libwebp: update to 0.5.0

third_party/libwebp/dsp/yuv_sse2.c

 // Copyright 2014 Google Inc. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the COPYING 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.
 // -----------------------------------------------------------------------------
 //
 // YUV->RGB conversion functions
 //
 // Author: Skal (pascal.massimino@gmail.com)
 
 #include "./yuv.h"
 
 #if defined(WEBP_USE_SSE2)
 
 #include <emmintrin.h>
-#include <string.h>   // for memcpy
-
-typedef union {   // handy struct for converting SSE2 registers
-  int32_t i32[4];
-  uint8_t u8[16];
-  __m128i m;
-} VP8kCstSSE2;
-
-#if defined(WEBP_YUV_USE_SSE2_TABLES)
-
-#include "./yuv_tables_sse2.h"
-
-void VP8YUVInitSSE2(void) {}
-
-#else
-
-static int done_sse2 = 0;
-static VP8kCstSSE2 VP8kUtoRGBA[256], VP8kVtoRGBA[256], VP8kYtoRGBA[256];
-
-void VP8YUVInitSSE2(void) {
-  if (!done_sse2) {
-    int i;
-    for (i = 0; i < 256; ++i) {
-      VP8kYtoRGBA[i].i32[0] =
-        VP8kYtoRGBA[i].i32[1] =
-        VP8kYtoRGBA[i].i32[2] = (i - 16) * kYScale + YUV_HALF2;
-      VP8kYtoRGBA[i].i32[3] = 0xff << YUV_FIX2;
-
-      VP8kUtoRGBA[i].i32[0] = 0;
-      VP8kUtoRGBA[i].i32[1] = -kUToG * (i - 128);
-      VP8kUtoRGBA[i].i32[2] =  kUToB * (i - 128);
-      VP8kUtoRGBA[i].i32[3] = 0;
-
-      VP8kVtoRGBA[i].i32[0] =  kVToR * (i - 128);
-      VP8kVtoRGBA[i].i32[1] = -kVToG * (i - 128);
-      VP8kVtoRGBA[i].i32[2] = 0;
-      VP8kVtoRGBA[i].i32[3] = 0;
-    }
-    done_sse2 = 1;
-
-#if 0   // code used to generate 'yuv_tables_sse2.h'
-    printf("static const VP8kCstSSE2 VP8kYtoRGBA[256] = {\n");
-    for (i = 0; i < 256; ++i) {
-      printf("  {{0x%.8x, 0x%.8x, 0x%.8x, 0x%.8x}},\n",
-             VP8kYtoRGBA[i].i32[0], VP8kYtoRGBA[i].i32[1],
-             VP8kYtoRGBA[i].i32[2], VP8kYtoRGBA[i].i32[3]);
-    }
-    printf("};\n\n");
-    printf("static const VP8kCstSSE2 VP8kUtoRGBA[256] = {\n");
-    for (i = 0; i < 256; ++i) {
-      printf("  {{0, 0x%.8x, 0x%.8x, 0}},\n",
-             VP8kUtoRGBA[i].i32[1], VP8kUtoRGBA[i].i32[2]);
-    }
-    printf("};\n\n");
-    printf("static VP8kCstSSE2 VP8kVtoRGBA[256] = {\n");
-    for (i = 0; i < 256; ++i) {
-      printf("  {{0x%.8x, 0x%.8x, 0, 0}},\n",
-             VP8kVtoRGBA[i].i32[0], VP8kVtoRGBA[i].i32[1]);
-    }
-    printf("};\n\n");
-#endif
-  }
-}
-
-#endif  // WEBP_YUV_USE_SSE2_TABLES
-
-//-----------------------------------------------------------------------------
-
-static WEBP_INLINE __m128i LoadUVPart(int u, int v) {
-  const __m128i u_part = _mm_loadu_si128(&VP8kUtoRGBA[u].m);
-  const __m128i v_part = _mm_loadu_si128(&VP8kVtoRGBA[v].m);
-  const __m128i uv_part = _mm_add_epi32(u_part, v_part);
-  return uv_part;
-}
-
-static WEBP_INLINE __m128i GetRGBA32bWithUV(int y, const __m128i uv_part) {
-  const __m128i y_part = _mm_loadu_si128(&VP8kYtoRGBA[y].m);
-  const __m128i rgba1 = _mm_add_epi32(y_part, uv_part);
-  const __m128i rgba2 = _mm_srai_epi32(rgba1, YUV_FIX2);
-  return rgba2;
-}
-
-static WEBP_INLINE __m128i GetRGBA32b(int y, int u, int v) {
-  const __m128i uv_part = LoadUVPart(u, v);
-  return GetRGBA32bWithUV(y, uv_part);
-}
-
-static WEBP_INLINE void YuvToRgbSSE2(uint8_t y, uint8_t u, uint8_t v,
-                                     uint8_t* const rgb) {
-  const __m128i tmp0 = GetRGBA32b(y, u, v);
-  const __m128i tmp1 = _mm_packs_epi32(tmp0, tmp0);
-  const __m128i tmp2 = _mm_packus_epi16(tmp1, tmp1);
-  // Note: we store 8 bytes at a time, not 3 bytes! -> memory stomp
-  _mm_storel_epi64((__m128i*)rgb, tmp2);
-}
-
-static WEBP_INLINE void YuvToBgrSSE2(uint8_t y, uint8_t u, uint8_t v,
-                                     uint8_t* const bgr) {
-  const __m128i tmp0 = GetRGBA32b(y, u, v);
-  const __m128i tmp1 = _mm_shuffle_epi32(tmp0, _MM_SHUFFLE(3, 0, 1, 2));
-  const __m128i tmp2 = _mm_packs_epi32(tmp1, tmp1);
-  const __m128i tmp3 = _mm_packus_epi16(tmp2, tmp2);
-  // Note: we store 8 bytes at a time, not 3 bytes! -> memory stomp
-  _mm_storel_epi64((__m128i*)bgr, tmp3);
-}
 
 //-----------------------------------------------------------------------------
 // Convert spans of 32 pixels to various RGB formats for the fancy upsampler.
 
-#ifdef FANCY_UPSAMPLING
+// These constants are 14b fixed-point version of ITU-R BT.601 constants.
+// R = (19077 * y             + 26149 * v - 14234) >> 6
+// G = (19077 * y -  6419 * u - 13320 * v +  8708) >> 6
+// B = (19077 * y + 33050 * u             - 17685) >> 6
+static void ConvertYUV444ToRGB(const __m128i* const Y0,
+                               const __m128i* const U0,
+                               const __m128i* const V0,
+                               __m128i* const R,
+                               __m128i* const G,
+                               __m128i* const B) {
+  const __m128i k19077 = _mm_set1_epi16(19077);
+  const __m128i k26149 = _mm_set1_epi16(26149);
+  const __m128i k14234 = _mm_set1_epi16(14234);
+  const __m128i k33050 = _mm_set1_epi16(33050);
+  const __m128i k17685 = _mm_set1_epi16(17685);
+  const __m128i k6419  = _mm_set1_epi16(6419);
+  const __m128i k13320 = _mm_set1_epi16(13320);
+  const __m128i k8708  = _mm_set1_epi16(8708);
+
+  const __m128i Y1 = _mm_mulhi_epu16(*Y0, k19077);
+
+  const __m128i R0 = _mm_mulhi_epu16(*V0, k26149);
+  const __m128i R1 = _mm_sub_epi16(Y1, k14234);
+  const __m128i R2 = _mm_add_epi16(R1, R0);
+
+  const __m128i G0 = _mm_mulhi_epu16(*U0, k6419);
+  const __m128i G1 = _mm_mulhi_epu16(*V0, k13320);
+  const __m128i G2 = _mm_add_epi16(Y1, k8708);
+  const __m128i G3 = _mm_add_epi16(G0, G1);
+  const __m128i G4 = _mm_sub_epi16(G2, G3);
+
+  // be careful with the saturated *unsigned* arithmetic here!
+  const __m128i B0 = _mm_mulhi_epu16(*U0, k33050);
+  const __m128i B1 = _mm_adds_epu16(B0, Y1);
+  const __m128i B2 = _mm_subs_epu16(B1, k17685);
+
+  // use logical shift for B2, which can be larger than 32767
+  *R = _mm_srai_epi16(R2, 6);   // range: [-14234, 30815]
+  *G = _mm_srai_epi16(G4, 6);   // range: [-10953, 27710]
+  *B = _mm_srli_epi16(B2, 6);   // range: [0, 34238]
+}
+
+// Load the bytes into the *upper* part of 16b words. That's "<< 8", basically.
+static WEBP_INLINE __m128i Load_HI_16(const uint8_t* src) {
+  const __m128i zero = _mm_setzero_si128();
+  return _mm_unpacklo_epi8(zero, _mm_loadl_epi64((const __m128i*)src));
+}
+
+// Load and replicate the U/V samples
+static WEBP_INLINE __m128i Load_UV_HI_8(const uint8_t* src) {
+  const __m128i zero = _mm_setzero_si128();
+  const __m128i tmp0 = _mm_cvtsi32_si128(*(const uint32_t*)src);
+  const __m128i tmp1 = _mm_unpacklo_epi8(zero, tmp0);
+  return _mm_unpacklo_epi16(tmp1, tmp1);   // replicate samples
+}
+
+// Convert 32 samples of YUV444 to R/G/B
+static void YUV444ToRGB(const uint8_t* const y,
+                        const uint8_t* const u,
+                        const uint8_t* const v,
+                        __m128i* const R, __m128i* const G, __m128i* const B) {
+  const __m128i Y0 = Load_HI_16(y), U0 = Load_HI_16(u), V0 = Load_HI_16(v);
+  ConvertYUV444ToRGB(&Y0, &U0, &V0, R, G, B);
+}
+
+// Convert 32 samples of YUV420 to R/G/B
+static void YUV420ToRGB(const uint8_t* const y,
+                        const uint8_t* const u,
+                        const uint8_t* const v,
+                        __m128i* const R, __m128i* const G, __m128i* const B) {
+  const __m128i Y0 = Load_HI_16(y), U0 = Load_UV_HI_8(u), V0 = Load_UV_HI_8(v);
+  ConvertYUV444ToRGB(&Y0, &U0, &V0, R, G, B);
+}
+
+// Pack R/G/B/A results into 32b output.
+static WEBP_INLINE void PackAndStore4(const __m128i* const R,
+                                      const __m128i* const G,
+                                      const __m128i* const B,
+                                      const __m128i* const A,
+                                      uint8_t* const dst) {
+  const __m128i rb = _mm_packus_epi16(*R, *B);
+  const __m128i ga = _mm_packus_epi16(*G, *A);
+  const __m128i rg = _mm_unpacklo_epi8(rb, ga);
+  const __m128i ba = _mm_unpackhi_epi8(rb, ga);
+  const __m128i RGBA_lo = _mm_unpacklo_epi16(rg, ba);
+  const __m128i RGBA_hi = _mm_unpackhi_epi16(rg, ba);
+  _mm_storeu_si128((__m128i*)(dst +  0), RGBA_lo);
+  _mm_storeu_si128((__m128i*)(dst + 16), RGBA_hi);
+}
+
+// Pack R/G/B/A results into 16b output.
+static WEBP_INLINE void PackAndStore4444(const __m128i* const R,
+                                         const __m128i* const G,
+                                         const __m128i* const B,
+                                         const __m128i* const A,
+                                         uint8_t* const dst) {
+#if !defined(WEBP_SWAP_16BIT_CSP)
+  const __m128i rg0 = _mm_packus_epi16(*R, *G);
+  const __m128i ba0 = _mm_packus_epi16(*B, *A);
+#else
+  const __m128i rg0 = _mm_packus_epi16(*B, *A);
+  const __m128i ba0 = _mm_packus_epi16(*R, *G);
+#endif
+  const __m128i mask_0xf0 = _mm_set1_epi8(0xf0);
+  const __m128i rb1 = _mm_unpacklo_epi8(rg0, ba0);  // rbrbrbrbrb...
+  const __m128i ga1 = _mm_unpackhi_epi8(rg0, ba0);  // gagagagaga...
+  const __m128i rb2 = _mm_and_si128(rb1, mask_0xf0);
+  const __m128i ga2 = _mm_srli_epi16(_mm_and_si128(ga1, mask_0xf0), 4);
+  const __m128i rgba4444 = _mm_or_si128(rb2, ga2);
+  _mm_storeu_si128((__m128i*)dst, rgba4444);
+}
+
+// Pack R/G/B results into 16b output.
+static WEBP_INLINE void PackAndStore565(const __m128i* const R,
+                                        const __m128i* const G,
+                                        const __m128i* const B,
+                                        uint8_t* const dst) {
+  const __m128i r0 = _mm_packus_epi16(*R, *R);
+  const __m128i g0 = _mm_packus_epi16(*G, *G);
+  const __m128i b0 = _mm_packus_epi16(*B, *B);
+  const __m128i r1 = _mm_and_si128(r0, _mm_set1_epi8(0xf8));
+  const __m128i b1 = _mm_and_si128(_mm_srli_epi16(b0, 3), _mm_set1_epi8(0x1f));
+  const __m128i g1 = _mm_srli_epi16(_mm_and_si128(g0, _mm_set1_epi8(0xe0)), 5);
+  const __m128i g2 = _mm_slli_epi16(_mm_and_si128(g0, _mm_set1_epi8(0x1c)), 3);
+  const __m128i rg = _mm_or_si128(r1, g1);
+  const __m128i gb = _mm_or_si128(g2, b1);
+#if !defined(WEBP_SWAP_16BIT_CSP)
+  const __m128i rgb565 = _mm_unpacklo_epi8(rg, gb);
+#else
+  const __m128i rgb565 = _mm_unpacklo_epi8(gb, rg);
+#endif
+  _mm_storeu_si128((__m128i*)dst, rgb565);
+}
+
+// Function used several times in PlanarTo24b.
+// It samples the in buffer as follows: one every two unsigned char is stored
+// at the beginning of the buffer, while the other half is stored at the end.
+static WEBP_INLINE void PlanarTo24bHelper(const __m128i* const in /*in[6]*/,
+                                          __m128i* const out /*out[6]*/) {
+  const __m128i v_mask = _mm_set1_epi16(0x00ff);
+
+  // Take one every two upper 8b values.
+  out[0] = _mm_packus_epi16(_mm_and_si128(in[0], v_mask),
+                            _mm_and_si128(in[1], v_mask));
+  out[1] = _mm_packus_epi16(_mm_and_si128(in[2], v_mask),
+                            _mm_and_si128(in[3], v_mask));
+  out[2] = _mm_packus_epi16(_mm_and_si128(in[4], v_mask),
+                            _mm_and_si128(in[5], v_mask));
+  // Take one every two lower 8b values.
+  out[3] = _mm_packus_epi16(_mm_srli_epi16(in[0], 8), _mm_srli_epi16(in[1], 8));
+  out[4] = _mm_packus_epi16(_mm_srli_epi16(in[2], 8), _mm_srli_epi16(in[3], 8));
+  out[5] = _mm_packus_epi16(_mm_srli_epi16(in[4], 8), _mm_srli_epi16(in[5], 8));
+}
+
+// Pack the planar buffers
+// rrrr... rrrr... gggg... gggg... bbbb... bbbb....
+// triplet by triplet in the output buffer rgb as rgbrgbrgbrgb ...
+static WEBP_INLINE void PlanarTo24b(__m128i* const in /*in[6]*/, uint8_t* rgb) {
+  // The input is 6 registers of sixteen 8b but for the sake of explanation,
+  // let's take 6 registers of four 8b values.
+  // To pack, we will keep taking one every two 8b integer and move it
+  // around as follows:
+  // Input:
+  //   r0r1r2r3 | r4r5r6r7 | g0g1g2g3 | g4g5g6g7 | b0b1b2b3 | b4b5b6b7
+  // Split the 6 registers in two sets of 3 registers: the first set as the even
+  // 8b bytes, the second the odd ones:
+  //   r0r2r4r6 | g0g2g4g6 | b0b2b4b6 | r1r3r5r7 | g1g3g5g7 | b1b3b5b7
+  // Repeat the same permutations twice more:
+  //   r0r4g0g4 | b0b4r1r5 | g1g5b1b5 | r2r6g2g6 | b2b6r3r7 | g3g7b3b7
+  //   r0g0b0r1 | g1b1r2g2 | b2r3g3b3 | r4g4b4r5 | g5b5r6g6 | b6r7g7b7
+  __m128i tmp[6];
+  PlanarTo24bHelper(in, tmp);
+  PlanarTo24bHelper(tmp, in);
+  PlanarTo24bHelper(in, tmp);
+  // We need to do it two more times than the example as we have sixteen bytes.
+  PlanarTo24bHelper(tmp, in);
+  PlanarTo24bHelper(in, tmp);
+
+  _mm_storeu_si128((__m128i*)(rgb +  0), tmp[0]);
+  _mm_storeu_si128((__m128i*)(rgb + 16), tmp[1]);
+  _mm_storeu_si128((__m128i*)(rgb + 32), tmp[2]);
+  _mm_storeu_si128((__m128i*)(rgb + 48), tmp[3]);
+  _mm_storeu_si128((__m128i*)(rgb + 64), tmp[4]);
+  _mm_storeu_si128((__m128i*)(rgb + 80), tmp[5]);
+}
+#undef MK_UINT32
 
 void VP8YuvToRgba32(const uint8_t* y, const uint8_t* u, const uint8_t* v,
                     uint8_t* dst) {
-  int n;
-  for (n = 0; n < 32; n += 4) {
-    const __m128i tmp0_1 = GetRGBA32b(y[n + 0], u[n + 0], v[n + 0]);
-    const __m128i tmp0_2 = GetRGBA32b(y[n + 1], u[n + 1], v[n + 1]);
-    const __m128i tmp0_3 = GetRGBA32b(y[n + 2], u[n + 2], v[n + 2]);
-    const __m128i tmp0_4 = GetRGBA32b(y[n + 3], u[n + 3], v[n + 3]);
-    const __m128i tmp1_1 = _mm_packs_epi32(tmp0_1, tmp0_2);
-    const __m128i tmp1_2 = _mm_packs_epi32(tmp0_3, tmp0_4);
-    const __m128i tmp2 = _mm_packus_epi16(tmp1_1, tmp1_2);
-    _mm_storeu_si128((__m128i*)dst, tmp2);
-    dst += 4 * 4;
+  const __m128i kAlpha = _mm_set1_epi16(255);
+  int n;
+  for (n = 0; n < 32; n += 8, dst += 32) {
+    __m128i R, G, B;
+    YUV444ToRGB(y + n, u + n, v + n, &R, &G, &B);
+    PackAndStore4(&R, &G, &B, &kAlpha, dst);
   }
 }
 
 void VP8YuvToBgra32(const uint8_t* y, const uint8_t* u, const uint8_t* v,
                     uint8_t* dst) {
-  int n;
-  for (n = 0; n < 32; n += 2) {
-    const __m128i tmp0_1 = GetRGBA32b(y[n + 0], u[n + 0], v[n + 0]);
-    const __m128i tmp0_2 = GetRGBA32b(y[n + 1], u[n + 1], v[n + 1]);
-    const __m128i tmp1_1 = _mm_shuffle_epi32(tmp0_1, _MM_SHUFFLE(3, 0, 1, 2));
-    const __m128i tmp1_2 = _mm_shuffle_epi32(tmp0_2, _MM_SHUFFLE(3, 0, 1, 2));
-    const __m128i tmp2_1 = _mm_packs_epi32(tmp1_1, tmp1_2);
-    const __m128i tmp3 = _mm_packus_epi16(tmp2_1, tmp2_1);
-    _mm_storel_epi64((__m128i*)dst, tmp3);
-    dst += 4 * 2;
+  const __m128i kAlpha = _mm_set1_epi16(255);
+  int n;
+  for (n = 0; n < 32; n += 8, dst += 32) {
+    __m128i R, G, B;
+    YUV444ToRGB(y + n, u + n, v + n, &R, &G, &B);
+    PackAndStore4(&B, &G, &R, &kAlpha, dst);
+  }
+}
+
+void VP8YuvToArgb32(const uint8_t* y, const uint8_t* u, const uint8_t* v,
+                    uint8_t* dst) {
+  const __m128i kAlpha = _mm_set1_epi16(255);
+  int n;
+  for (n = 0; n < 32; n += 8, dst += 32) {
+    __m128i R, G, B;
+    YUV444ToRGB(y + n, u + n, v + n, &R, &G, &B);
+    PackAndStore4(&kAlpha, &R, &G, &B, dst);
+  }
+}
+
+void VP8YuvToRgba444432(const uint8_t* y, const uint8_t* u, const uint8_t* v,
+                        uint8_t* dst) {
+  const __m128i kAlpha = _mm_set1_epi16(255);
+  int n;
+  for (n = 0; n < 32; n += 8, dst += 16) {
+    __m128i R, G, B;
+    YUV444ToRGB(y + n, u + n, v + n, &R, &G, &B);
+    PackAndStore4444(&R, &G, &B, &kAlpha, dst);
+  }
+}
+
+void VP8YuvToRgb56532(const uint8_t* y, const uint8_t* u, const uint8_t* v,
+                      uint8_t* dst) {
+  int n;
+  for (n = 0; n < 32; n += 8, dst += 16) {
+    __m128i R, G, B;
+    YUV444ToRGB(y + n, u + n, v + n, &R, &G, &B);
+    PackAndStore565(&R, &G, &B, dst);
   }
 }
 
 void VP8YuvToRgb32(const uint8_t* y, const uint8_t* u, const uint8_t* v,
                    uint8_t* dst) {
-  int n;
-  uint8_t tmp0[2 * 3 + 5 + 15];
-  uint8_t* const tmp = (uint8_t*)((uintptr_t)(tmp0 + 15) & ~15);  // align
-  for (n = 0; n < 30; ++n) {   // we directly stomp the *dst memory
-    YuvToRgbSSE2(y[n], u[n], v[n], dst + n * 3);
-  }
-  // Last two pixels are special: we write in a tmp buffer before sending
-  // to dst.
-  YuvToRgbSSE2(y[n + 0], u[n + 0], v[n + 0], tmp + 0);
-  YuvToRgbSSE2(y[n + 1], u[n + 1], v[n + 1], tmp + 3);
-  memcpy(dst + n * 3, tmp, 2 * 3);
+  __m128i R0, R1, R2, R3, G0, G1, G2, G3, B0, B1, B2, B3;
+  __m128i rgb[6];
+
+  YUV444ToRGB(y +  0, u +  0, v +  0, &R0, &G0, &B0);
+  YUV444ToRGB(y +  8, u +  8, v +  8, &R1, &G1, &B1);
+  YUV444ToRGB(y + 16, u + 16, v + 16, &R2, &G2, &B2);
+  YUV444ToRGB(y + 24, u + 24, v + 24, &R3, &G3, &B3);
+
+  // Cast to 8b and store as RRRRGGGGBBBB.
+  rgb[0] = _mm_packus_epi16(R0, R1);
+  rgb[1] = _mm_packus_epi16(R2, R3);
+  rgb[2] = _mm_packus_epi16(G0, G1);
+  rgb[3] = _mm_packus_epi16(G2, G3);
+  rgb[4] = _mm_packus_epi16(B0, B1);
+  rgb[5] = _mm_packus_epi16(B2, B3);
+
+  // Pack as RGBRGBRGBRGB.
+  PlanarTo24b(rgb, dst);
 }
 
 void VP8YuvToBgr32(const uint8_t* y, const uint8_t* u, const uint8_t* v,
                    uint8_t* dst) {
-  int n;
-  uint8_t tmp0[2 * 3 + 5 + 15];
-  uint8_t* const tmp = (uint8_t*)((uintptr_t)(tmp0 + 15) & ~15);  // align
-  for (n = 0; n < 30; ++n) {
-    YuvToBgrSSE2(y[n], u[n], v[n], dst + n * 3);
-  }
-  YuvToBgrSSE2(y[n + 0], u[n + 0], v[n + 0], tmp + 0);
-  YuvToBgrSSE2(y[n + 1], u[n + 1], v[n + 1], tmp + 3);
-  memcpy(dst + n * 3, tmp, 2 * 3);
-}
-
-#endif  // FANCY_UPSAMPLING
+  __m128i R0, R1, R2, R3, G0, G1, G2, G3, B0, B1, B2, B3;
+  __m128i bgr[6];
+
+  YUV444ToRGB(y +  0, u +  0, v +  0, &R0, &G0, &B0);
+  YUV444ToRGB(y +  8, u +  8, v +  8, &R1, &G1, &B1);
+  YUV444ToRGB(y + 16, u + 16, v + 16, &R2, &G2, &B2);
+  YUV444ToRGB(y + 24, u + 24, v + 24, &R3, &G3, &B3);
+
+  // Cast to 8b and store as BBBBGGGGRRRR.
+  bgr[0] = _mm_packus_epi16(B0, B1);
+  bgr[1] = _mm_packus_epi16(B2, B3);
+  bgr[2] = _mm_packus_epi16(G0, G1);
+  bgr[3] = _mm_packus_epi16(G2, G3);
+  bgr[4] = _mm_packus_epi16(R0, R1);
+  bgr[5] = _mm_packus_epi16(R2, R3);
+
+  // Pack as BGRBGRBGRBGR.
+  PlanarTo24b(bgr, dst);
+}
 
 //-----------------------------------------------------------------------------
 // Arbitrary-length row conversion functions
 
-static void YuvToRgbaRowSSE2(const uint8_t* y,
-                             const uint8_t* u, const uint8_t* v,
-                             uint8_t* dst, int len) {
-  int n;
-  for (n = 0; n + 4 <= len; n += 4) {
-    const __m128i uv_0 = LoadUVPart(u[0], v[0]);
-    const __m128i uv_1 = LoadUVPart(u[1], v[1]);
-    const __m128i tmp0_1 = GetRGBA32bWithUV(y[0], uv_0);
-    const __m128i tmp0_2 = GetRGBA32bWithUV(y[1], uv_0);
-    const __m128i tmp0_3 = GetRGBA32bWithUV(y[2], uv_1);
-    const __m128i tmp0_4 = GetRGBA32bWithUV(y[3], uv_1);
-    const __m128i tmp1_1 = _mm_packs_epi32(tmp0_1, tmp0_2);
-    const __m128i tmp1_2 = _mm_packs_epi32(tmp0_3, tmp0_4);
-    const __m128i tmp2 = _mm_packus_epi16(tmp1_1, tmp1_2);
-    _mm_storeu_si128((__m128i*)dst, tmp2);
-    dst += 4 * 4;
-    y += 4;
-    u += 2;
-    v += 2;
-  }
-  // Finish off
-  while (n < len) {
+static void YuvToRgbaRow(const uint8_t* y, const uint8_t* u, const uint8_t* v,
+                         uint8_t* dst, int len) {
+  const __m128i kAlpha = _mm_set1_epi16(255);
+  int n;
+  for (n = 0; n + 8 <= len; n += 8, dst += 32) {
+    __m128i R, G, B;
+    YUV420ToRGB(y, u, v, &R, &G, &B);
+    PackAndStore4(&R, &G, &B, &kAlpha, dst);
+    y += 8;
+    u += 4;
+    v += 4;
+  }
+  for (; n < len; ++n) {   // Finish off
     VP8YuvToRgba(y[0], u[0], v[0], dst);
     dst += 4;
-    ++y;
+    y += 1;
     u += (n & 1);
     v += (n & 1);
-    ++n;
-  }
-}
-
-static void YuvToBgraRowSSE2(const uint8_t* y,
-                             const uint8_t* u, const uint8_t* v,
-                             uint8_t* dst, int len) {
-  int n;
-  for (n = 0; n + 2 <= len; n += 2) {
-    const __m128i uv_0 = LoadUVPart(u[0], v[0]);
-    const __m128i tmp0_1 = GetRGBA32bWithUV(y[0], uv_0);
-    const __m128i tmp0_2 = GetRGBA32bWithUV(y[1], uv_0);
-    const __m128i tmp1_1 = _mm_shuffle_epi32(tmp0_1, _MM_SHUFFLE(3, 0, 1, 2));
-    const __m128i tmp1_2 = _mm_shuffle_epi32(tmp0_2, _MM_SHUFFLE(3, 0, 1, 2));
-    const __m128i tmp2_1 = _mm_packs_epi32(tmp1_1, tmp1_2);
-    const __m128i tmp3 = _mm_packus_epi16(tmp2_1, tmp2_1);
-    _mm_storel_epi64((__m128i*)dst, tmp3);
-    dst += 4 * 2;
-    y += 2;
-    ++u;
-    ++v;
-  }
-  // Finish off
-  if (len & 1) {
+  }
+}
+
+static void YuvToBgraRow(const uint8_t* y, const uint8_t* u, const uint8_t* v,
+                         uint8_t* dst, int len) {
+  const __m128i kAlpha = _mm_set1_epi16(255);
+  int n;
+  for (n = 0; n + 8 <= len; n += 8, dst += 32) {
+    __m128i R, G, B;
+    YUV420ToRGB(y, u, v, &R, &G, &B);
+    PackAndStore4(&B, &G, &R, &kAlpha, dst);
+    y += 8;
+    u += 4;
+    v += 4;
+  }
+  for (; n < len; ++n) {   // Finish off
     VP8YuvToBgra(y[0], u[0], v[0], dst);
-  }
-}
-
-static void YuvToArgbRowSSE2(const uint8_t* y,
-                             const uint8_t* u, const uint8_t* v,
-                             uint8_t* dst, int len) {
-  int n;
-  for (n = 0; n + 2 <= len; n += 2) {
-    const __m128i uv_0 = LoadUVPart(u[0], v[0]);
-    const __m128i tmp0_1 = GetRGBA32bWithUV(y[0], uv_0);
-    const __m128i tmp0_2 = GetRGBA32bWithUV(y[1], uv_0);
-    const __m128i tmp1_1 = _mm_shuffle_epi32(tmp0_1, _MM_SHUFFLE(2, 1, 0, 3));
-    const __m128i tmp1_2 = _mm_shuffle_epi32(tmp0_2, _MM_SHUFFLE(2, 1, 0, 3));
-    const __m128i tmp2_1 = _mm_packs_epi32(tmp1_1, tmp1_2);
-    const __m128i tmp3 = _mm_packus_epi16(tmp2_1, tmp2_1);
-    _mm_storel_epi64((__m128i*)dst, tmp3);
-    dst += 4 * 2;
-    y += 2;
-    ++u;
-    ++v;
-  }
-  // Finish off
-  if (len & 1) {
-    VP8YuvToArgb(y[0], u[0], v[0], dst);
-  }
-}
-
-static void YuvToRgbRowSSE2(const uint8_t* y,
-                            const uint8_t* u, const uint8_t* v,
-                            uint8_t* dst, int len) {
-  int n;
-  for (n = 0; n + 2 < len; ++n) {   // we directly stomp the *dst memory
-    YuvToRgbSSE2(y[0], u[0], v[0], dst);  // stomps 8 bytes
-    dst += 3;
-    ++y;
+    dst += 4;
+    y += 1;
     u += (n & 1);
     v += (n & 1);
   }
-  VP8YuvToRgb(y[0], u[0], v[0], dst);
-  if (len > 1) {
-    VP8YuvToRgb(y[1], u[n & 1], v[n & 1], dst + 3);
-  }
-}
-
-static void YuvToBgrRowSSE2(const uint8_t* y,
-                            const uint8_t* u, const uint8_t* v,
-                            uint8_t* dst, int len) {
-  int n;
-  for (n = 0; n + 2 < len; ++n) {   // we directly stomp the *dst memory
-    YuvToBgrSSE2(y[0], u[0], v[0], dst);  // stomps 8 bytes
-    dst += 3;
-    ++y;
+}
+
+static void YuvToArgbRow(const uint8_t* y, const uint8_t* u, const uint8_t* v,
+                         uint8_t* dst, int len) {
+  const __m128i kAlpha = _mm_set1_epi16(255);
+  int n;
+  for (n = 0; n + 8 <= len; n += 8, dst += 32) {
+    __m128i R, G, B;
+    YUV420ToRGB(y, u, v, &R, &G, &B);
+    PackAndStore4(&kAlpha, &R, &G, &B, dst);
+    y += 8;
+    u += 4;
+    v += 4;
+  }
+  for (; n < len; ++n) {   // Finish off
+    VP8YuvToArgb(y[0], u[0], v[0], dst);
+    dst += 4;
+    y += 1;
     u += (n & 1);
     v += (n & 1);
   }
-  VP8YuvToBgr(y[0], u[0], v[0], dst + 0);
-  if (len > 1) {
-    VP8YuvToBgr(y[1], u[n & 1], v[n & 1], dst + 3);
-  }
-}
-
-#endif  // WEBP_USE_SSE2
+}
+
+static void YuvToRgbRow(const uint8_t* y, const uint8_t* u, const uint8_t* v,
+                        uint8_t* dst, int len) {
+  int n;
+  for (n = 0; n + 32 <= len; n += 32, dst += 32 * 3) {
+    __m128i R0, R1, R2, R3, G0, G1, G2, G3, B0, B1, B2, B3;
+    __m128i rgb[6];
+
+    YUV420ToRGB(y +  0, u +  0, v +  0, &R0, &G0, &B0);
+    YUV420ToRGB(y +  8, u +  4, v +  4, &R1, &G1, &B1);
+    YUV420ToRGB(y + 16, u +  8, v +  8, &R2, &G2, &B2);
+    YUV420ToRGB(y + 24, u + 12, v + 12, &R3, &G3, &B3);
+
+    // Cast to 8b and store as RRRRGGGGBBBB.
+    rgb[0] = _mm_packus_epi16(R0, R1);
+    rgb[1] = _mm_packus_epi16(R2, R3);
+    rgb[2] = _mm_packus_epi16(G0, G1);
+    rgb[3] = _mm_packus_epi16(G2, G3);
+    rgb[4] = _mm_packus_epi16(B0, B1);
+    rgb[5] = _mm_packus_epi16(B2, B3);
+
+    // Pack as RGBRGBRGBRGB.
+    PlanarTo24b(rgb, dst);
+
+    y += 32;
+    u += 16;
+    v += 16;
+  }
+  for (; n < len; ++n) {   // Finish off
+    VP8YuvToRgb(y[0], u[0], v[0], dst);
+    dst += 3;
+    y += 1;
+    u += (n & 1);
+    v += (n & 1);
+  }
+}
+
+static void YuvToBgrRow(const uint8_t* y, const uint8_t* u, const uint8_t* v,
+                        uint8_t* dst, int len) {
+  int n;
+  for (n = 0; n + 32 <= len; n += 32, dst += 32 * 3) {
+    __m128i R0, R1, R2, R3, G0, G1, G2, G3, B0, B1, B2, B3;
+    __m128i bgr[6];
+
+    YUV420ToRGB(y +  0, u +  0, v +  0, &R0, &G0, &B0);
+    YUV420ToRGB(y +  8, u +  4, v +  4, &R1, &G1, &B1);
+    YUV420ToRGB(y + 16, u +  8, v +  8, &R2, &G2, &B2);
+    YUV420ToRGB(y + 24, u + 12, v + 12, &R3, &G3, &B3);
+
+    // Cast to 8b and store as BBBBGGGGRRRR.
+    bgr[0] = _mm_packus_epi16(B0, B1);
+    bgr[1] = _mm_packus_epi16(B2, B3);
+    bgr[2] = _mm_packus_epi16(G0, G1);
+    bgr[3] = _mm_packus_epi16(G2, G3);
+    bgr[4] = _mm_packus_epi16(R0, R1);
+    bgr[5] = _mm_packus_epi16(R2, R3);
+
+    // Pack as BGRBGRBGRBGR.
+    PlanarTo24b(bgr, dst);
+
+    y += 32;
+    u += 16;
+    v += 16;
+  }
+  for (; n < len; ++n) {   // Finish off
+    VP8YuvToBgr(y[0], u[0], v[0], dst);
+    dst += 3;
+    y += 1;
+    u += (n & 1);
+    v += (n & 1);
+  }
+}
 
 //------------------------------------------------------------------------------
 // Entry point
 
 extern void WebPInitSamplersSSE2(void);
 
-void WebPInitSamplersSSE2(void) {
-#if defined(WEBP_USE_SSE2)
-  WebPSamplers[MODE_RGB]  = YuvToRgbRowSSE2;
-  WebPSamplers[MODE_RGBA] = YuvToRgbaRowSSE2;
-  WebPSamplers[MODE_BGR]  = YuvToBgrRowSSE2;
-  WebPSamplers[MODE_BGRA] = YuvToBgraRowSSE2;
-  WebPSamplers[MODE_ARGB] = YuvToArgbRowSSE2;
+WEBP_TSAN_IGNORE_FUNCTION void WebPInitSamplersSSE2(void) {
+  WebPSamplers[MODE_RGB]  = YuvToRgbRow;
+  WebPSamplers[MODE_RGBA] = YuvToRgbaRow;
+  WebPSamplers[MODE_BGR]  = YuvToBgrRow;
+  WebPSamplers[MODE_BGRA] = YuvToBgraRow;
+  WebPSamplers[MODE_ARGB] = YuvToArgbRow;
+}
+
+//------------------------------------------------------------------------------
+// RGB24/32 -> YUV converters
+
+// Load eight 16b-words from *src.
+#define LOAD_16(src) _mm_loadu_si128((const __m128i*)(src))
+// Store either 16b-words into *dst
+#define STORE_16(V, dst) _mm_storeu_si128((__m128i*)(dst), (V))
+
+// Function that inserts a value of the second half of the in buffer in between
+// every two char of the first half.
+static WEBP_INLINE void RGB24PackedToPlanarHelper(
+    const __m128i* const in /*in[6]*/, __m128i* const out /*out[6]*/) {
+  out[0] = _mm_unpacklo_epi8(in[0], in[3]);
+  out[1] = _mm_unpackhi_epi8(in[0], in[3]);
+  out[2] = _mm_unpacklo_epi8(in[1], in[4]);
+  out[3] = _mm_unpackhi_epi8(in[1], in[4]);
+  out[4] = _mm_unpacklo_epi8(in[2], in[5]);
+  out[5] = _mm_unpackhi_epi8(in[2], in[5]);
+}
+
+// Unpack the 8b input rgbrgbrgbrgb ... as contiguous registers:
+// rrrr... rrrr... gggg... gggg... bbbb... bbbb....
+// Similar to PlanarTo24bHelper(), but in reverse order.
+static WEBP_INLINE void RGB24PackedToPlanar(const uint8_t* const rgb,
+                                            __m128i* const out /*out[6]*/) {
+  __m128i tmp[6];
+  tmp[0] = _mm_loadu_si128((const __m128i*)(rgb +  0));
+  tmp[1] = _mm_loadu_si128((const __m128i*)(rgb + 16));
+  tmp[2] = _mm_loadu_si128((const __m128i*)(rgb + 32));
+  tmp[3] = _mm_loadu_si128((const __m128i*)(rgb + 48));
+  tmp[4] = _mm_loadu_si128((const __m128i*)(rgb + 64));
+  tmp[5] = _mm_loadu_si128((const __m128i*)(rgb + 80));
+
+  RGB24PackedToPlanarHelper(tmp, out);
+  RGB24PackedToPlanarHelper(out, tmp);
+  RGB24PackedToPlanarHelper(tmp, out);
+  RGB24PackedToPlanarHelper(out, tmp);
+  RGB24PackedToPlanarHelper(tmp, out);
+}
+
+// Convert 8 packed ARGB to r[], g[], b[]
+static WEBP_INLINE void RGB32PackedToPlanar(const uint32_t* const argb,
+                                            __m128i* const r,
+                                            __m128i* const g,
+                                            __m128i* const b) {
+  const __m128i zero = _mm_setzero_si128();
+  const __m128i in0 = LOAD_16(argb + 0);    // argb3 | argb2 | argb1 | argb0
+  const __m128i in1 = LOAD_16(argb + 4);    // argb7 | argb6 | argb5 | argb4
+  // column-wise transpose
+  const __m128i A0 = _mm_unpacklo_epi8(in0, in1);
+  const __m128i A1 = _mm_unpackhi_epi8(in0, in1);
+  const __m128i B0 = _mm_unpacklo_epi8(A0, A1);
+  const __m128i B1 = _mm_unpackhi_epi8(A0, A1);
+  // C0 = g7 g6 ... g1 g0 | b7 b6 ... b1 b0
+  // C1 = a7 a6 ... a1 a0 | r7 r6 ... r1 r0
+  const __m128i C0 = _mm_unpacklo_epi8(B0, B1);
+  const __m128i C1 = _mm_unpackhi_epi8(B0, B1);
+  // store 16b
+  *r = _mm_unpacklo_epi8(C1, zero);
+  *g = _mm_unpackhi_epi8(C0, zero);
+  *b = _mm_unpacklo_epi8(C0, zero);
+}
+
+// This macro computes (RG * MULT_RG + GB * MULT_GB + ROUNDER) >> DESCALE_FIX
+// It's a macro and not a function because we need to use immediate values with
+// srai_epi32, e.g.
+#define TRANSFORM(RG_LO, RG_HI, GB_LO, GB_HI, MULT_RG, MULT_GB, \
+                  ROUNDER, DESCALE_FIX, OUT) do {               \
+  const __m128i V0_lo = _mm_madd_epi16(RG_LO, MULT_RG);         \
+  const __m128i V0_hi = _mm_madd_epi16(RG_HI, MULT_RG);         \
+  const __m128i V1_lo = _mm_madd_epi16(GB_LO, MULT_GB);         \
+  const __m128i V1_hi = _mm_madd_epi16(GB_HI, MULT_GB);         \
+  const __m128i V2_lo = _mm_add_epi32(V0_lo, V1_lo);            \
+  const __m128i V2_hi = _mm_add_epi32(V0_hi, V1_hi);            \
+  const __m128i V3_lo = _mm_add_epi32(V2_lo, ROUNDER);          \
+  const __m128i V3_hi = _mm_add_epi32(V2_hi, ROUNDER);          \
+  const __m128i V5_lo = _mm_srai_epi32(V3_lo, DESCALE_FIX);     \
+  const __m128i V5_hi = _mm_srai_epi32(V3_hi, DESCALE_FIX);     \
+  (OUT) = _mm_packs_epi32(V5_lo, V5_hi);                        \
+} while (0)
+
+#define MK_CST_16(A, B) _mm_set_epi16((B), (A), (B), (A), (B), (A), (B), (A))
+static WEBP_INLINE void ConvertRGBToY(const __m128i* const R,
+                                      const __m128i* const G,
+                                      const __m128i* const B,
+                                      __m128i* const Y) {
+  const __m128i kRG_y = MK_CST_16(16839, 33059 - 16384);
+  const __m128i kGB_y = MK_CST_16(16384, 6420);
+  const __m128i kHALF_Y = _mm_set1_epi32((16 << YUV_FIX) + YUV_HALF);
+
+  const __m128i RG_lo = _mm_unpacklo_epi16(*R, *G);
+  const __m128i RG_hi = _mm_unpackhi_epi16(*R, *G);
+  const __m128i GB_lo = _mm_unpacklo_epi16(*G, *B);
+  const __m128i GB_hi = _mm_unpackhi_epi16(*G, *B);
+  TRANSFORM(RG_lo, RG_hi, GB_lo, GB_hi, kRG_y, kGB_y, kHALF_Y, YUV_FIX, *Y);
+}
+
+static WEBP_INLINE void ConvertRGBToUV(const __m128i* const R,
+                                       const __m128i* const G,
+                                       const __m128i* const B,
+                                       __m128i* const U, __m128i* const V) {
+  const __m128i kRG_u = MK_CST_16(-9719, -19081);
+  const __m128i kGB_u = MK_CST_16(0, 28800);
+  const __m128i kRG_v = MK_CST_16(28800, 0);
+  const __m128i kGB_v = MK_CST_16(-24116, -4684);
+  const __m128i kHALF_UV = _mm_set1_epi32(((128 << YUV_FIX) + YUV_HALF) << 2);
+
+  const __m128i RG_lo = _mm_unpacklo_epi16(*R, *G);
+  const __m128i RG_hi = _mm_unpackhi_epi16(*R, *G);
+  const __m128i GB_lo = _mm_unpacklo_epi16(*G, *B);
+  const __m128i GB_hi = _mm_unpackhi_epi16(*G, *B);
+  TRANSFORM(RG_lo, RG_hi, GB_lo, GB_hi, kRG_u, kGB_u,
+            kHALF_UV, YUV_FIX + 2, *U);
+  TRANSFORM(RG_lo, RG_hi, GB_lo, GB_hi, kRG_v, kGB_v,
+            kHALF_UV, YUV_FIX + 2, *V);
+}
+
+#undef MK_CST_16
+#undef TRANSFORM
+
+static void ConvertRGB24ToY(const uint8_t* rgb, uint8_t* y, int width) {
+  const int max_width = width & ~31;
+  int i;
+  for (i = 0; i < max_width; rgb += 3 * 16 * 2) {
+    __m128i rgb_plane[6];
+    int j;
+
+    RGB24PackedToPlanar(rgb, rgb_plane);
+
+    for (j = 0; j < 2; ++j, i += 16) {
+      const __m128i zero = _mm_setzero_si128();
+      __m128i r, g, b, Y0, Y1;
+
+      // Convert to 16-bit Y.
+      r = _mm_unpacklo_epi8(rgb_plane[0 + j], zero);
+      g = _mm_unpacklo_epi8(rgb_plane[2 + j], zero);
+      b = _mm_unpacklo_epi8(rgb_plane[4 + j], zero);
+      ConvertRGBToY(&r, &g, &b, &Y0);
+
+      // Convert to 16-bit Y.
+      r = _mm_unpackhi_epi8(rgb_plane[0 + j], zero);
+      g = _mm_unpackhi_epi8(rgb_plane[2 + j], zero);
+      b = _mm_unpackhi_epi8(rgb_plane[4 + j], zero);
+      ConvertRGBToY(&r, &g, &b, &Y1);
+
+      // Cast to 8-bit and store.
+      STORE_16(_mm_packus_epi16(Y0, Y1), y + i);
+    }
+  }
+  for (; i < width; ++i, rgb += 3) {   // left-over
+    y[i] = VP8RGBToY(rgb[0], rgb[1], rgb[2], YUV_HALF);
+  }
+}
+
+static void ConvertBGR24ToY(const uint8_t* bgr, uint8_t* y, int width) {
+  const int max_width = width & ~31;
+  int i;
+  for (i = 0; i < max_width; bgr += 3 * 16 * 2) {
+    __m128i bgr_plane[6];
+    int j;
+
+    RGB24PackedToPlanar(bgr, bgr_plane);
+
+    for (j = 0; j < 2; ++j, i += 16) {
+      const __m128i zero = _mm_setzero_si128();
+      __m128i r, g, b, Y0, Y1;
+
+      // Convert to 16-bit Y.
+      b = _mm_unpacklo_epi8(bgr_plane[0 + j], zero);
+      g = _mm_unpacklo_epi8(bgr_plane[2 + j], zero);
+      r = _mm_unpacklo_epi8(bgr_plane[4 + j], zero);
+      ConvertRGBToY(&r, &g, &b, &Y0);
+
+      // Convert to 16-bit Y.
+      b = _mm_unpackhi_epi8(bgr_plane[0 + j], zero);
+      g = _mm_unpackhi_epi8(bgr_plane[2 + j], zero);
+      r = _mm_unpackhi_epi8(bgr_plane[4 + j], zero);
+      ConvertRGBToY(&r, &g, &b, &Y1);
+
+      // Cast to 8-bit and store.
+      STORE_16(_mm_packus_epi16(Y0, Y1), y + i);
+    }
+  }
+  for (; i < width; ++i, bgr += 3) {  // left-over
+    y[i] = VP8RGBToY(bgr[2], bgr[1], bgr[0], YUV_HALF);
+  }
+}
+
+static void ConvertARGBToY(const uint32_t* argb, uint8_t* y, int width) {
+  const int max_width = width & ~15;
+  int i;
+  for (i = 0; i < max_width; i += 16) {
+    __m128i r, g, b, Y0, Y1;
+    RGB32PackedToPlanar(&argb[i + 0], &r, &g, &b);
+    ConvertRGBToY(&r, &g, &b, &Y0);
+    RGB32PackedToPlanar(&argb[i + 8], &r, &g, &b);
+    ConvertRGBToY(&r, &g, &b, &Y1);
+    STORE_16(_mm_packus_epi16(Y0, Y1), y + i);
+  }
+  for (; i < width; ++i) {   // left-over
+    const uint32_t p = argb[i];
+    y[i] = VP8RGBToY((p >> 16) & 0xff, (p >> 8) & 0xff, (p >>  0) & 0xff,
+                     YUV_HALF);
+  }
+}
+
+// Horizontal add (doubled) of two 16b values, result is 16b.
+// in: A | B | C | D | ... -> out: 2*(A+B) | 2*(C+D) | ...
+static void HorizontalAddPack(const __m128i* const A, const __m128i* const B,
+                              __m128i* const out) {
+  const __m128i k2 = _mm_set1_epi16(2);
+  const __m128i C = _mm_madd_epi16(*A, k2);
+  const __m128i D = _mm_madd_epi16(*B, k2);
+  *out = _mm_packs_epi32(C, D);
+}
+
+static void ConvertARGBToUV(const uint32_t* argb, uint8_t* u, uint8_t* v,
+                            int src_width, int do_store) {
+  const int max_width = src_width & ~31;
+  int i;
+  for (i = 0; i < max_width; i += 32, u += 16, v += 16) {
+    __m128i r0, g0, b0, r1, g1, b1, U0, V0, U1, V1;
+    RGB32PackedToPlanar(&argb[i +  0], &r0, &g0, &b0);
+    RGB32PackedToPlanar(&argb[i +  8], &r1, &g1, &b1);
+    HorizontalAddPack(&r0, &r1, &r0);
+    HorizontalAddPack(&g0, &g1, &g0);
+    HorizontalAddPack(&b0, &b1, &b0);
+    ConvertRGBToUV(&r0, &g0, &b0, &U0, &V0);
+
+    RGB32PackedToPlanar(&argb[i + 16], &r0, &g0, &b0);
+    RGB32PackedToPlanar(&argb[i + 24], &r1, &g1, &b1);
+    HorizontalAddPack(&r0, &r1, &r0);
+    HorizontalAddPack(&g0, &g1, &g0);
+    HorizontalAddPack(&b0, &b1, &b0);
+    ConvertRGBToUV(&r0, &g0, &b0, &U1, &V1);
+
+    U0 = _mm_packus_epi16(U0, U1);
+    V0 = _mm_packus_epi16(V0, V1);
+    if (!do_store) {
+      const __m128i prev_u = LOAD_16(u);
+      const __m128i prev_v = LOAD_16(v);
+      U0 = _mm_avg_epu8(U0, prev_u);
+      V0 = _mm_avg_epu8(V0, prev_v);
+    }
+    STORE_16(U0, u);
+    STORE_16(V0, v);
+  }
+  if (i < src_width) {  // left-over
+    WebPConvertARGBToUV_C(argb + i, u, v, src_width - i, do_store);
+  }
+}
+
+// Convert 16 packed ARGB 16b-values to r[], g[], b[]
+static WEBP_INLINE void RGBA32PackedToPlanar_16b(const uint16_t* const rgbx,
+                                                 __m128i* const r,
+                                                 __m128i* const g,
+                                                 __m128i* const b) {
+  const __m128i in0 = LOAD_16(rgbx +  0);  // r0 | g0 | b0 |x| r1 | g1 | b1 |x
+  const __m128i in1 = LOAD_16(rgbx +  8);  // r2 | g2 | b2 |x| r3 | g3 | b3 |x
+  const __m128i in2 = LOAD_16(rgbx + 16);  // r4 | ...
+  const __m128i in3 = LOAD_16(rgbx + 24);  // r6 | ...
+  // column-wise transpose
+  const __m128i A0 = _mm_unpacklo_epi16(in0, in1);
+  const __m128i A1 = _mm_unpackhi_epi16(in0, in1);
+  const __m128i A2 = _mm_unpacklo_epi16(in2, in3);
+  const __m128i A3 = _mm_unpackhi_epi16(in2, in3);
+  const __m128i B0 = _mm_unpacklo_epi16(A0, A1);  // r0 r1 r2 r3 | g0 g1 ..
+  const __m128i B1 = _mm_unpackhi_epi16(A0, A1);  // b0 b1 b2 b3 | x x x x
+  const __m128i B2 = _mm_unpacklo_epi16(A2, A3);  // r4 r5 r6 r7 | g4 g5 ..
+  const __m128i B3 = _mm_unpackhi_epi16(A2, A3);  // b4 b5 b6 b7 | x x x x
+  *r = _mm_unpacklo_epi64(B0, B2);
+  *g = _mm_unpackhi_epi64(B0, B2);
+  *b = _mm_unpacklo_epi64(B1, B3);
+}
+
+static void ConvertRGBA32ToUV(const uint16_t* rgb,
+                              uint8_t* u, uint8_t* v, int width) {
+  const int max_width = width & ~15;
+  const uint16_t* const last_rgb = rgb + 4 * max_width;
+  while (rgb < last_rgb) {
+    __m128i r, g, b, U0, V0, U1, V1;
+    RGBA32PackedToPlanar_16b(rgb +  0, &r, &g, &b);
+    ConvertRGBToUV(&r, &g, &b, &U0, &V0);
+    RGBA32PackedToPlanar_16b(rgb + 32, &r, &g, &b);
+    ConvertRGBToUV(&r, &g, &b, &U1, &V1);
+    STORE_16(_mm_packus_epi16(U0, U1), u);
+    STORE_16(_mm_packus_epi16(V0, V1), v);
+    u += 16;
+    v += 16;
+    rgb += 2 * 32;
+  }
+  if (max_width < width) {  // left-over
+    WebPConvertRGBA32ToUV_C(rgb, u, v, width - max_width);
+  }
+}
+
+//------------------------------------------------------------------------------
+
+extern void WebPInitConvertARGBToYUVSSE2(void);
+
+WEBP_TSAN_IGNORE_FUNCTION void WebPInitConvertARGBToYUVSSE2(void) {
+  WebPConvertARGBToY = ConvertARGBToY;
+  WebPConvertARGBToUV = ConvertARGBToUV;
+
+  WebPConvertRGB24ToY = ConvertRGB24ToY;
+  WebPConvertBGR24ToY = ConvertBGR24ToY;
+
+  WebPConvertRGBA32ToUV = ConvertRGBA32ToUV;
+}
+
+#else  // !WEBP_USE_SSE2
+
+WEBP_DSP_INIT_STUB(WebPInitSamplersSSE2)
+WEBP_DSP_INIT_STUB(WebPInitConvertARGBToYUVSSE2)
+
 #endif  // WEBP_USE_SSE2
-}