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

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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
This commit is contained in:
tomhudson@google.com 2011-06-06 15:18:28 +00:00
parent f910b36e45
commit ac3852571e
1 changed files with 19 additions and 6 deletions
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25
src/core/SkMatrix.cpp
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@ -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
}