Use Sk4x to speed-up bounds of an array of points

src/core/SkRect.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkRect.h"
 
@@ skipping 27 matching lines @@
 
 void SkRect::toQuad(SkPoint quad[4]) const {
     SkASSERT(quad);
 
     quad[0].set(fLeft, fTop);
     quad[1].set(fRight, fTop);
     quad[2].set(fRight, fBottom);
     quad[3].set(fLeft, fBottom);
 }
 
+//#include "Sk2x.h"
+#include "Sk4x.h"
+
+static inline bool is_finite(const Sk4f& value) {
+    Sk4i finite = value * Sk4f(0) == Sk4f(0);
+    return finite.allTrue();
+}
+
 bool SkRect::setBoundsCheck(const SkPoint pts[], int count) {
     SkASSERT((pts && count > 0) || count == 0);
 
     bool isFinite = true;
 
     if (count <= 0) {
         sk_bzero(this, sizeof(SkRect));
     } else {
+#if 0
         SkScalar    l, t, r, b;
 
         l = r = pts[0].fX;
         t = b = pts[0].fY;
 
         // If all of the points are finite, accum should stay 0. If we encounter
         // a NaN or infinity, then accum should become NaN.
         float accum = 0;
         accum *= l; accum *= t;
 
         for (int i = 1; i < count; i++) {
             SkScalar x = pts[i].fX;
             SkScalar y = pts[i].fY;
 
             accum *= x; accum *= y;
 
             // we use if instead of if/else, so we can generate min/max
             // float instructions (at least on SSE)
             if (x < l) l = x;
             if (x > r) r = x;
 
             if (y < t) t = y;
             if (y > b) b = y;
         }
 
         SkASSERT(!accum || !SkScalarIsFinite(accum));
+        accum = 0;
         if (accum) {
             l = t = r = b = 0;
             isFinite = false;
         }
         this->set(l, t, r, b);
+#else
+        Sk4f min, max, accum;
+
+        if (count & 1) {
+            min = Sk4f(pts[0].fX, pts[0].fY, pts[0].fX, pts[0].fY);
+            pts += 1;
+            count -= 1;
+        } else {
+            min = Sk4f::Load(&pts[0].fX);
+            pts += 2;
+            count -= 2;
+        }
+        accum = max = min;
+        accum *= Sk4f(0);
+
+        count >>= 1;
+        for (int i = 0; i < count; ++i) {
+            Sk4f xy = Sk4f::Load(&pts->fX);
+            accum *= xy;
+            min = Sk4f::Min(min, xy);
+            max = Sk4f::Max(max, xy);
+            pts += 2;
+        }
+
+        /**
+         *  With some trickery, we may be able to use Min/Max to also propogate non-finites,
+         *  in which case we could eliminate accum entirely, and just check min and max for
+         *  "is_finite".
+         */
+        if (is_finite(accum)) {
+            float minArray[4], maxArray[4];
+            min.store(minArray);
+            max.store(maxArray);
+            this->set(SkTMin(minArray[0], minArray[2]), SkTMin(minArray[1], minArray[3]),
+                      SkTMax(maxArray[0], maxArray[2]), SkTMax(maxArray[1], maxArray[3]));
+        } else {
+            // we hit a non-finite value, so zero everything and return false
+            this->setEmpty();
+            isFinite = false;
+        }
+#endif
     }
 
     return isFinite;
 }
 
 #define CHECK_INTERSECT(al, at, ar, ab, bl, bt, br, bb) \
     SkScalar L = SkMaxScalar(al, bl);                   \
     SkScalar R = SkMinScalar(ar, br);                   \
     SkScalar T = SkMaxScalar(at, bt);                   \
     SkScalar B = SkMinScalar(ab, bb);                   \
@@ skipping 57 matching lines @@
         SkString strL, strT, strR, strB;
         SkAppendScalarDec(&strL, fLeft);
         SkAppendScalarDec(&strT, fTop);
         SkAppendScalarDec(&strR, fRight);
         SkAppendScalarDec(&strB, fBottom);
         line.printf("SkRect::MakeLTRB(%s, %s, %s, %s);",
                     strL.c_str(), strT.c_str(), strR.c_str(), strB.c_str());
     }
     SkDebugf("%s\n", line.c_str());
 }