Исходники и презентации

lessons/slices_and_arrays/without_bound_checks/bench_test.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"testing"
+	"unsafe"
+)
+
+// go test -gcflags="-d=ssa/check_bce" -bench=. bench_test.go
+
+func sum1(values []int, size int) int {
+	sum := 0
+	for i := 0; i < size; i++ {
+		sum += values[i]
+	}
+
+	return sum
+}
+
+func sum2(values []int, size int) int {
+	sum := 0
+	startPtr := unsafe.Pointer(&values[0])
+	for i := 0; i < size-1; i++ {
+		sum += *(*int)(
+			unsafe.Pointer(uintptr(startPtr) + uintptr(i)*unsafe.Sizeof(values[0])),
+		)
+	}
+
+	return sum
+}
+
+var Result int
+
+func BenchmarkSum1(b *testing.B) {
+	values := make([]int, 1<<20)
+	for i := 0; i < b.N; i++ {
+		Result = sum1(values, 1<<20)
+	}
+}
+
+func BenchmarkSum2(b *testing.B) {
+	values := make([]int, 1<<20)
+	for i := 0; i < b.N; i++ {
+		Result = sum2(values, 1<<20)
+	}
+}