如何解决C＃中的64位指针算术，检查算术溢出是否改变行为
|| 我有一些不安全的C＃代码，它在64位计算机上运行的类型为“ 0”的大型内存块上执行指针算术运算。它在大多数时候都能正常工作，但是当事情变大时，我经常会遇到指针不正确的损坏。 奇怪的是，如果我打开“检查算术上溢/下溢”，则一切正常。我没有任何溢出异常。但是由于性能下降，我需要在不使用此选项的情况下运行代码。 是什么造成这种行为差异？解决方法
这是C＃编译器错误（在Connect上提交）。 @Grant表明，由C＃编译器生成的MSIL将
uint
+
-
void*
T* operator +(T* x,int y);
T* operator +(T* x,uint y);
T* operator +(T* x,long y);
T* operator +(T* x,ulong y);
T* operator +(int x,T* y);
T* operator +(uint x,T* y);
T* operator +(long x,T* y);
T* operator +(ulong x,T* y);
T* operator –(T* x,int y);
T* operator –(T* x,uint y);
T* operator –(T* x,long y);
T* operator –(T* x,ulong y);
long operator –(T* x,T* y);
P
int
uint
long
ulong
N
P + N
N + P
T*
N * sizeof(T)
P
Q
P – Q
P
Q
long
P - Q
((long)(P) - (long)(Q)) / sizeof(T)
//000008: unchecked
//000009: {
//000010: Console.WriteLine(\"{0:x}\",(long)(testPtr + offset));
IL_000a: ldstr \"{0:x}\"
IL_000f: ldloc.0
IL_0010: ldloc.1
IL_0011: add
IL_0012: conv.u8
IL_0013: box [mscorlib]System.Int64
IL_0018: call void [mscorlib]System.Console::WriteLine(string,object)
//000012: checked
//000013: {
//000014: Console.WriteLine(\"{0:x}\",(long)(testPtr + offset));
IL_001d: ldstr \"{0:x}\"
IL_0022: ldloc.0
IL_0023: ldloc.1
IL_0024: add.ovf.un
IL_0025: conv.ovf.i8.un
IL_0026: box [mscorlib]System.Int64
IL_002b: call void [mscorlib]System.Console::WriteLine(string,object)
long
public static unsafe void Main(string[] args)
{
// Dummy pointer,never dereferenced
byte* testPtr = (byte*)0x00000008000000L;
uint offset = uint.MaxValue;
unchecked
{
Console.WriteLine(\"{0:x}\",(long)(testPtr + offset));
}
checked
{
Console.WriteLine(\"{0:x}\",(long)(testPtr + offset));
}
unchecked
{
Console.WriteLine(\"{0:x}\",(long)(testPtr + (long)offset));
}
checked
{
Console.WriteLine(\"{0:x}\",(long)(testPtr + (long)offset));
}
}
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