Revert of De-proc Color32 (patchset #4 id:60001 of https://codereview.chromium.org/1104183004/)

Reason for revert:
MIPS

Original issue's description:
> De-proc Color32
>
> Also strips SK_SUPPORT_LEGACY_COLOR32_MATH,
> which is no longer needed.
>
> Seems handy to have SkTypes include the relevant intrinsics when
> we know we've got them, but I'm not married to it.
>
> Locally this looks like a pointlessly small perf win, but I'm mostly
> keen to get all the code together.
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/376e9bc206b69d9190f38dfebb132a8769bbd72b

TBR=reed@google.com,mtklein@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/1108163002

1 files changed, 21 insertions, 84 deletions

diff --git a/src/core/SkBlitRow_D32.cpp b/src/core/SkBlitRow_D32.cpp
index 0b9e916e6e..ac01e427bf 100644
--- a/src/core/SkBlitRow_D32.cpp
+++ b/src/core/SkBlitRow_D32.cpp
@@ -131,99 +131,37 @@ SkBlitRow::Proc32 SkBlitRow::Factory32(unsigned flags) {
     return proc;
 }
 
-// Color32 uses the blend_256_round_alt algorithm from tests/BlendTest.cpp.
-// It's not quite perfect, but it's never wrong in the interesting edge cases,
-// and it's quite a bit faster than blend_perfect.
+SkBlitRow::Proc32 SkBlitRow::ColorProcFactory() {
+    SkBlitRow::ColorProc proc = PlatformColorProc();
+    if (NULL == proc) {
+        proc = Color32;
+    }
+    SkASSERT(proc);
+    return proc;
+}
+
+#define SK_SUPPORT_LEGACY_COLOR32_MATHx
+
+// Color32 and its SIMD specializations use the blend_256_round_alt algorithm
+// from tests/BlendTest.cpp.  It's not quite perfect, but it's never wrong in the
+// interesting edge cases, and it's quite a bit faster than blend_perfect.
 //
 // blend_256_round_alt is our currently blessed algorithm.  Please use it or an analogous one.
-void SkBlitRow::Color32(SkPMColor dst[], const SkPMColor src[], int count, SkPMColor color) {
+void SkBlitRow::Color32(SkPMColor* SK_RESTRICT dst,
+                        const SkPMColor* SK_RESTRICT src,
+                        int count, SkPMColor color) {
     switch (SkGetPackedA32(color)) {
         case   0: memmove(dst, src, count * sizeof(SkPMColor)); return;
         case 255: sk_memset32(dst, color, count);               return;
     }
 
     unsigned invA = 255 - SkGetPackedA32(color);
+#ifdef SK_SUPPORT_LEGACY_COLOR32_MATH  // blend_256_plus1_trunc, busted
+    unsigned round = 0;
+#else                          // blend_256_round_alt, good
     invA += invA >> 7;
-    SkASSERT(invA < 256);  // We've already handled alpha == 0 above.
-
-#if defined(SK_ARM_HAS_NEON)
-    uint16x8_t colorHigh = vshll_n_u8((uint8x8_t)vdup_n_u32(color), 8);
-    uint16x8_t colorAndRound = vaddq_u16(colorHigh, vdupq_n_u16(128));
-    uint8x8_t invA8 = vdup_n_u8(invA);
-
-    // Does the core work of blending color onto 4 pixels, returning the resulting 4 pixels.
-    auto kernel = [&](const uint32x4_t& src4) -> uint32x4_t {
-        uint16x8_t lo = vmull_u8(vget_low_u8( (uint8x16_t)src4), invA8),
-                   hi = vmull_u8(vget_high_u8((uint8x16_t)src4), invA8);
-        return (uint32x4_t)
-            vcombine_u8(vaddhn_u16(colorAndRound, lo), vaddhn_u16(colorAndRound, hi));
-    };
-
-    while (count >= 8) {
-        uint32x4_t dst0 = kernel(vld1q_u32(src+0)),
-                   dst4 = kernel(vld1q_u32(src+4));
-        vst1q_u32(dst+0, dst0);
-        vst1q_u32(dst+4, dst4);
-        src   += 8;
-        dst   += 8;
-        count -= 8;
-    }
-    if (count >= 4) {
-        vst1q_u32(dst, kernel(vld1q_u32(src)));
-        src   += 4;
-        dst   += 4;
-        count -= 4;
-    }
-    if (count >= 2) {
-        uint32x2_t src2 = vld1_u32(src);
-        vst1_u32(dst, vget_low_u32(kernel(vcombine_u32(src2, src2))));
-        src   += 2;
-        dst   += 2;
-        count -= 2;
-    }
-    if (count >= 1) {
-        vst1q_lane_u32(dst, kernel(vdupq_n_u32(*src)), 0);
-    }
-
-#elif SK_CPU_SSE_LEVEL >= SK_CPU_LEVEL_SSE2
-    __m128i colorHigh = _mm_unpacklo_epi8(_mm_setzero_si128(), _mm_set1_epi32(color));
-    __m128i colorAndRound = _mm_add_epi16(colorHigh, _mm_set1_epi16(128));
-    __m128i invA16 = _mm_set1_epi16(invA);
-
-    // Does the core work of blending color onto 4 pixels, returning the resulting 4 pixels.
-    auto kernel = [&](const __m128i& src4) -> __m128i {
-        __m128i lo = _mm_mullo_epi16(invA16, _mm_unpacklo_epi8(src4, _mm_setzero_si128())),
-                hi = _mm_mullo_epi16(invA16, _mm_unpackhi_epi8(src4, _mm_setzero_si128()));
-        return _mm_packus_epi16(_mm_srli_epi16(_mm_add_epi16(colorAndRound, lo), 8),
-                                _mm_srli_epi16(_mm_add_epi16(colorAndRound, hi), 8));
-    };
-
-    while (count >= 8) {
-        __m128i dst0 = kernel(_mm_loadu_si128((const __m128i*)(src+0))),
-                dst4 = kernel(_mm_loadu_si128((const __m128i*)(src+4)));
-        _mm_storeu_si128((__m128i*)(dst+0), dst0);
-        _mm_storeu_si128((__m128i*)(dst+4), dst4);
-        src   += 8;
-        dst   += 8;
-        count -= 8;
-    }
-    if (count >= 4) {
-        _mm_storeu_si128((__m128i*)dst, kernel(_mm_loadu_si128((const __m128i*)src)));
-        src   += 4;
-        dst   += 4;
-        count -= 4;
-    }
-    if (count >= 2) {
-        _mm_storel_epi64((__m128i*)dst, kernel(_mm_loadl_epi64((const __m128i*)src)));
-        src   += 2;
-        dst   += 2;
-        count -= 2;
-    }
-    if (count >= 1) {
-        *dst = _mm_cvtsi128_si32(kernel(_mm_cvtsi32_si128(*src)));
-    }
-#else  // Neither NEON nor SSE2.
     unsigned round = (128 << 16) + (128 << 0);
+#endif
 
     while (count --> 0) {
         // Our math is 16-bit, so we can do a little bit of SIMD in 32-bit registers.
@@ -234,6 +172,5 @@ void SkBlitRow::Color32(SkPMColor dst[], const SkPMColor src[], int count, SkPMC
         src++;
         dst++;
     }
-#endif
 }