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Replace raster pipeline nextafter() calls with SkNu nudging

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(courtesy of mtklein@)

  nanobench -m gradient_linear_clamp\$ --config f16 --ms 2000 -q

Before: 753.66
After:  658.69

R=mtklein@google.com,herb@google.com

CQ_INCLUDE_TRYBOTS=skia.primary:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD

Change-Id: Ie1442da340f6cfc9aef65bec1f114c0e5db89fcb
Reviewed-on: https://skia-review.googlesource.com/7351
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
This commit is contained in:
Florin Malita 2017-01-20 14:53:03 -05:00 committed by Skia Commit-Bot
parent 5be6c95fa9
commit 5b2f579331
1 changed files with 10 additions and 3 deletions
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13
src/opts/SkRasterPipeline_opts.h
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@ -871,21 +871,28 @@ SI SkNf assert_in_tile(const SkNf& v, float limit) {
return v;
}
SI SkNf ulp_before(float v) {
SkASSERT(v > 0);
SkNf vs(v);
SkNu uvs = SkNu::Load(&vs) - 1;
return SkNf::Load(&uvs);
}
SI SkNf clamp(const SkNf& v, float limit) {
SkNf result = SkNf::Max(0, SkNf::Min(v, nextafterf(limit, 0)));
SkNf result = SkNf::Max(0, SkNf::Min(v, ulp_before(limit)));
return assert_in_tile(result, limit);
}
SI SkNf repeat(const SkNf& v, float limit) {
SkNf result = v - (v/limit).floor()*limit;
// For small negative v, (v/limit).floor()*limit can dominate v in the subtraction,
// which leaves result == limit. We want result < limit, so clamp it one ULP.
result = SkNf::Min(result, nextafterf(limit, 0));
result = SkNf::Min(result, ulp_before(limit));
return assert_in_tile(result, limit);
}
SI SkNf mirror(const SkNf& v, float l/*imit*/) {
SkNf result = ((v - l) - ((v - l) / (2*l)).floor()*(2*l) - l).abs();
// Same deal as repeat.
result = SkNf::Min(result, nextafterf(l, 0));
result = SkNf::Min(result, ulp_before(l));
return assert_in_tile(result, l);
}
STAGE_CTX( clamp_x, const float*) { r = clamp (r, *ctx); }