Benchmarking suggests that replacing some of the conversions from float to int

with direct floating-point comparisons in computeTypeMask() is a significant win
(up to 40%?).
In practice, we see a 10-15% speedup in this function (the current most
expensive Skia function) in Chrome on the FishIETank demo.

The remainder of the function looks like it ought to be amenable to similar
speedups, but we haven't found a rewrite that behaves well in benchmarking yet.

http://codereview.appspot.com/4551097/


git-svn-id: http://skia.googlecode.com/svn/trunk@1512 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 19 insertions, 6 deletions

diff --git a/src/core/SkMatrix.cpp b/src/core/SkMatrix.cpp
index 06bca1e59d..a5a1eba71f 100644
--- a/src/core/SkMatrix.cpp
+++ b/src/core/SkMatrix.cpp
@@ -71,22 +71,36 @@ enum {
 uint8_t SkMatrix::computeTypeMask() const {
     unsigned mask = 0;
 
+#ifdef SK_SCALAR_SLOW_COMPARES
     if (SkScalarAs2sCompliment(fMat[kMPersp0]) |
             SkScalarAs2sCompliment(fMat[kMPersp1]) |
             (SkScalarAs2sCompliment(fMat[kMPersp2]) - kPersp1Int)) {
         mask |= kPerspective_Mask;
     }
-    
+
     if (SkScalarAs2sCompliment(fMat[kMTransX]) |
             SkScalarAs2sCompliment(fMat[kMTransY])) {
         mask |= kTranslate_Mask;
     }
+#else
+    // Benchmarking suggests that replacing this set of SkScalarAs2sCompliment
+    // is a win, but replacing those below is not. We don't yet understand
+    // that result.
+    if (fMat[kMPersp0] != 0 || fMat[kMPersp1] != 0 ||
+        fMat[kMPersp2] != SK_Scalar1) {
+        mask |= kPerspective_Mask;
+    }
+
+    if (fMat[kMTransX] != 0 || fMat[kMTransY] != 0) {
+        mask |= kTranslate_Mask;
+    }
+#endif
 
     int m00 = SkScalarAs2sCompliment(fMat[SkMatrix::kMScaleX]);
     int m01 = SkScalarAs2sCompliment(fMat[SkMatrix::kMSkewX]);
     int m10 = SkScalarAs2sCompliment(fMat[SkMatrix::kMSkewY]);
     int m11 = SkScalarAs2sCompliment(fMat[SkMatrix::kMScaleY]);
-    
+
     if (m01 | m10) {
         mask |= kAffine_Mask;
     }
@@ -94,21 +108,21 @@ uint8_t SkMatrix::computeTypeMask() const {
     if ((m00 - kScalar1Int) | (m11 - kScalar1Int)) {
         mask |= kScale_Mask;
     }
-    
+
     if ((mask & kPerspective_Mask) == 0) {
         // map non-zero to 1
         m00 = m00 != 0;
         m01 = m01 != 0;
         m10 = m10 != 0;
         m11 = m11 != 0;
-        
+
         // record if the (p)rimary and (s)econdary diagonals are all 0 or
         // all non-zero (answer is 0 or 1)
         int dp0 = (m00 | m11) ^ 1;  // true if both are 0
         int dp1 = m00 & m11;        // true if both are 1
         int ds0 = (m01 | m10) ^ 1;  // true if both are 0
         int ds1 = m01 & m10;        // true if both are 1
-        
+
         // return 1 if primary is 1 and secondary is 0 or
         // primary is 0 and secondary is 1
         mask |= ((dp0 & ds1) | (dp1 & ds0)) << kRectStaysRect_Shift;
@@ -1747,4 +1761,3 @@ void SkMatrix::toDumpString(SkString* str) const {
                 fMat[6], fMat[7], fMat[8]);
 #endif
 }
-