golang mulconst_test 代码
文件路径：/src/cmd/compile/internal/test/mulconst_test.go
/ Copyright 2020 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
package test
import "testing"
/ Benchmark multiplication of an integer by various constants.
/
/ The comment above each sub-benchmark provides an example of how the
/ target multiplication operation might be implemented using shift
/ (multiplication by a power of 2), addition and subtraction
/ operations. It is platform-dependent whether these transformations
/ are actually applied.
var (
mulSinkI32 int32
mulSinkI64 int64
mulSinkU32 uint32
mulSinkU64 uint64
)
func BenchmarkMulconstI32(b *testing.B) {
/ 3x = 2x + x
b.Run("3", func(b *testing.B) {
x := int32(1)
for i := 0; i < b.N; i++ {
x *= 3
}
mulSinkI32 = x
})
/ 5x = 4x + x
b.Run("5", func(b *testing.B) {
x := int32(1)
for i := 0; i < b.N; i++ {
x *= 5
}
mulSinkI32 = x
})
/ 12x = 8x + 4x
b.Run("12", func(b *testing.B) {
x := int32(1)
for i := 0; i < b.N; i++ {
x *= 12
}
mulSinkI32 = x
})
/ 120x = 128x - 8x
b.Run("120", func(b *testing.B) {
x := int32(1)
for i := 0; i < b.N; i++ {
x *= 120
}
mulSinkI32 = x
})
/ -120x = 8x - 120x
b.Run("-120", func(b *testing.B) {
x := int32(1)
for i := 0; i < b.N; i++ {
x *= -120
}
mulSinkI32 = x
})
/ 65537x = 65536x + x
b.Run("65537", func(b *testing.B) {
x := int32(1)
for i := 0; i < b.N; i++ {
x *= 65537
}
mulSinkI32 = x
})
/ 65538x = 65536x + 2x
b.Run("65538", func(b *testing.B) {
x := int32(1)
for i := 0; i < b.N; i++ {
x *= 65538
}
mulSinkI32 = x
})
}
func BenchmarkMulconstI64(b *testing.B) {
/ 3x = 2x + x
b.Run("3", func(b *testing.B) {
x := int64(1)
for i := 0; i < b.N; i++ {
x *= 3
}
mulSinkI64 = x
})
/ 5x = 4x + x
b.Run("5", func(b *testing.B) {
x := int64(1)
for i := 0; i < b.N; i++ {
x *= 5
}
mulSinkI64 = x
})
/ 12x = 8x + 4x
b.Run("12", func(b *testing.B) {
x := int64(1)
for i := 0; i < b.N; i++ {
x *= 12
}
mulSinkI64 = x
})
/ 120x = 128x - 8x
b.Run("120", func(b *testing.B) {
x := int64(1)
for i := 0; i < b.N; i++ {
x *= 120
}
mulSinkI64 = x
})
/ -120x = 8x - 120x
b.Run("-120", func(b *testing.B) {
x := int64(1)
for i := 0; i < b.N; i++ {
x *= -120
}
mulSinkI64 = x
})
/ 65537x = 65536x + x
b.Run("65537", func(b *testing.B) {
x := int64(1)
for i := 0; i < b.N; i++ {
x *= 65537
}
mulSinkI64 = x
})
/ 65538x = 65536x + 2x
b.Run("65538", func(b *testing.B) {
x := int64(1)
for i := 0; i < b.N; i++ {
x *= 65538
}
mulSinkI64 = x
})
}
func BenchmarkMulconstU32(b *testing.B) {
/ 3x = 2x + x
b.Run("3", func(b *testing.B) {
x := uint32(1)
for i := 0; i < b.N; i++ {
x *= 3
}
mulSinkU32 = x
})
/ 5x = 4x + x
b.Run("5", func(b *testing.B) {
x := uint32(1)
for i := 0; i < b.N; i++ {
x *= 5
}
mulSinkU32 = x
})
/ 12x = 8x + 4x
b.Run("12", func(b *testing.B) {
x := uint32(1)
for i := 0; i < b.N; i++ {
x *= 12
}
mulSinkU32 = x
})
/ 120x = 128x - 8x
b.Run("120", func(b *testing.B) {
x := uint32(1)
for i := 0; i < b.N; i++ {
x *= 120
}
mulSinkU32 = x
})
/ 65537x = 65536x + x
b.Run("65537", func(b *testing.B) {
x := uint32(1)
for i := 0; i < b.N; i++ {
x *= 65537
}
mulSinkU32 = x
})
/ 65538x = 65536x + 2x
b.Run("65538", func(b *testing.B) {
x := uint32(1)
for i := 0; i < b.N; i++ {
x *= 65538
}
mulSinkU32 = x
})
}
func BenchmarkMulconstU64(b *testing.B) {
/ 3x = 2x + x
b.Run("3", func(b *testing.B) {
x := uint64(1)
for i := 0; i < b.N; i++ {
x *= 3
}
mulSinkU64 = x
})
/ 5x = 4x + x
b.Run("5", func(b *testing.B) {
x := uint64(1)
for i := 0; i < b.N; i++ {
x *= 5
}
mulSinkU64 = x
})
/ 12x = 8x + 4x
b.Run("12", func(b *testing.B) {
x := uint64(1)
for i := 0; i < b.N; i++ {
x *= 12
}
mulSinkU64 = x
})
/ 120x = 128x - 8x
b.Run("120", func(b *testing.B) {
x := uint64(1)
for i := 0; i < b.N; i++ {
x *= 120
}
mulSinkU64 = x
})
/ 65537x = 65536x + x
b.Run("65537", func(b *testing.B) {
x := uint64(1)
for i := 0; i < b.N; i++ {
x *= 65537
}
mulSinkU64 = x
})
/ 65538x = 65536x + 2x
b.Run("65538", func(b *testing.B) {
x := uint64(1)
for i := 0; i < b.N; i++ {
x *= 65538
}
mulSinkU64 = x
})
}