Arm64 codegen bug. #56522
Description
Such tests produces different results with COMPlus_JitDoValueNumber=0 and COMPlus_JitDoValueNumber=1:
The issue is in TestConvertFromFloatToU8.
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using System.Runtime.Intrinsics;
using System.Reflection;
using System.Reflection.Emit;
namespace CheckGenericSbyte
{
class Program
{
static int failedCount = 0;
static readonly bool ExpectException = true;
static readonly bool DontExpectException = false;
static readonly bool UnspecifiedBehaviour = true;
[MethodImpl(MethodImplOptions.NoInlining)]
static void GenerateTest<F, T>(F from, OpCode fromOpcode, OpCode convOpcode, bool exceptionExpected, T expectedTo, bool undefined = false) where F : struct where T : struct, IEquatable<T>
{
bool checkResult = !exceptionExpected && !undefined;
Debug.Assert(!exceptionExpected || !checkResult);
Debug.Assert(checkResult || expectedTo.Equals(default(T)));
Type[] args = new Type[] { }; // No args.
Type returnType = typeof(T);
Console.WriteLine("Run test from " + typeof(F).FullName + ", value " + from.ToString() + " To " + typeof(T).FullName + "with Op " + convOpcode.Name + " exception expected: " + exceptionExpected);
string name = "DynamicConvertFrom" + typeof(F).FullName + "To" + typeof(T).FullName + from.ToString() + "Op" + convOpcode.Name;
DynamicMethod dm = new DynamicMethod(name, returnType, args);
ILGenerator generator = dm.GetILGenerator();
if (typeof(F) == typeof(int)) generator.Emit(fromOpcode, (int)(object)from);
else if (typeof(F) == typeof(long)) generator.Emit(fromOpcode, (long)(object)from);
else if (typeof(F) == typeof(nint)) generator.Emit(fromOpcode, (nint)(object)from);
else if (typeof(F) == typeof(float)) generator.Emit(fromOpcode, (float)(object)from);
else if (typeof(F) == typeof(double)) generator.Emit(fromOpcode, (double)(object)from);
else
{
throw new NotSupportedException();
}
generator.Emit(convOpcode);
generator.Emit(OpCodes.Ret);
try
{
T res = (T)dm.Invoke(null, BindingFlags.Default, null, new object[] { }, null);
if (exceptionExpected)
{
failedCount++;
Console.WriteLine("No exception in " + name);
}
if (checkResult && !expectedTo.Equals(res))
{
failedCount++;
Console.WriteLine("Wrong result in " + name);
}
}
catch
{
if (!exceptionExpected)
{
failedCount++;
Console.WriteLine("Not expected exception in " + name);
}
}
}
[MethodImpl(MethodImplOptions.NoInlining)]
static void TestConvertFromFloatToU8()
{
OpCode sourceOp = OpCodes.Ldc_R4;
OpCode convNoOvf = OpCodes.Conv_U8;
GenerateTest<float, ulong>(long.MinValue, sourceOp, convNoOvf, DontExpectException, 0, UnspecifiedBehaviour);
OpCode convOvf = OpCodes.Conv_Ovf_U8;
GenerateTest<float, ulong>(long.MinValue, sourceOp, convOvf, ExpectException, 0);
OpCode convOvfUn = OpCodes.Conv_Ovf_U8_Un;
GenerateTest<float, ulong>(int.MinValue, sourceOp, convOvfUn, ExpectException, 0);
GenerateTest<float, ulong>(long.MinValue, sourceOp, convOvfUn, ExpectException, 0);
TestSimple(long.MinValue, (float)long.MinValue);
}
[MethodImpl(MethodImplOptions.NoInlining)]
public static void TestSimple(float f, object f1)
{
Console.WriteLine("Test Simple value is " + f + ", f1 is " + f1.ToString());
Debug.Assert(f < -1E-9);
}
static int Main(string[] args)
{
TestConvertFromFloatToU8();
return 100;
}
}
}
It looks like we do wrong CSE in TestConvertFromFloatToU8 and we pass 0 instead of long.MinValue in some cases:
seandree@seandreemac TestConvertFromIntegral % export COMPlus_JitDoValueNumber=1
seandree@seandreemac TestConvertFromIntegral % ./TestConvertFromIntegral.sh
BEGIN EXECUTION
/Users/seandree/git/runtime/artifacts/tests/coreclr/OSX.arm64.Checked/Tests/Core_Root/corerun TestConvertFromIntegral.dll ''
Run test from System.Single, value -9.223372E+18 To System.UInt64with Op conv.u8 exception expected: False
Run test from System.Single, value -9.223372E+18 To System.UInt64with Op conv.ovf.u8 exception expected: True
Run test from System.Single, value -2.1474836E+09 To System.UInt64with Op conv.ovf.u8.un exception expected: True
Run test from System.Single, value 0 To System.UInt64with Op conv.ovf.u8.un exception expected: True
No exception in DynamicConvertFromSystem.SingleToSystem.UInt640Opconv.ovf.u8.un <- wrong
Test Simple value is 0, f1 is 0 <- wrong
seandree@seandreemac TestConvertFromIntegral % export COMPlus_JitDoValueNumber=0
seandree@seandreemac TestConvertFromIntegral % ./TestConvertFromIntegral.sh
BEGIN EXECUTION
/Users/seandree/git/runtime/artifacts/tests/coreclr/OSX.arm64.Checked/Tests/Core_Root/corerun TestConvertFromIntegral.dll ''
Run test from System.Single, value -9.223372E+18 To System.UInt64with Op conv.u8 exception expected: False
Run test from System.Single, value -9.223372E+18 To System.UInt64with Op conv.ovf.u8 exception expected: True
Run test from System.Single, value -2.1474836E+09 To System.UInt64with Op conv.ovf.u8.un exception expected: True
Run test from System.Single, value -9.223372E+18 To System.UInt64with Op conv.ovf.u8.un exception expected: True
Test Simple value is -9.223372E+18, f1 is -9.223372E+18
found during work on #56450.
It is not a minimum repro but if I replace GenerateTest body with something trivial it goes away, so I am not sure what happens there.