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Slim down Sk4fRoundtrip benches.

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Looks like the conversions are complicated enough to not compile away.
No need to mess with random number generation, etc.
We still need to blackhole it into a volatile in the end.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1682793002

Review URL: https://codereview.chromium.org/1682793002
This commit is contained in:
mtklein 2016-02-09 11:03:40 -08:00 committed by Commit bot
parent e4c0beed74
commit 77aa62c01e
1 changed files with 8 additions and 20 deletions
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28
bench/Sk4fBench.cpp
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@ -9,16 +9,8 @@
#include "SkColor.h"
#include "SkNx.h"
// Used to prevent the compiler from optimizing away the whole loop.
volatile uint64_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 uint64_t lcg_rand(uint64_t* seed) {
*seed *= 1664525;
*seed += 1013904223;
return *seed;
}
// Writing into this array prevents the loops from being compiled away.
static volatile float blackhole[4];
template <typename T>
struct Sk4fRoundtripBench : public Benchmark {
@ -28,6 +20,7 @@ struct Sk4fRoundtripBench : public Benchmark {
switch (sizeof(T)) {
case 1: return "Sk4f_roundtrip_u8";
case 2: return "Sk4f_roundtrip_u16";
case 4: return "Sk4f_roundtrip_int";
}
SkASSERT(false);
return "";
@ -36,21 +29,16 @@ struct Sk4fRoundtripBench : public Benchmark {
bool isSuitableFor(Backend backend) override { return backend == kNonRendering_Backend; }
void onDraw(int loops, SkCanvas* canvas) override {
// Unlike blackhole, junk can and probably will be a register.
uint64_t junk = 0;
uint64_t seed = 0;
for (int i = 0; i < loops; i++) {
uint64_t src = lcg_rand(&seed),
back;
auto f = SkNx_cast<float>(SkNx<4,T>::Load(&src));
SkNx_cast<T>(f).store(&back);
junk ^= back;
Sk4f fs(1,2,3,4);
while (loops --> 0) {
fs = SkNx_cast<float>(SkNx_cast<T>(fs));
}
blackhole ^= junk;
fs.store((float*)blackhole);
}
};
DEF_BENCH(return new Sk4fRoundtripBench<uint8_t>;)
DEF_BENCH(return new Sk4fRoundtripBench<uint16_t>;)
DEF_BENCH(return new Sk4fRoundtripBench<int>;)
struct Sk4fGradientBench : public Benchmark {
const char* onGetName() override { return "Sk4f_gradient"; }