diff options
Diffstat (limited to 'bench/ScalarBench.cpp')
| -rw-r--r-- | bench/ScalarBench.cpp | 30 |
1 files changed, 19 insertions, 11 deletions
diff --git a/bench/ScalarBench.cpp b/bench/ScalarBench.cpp index a023704fcd..54ee0fcd19 100644 --- a/bench/ScalarBench.cpp +++ b/bench/ScalarBench.cpp @@ -41,6 +41,18 @@ private: typedef SkBenchmark INHERITED; }; +// we want to stop the compiler from eliminating code that it thinks is a no-op +// so we have a non-static global we increment, hoping that will convince the +// compiler to execute everything +int gScalarBench_NonStaticGlobal; + +#define always_do(pred) \ + do { \ + if (pred) { \ + ++gScalarBench_NonStaticGlobal; \ + } \ + } while (0) + // having unknown values in our arrays can throw off the timing a lot, perhaps // handling NaN values is a lot slower. Anyway, this guy is just meant to put // reasonable values in our arrays. @@ -59,10 +71,8 @@ public: protected: virtual int mulLoopCount() const { return 4; } virtual void performTest() { - // xoring into a volatile prevents the compiler from optimizing these checks away. - volatile bool junk = false; - junk ^= (fArray[6] != 0.0f || fArray[7] != 0.0f || fArray[8] != 1.0f); - junk ^= (fArray[2] != 0.0f || fArray[5] != 0.0f); + always_do(fArray[6] != 0.0f || fArray[7] != 0.0f || fArray[8] != 1.0f); + always_do(fArray[2] != 0.0f || fArray[5] != 0.0f); } private: float fArray[9]; @@ -78,13 +88,11 @@ public: protected: virtual int mulLoopCount() const { return 4; } virtual void performTest() { - // xoring into a volatile prevents the compiler from optimizing these checks away. - volatile bool junk = false; - junk ^= (SkScalarAs2sCompliment(fArray[6]) | - SkScalarAs2sCompliment(fArray[7]) | - (SkScalarAs2sCompliment(fArray[8]) - kPersp1Int)); - junk ^= (SkScalarAs2sCompliment(fArray[2]) | - SkScalarAs2sCompliment(fArray[5])); + always_do(SkScalarAs2sCompliment(fArray[6]) | + SkScalarAs2sCompliment(fArray[7]) | + (SkScalarAs2sCompliment(fArray[8]) - kPersp1Int)); + always_do(SkScalarAs2sCompliment(fArray[2]) | + SkScalarAs2sCompliment(fArray[5])); } private: static const int32_t kPersp1Int = 0x3f800000; |