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using System;
using System.Runtime.CompilerServices;
namespace ReadMemBytes
{
class Program
{
static int Pass = 100;
static int Fail = -1;
[MethodImpl(MethodImplOptions.NoInlining)]
static unsafe int TestMemBytesNotReadPastTheLimit(byte *p, int byteLength)
{
int count = 0;
for (int i= 0; i< byteLength; ++i)
{
// RyuJIT lowering has an optimization to recognize the condition in
// "If" stmnt and generate "test byte ptr [p+i], 0" instruction. Due
// to a bug that has been fixed it will end up generating "test dword ptr [p+i], 0"
// that will lead to reading 4 bytes instead of a single byte.
if ((p[i] & 0xffffff00) != 0)
{
++count;
}
}
return count;
}
static unsafe int Main(string[] args)
{
byte* buffer = stackalloc byte[4];
buffer[0] = 0;
buffer[1] = buffer[2] = buffer[3] = 0xff;
int result = TestMemBytesNotReadPastTheLimit(buffer, 1);
if (result != 0)
{
Console.WriteLine("Failed: Read past the end of buffer");
return Fail;
}
else
{
Console.WriteLine("Pass");
}
return Pass;
}
}
}
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