Add 16 wide neon horz loopfilter.

Add support to do 16 pixel horizontal filtering in Neon.
Nexus devices saw about 0.5% decode speed increase.

Change-Id: I2993f6c2d49f31fa74976879eeaa289fd3f4e15d

vp9/common/arm/neon/vp9_loopfilter_16_neon.asm

+;
+;  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
+;
+;  Use of this source code is governed by a BSD-style license
+;  that can be found in the LICENSE file in the root of the source
+;  tree. An additional intellectual property rights grant can be found
+;  in the file PATENTS.  All contributing project authors may
+;  be found in the AUTHORS file in the root of the source tree.
+;
+
+    EXPORT  |vp9_loop_filter_horizontal_edge_16_neon|
+    ARM
+
+    AREA ||.text||, CODE, READONLY, ALIGN=2
+
+;void vp9_loop_filter_horizontal_edge_16_neon(uint8_t *s, int p,
+;                                             const uint8_t *blimit0,
+;                                             const uint8_t *limit0,
+;                                             const uint8_t *thresh0,
+;                                             const uint8_t *blimit1,
+;                                             const uint8_t *limit1,
+;                                             const uint8_t *thresh1)
+; r0    uint8_t *s,
+; r1    int p,
+; r2    const uint8_t *blimit0,
+; r3    const uint8_t *limit0,
+; sp    const uint8_t *thresh0,
+; sp+4  const uint8_t *blimit1,
+; sp+8  const uint8_t *limit1,
+; sp+12 const uint8_t *thresh1,
+
+|vp9_loop_filter_horizontal_edge_16_neon| PROC
+    push        {lr}
+
+    ldr         r12, [sp, #4]              ; load thresh0
+    vld1.8      {d0}, [r2]                 ; load blimit0 to first half q
+    vld1.8      {d2}, [r3]                 ; load limit0 to first half q
+
+    add         r1, r1, r1                 ; double pitch
+    ldr         r2, [sp, #8]               ; load blimit1
+
+    vld1.8      {d4}, [r12]                ; load thresh0 to first half q
+
+    ldr         r3, [sp, #12]              ; load limit1
+    ldr         r12, [sp, #16]             ; load thresh1
+    vld1.8      {d1}, [r2]                 ; load blimit1 to 2nd half q
+
+    sub         r2, r0, r1, lsl #1         ; s[-4 * p]
+
+    vld1.8      {d3}, [r3]                 ; load limit1 to 2nd half q
+    vld1.8      {d5}, [r12]                ; load thresh1 to 2nd half q
+
+    vpush       {d8-d15}                   ; save neon registers
+
+    add         r3, r2, r1, lsr #1         ; s[-3 * p]
+
+    vld1.u8     {q3}, [r2@64], r1          ; p3
+    vld1.u8     {q4}, [r3@64], r1          ; p2
+    vld1.u8     {q5}, [r2@64], r1          ; p1
+    vld1.u8     {q6}, [r3@64], r1          ; p0
+    vld1.u8     {q7}, [r2@64], r1          ; q0
+    vld1.u8     {q8}, [r3@64], r1          ; q1
+    vld1.u8     {q9}, [r2@64]              ; q2
+    vld1.u8     {q10}, [r3@64]             ; q3
+
+    sub         r2, r2, r1, lsl #1
+    sub         r3, r3, r1, lsl #1
+
+    bl          vp9_loop_filter_neon_16
+
+    vst1.u8     {q5}, [r2@64], r1          ; store op1
+    vst1.u8     {q6}, [r3@64], r1          ; store op0
+    vst1.u8     {q7}, [r2@64], r1          ; store oq0
+    vst1.u8     {q8}, [r3@64], r1          ; store oq1
+
+    vpop        {d8-d15}                   ; restore neon registers
+
+    pop         {pc}
+    ENDP        ; |vp9_loop_filter_horizontal_edge_16_neon|
+
+; void vp9_loop_filter_neon_16();
+; This is a helper function for the loopfilters. The invidual functions do the
+; necessary load, transpose (if necessary) and store. This function uses
+; registers d8-d15, so the calling function must save those registers.
+;
+; r0-r3, r12 PRESERVE
+; q0    blimit
+; q1    limit
+; q2    thresh
+; q3    p3
+; q4    p2
+; q5    p1
+; q6    p0
+; q7    q0
+; q8    q1
+; q9    q2
+; q10   q3
+;
+; Outputs:
+; q5    op1
+; q6    op0
+; q7    oq0
+; q8    oq1
+|vp9_loop_filter_neon_16| PROC
+
+    ; filter_mask
+    vabd.u8     q11, q3, q4                 ; m1 = abs(p3 - p2)
+    vabd.u8     q12, q4, q5                 ; m2 = abs(p2 - p1)
+    vabd.u8     q13, q5, q6                 ; m3 = abs(p1 - p0)
+    vabd.u8     q14, q8, q7                 ; m4 = abs(q1 - q0)
+    vabd.u8     q3, q9, q8                  ; m5 = abs(q2 - q1)
+    vabd.u8     q4, q10, q9                 ; m6 = abs(q3 - q2)
+
+    ; only compare the largest value to limit
+    vmax.u8     q11, q11, q12               ; m1 = max(m1, m2)
+    vmax.u8     q12, q13, q14               ; m2 = max(m3, m4)
+
+    vabd.u8     q9, q6, q7                  ; abs(p0 - q0)
+
+    vmax.u8     q3, q3, q4                  ; m3 = max(m5, m6)
+
+    vmov.u8     q10, #0x80
+
+    vmax.u8     q15, q11, q12               ; m1 = max(m1, m2)
+
+    vcgt.u8     q13, q13, q2                ; (abs(p1 - p0) > thresh)*-1
+    vcgt.u8     q14, q14, q2                ; (abs(q1 - q0) > thresh)*-1
+    vmax.u8     q15, q15, q3                ; m1 = max(m1, m3)
+
+    vabd.u8     q2, q5, q8                  ; a = abs(p1 - q1)
+    vqadd.u8    q9, q9, q9                  ; b = abs(p0 - q0) * 2
+
+    veor        q7, q7, q10                 ; qs0
+
+    vcge.u8     q15, q1, q15                ; abs(m1) > limit
+
+    vshr.u8     q2, q2, #1                  ; a = a / 2
+    veor        q6, q6, q10                 ; ps0
+
+    veor        q5, q5, q10                 ; ps1
+    vqadd.u8    q9, q9, q2                  ; a = b + a
+
+    veor        q8, q8, q10                 ; qs1
+
+    vmov.u8     q4, #3
+
+    vsubl.s8    q2, d14, d12                ; ( qs0 - ps0)
+    vsubl.s8    q11, d15, d13
+
+    vcge.u8     q9, q0, q9                  ; a > blimit
+
+    vqsub.s8    q1, q5, q8                  ; filter = clamp(ps1-qs1)
+    vorr        q14, q13, q14               ; hevmask
+
+    vmul.i16    q2, q2, q4                  ; 3 * ( qs0 - ps0)
+    vmul.i16    q11, q11, q4
+
+    vand        q1, q1, q14                 ; filter &= hev
+    vand        q15, q15, q9                ; filter_mask
+
+    vaddw.s8    q2, q2, d2                  ; filter + 3 * (qs0 - ps0)
+    vaddw.s8    q11, q11, d3
+
+    vmov.u8     q9, #4
+
+    ; filter = clamp(filter + 3 * ( qs0 - ps0))
+    vqmovn.s16  d2, q2
+    vqmovn.s16  d3, q11
+    vand        q1, q1, q15                 ; filter &= mask
+
+    vqadd.s8    q2, q1, q4                  ; filter2 = clamp(filter+3)
+    vqadd.s8    q1, q1, q9                  ; filter1 = clamp(filter+4)
+    vshr.s8     q2, q2, #3                  ; filter2 >>= 3
+    vshr.s8     q1, q1, #3                  ; filter1 >>= 3
+
+
+    vqadd.s8    q11, q6, q2                 ; u = clamp(ps0 + filter2)
+    vqsub.s8    q0, q7, q1                  ; u = clamp(qs0 - filter1)
+
+    ; outer tap adjustments
+    vrshr.s8    q1, q1, #1                  ; filter = ++filter1 >> 1
+
+    veor        q6, q11, q10                ; *op0 = u^0x80
+
+    vbic        q1, q1, q14                 ; filter &= ~hev
+
+    vqadd.s8    q13, q5, q1                 ; u = clamp(ps1 + filter)
+    vqsub.s8    q12, q8, q1                 ; u = clamp(qs1 - filter)
+
+
+    veor        q7, q0,  q10                ; *oq0 = u^0x80
+    veor        q5, q13, q10                ; *op1 = u^0x80
+    veor        q8, q12, q10                ; *oq1 = u^0x80
+
+    bx          lr
+    ENDP        ; |vp9_loop_filter_neon_16|
+
+    END

vp9/common/arm/neon/vp9_loopfilter_16_neon.c

@@ -10,17 +10,6 @@
 
 #include "./vp9_rtcd.h"
 
-void vp9_loop_filter_horizontal_edge_16_neon(uint8_t *s, int p /* pitch */,
-                                             const uint8_t *blimit0,
-                                             const uint8_t *limit0,
-                                             const uint8_t *thresh0,
-                                             const uint8_t *blimit1,
-                                             const uint8_t *limit1,
-                                             const uint8_t *thresh1) {
-  vp9_loop_filter_horizontal_edge(s, p, blimit0, limit0, thresh0, 1);
-  vp9_loop_filter_horizontal_edge(s + 8, p, blimit1, limit1, thresh1, 1);
-}
-
 void vp9_mbloop_filter_horizontal_edge_16_neon(uint8_t *s, int p /* pitch */,
                                                const uint8_t *blimit0,
                                                const uint8_t *limit0,

vp9/vp9_common.mk

@@ -125,6 +125,7 @@ VP9_COMMON_SRCS-$(HAVE_NEON) += common/arm/neon/vp9_loopfilter_16_neon.c
 VP9_COMMON_SRCS-$(HAVE_NEON) += common/arm/neon/vp9_convolve8_neon$(ASM)
 VP9_COMMON_SRCS-$(HAVE_NEON) += common/arm/neon/vp9_convolve8_avg_neon$(ASM)
 VP9_COMMON_SRCS-$(HAVE_NEON) += common/arm/neon/vp9_loopfilter_neon$(ASM)
+VP9_COMMON_SRCS-$(HAVE_NEON) += common/arm/neon/vp9_loopfilter_16_neon$(ASM)
 VP9_COMMON_SRCS-$(HAVE_NEON) += common/arm/neon/vp9_dc_only_idct_add_neon$(ASM)
 VP9_COMMON_SRCS-$(HAVE_NEON) += common/arm/neon/vp9_short_idct4x4_1_add_neon$(ASM)
 VP9_COMMON_SRCS-$(HAVE_NEON) += common/arm/neon/vp9_short_idct4x4_add_neon$(ASM)