extend gm to test aa[] parameter on xfer4f procs

src/core/SkXfermode4f.cpp

Index: src/core/SkXfermode4f.cpp
diff --git a/src/core/SkXfermode4f.cpp b/src/core/SkXfermode4f.cpp
index 1bf66a2b6998afed75158e842f3ac6b7445783a3..0ec3ec15f79e2e26e857ff3ce4cd357a66b79927 100644
--- a/src/core/SkXfermode4f.cpp
+++ b/src/core/SkXfermode4f.cpp
@@ -39,10 +39,6 @@ template <DstType D> uint32_t store_dst(const Sk4f& x4) {
     return (D == kSRGB_Dst) ? Sk4f_toS32(x4) : Sk4f_toL32(x4);
 }
 
-static uint32_t linear_unit_to_srgb_32(const Sk4f& l4) {
-    return Sk4f_toL32(l4);
-}
-
 static Sk4f linear_unit_to_srgb_255f(const Sk4f& l4) {
     return linear_to_srgb(l4) * Sk4f(255) + Sk4f(0.5f);
 }
@@ -268,8 +264,8 @@ template <DstType D> void srcover_n(const SkXfermode::PM4fState& state, uint32_t
 
 static void srcover_linear_dst_1(const SkXfermode::PM4fState& state, uint32_t dst[],
                                  const SkPM4f& src, int count, const SkAlpha aa[]) {
-    Sk4f s4 = Sk4f::Load(src.fVec);
-    Sk4f dst_scale = Sk4f(1 - get_alpha(s4));
+    const Sk4f s4 = Sk4f::Load(src.fVec);
+    const Sk4f dst_scale = Sk4f(1 - get_alpha(s4));
     
     if (aa) {
         for (int i = 0; i < count; ++i) {
@@ -280,31 +276,31 @@ static void srcover_linear_dst_1(const SkXfermode::PM4fState& state, uint32_t ds
             Sk4f d4 = Sk4f_fromL32(dst[i]);
             Sk4f r4;
             if (a != 0xFF) {
-                s4 = scale_by_coverage(s4, a);
-                r4 = s4 + d4 * Sk4f(1 - get_alpha(s4));
+                Sk4f s4_aa = scale_by_coverage(s4, a);
+                r4 = s4_aa + d4 * Sk4f(1 - get_alpha(s4_aa));
             } else {
                 r4 = s4 + d4 * dst_scale;
             }
             dst[i] = Sk4f_toL32(r4);
         }
     } else {
-        s4 = s4 * Sk4f(255) + Sk4f(0.5f);   // +0.5 to pre-bias for rounding
+        const Sk4f s4_255 = s4 * Sk4f(255) + Sk4f(0.5f);   // +0.5 to pre-bias for rounding
         while (count >= 4) {
             Sk4f d0 = to_4f(dst[0]);
             Sk4f d1 = to_4f(dst[1]);
             Sk4f d2 = to_4f(dst[2]);
             Sk4f d3 = to_4f(dst[3]);
             Sk4f_ToBytes((uint8_t*)dst,
-                         s4 + d0 * dst_scale,
-                         s4 + d1 * dst_scale,
-                         s4 + d2 * dst_scale,
-                         s4 + d3 * dst_scale);
+                         s4_255 + d0 * dst_scale,
+                         s4_255 + d1 * dst_scale,
+                         s4_255 + d2 * dst_scale,
+                         s4_255 + d3 * dst_scale);
             dst += 4;
             count -= 4;
         }
         for (int i = 0; i < count; ++i) {
             Sk4f d4 = to_4f(dst[i]);
-            dst[i] = to_4b(s4 + d4 * dst_scale);
+            dst[i] = to_4b(s4_255 + d4 * dst_scale);
         }
     }
 }
@@ -323,12 +319,12 @@ static void srcover_srgb_dst_1(const SkXfermode::PM4fState& state, uint32_t dst[
             Sk4f d4 = srgb_4b_to_linear_unit(dst[i]);
             Sk4f r4;
             if (a != 0xFF) {
-                s4 = scale_by_coverage(s4, a);
-                r4 = s4 + d4 * Sk4f(1 - get_alpha(s4));
+                const Sk4f s4_aa = scale_by_coverage(s4, a);
+                r4 = s4_aa + d4 * Sk4f(1 - get_alpha(s4_aa));
             } else {
                 r4 = s4 + d4 * dst_scale;
             }
-            dst[i] = linear_unit_to_srgb_32(r4);
+            dst[i] = to_4b(linear_unit_to_srgb_255f(r4));
         }
     } else {
         while (count >= 4) {