Optimize mipmap downsample_2_2 in sRGB mode

Reland of:
https://skia-review.googlesource.com/c/9386/

Desktop (HP z620)
Before:
mipmap_build_2048x2048_0_gamma 10.5 ms
mipmap_build_2048x2048_1_gamma 77.1 ms
After:
mipmap_build_2048x2048_0_gamma 10.5 ms
mipmap_build_2048x2048_1_gamma 41.0 ms

Pixel XL
Before:
mipmap_build_2048x2048_0_gamma 160 ms
mipmap_build_2048x2048_1_gamma 1.5 s
After:
mipmap_build_2048x2048_0_gamma 160 ms
mipmap_build_2048x2048_1_gamma 570 ms

Also provides marginal performance improvements
for other sRGB downsamples.

CQ_INCLUDE_TRYBOTS=skia.primary:Test-Ubuntu-GCC-ShuttleA-GPU-GTX550Ti-x86_64-Release-Valgrind_PreAbandonGpuContext

BUG=skia:

Change-Id: Ia82fc2ef795e1bb63a4a9deac5e38f5fde39f651
Reviewed-on: https://skia-review.googlesource.com/9455
Reviewed-by: Matt Sarett <msarett@google.com>

4 files changed, 338 insertions, 6 deletions

diff --git a/bench/MipMapBench.cpp b/bench/MipMapBench.cpp
index bffae4292d..1ffd624fee 100644
--- a/bench/MipMapBench.cpp
+++ b/bench/MipMapBench.cpp
@@ -65,3 +65,6 @@ DEF_BENCH( return new MipMapBench(511, 511,
                                   SkDestinationSurfaceColorMode::kGammaAndColorSpaceAware); )
 DEF_BENCH( return new MipMapBench(512, 512, SkDestinationSurfaceColorMode::kLegacy, true); )
 DEF_BENCH( return new MipMapBench(511, 511, SkDestinationSurfaceColorMode::kLegacy, true); )
+DEF_BENCH( return new MipMapBench(2048, 2048, SkDestinationSurfaceColorMode::kLegacy); )
+DEF_BENCH( return new MipMapBench(2048, 2048,
+                                  SkDestinationSurfaceColorMode::kGammaAndColorSpaceAware); )
diff --git a/src/core/SkMipMap.cpp b/src/core/SkMipMap.cpp
index 987949fea0..7a6897e1d9 100644
--- a/src/core/SkMipMap.cpp
+++ b/src/core/SkMipMap.cpp
@@ -12,6 +12,7 @@
 #include "SkMathPriv.h"
 #include "SkNx.h"
 #include "SkPM4fPriv.h"
+#include "SkSRGB.h"
 #include "SkTypes.h"
 
 //
@@ -35,11 +36,17 @@ struct ColorTypeFilter_8888 {
 
 struct ColorTypeFilter_S32 {
     typedef uint32_t Type;
-    static Sk4f Expand(uint32_t x) {
-        return Sk4f_fromS32(x);
+    static Sk4h Expand(uint32_t x) {
+        return Sk4h(sk_linear12_from_srgb[(x      ) & 0xFF],
+                    sk_linear12_from_srgb[(x >>  8) & 0xFF],
+                    sk_linear12_from_srgb[(x >> 16) & 0xFF],
+                                          (x >> 24) <<   4);
     }
-    static uint32_t Compact(const Sk4f& x) {
-        return Sk4f_toS32(x);
+    static uint32_t Compact(const Sk4h& x) {
+        return sk_linear12_to_srgb[x[0]]       |
+               sk_linear12_to_srgb[x[1]] <<  8 |
+               sk_linear12_to_srgb[x[2]] << 16 |
+               (x[3] >> 4)               << 24;
     }
 };
 
@@ -286,6 +293,77 @@ template <typename F> void downsample_3_3(void* dst, const void* src, size_t src
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
+// Some sRGB specific performance optimizations.
+
+void downsample_2_2_srgb(void* dst, const void* src, size_t srcRB, int count) {
+    const uint8_t* p0 = ((const uint8_t*) src);
+    const uint8_t* p1 = ((const uint8_t*) src) + srcRB;
+    uint8_t* d = (uint8_t*) dst;
+
+    // Given pixels:
+    // a0 b0 c0 d0 ...
+    // a1 b1 c1 d1 ...
+    // We want:
+    // (a0 + b0 + a1 + b1) / 4
+    // (c0 + d0 + c1 + d1) / 4
+    // ...
+    while (count >= 2) {
+        Sk8h a0c0 = Sk8h(sk_linear12_from_srgb[p0[ 0]],
+                         sk_linear12_from_srgb[p0[ 1]],
+                         sk_linear12_from_srgb[p0[ 2]],
+                         p0[ 3] << 4                  ,
+                         sk_linear12_from_srgb[p0[ 8]],
+                         sk_linear12_from_srgb[p0[ 9]],
+                         sk_linear12_from_srgb[p0[10]],
+                         p0[11] << 4               );
+        Sk8h b0d0 = Sk8h(sk_linear12_from_srgb[p0[ 4]],
+                         sk_linear12_from_srgb[p0[ 5]],
+                         sk_linear12_from_srgb[p0[ 6]],
+                         p0[ 7] << 4                  ,
+                         sk_linear12_from_srgb[p0[12]],
+                         sk_linear12_from_srgb[p0[13]],
+                         sk_linear12_from_srgb[p0[14]],
+                         p0[15] << 4                 );
+        Sk8h a1c1 = Sk8h(sk_linear12_from_srgb[p1[ 0]],
+                         sk_linear12_from_srgb[p1[ 1]],
+                         sk_linear12_from_srgb[p1[ 2]],
+                         p1[ 3] << 4                  ,
+                         sk_linear12_from_srgb[p1[ 8]],
+                         sk_linear12_from_srgb[p1[ 9]],
+                         sk_linear12_from_srgb[p1[10]],
+                         p1[11] << 4                 );
+        Sk8h b1d1 = Sk8h(sk_linear12_from_srgb[p1[ 4]],
+                         sk_linear12_from_srgb[p1[ 5]],
+                         sk_linear12_from_srgb[p1[ 6]],
+                         p1[ 7] << 4                  ,
+                         sk_linear12_from_srgb[p1[12]],
+                         sk_linear12_from_srgb[p1[13]],
+                         sk_linear12_from_srgb[p1[14]],
+                         p1[15] << 4                 );
+
+        Sk8h avg = (a0c0 + b0d0 + a1c1 + b1d1) >> 2;
+        d[0] = sk_linear12_to_srgb[avg[0]];
+        d[1] = sk_linear12_to_srgb[avg[1]];
+        d[2] = sk_linear12_to_srgb[avg[2]];
+        d[3] = avg[3] >> 4;
+        d[4] = sk_linear12_to_srgb[avg[4]];
+        d[5] = sk_linear12_to_srgb[avg[5]];
+        d[6] = sk_linear12_to_srgb[avg[6]];
+        d[7] = avg[7] >> 4;
+
+        p0 += 16;
+        p1 += 16;
+        d += 8;
+        count -= 2;
+    }
+
+    if (count) {
+        downsample_2_2<ColorTypeFilter_S32>(d, p0, srcRB, count);
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
 size_t SkMipMap::AllocLevelsSize(int levelCount, size_t pixelSize) {
     if (levelCount < 0) {
         return 0;
@@ -322,7 +400,7 @@ SkMipMap* SkMipMap::Build(const SkPixmap& src, SkDestinationSurfaceColorMode col
                 proc_1_2 = downsample_1_2<ColorTypeFilter_S32>;
                 proc_1_3 = downsample_1_3<ColorTypeFilter_S32>;
                 proc_2_1 = downsample_2_1<ColorTypeFilter_S32>;
-                proc_2_2 = downsample_2_2<ColorTypeFilter_S32>;
+                proc_2_2 = downsample_2_2_srgb;
                 proc_2_3 = downsample_2_3<ColorTypeFilter_S32>;
                 proc_3_1 = downsample_3_1<ColorTypeFilter_S32>;
                 proc_3_2 = downsample_3_2<ColorTypeFilter_S32>;
diff --git a/src/core/SkSRGB.cpp b/src/core/SkSRGB.cpp
index 57d2ae0373..327c7d809d 100644
--- a/src/core/SkSRGB.cpp
+++ b/src/core/SkSRGB.cpp
@@ -73,3 +73,252 @@ const float sk_linear_from_srgb[256] = {
         0.938685728457888000f, 0.947306536733200000f, 0.955973353249286000f, 0.964686247894465000f,
         0.973445290398413000f, 0.982250550333117000f, 0.991102097113830000f, 1.000000000000000000f,
 };
+
+/*
+ * Converts sRGB encoded bytes to a 12-bit linear representation.
+ */
+const uint16_t sk_linear12_from_srgb[256] = {
+        0, 1, 2, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15, 16, 18, 20, 21, 23, 25, 27, 29, 31, 33, 35, 37,
+        40, 42, 45, 48, 50, 53, 56, 59, 62, 66, 69, 72, 76, 79, 83, 87, 91, 95, 99, 103, 107, 112,
+        116, 121, 126, 131, 136, 141, 146, 151, 156, 162, 168, 173, 179, 185, 191, 197, 204, 210,
+        216, 223, 230, 237, 244, 251, 258, 265, 273, 280, 288, 296, 304, 312, 320, 329, 337, 346,
+        354, 363, 372, 381, 390, 400, 409, 419, 428, 438, 448, 458, 469, 479, 490, 500, 511, 522,
+        533, 544, 555, 567, 578, 590, 602, 614, 626, 639, 651, 664, 676, 689, 702, 715, 728, 742,
+        755, 769, 783, 797, 811, 825, 840, 854, 869, 884, 899, 914, 929, 945, 960, 976, 992, 1008,
+        1024, 1041, 1057, 1074, 1091, 1108, 1125, 1142, 1159, 1177, 1195, 1213, 1231, 1249, 1267,
+        1286, 1304, 1323, 1342, 1361, 1381, 1400, 1420, 1440, 1459, 1480, 1500, 1520, 1541, 1562,
+        1582, 1603, 1625, 1646, 1668, 1689, 1711, 1733, 1755, 1778, 1800, 1823, 1846, 1869, 1892,
+        1916, 1939, 1963, 1987, 2011, 2035, 2059, 2084, 2109, 2133, 2159, 2184, 2209, 2235, 2260,
+        2286, 2312, 2339, 2365, 2392, 2419, 2446, 2473, 2500, 2527, 2555, 2583, 2611, 2639, 2668,
+        2696, 2725, 2754, 2783, 2812, 2841, 2871, 2901, 2931, 2961, 2991, 3022, 3052, 3083, 3114,
+        3146, 3177, 3209, 3240, 3272, 3304, 3337, 3369, 3402, 3435, 3468, 3501, 3535, 3568, 3602,
+        3636, 3670, 3705, 3739, 3774, 3809, 3844, 3879, 3915, 3950, 3986, 4022, 4059, 4095,
+};
+
+/*
+ * Converts 12-bit linear to sRGB encoded bytes.
+ */
+const uint8_t sk_linear12_to_srgb[4096] = {
+        0, 1, 2, 2, 3, 4, 5, 6, 6, 7, 8, 9, 10, 10, 11, 12, 13, 13, 14, 15, 15, 16, 16, 17, 18, 18,
+        19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 23, 24, 24, 25, 25, 25, 26, 26, 27, 27, 27, 28, 28,
+        29, 29, 29, 30, 30, 30, 31, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34, 34, 34, 35, 35, 35, 36,
+        36, 36, 37, 37, 37, 37, 38, 38, 38, 38, 39, 39, 39, 40, 40, 40, 40, 41, 41, 41, 41, 42, 42,
+        42, 42, 43, 43, 43, 43, 43, 44, 44, 44, 44, 45, 45, 45, 45, 46, 46, 46, 46, 46, 47, 47, 47,
+        47, 48, 48, 48, 48, 48, 49, 49, 49, 49, 49, 50, 50, 50, 50, 50, 51, 51, 51, 51, 51, 52, 52,
+        52, 52, 52, 53, 53, 53, 53, 53, 54, 54, 54, 54, 54, 55, 55, 55, 55, 55, 55, 56, 56, 56, 56,
+        56, 57, 57, 57, 57, 57, 57, 58, 58, 58, 58, 58, 58, 59, 59, 59, 59, 59, 59, 60, 60, 60, 60,
+        60, 60, 61, 61, 61, 61, 61, 61, 62, 62, 62, 62, 62, 62, 63, 63, 63, 63, 63, 63, 64, 64, 64,
+        64, 64, 64, 64, 65, 65, 65, 65, 65, 65, 66, 66, 66, 66, 66, 66, 66, 67, 67, 67, 67, 67, 67,
+        67, 68, 68, 68, 68, 68, 68, 68, 69, 69, 69, 69, 69, 69, 69, 70, 70, 70, 70, 70, 70, 70, 71,
+        71, 71, 71, 71, 71, 71, 72, 72, 72, 72, 72, 72, 72, 72, 73, 73, 73, 73, 73, 73, 73, 74, 74,
+        74, 74, 74, 74, 74, 74, 75, 75, 75, 75, 75, 75, 75, 75, 76, 76, 76, 76, 76, 76, 76, 77, 77,
+        77, 77, 77, 77, 77, 77, 78, 78, 78, 78, 78, 78, 78, 78, 78, 79, 79, 79, 79, 79, 79, 79, 79,
+        80, 80, 80, 80, 80, 80, 80, 80, 81, 81, 81, 81, 81, 81, 81, 81, 81, 82, 82, 82, 82, 82, 82,
+        82, 82, 83, 83, 83, 83, 83, 83, 83, 83, 83, 84, 84, 84, 84, 84, 84, 84, 84, 84, 85, 85, 85,
+        85, 85, 85, 85, 85, 85, 86, 86, 86, 86, 86, 86, 86, 86, 86, 87, 87, 87, 87, 87, 87, 87, 87,
+        87, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 89, 89, 89, 89, 89, 89, 89, 89, 89, 90, 90, 90,
+        90, 90, 90, 90, 90, 90, 90, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 92, 92, 92, 92, 92, 92,
+        92, 92, 92, 92, 93, 93, 93, 93, 93, 93, 93, 93, 93, 93, 94, 94, 94, 94, 94, 94, 94, 94, 94,
+        94, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 97,
+        97, 97, 97, 97, 97, 97, 97, 97, 97, 98, 98, 98, 98, 98, 98, 98, 98, 98, 98, 98, 99, 99, 99,
+        99, 99, 99, 99, 99, 99, 99, 99, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 101,
+        101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 102, 102, 102, 102, 102, 102, 102, 102,
+        102, 102, 102, 103, 103, 103, 103, 103, 103, 103, 103, 103, 103, 103, 103, 104, 104, 104,
+        104, 104, 104, 104, 104, 104, 104, 104, 105, 105, 105, 105, 105, 105, 105, 105, 105, 105,
+        105, 105, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 107, 107, 107, 107,
+        107, 107, 107, 107, 107, 107, 107, 107, 108, 108, 108, 108, 108, 108, 108, 108, 108, 108,
+        108, 108, 109, 109, 109, 109, 109, 109, 109, 109, 109, 109, 109, 109, 110, 110, 110, 110,
+        110, 110, 110, 110, 110, 110, 110, 110, 111, 111, 111, 111, 111, 111, 111, 111, 111, 111,
+        111, 111, 111, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 113, 113, 113,
+        113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 114, 114, 114, 114, 114, 114, 114, 114,
+        114, 114, 114, 114, 114, 115, 115, 115, 115, 115, 115, 115, 115, 115, 115, 115, 115, 115,
+        116, 116, 116, 116, 116, 116, 116, 116, 116, 116, 116, 116, 116, 117, 117, 117, 117, 117,
+        117, 117, 117, 117, 117, 117, 117, 117, 117, 118, 118, 118, 118, 118, 118, 118, 118, 118,
+        118, 118, 118, 118, 119, 119, 119, 119, 119, 119, 119, 119, 119, 119, 119, 119, 119, 119,
+        120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 120, 121, 121, 121, 121,
+        121, 121, 121, 121, 121, 121, 121, 121, 121, 122, 122, 122, 122, 122, 122, 122, 122, 122,
+        122, 122, 122, 122, 122, 122, 123, 123, 123, 123, 123, 123, 123, 123, 123, 123, 123, 123,
+        123, 123, 124, 124, 124, 124, 124, 124, 124, 124, 124, 124, 124, 124, 124, 124, 125, 125,
+        125, 125, 125, 125, 125, 125, 125, 125, 125, 125, 125, 125, 125, 126, 126, 126, 126, 126,
+        126, 126, 126, 126, 126, 126, 126, 126, 126, 127, 127, 127, 127, 127, 127, 127, 127, 127,
+        127, 127, 127, 127, 127, 127, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
+        128, 128, 128, 129, 129, 129, 129, 129, 129, 129, 129, 129, 129, 129, 129, 129, 129, 129,
+        130, 130, 130, 130, 130, 130, 130, 130, 130, 130, 130, 130, 130, 130, 130, 131, 131, 131,
+        131, 131, 131, 131, 131, 131, 131, 131, 131, 131, 131, 131, 131, 132, 132, 132, 132, 132,
+        132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 133, 133, 133, 133, 133, 133, 133, 133,
+        133, 133, 133, 133, 133, 133, 133, 133, 134, 134, 134, 134, 134, 134, 134, 134, 134, 134,
+        134, 134, 134, 134, 134, 134, 135, 135, 135, 135, 135, 135, 135, 135, 135, 135, 135, 135,
+        135, 135, 135, 135, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136,
+        136, 136, 137, 137, 137, 137, 137, 137, 137, 137, 137, 137, 137, 137, 137, 137, 137, 137,
+        138, 138, 138, 138, 138, 138, 138, 138, 138, 138, 138, 138, 138, 138, 138, 138, 139, 139,
+        139, 139, 139, 139, 139, 139, 139, 139, 139, 139, 139, 139, 139, 139, 139, 140, 140, 140,
+        140, 140, 140, 140, 140, 140, 140, 140, 140, 140, 140, 140, 140, 140, 141, 141, 141, 141,
+        141, 141, 141, 141, 141, 141, 141, 141, 141, 141, 141, 141, 141, 142, 142, 142, 142, 142,
+        142, 142, 142, 142, 142, 142, 142, 142, 142, 142, 142, 142, 143, 143, 143, 143, 143, 143,
+        143, 143, 143, 143, 143, 143, 143, 143, 143, 143, 143, 144, 144, 144, 144, 144, 144, 144,
+        144, 144, 144, 144, 144, 144, 144, 144, 144, 144, 145, 145, 145, 145, 145, 145, 145, 145,
+        145, 145, 145, 145, 145, 145, 145, 145, 145, 145, 146, 146, 146, 146, 146, 146, 146, 146,
+        146, 146, 146, 146, 146, 146, 146, 146, 146, 147, 147, 147, 147, 147, 147, 147, 147, 147,
+        147, 147, 147, 147, 147, 147, 147, 147, 147, 148, 148, 148, 148, 148, 148, 148, 148, 148,
+        148, 148, 148, 148, 148, 148, 148, 148, 148, 149, 149, 149, 149, 149, 149, 149, 149, 149,
+        149, 149, 149, 149, 149, 149, 149, 149, 149, 150, 150, 150, 150, 150, 150, 150, 150, 150,
+        150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 151, 151, 151, 151, 151, 151, 151, 151,
+        151, 151, 151, 151, 151, 151, 151, 151, 151, 151, 152, 152, 152, 152, 152, 152, 152, 152,
+        152, 152, 152, 152, 152, 152, 152, 152, 152, 152, 152, 153, 153, 153, 153, 153, 153, 153,
+        153, 153, 153, 153, 153, 153, 153, 153, 153, 153, 153, 154, 154, 154, 154, 154, 154, 154,
+        154, 154, 154, 154, 154, 154, 154, 154, 154, 154, 154, 154, 155, 155, 155, 155, 155, 155,
+        155, 155, 155, 155, 155, 155, 155, 155, 155, 155, 155, 155, 155, 156, 156, 156, 156, 156,
+        156, 156, 156, 156, 156, 156, 156, 156, 156, 156, 156, 156, 156, 156, 156, 157, 157, 157,
+        157, 157, 157, 157, 157, 157, 157, 157, 157, 157, 157, 157, 157, 157, 157, 157, 158, 158,
+        158, 158, 158, 158, 158, 158, 158, 158, 158, 158, 158, 158, 158, 158, 158, 158, 158, 159,
+        159, 159, 159, 159, 159, 159, 159, 159, 159, 159, 159, 159, 159, 159, 159, 159, 159, 159,
+        159, 160, 160, 160, 160, 160, 160, 160, 160, 160, 160, 160, 160, 160, 160, 160, 160, 160,
+        160, 160, 160, 161, 161, 161, 161, 161, 161, 161, 161, 161, 161, 161, 161, 161, 161, 161,
+        161, 161, 161, 161, 161, 162, 162, 162, 162, 162, 162, 162, 162, 162, 162, 162, 162, 162,
+        162, 162, 162, 162, 162, 162, 162, 163, 163, 163, 163, 163, 163, 163, 163, 163, 163, 163,
+        163, 163, 163, 163, 163, 163, 163, 163, 163, 164, 164, 164, 164, 164, 164, 164, 164, 164,
+        164, 164, 164, 164, 164, 164, 164, 164, 164, 164, 164, 164, 165, 165, 165, 165, 165, 165,
+        165, 165, 165, 165, 165, 165, 165, 165, 165, 165, 165, 165, 165, 165, 165, 166, 166, 166,
+        166, 166, 166, 166, 166, 166, 166, 166, 166, 166, 166, 166, 166, 166, 166, 166, 166, 167,
+        167, 167, 167, 167, 167, 167, 167, 167, 167, 167, 167, 167, 167, 167, 167, 167, 167, 167,
+        167, 167, 168, 168, 168, 168, 168, 168, 168, 168, 168, 168, 168, 168, 168, 168, 168, 168,
+        168, 168, 168, 168, 168, 168, 169, 169, 169, 169, 169, 169, 169, 169, 169, 169, 169, 169,
+        169, 169, 169, 169, 169, 169, 169, 169, 169, 170, 170, 170, 170, 170, 170, 170, 170, 170,
+        170, 170, 170, 170, 170, 170, 170, 170, 170, 170, 170, 170, 171, 171, 171, 171, 171, 171,
+        171, 171, 171, 171, 171, 171, 171, 171, 171, 171, 171, 171, 171, 171, 171, 171, 172, 172,
+        172, 172, 172, 172, 172, 172, 172, 172, 172, 172, 172, 172, 172, 172, 172, 172, 172, 172,
+        172, 172, 173, 173, 173, 173, 173, 173, 173, 173, 173, 173, 173, 173, 173, 173, 173, 173,
+        173, 173, 173, 173, 173, 173, 174, 174, 174, 174, 174, 174, 174, 174, 174, 174, 174, 174,
+        174, 174, 174, 174, 174, 174, 174, 174, 174, 174, 175, 175, 175, 175, 175, 175, 175, 175,
+        175, 175, 175, 175, 175, 175, 175, 175, 175, 175, 175, 175, 175, 175, 176, 176, 176, 176,
+        176, 176, 176, 176, 176, 176, 176, 176, 176, 176, 176, 176, 176, 176, 176, 176, 176, 176,
+        176, 177, 177, 177, 177, 177, 177, 177, 177, 177, 177, 177, 177, 177, 177, 177, 177, 177,
+        177, 177, 177, 177, 177, 178, 178, 178, 178, 178, 178, 178, 178, 178, 178, 178, 178, 178,
+        178, 178, 178, 178, 178, 178, 178, 178, 178, 178, 179, 179, 179, 179, 179, 179, 179, 179,
+        179, 179, 179, 179, 179, 179, 179, 179, 179, 179, 179, 179, 179, 179, 179, 180, 180, 180,
+        180, 180, 180, 180, 180, 180, 180, 180, 180, 180, 180, 180, 180, 180, 180, 180, 180, 180,
+        180, 180, 181, 181, 181, 181, 181, 181, 181, 181, 181, 181, 181, 181, 181, 181, 181, 181,
+        181, 181, 181, 181, 181, 181, 181, 182, 182, 182, 182, 182, 182, 182, 182, 182, 182, 182,
+        182, 182, 182, 182, 182, 182, 182, 182, 182, 182, 182, 182, 182, 183, 183, 183, 183, 183,
+        183, 183, 183, 183, 183, 183, 183, 183, 183, 183, 183, 183, 183, 183, 183, 183, 183, 183,
+        184, 184, 184, 184, 184, 184, 184, 184, 184, 184, 184, 184, 184, 184, 184, 184, 184, 184,
+        184, 184, 184, 184, 184, 184, 185, 185, 185, 185, 185, 185, 185, 185, 185, 185, 185, 185,
+        185, 185, 185, 185, 185, 185, 185, 185, 185, 185, 185, 185, 186, 186, 186, 186, 186, 186,
+        186, 186, 186, 186, 186, 186, 186, 186, 186, 186, 186, 186, 186, 186, 186, 186, 186, 186,
+        187, 187, 187, 187, 187, 187, 187, 187, 187, 187, 187, 187, 187, 187, 187, 187, 187, 187,
+        187, 187, 187, 187, 187, 187, 187, 188, 188, 188, 188, 188, 188, 188, 188, 188, 188, 188,
+        188, 188, 188, 188, 188, 188, 188, 188, 188, 188, 188, 188, 188, 189, 189, 189, 189, 189,
+        189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189, 189,
+        189, 189, 190, 190, 190, 190, 190, 190, 190, 190, 190, 190, 190, 190, 190, 190, 190, 190,
+        190, 190, 190, 190, 190, 190, 190, 190, 190, 191, 191, 191, 191, 191, 191, 191, 191, 191,
+        191, 191, 191, 191, 191, 191, 191, 191, 191, 191, 191, 191, 191, 191, 191, 192, 192, 192,
+        192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192, 192,
+        192, 192, 192, 192, 192, 193, 193, 193, 193, 193, 193, 193, 193, 193, 193, 193, 193, 193,
+        193, 193, 193, 193, 193, 193, 193, 193, 193, 193, 193, 193, 194, 194, 194, 194, 194, 194,
+        194, 194, 194, 194, 194, 194, 194, 194, 194, 194, 194, 194, 194, 194, 194, 194, 194, 194,
+        194, 195, 195, 195, 195, 195, 195, 195, 195, 195, 195, 195, 195, 195, 195, 195, 195, 195,
+        195, 195, 195, 195, 195, 195, 195, 195, 195, 196, 196, 196, 196, 196, 196, 196, 196, 196,
+        196, 196, 196, 196, 196, 196, 196, 196, 196, 196, 196, 196, 196, 196, 196, 196, 196, 197,
+        197, 197, 197, 197, 197, 197, 197, 197, 197, 197, 197, 197, 197, 197, 197, 197, 197, 197,
+        197, 197, 197, 197, 197, 197, 197, 198, 198, 198, 198, 198, 198, 198, 198, 198, 198, 198,
+        198, 198, 198, 198, 198, 198, 198, 198, 198, 198, 198, 198, 198, 198, 198, 199, 199, 199,
+        199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199,
+        199, 199, 199, 199, 199, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200,
+        200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 201, 201, 201, 201,
+        201, 201, 201, 201, 201, 201, 201, 201, 201, 201, 201, 201, 201, 201, 201, 201, 201, 201,
+        201, 201, 201, 201, 201, 202, 202, 202, 202, 202, 202, 202, 202, 202, 202, 202, 202, 202,
+        202, 202, 202, 202, 202, 202, 202, 202, 202, 202, 202, 202, 202, 202, 203, 203, 203, 203,
+        203, 203, 203, 203, 203, 203, 203, 203, 203, 203, 203, 203, 203, 203, 203, 203, 203, 203,
+        203, 203, 203, 203, 203, 204, 204, 204, 204, 204, 204, 204, 204, 204, 204, 204, 204, 204,
+        204, 204, 204, 204, 204, 204, 204, 204, 204, 204, 204, 204, 204, 204, 205, 205, 205, 205,
+        205, 205, 205, 205, 205, 205, 205, 205, 205, 205, 205, 205, 205, 205, 205, 205, 205, 205,
+        205, 205, 205, 205, 205, 206, 206, 206, 206, 206, 206, 206, 206, 206, 206, 206, 206, 206,
+        206, 206, 206, 206, 206, 206, 206, 206, 206, 206, 206, 206, 206, 206, 206, 207, 207, 207,
+        207, 207, 207, 207, 207, 207, 207, 207, 207, 207, 207, 207, 207, 207, 207, 207, 207, 207,
+        207, 207, 207, 207, 207, 207, 207, 208, 208, 208, 208, 208, 208, 208, 208, 208, 208, 208,
+        208, 208, 208, 208, 208, 208, 208, 208, 208, 208, 208, 208, 208, 208, 208, 208, 209, 209,
+        209, 209, 209, 209, 209, 209, 209, 209, 209, 209, 209, 209, 209, 209, 209, 209, 209, 209,
+        209, 209, 209, 209, 209, 209, 209, 209, 209, 210, 210, 210, 210, 210, 210, 210, 210, 210,
+        210, 210, 210, 210, 210, 210, 210, 210, 210, 210, 210, 210, 210, 210, 210, 210, 210, 210,
+        210, 211, 211, 211, 211, 211, 211, 211, 211, 211, 211, 211, 211, 211, 211, 211, 211, 211,
+        211, 211, 211, 211, 211, 211, 211, 211, 211, 211, 211, 212, 212, 212, 212, 212, 212, 212,
+        212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212, 212,
+        212, 212, 212, 212, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213,
+        213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 213, 214, 214, 214,
+        214, 214, 214, 214, 214, 214, 214, 214, 214, 214, 214, 214, 214, 214, 214, 214, 214, 214,
+        214, 214, 214, 214, 214, 214, 214, 214, 215, 215, 215, 215, 215, 215, 215, 215, 215, 215,
+        215, 215, 215, 215, 215, 215, 215, 215, 215, 215, 215, 215, 215, 215, 215, 215, 215, 215,
+        215, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216,
+        216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 216, 217, 217, 217, 217, 217, 217,
+        217, 217, 217, 217, 217, 217, 217, 217, 217, 217, 217, 217, 217, 217, 217, 217, 217, 217,
+        217, 217, 217, 217, 217, 217, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218,
+        218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 218, 219,
+        219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 219,
+        219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 219, 220, 220, 220, 220, 220, 220, 220,
+        220, 220, 220, 220, 220, 220, 220, 220, 220, 220, 220, 220, 220, 220, 220, 220, 220, 220,
+        220, 220, 220, 220, 220, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221,
+        221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221, 221,
+        222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222,
+        222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 222, 223, 223, 223, 223, 223, 223,
+        223, 223, 223, 223, 223, 223, 223, 223, 223, 223, 223, 223, 223, 223, 223, 223, 223, 223,
+        223, 223, 223, 223, 223, 223, 223, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224,
+        224, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224, 224,
+        224, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225,
+        225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 225, 226, 226, 226, 226,
+        226, 226, 226, 226, 226, 226, 226, 226, 226, 226, 226, 226, 226, 226, 226, 226, 226, 226,
+        226, 226, 226, 226, 226, 226, 226, 226, 226, 227, 227, 227, 227, 227, 227, 227, 227, 227,
+        227, 227, 227, 227, 227, 227, 227, 227, 227, 227, 227, 227, 227, 227, 227, 227, 227, 227,
+        227, 227, 227, 227, 227, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228,
+        228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228, 228,
+        229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229,
+        229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 229, 230, 230, 230, 230,
+        230, 230, 230, 230, 230, 230, 230, 230, 230, 230, 230, 230, 230, 230, 230, 230, 230, 230,
+        230, 230, 230, 230, 230, 230, 230, 230, 230, 230, 231, 231, 231, 231, 231, 231, 231, 231,
+        231, 231, 231, 231, 231, 231, 231, 231, 231, 231, 231, 231, 231, 231, 231, 231, 231, 231,
+        231, 231, 231, 231, 231, 231, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232,
+        232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232, 232,
+        232, 232, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233,
+        233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 233, 234,
+        234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234,
+        234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 234, 235, 235, 235, 235, 235,
+        235, 235, 235, 235, 235, 235, 235, 235, 235, 235, 235, 235, 235, 235, 235, 235, 235, 235,
+        235, 235, 235, 235, 235, 235, 235, 235, 235, 235, 236, 236, 236, 236, 236, 236, 236, 236,
+        236, 236, 236, 236, 236, 236, 236, 236, 236, 236, 236, 236, 236, 236, 236, 236, 236, 236,
+        236, 236, 236, 236, 236, 236, 236, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237,
+        237, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237, 237,
+        237, 237, 237, 237, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238,
+        238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238, 238,
+        238, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239,
+        239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 239, 240,
+        240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240,
+        240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 240, 241, 241, 241,
+        241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241,
+        241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 241, 242, 242, 242, 242, 242,
+        242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 242,
+        242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 242, 243, 243, 243, 243, 243, 243, 243,
+        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
+        243, 243, 243, 243, 243, 243, 243, 243, 243, 244, 244, 244, 244, 244, 244, 244, 244, 244,
+        244, 244, 244, 244, 244, 244, 244, 244, 244, 244, 244, 244, 244, 244, 244, 244, 244, 244,
+        244, 244, 244, 244, 244, 244, 244, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245,
+        245, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245, 245,
+        245, 245, 245, 245, 245, 245, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246,
+        246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246, 246,
+        246, 246, 246, 246, 246, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247,
+        247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247, 247,
+        247, 247, 247, 247, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248,
+        248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248, 248,
+        248, 248, 248, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249,
+        249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249, 249,
+        249, 249, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250,
+        250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250,
+        250, 250, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251,
+        251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251,
+        251, 251, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252,
+        252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252,
+        252, 252, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253,
+        253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253,
+        253, 253, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254,
+        254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254,
+        254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+        255, 255, 255,
+};
diff --git a/src/core/SkSRGB.h b/src/core/SkSRGB.h
index 88f2cd78dc..83ae5a4b27 100644
--- a/src/core/SkSRGB.h
+++ b/src/core/SkSRGB.h
@@ -20,7 +20,9 @@
  *  sk_linear_to_srgb() will run a little faster than usual when compiled with SSE4.1+.
  */
 
-extern const float sk_linear_from_srgb[256];
+extern const float    sk_linear_from_srgb[256];
+extern const uint16_t sk_linear12_from_srgb[256];
+extern const uint8_t  sk_linear12_to_srgb[4096];
 
 template <typename V>
 static inline V sk_clamp_0_255(const V& x) {