x86: ac3dsp: Remove 3dnow version of ff_ac3_extract_exponents

The function requires increasing the fuzz factor for the ac3/eac3 encode
tests and even so makes fate fail. It only provides a slight encoding
speedup for legacy CPUs that do not support SS2. Thus its benefit is not
worth the trouble it creates and fixing it would be a waste of time.

libavcodec/x86/ac3dsp.asm

@@ -379,42 +379,6 @@ cglobal ac3_compute_mantissa_size, 1, 2, 4, mant_cnt, sum
 %endif
 %endmacro
 
-%if HAVE_AMD3DNOW_EXTERNAL
-INIT_MMX 3dnow
-cglobal ac3_extract_exponents, 3, 3, 0, exp, coef, len
-    add      expq, lenq
-    lea     coefq, [coefq+4*lenq]
-    neg      lenq
-    movq       m3, [pd_1]
-    movq       m4, [pd_151]
-.loop:
-    movq       m0, [coefq+4*lenq  ]
-    movq       m1, [coefq+4*lenq+8]
-    PABSD      m0, m2
-    PABSD      m1, m2
-    pslld      m0, 1
-    por        m0, m3
-    pi2fd      m2, m0
-    psrld      m2, 23
-    movq       m0, m4
-    psubd      m0, m2
-    pslld      m1, 1
-    por        m1, m3
-    pi2fd      m2, m1
-    psrld      m2, 23
-    movq       m1, m4
-    psubd      m1, m2
-    packssdw   m0, m0
-    packuswb   m0, m0
-    packssdw   m1, m1
-    packuswb   m1, m1
-    punpcklwd  m0, m1
-    movd  [expq+lenq], m0
-    add      lenq, 4
-    jl .loop
-    REP_RET
-%endif
-
 %macro AC3_EXTRACT_EXPONENTS 0
 cglobal ac3_extract_exponents, 3, 3, 4, exp, coef, len
     add     expq, lenq

libavcodec/x86/ac3dsp_init.c

@@ -189,7 +189,6 @@ av_cold void ff_ac3dsp_init_x86(AC3DSPContext *c, int bit_exact)
         c->ac3_rshift_int32 = ff_ac3_rshift_int32_mmx;
     }
     if (EXTERNAL_AMD3DNOW(mm_flags)) {
-        c->extract_exponents = ff_ac3_extract_exponents_3dnow;
         if (!bit_exact) {
             c->float_to_fixed24 = ff_float_to_fixed24_3dnow;
         }

tests/fate/ac3.mak

@@ -52,14 +52,12 @@ fate-ac3-encode: CMD = enc_dec_pcm ac3 wav s16le $(REF) -c:a ac3 -b:a 128k
 fate-ac3-encode: CMP_SHIFT = -1024
 fate-ac3-encode: CMP_TARGET = 404.53
 fate-ac3-encode: SIZE_TOLERANCE = 488
-fate-ac3-encode: FUZZ = 3
 
 FATE_EAC3-$(call ENCDEC, EAC3, EAC3) += fate-eac3-encode
 fate-eac3-encode: CMD = enc_dec_pcm eac3 wav s16le $(REF) -c:a eac3 -b:a 128k
 fate-eac3-encode: CMP_SHIFT = -1024
 fate-eac3-encode: CMP_TARGET = 516.94
 fate-eac3-encode: SIZE_TOLERANCE = 488
-fate-eac3-encode: FUZZ = 3
 
 fate-ac3-encode fate-eac3-encode: CMP = stddev
 fate-ac3-encode fate-eac3-encode: REF = $(SAMPLES)/audio-reference/luckynight_2ch_44kHz_s16.wav