skia2/bench/PMFloatBench.cpp
mtklein e9a3e3c17a Convert SkPMFloat to [0,1] range and prune its API.
Now that Sk4px exists, there's a lot less sense in eeking out every
cycle of speed from SkPMFloat: if we need to go _really_ fast, we
should use Sk4px.  SkPMFloat's going to be used for things that are
already slow: large-range intermediates, divides, sqrts, etc.

A [0,1] range is easier to work with, and can even be faster if we
eliminate enough *255 and *1/255 steps.  This is particularly true
on ARM, where NEON can do the *255 and /255 steps for us while
converting float<->int.

We have lots of experimental SkPMFloat <-> SkPMColor APIs that
I'm now removing.  Of the existing APIs, roundClamp() is the sanest,
so I've kept only that, now called round().  The 4-at-a-time APIs
never panned out, so they're gone.

There will be small diffs on:
colormatrix coloremoji colorfilterimagefilter fadefilter imagefilters_xfermodes imagefilterscropexpand imagefiltersgraph tileimagefilter

BUG=skia:

Review URL: https://codereview.chromium.org/1201343004
2015-06-25 08:56:28 -07:00

86 lines
2.8 KiB
C++

/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "Benchmark.h"
#include "SkPMFloat.h"
// Used to prevent the compiler from optimizing away the whole loop.
volatile uint32_t blackhole = 0;
// Not a great random number generator, but it's very fast.
// The code we're measuring is quite fast, so low overhead is essential.
static uint32_t lcg_rand(uint32_t* seed) {
*seed *= 1664525;
*seed += 1013904223;
return *seed;
}
// I'm having better luck getting these to constant-propagate away as template parameters.
struct PMFloatRoundtripBench : public Benchmark {
PMFloatRoundtripBench() {}
const char* onGetName() override { return "SkPMFloat_roundtrip"; }
bool isSuitableFor(Backend backend) override { return backend == kNonRendering_Backend; }
void onDraw(const int loops, SkCanvas* canvas) override {
// Unlike blackhole, junk can and probably will be a register.
uint32_t junk = 0;
uint32_t seed = 0;
for (int i = 0; i < loops; i++) {
SkPMColor color;
#ifdef SK_DEBUG
// Our SkASSERTs will remind us that it's technically required that we premultiply.
color = SkPreMultiplyColor(lcg_rand(&seed));
#else
// But it's a lot faster not to, and this code won't really mind the non-PM colors.
color = lcg_rand(&seed);
#endif
auto f = SkPMFloat::FromPMColor(color);
SkPMColor back = f.round();
junk ^= back;
}
blackhole ^= junk;
}
};
DEF_BENCH(return new PMFloatRoundtripBench;)
struct PMFloatGradientBench : public Benchmark {
const char* onGetName() override { return "PMFloat_gradient"; }
bool isSuitableFor(Backend backend) override { return backend == kNonRendering_Backend; }
SkPMColor fDevice[100];
void onDraw(const int loops, SkCanvas*) override {
Sk4f c0 = SkPMFloat::FromARGB(1, 1, 0, 0),
c1 = SkPMFloat::FromARGB(1, 0, 0, 1),
dc = c1 - c0,
fx(0.1f),
dx(0.002f),
dcdx(dc*dx),
dcdx4(dcdx+dcdx+dcdx+dcdx);
for (int n = 0; n < loops; n++) {
Sk4f a = c0 + dc*fx,
b = a + dcdx,
c = b + dcdx,
d = c + dcdx;
for (size_t i = 0; i < SK_ARRAY_COUNT(fDevice); i += 4) {
fDevice[i+0] = SkPMFloat(a).round();
fDevice[i+1] = SkPMFloat(b).round();
fDevice[i+2] = SkPMFloat(c).round();
fDevice[i+3] = SkPMFloat(d).round();
a = a + dcdx4;
b = b + dcdx4;
c = c + dcdx4;
d = d + dcdx4;
}
}
}
};
DEF_BENCH(return new PMFloatGradientBench;)