+ mov lutq, [ctxq + AVTXContext.map]
mov tgtq, lenq
; Bottom-most/32-point transform ===============================================
@@ -1289,3 +1289,165 @@ FFT_SPLIT_RADIX_FN avx2, float, 0
FFT_SPLIT_RADIX_FN avx2, ns_float, 1
%endif
%endif
+
+%macro IMDCT_FN 1
+INIT_YMM %1
+cglobal mdct_sr_inv_float, 4, 9, 16, 272, ctx, out, in, stride, len, lut, exp, t1, t2
+ movsxd lenq, dword [ctxq + AVTXContext.len]
+ mov lutq, [ctxq + AVTXContext.map]
+ mov expq, [ctxq + AVTXContext.exp]
+
+ lea t1d, [lend*2 - 1]
+ imul t1d, strided
+ lea t1q, [inq + t1q]
+
+ cmp strideq, 4
+ je .stride4
+
+ mov t2d, strided
+ movd xmm4, strided
+ neg t2d
+ movd xmm5, t2d
+ SPLATD xmm4
+ SPLATD xmm5
+ vperm2f128 m4, m4, m4, 0x00 ; +stride splatted
+ vperm2f128 m5, m5, m5, 0x00 ; -stride splatted
+
+ mov t2q, outq
+
+.stridex_pre:
+ mova m2, [lutq] ; load LUT indices
+ pcmpeqd m0, m0 ; zero out a register
+ pmulld m3, m2, m4 ; multiply by +stride
+ pmulld m2, m5 ; multiply by -stride
+ movaps m1, m0
+ vgatherdps m6, [inq + 2*m3], m0 ; im
+ vgatherdps m7, [t1q + 2*m2], m1 ; re
+
+ movaps m8, [expq + 0*mmsize] ; tab 1
+ movaps m9, [expq + 1*mmsize] ; tab 2
+
+ unpcklps m0, m7, m6 ; re, im, re, im
+ unpckhps m1, m7, m6 ; re, im, re, im
+
+ vperm2f128 m2, m1, m0, 0x02 ; output order
+ vperm2f128 m3, m1, m0, 0x13 ; output order
+
+ movshdup m10, m8 ; tab 1 imim
+ movshdup m11, m9 ; tab 2 imim
+ movsldup m12, m8 ; tab 1 rere
+ movsldup m13, m9 ; tab 2 rere
+
+ mulps m10, m2 ; 1 reim * imim
+ mulps m11, m3 ; 2 reim * imim
+
+ shufps m10, m10, q2301
+ shufps m11, m11, q2301
+
+ fmaddsubps m10, m12, m2, m10
+ fmaddsubps m11, m13, m3, m11
+
+ mova [outq + 0*mmsize], m10
+ mova [outq + 1*mmsize], m11
+
+ add expq, mmsize*2
+ add lutq, mmsize
+ add outq, mmsize*2
+ sub lenq, mmsize/4
+ jg .stridex_pre
+ mov outq, t2q ; restore output
+ jmp .transform
+
+.stride4:
+ lea expq, [expq + lenq*8]
+ lea lutq, [lutq + lenq*4]
+ lea t1q, [t1q + strideq - mmsize]
+
+.stride4_pre:
+ movsldup m1, [inq] ; im im, im im
+ movshdup m0, [t1q] ; re re, re re
+
+ vperm2f128 m0, m0, 0x01 ; flip
+ shufpd m0, m0, 101b
+
+ movaps m2, [expq] ; tab
+
+ mulps m0, m2 ; re re * tab.reim
+ mulps m1, m2 ; im im * tab.reim
+
+ shufps m1, m1, m1, q2301
+ addsubps m0, m1
+
+ vextractf128 xm3, m0, 1
+
+ ; scatter
+ movsxd strideq, dword [lutq + 0*4]
+ movlps [outq + strideq*8], xm0
+ movsxd strideq, dword [lutq + 1*4]
+ movhps [outq + strideq*8], xm0
+ movsxd strideq, dword [lutq + 2*4]
+ movlps [outq + strideq*8], xm3
+ movsxd strideq, dword [lutq + 3*4]
+ movhps [outq + strideq*8], xm3
+
+ add lutq, mmsize/2
+ add expq, mmsize
+ add inq, mmsize
+ sub t1q, mmsize
+ sub lenq, mmsize/8
+ jg .stride4_pre
+
+.transform:
+ mov inq, outq ; in-place transform
+ call ff_tx_fft_sr_ns_float_avx2 ; call the FFT
+
+ movsxd lenq, dword [ctxq + AVTXContext.len]
+ mov expq, [ctxq + AVTXContext.exp]
+ lea expq, [expq + lenq*8]
+
+ lea t1q, [lenq*4] ; high
+ lea t2q, [lenq*4 - mmsize] ; low
+
+ neg lenq
+ lea outq, [inq + lenq*8]
+
+.post:
+ movaps m2, [expq + t1q] ; tab h
+ movaps m3, [expq + t2q] ; tab l
+ movaps m0, [outq + t1q] ; in h
+ movaps m1, [outq + t2q] ; in l
+
+ movshdup m4, m2 ; tab h imim
+ movshdup m5, m3 ; tab l imim
+ movsldup m6, m2 ; tab h rere
+ movsldup m7, m3 ; tab l rere
+
+ shufps m2, m0, m0, q2301 ; in h imre
+ shufps m3, m1, m1, q2301 ; in l imre
+
+ mulps m6, m0
+ mulps m7, m1
+
+ fmaddsubps m4, m4, m2, m6
+ fmaddsubps m5, m5, m3, m7
+
+ vperm2f128 m0, m4, m4, 0x01 ; flip
+ vperm2f128 m1, m5, m5, 0x01 ; flip
+
+ shufps m2, m0, m0, q1230
+ shufps m3, m1, m1, q1230
+
+ blendps m0, m3, m4, 01010101b
+ blendps m1, m2, m5, 01010101b
+
+ movaps [outq + t1q], m0
+ movaps [outq + t2q], m1
+
+ add t1q, mmsize
+ sub t2q, mmsize
+ jge .post
+
+ RET
+%endmacro
+
+IMDCT_FN avx2
@@ -43,6 +43,8 @@ TX_DECL_FN(fft_sr_ns, fma3)
TX_DECL_FN(fft_sr, avx2)
TX_DECL_FN(fft_sr_ns, avx2)
+TX_DECL_FN(mdct_sr_inv, avx2)
+
#define DECL_INIT_FN(basis, interleave) \
static av_cold int b ##basis## _i ##interleave(AVTXContext *s, \
const FFTXCodelet *cd, \
@@ -56,13 +58,35 @@ static av_cold int b ##basis## _i ##interleave(AVTXContext *s, \
if (cd->max_len == 2) \
return ff_tx_gen_ptwo_revtab(s, inv_lookup); \
else \
- return ff_tx_gen_split_radix_parity_revtab(s, inv_lookup, \
+ return ff_tx_gen_split_radix_parity_revtab(s, len, inv, inv_lookup, \
basis, interleave); \
}
DECL_INIT_FN(8, 0)
DECL_INIT_FN(8, 2)
+static av_cold int m_inv_init(AVTXContext *s, const FFTXCodelet *cd,
+ uint64_t flags, FFTXCodeletOptions *opts,
+ int len, int inv, const void *scale)
+{
+ int ret;
+
+ s->scale_d = *((SCALE_TYPE *)scale);
+ s->scale_f = s->scale_d;
+
+ ff_tx_init_tabs_float(len >> 1);
+
+ if ((ret = ff_tx_gen_split_radix_parity_revtab(s, len >> 1, 1, -1, 8, 2)) < 0)
+ return ret;
+
+ if ((ret = ff_tx_mdct_gen_exp_float(s, s->map)))
+ return ret;
+
+ s->len >>= 1;
+
+ return 0;
+}
+
const FFTXCodelet * const ff_tx_codelet_list_float_x86[] = {
TX_DEF(fft2, FFT, 2, 2, 2, 0, 128, NULL, sse3, SSE3, AV_TX_INPLACE, 0),
TX_DEF(fft2, FFT, 2, 2, 2, 0, 192, b8_i0, sse3, SSE3, AV_TX_INPLACE | FF_TX_PRESHUFFLE, 0),
@@ -81,6 +105,9 @@ const FFTXCodelet * const ff_tx_codelet_list_float_x86[] = {
TX_DEF(fft16_ns, FFT, 16, 16, 2, 0, 352, b8_i2, fma3, FMA3, AV_TX_INPLACE | FF_TX_PRESHUFFLE,
AV_CPU_FLAG_AVXSLOW),
+ TX_DEF(mdct_sr_inv, MDCT, 128, TX_LEN_UNLIMITED, 2, TX_FACTOR_ANY, 384, m_inv_init, avx2, AVX2,
+ FF_TX_INVERSE_ONLY, AV_CPU_FLAG_AVXSLOW | AV_CPU_FLAG_SLOW_GATHER),
+
#if ARCH_X86_64
TX_DEF(fft32, FFT, 32, 32, 2, 0, 256, b8_i2, avx, AVX, AV_TX_INPLACE, AV_CPU_FLAG_AVXSLOW),
TX_DEF(fft32_ns, FFT, 32, 32, 2, 0, 320, b8_i2, avx, AVX, AV_TX_INPLACE | FF_TX_PRESHUFFLE,
--
2.37.2.609.g9ff673ca1a