Expand _01 half<->float limitation to _finite. Simplify.

src/opts/SkNx_sse.h

Index: src/opts/SkNx_sse.h
diff --git a/src/opts/SkNx_sse.h b/src/opts/SkNx_sse.h
index 78cea3b3d8abac8f830a57438326b943a0ba94c5..ab88382bd2a111ccb4d4ebf082fda6480ce6e560 100644
--- a/src/opts/SkNx_sse.h
+++ b/src/opts/SkNx_sse.h
@@ -152,16 +152,30 @@ public:
 
     SkNx operator & (const SkNx& o) const { return _mm_and_si128(fVec, o.fVec); }
     SkNx operator | (const SkNx& o) const { return _mm_or_si128(fVec, o.fVec); }
+    SkNx operator ^ (const SkNx& o) const { return _mm_xor_si128(fVec, o.fVec); }
 
     SkNx operator << (int bits) const { return _mm_slli_epi32(fVec, bits); }
     SkNx operator >> (int bits) const { return _mm_srai_epi32(fVec, bits); }
 
+    SkNx operator == (const SkNx& o) const { return _mm_cmpeq_epi32 (fVec, o.fVec); }
+    SkNx operator  < (const SkNx& o) const { return _mm_cmplt_epi32 (fVec, o.fVec); }
+    SkNx operator  > (const SkNx& o) const { return _mm_cmpgt_epi32 (fVec, o.fVec); }
+
     int operator[](int k) const {
         SkASSERT(0 <= k && k < 4);
         union { __m128i v; int is[4]; } pun = {fVec};
         return pun.is[k&3];
     }
 
+    SkNx thenElse(const SkNx& t, const SkNx& e) const {
+    #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE41
+        return _mm_blendv_epi8(e.fVec, t.fVec, fVec);
+    #else
+        return _mm_or_si128(_mm_and_si128   (fVec, t.fVec),
+                            _mm_andnot_si128(fVec, e.fVec));
+    #endif
+    }
+
     __m128i fVec;
 };
 
@@ -372,7 +386,19 @@ template<> /*static*/ inline Sk4b SkNx_cast<uint8_t, uint16_t>(const Sk4h& src)
     return _mm_packus_epi16(src.fVec, src.fVec);
 }
 
-template<> inline Sk4b SkNx_cast<uint8_t, int>(const Sk4i& src) {
+template<> /*static*/ inline Sk4i SkNx_cast<int, uint16_t>(const Sk4h& src) {
+    return _mm_unpacklo_epi16(src.fVec, _mm_setzero_si128());
+}
+
+template<> /*static*/ inline Sk4h SkNx_cast<uint16_t, int>(const Sk4i& src) {
+    // TODO: merge with other work exploring best int -> uint16_t conversion.
+
+    // Sign extend to trick _mm_packs_epi32() into doing the pack we want.
+    __m128i x = _mm_srai_epi32(_mm_slli_epi32(src.fVec, 16), 16);
+    return _mm_packs_epi32(x,x);
+}
+
+template<> /*static*/ inline Sk4b SkNx_cast<uint8_t, int>(const Sk4i& src) {
     return _mm_packus_epi16(_mm_packus_epi16(src.fVec, src.fVec), src.fVec);
 }