skeleton for float <-> half optimized procs

Nothing fancy yet, just calls the serial code in a loop.

I will try to folow this up with at least some of:
   - SSE2 version of serial code
   - NEON version of serial code
   - NEON version using vcvt.f32.f16/vcvt.f16.f32
   - F16C (between AVX and AVX2) version using vcvtph2ps/vcvtps2ph
The last two are fastest but need runtime detection.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1686543003

Review URL: https://codereview.chromium.org/1686543003

1 files changed, 48 insertions, 0 deletions

diff --git a/bench/HalfBench.cpp b/bench/HalfBench.cpp
new file mode 100644
index 0000000000..1c76c572a4
--- /dev/null
+++ b/bench/HalfBench.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2016 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 "SkOpts.h"
+#include "SkRandom.h"
+
+struct FloatToHalfBench : public Benchmark {
+    const char* onGetName() override { return "float_to_half"; }
+    bool isSuitableFor(Backend backend) override { return backend == kNonRendering_Backend; }
+
+    void onDraw(int loops, SkCanvas* canvas) override {
+        SkRandom rand;
+        float fs[1023];
+        for (float& f : fs) {
+            f = rand.nextF();
+        }
+
+        uint16_t hs[1023];
+        while (loops --> 0) {
+            SkOpts::float_to_half(hs, fs, 1023);
+        }
+    }
+};
+DEF_BENCH(return new FloatToHalfBench;)
+
+struct HalfToFloatBench : public Benchmark {
+    const char* onGetName() override { return "half_to_float"; }
+    bool isSuitableFor(Backend backend) override { return backend == kNonRendering_Backend; }
+
+    void onDraw(int loops, SkCanvas* canvas) override {
+        SkRandom rand;
+        uint16_t hs[1023];
+        for (uint16_t& h : hs) {
+            h = rand.nextU16();
+        }
+
+        float fs[1023];
+        while (loops --> 0) {
+            SkOpts::half_to_float(fs, hs, 1023);
+        }
+    }
+};
+DEF_BENCH(return new HalfToFloatBench;)