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繼續我的F＃性能測試。對於一些更多的背景看這裏：F＃NativePtr.stackalloc比C＃更快 - stackalloc - 包含反編譯代碼
f# NativePtr.stackalloc in Struct Constructor
F# NativePtr.stackalloc Unexpected Stack Overflow
在F＃的工作現在，我已經得到了堆陣列。但是，由於某些原因，等效的C＃大約快50倍。我已經在下面包含了ILSpy反編譯版本，看起來只有一行是真的不同（在stackAlloc中）。
這是怎麼回事？未經檢驗的算術是否真的爲這種巨大差異負責？不知道我怎麼能測試這？
https://msdn.microsoft.com/en-us/library/a569z7k8.aspx
F＃代碼
#nowarn "9"
open Microsoft.FSharp.NativeInterop
open System
open System.Diagnostics
open System.Runtime.CompilerServices
[<MethodImpl(MethodImplOptions.NoInlining)>]
let stackAlloc x =
let mutable ints:nativeptr<byte> = NativePtr.stackalloc x
()
[<EntryPoint>]
let main argv =
printfn "%A" argv
let size = 8192
let reps = 10000
stackAlloc size // JIT
let clock = Stopwatch()
clock.Start()
for i = 1 to reps do
stackAlloc size
clock.Stop()
let elapsed = clock.Elapsed.TotalMilliseconds
let description = "F# NativePtr.stackalloc"
Console.WriteLine("{0} ({1} bytes, {2} reps): {3:#,##0.####}ms", description, size, reps, elapsed)
Console.ReadKey() |> ignore
0
C＃代碼
using System;
using System.Diagnostics;
namespace CSharpLanguageFeatures
{
class CSharpStackArray
{
static void Main(string[] args)
{
int size = 8192;
int reps = 10000;
stackAlloc(size); // JIT
Stopwatch clock = new Stopwatch();
clock.Start();
for (int i = 0; i < reps; i++)
{
stackAlloc(size);
}
clock.Stop();
string elapsed = clock.Elapsed.TotalMilliseconds.ToString("#,##0.####");
string description = "C# stackalloc";
Console.WriteLine("{0} ({1} bytes, {2} reps): {3:#,##0.####}ms", description, size, reps, elapsed);
Console.ReadKey();
}
public unsafe static void stackAlloc(int arraySize)
{
byte* pArr = stackalloc byte[arraySize];
}
}
}
F＃版本反編譯
using Microsoft.FSharp.Core;
using System;
using System.Diagnostics;
using System.IO;
using System.Runtime.CompilerServices;
[CompilationMapping(SourceConstructFlags.Module)]
public static class FSharpStackArray
{
[MethodImpl(MethodImplOptions.NoInlining)]
public unsafe static void stackAlloc(int x)
{
IntPtr ints = stackalloc byte[x * sizeof(byte)];
}
[EntryPoint]
public static int main(string[] argv)
{
PrintfFormat<FSharpFunc<string[], Unit>, TextWriter, Unit, Unit> format = new PrintfFormat<FSharpFunc<string[], Unit>, TextWriter, Unit, Unit, string[]>("%A");
PrintfModule.PrintFormatLineToTextWriter<FSharpFunc<string[], Unit>>(Console.Out, format).Invoke(argv);
FSharpStackArray.stackAlloc(8192);
Stopwatch clock = new Stopwatch();
clock.Start();
for (int i = 1; i < 10001; i++)
{
FSharpStackArray.stackAlloc(8192);
}
clock.Stop();
double elapsed = clock.Elapsed.TotalMilliseconds;
Console.WriteLine("{0} ({1} bytes, {2} reps): {3:#,##0.####}ms", "F# NativePtr.stackalloc", 8192, 10000, elapsed);
ConsoleKeyInfo consoleKeyInfo = Console.ReadKey();
return 0;
}
}
C＃版反編譯
using System;
using System.Diagnostics;
namespace CSharpLanguageFeatures
{
internal class CSharpStackArray
{
private static void Main(string[] args)
{
int size = 8192;
int reps = 10000;
CSharpStackArray.stackAlloc(size);
Stopwatch clock = new Stopwatch();
clock.Start();
for (int i = 0; i < reps; i++)
{
CSharpStackArray.stackAlloc(size);
}
clock.Stop();
string elapsed = clock.Elapsed.TotalMilliseconds.ToString("#,##0.####");
string description = "C# stackalloc";
Console.WriteLine("{0} ({1} bytes, {2} reps): {3:#,##0.####}ms", new object[]
{
description,
size,
reps,
elapsed
});
Console.ReadKey();
}
public unsafe static void stackAlloc(int arraySize)
{
IntPtr arg_06_0 = stackalloc byte[checked(unchecked((UIntPtr)arraySize) * 1)];
}
}
}
F＃版IL - 字節分配
.method public static
void stackAlloc (
int32 x
) cil managed noinlining
{
// Method begins at RVA 0x2050
// Code size 13 (0xd)
.maxstack 4
.locals init (
[0] native int ints
)
IL_0000: nop
IL_0001: ldarg.0
IL_0002: sizeof [mscorlib]System.Byte
IL_0008: mul
IL_0009: localloc
IL_000b: stloc.0
IL_000c: ret
} // end of method FSharpStackArray::stackAlloc
C＃版IL - 字節分配
.method public hidebysig static
void stackAlloc (
int32 arraySize
) cil managed
{
// Method begins at RVA 0x2094
// Code size 8 (0x8)
.maxstack 8
IL_0000: ldarg.0
IL_0001: conv.u
IL_0002: ldc.i4.1
IL_0003: mul.ovf.un
IL_0004: localloc
IL_0006: pop
IL_0007: ret
} // end of method CSharpStackArray::stackAlloc
更新F＃IL - IntPtr的分配
.method public static
void stackAlloc (
int32 x
) cil managed noinlining
{
// Method begins at RVA 0x2050
// Code size 13 (0xd)
.maxstack 4
.locals init (
[0] native int ints
)
IL_0000: nop
IL_0001: ldarg.0
IL_0002: sizeof [mscorlib]System.IntPtr
IL_0008: mul
IL_0009: localloc
IL_000b: stloc.0
IL_000c: ret
} // end of method FSharpStackArray::stackAlloc
更新C＃IL - IntPtr的分配
.method public hidebysig static
void stackAlloc (
int32 arraySize
) cil managed
{
// Method begins at RVA 0x2415
// Code size 13 (0xd)
.maxstack 8
IL_0000: ldarg.0
IL_0001: conv.u
IL_0002: sizeof [mscorlib]System.IntPtr
IL_0008: mul.ovf.un
IL_0009: localloc
IL_000b: pop
IL_000c: ret
} // end of method CSharpStackArray::stackAlloc
你可以顯示所有的'stackAlloc'方法的實際IL？ –
嗯，可能是[mscorlib] System.Byte或nop的大小？循環中還有一個缺陷？ – Researcher
'sizeof'肯定起作用，但我覺得'mul'更重要。 –