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Readd .NET implementations of GC slots again #913

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Merged
merged 2 commits into from
Aug 2, 2019
Merged

Readd .NET implementations of GC slots again #913

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9bb2def
Readd .NET implementations of GC slots again
filmor Jul 10, 2019
0ab33e3
Merge branch 'master' into use-dotnet-rets-as-fallback
filmor Aug 2, 2019
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75 changes: 31 additions & 44 deletions src/runtime/typemanager.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -512,12 +512,8 @@ public static NativeCode Active
return I386;
case MachineType.x86_64:
return X86_64;
case MachineType.armv7l:
return Armv7l;
case MachineType.armv8:
return Armv8;
default:
throw new NotImplementedException($"No support for {Runtime.MachineName}");
return null;
}
}
}
Expand Down Expand Up @@ -552,34 +548,6 @@ public static NativeCode Active
/// <see cref="NativeCode.X86_64"/>
/// </summary>
public static readonly NativeCode I386 = X86_64;

public static readonly NativeCode Armv7l = new NativeCode()
{
Return0 = 0,
Return1 = 0x08,
Code = new byte[]
{
0xe3, 0xa0, 0x00, 0x00, // mov r0, #0
0xe1, 0x2f, 0xff, 0x1e, // bx lr

0xe3, 0xa0, 0x00, 0x01, // mov r0, #1
0xe1, 0x2f, 0xff, 0x1e, // bx lr
}
};

public static readonly NativeCode Armv8 = new NativeCode()
{
Return0 = 0,
Return1 = 0x08,
Code = new byte[]
{
0x52, 0x80, 0x00, 0x00, // mov w0, #0x0
0xd6, 0x5f, 0x03, 0xc0, // ret

0x52, 0x80, 0x00, 0x20, // mov w0, #0x1
0xd6, 0x5f, 0x03, 0xc0, // ret
}
};
}

/// <summary>
Expand Down Expand Up @@ -702,7 +670,7 @@ internal static void InitializeNativeCodePage()
Marshal.Copy(NativeCode.Active.Code, 0, NativeCodePage, codeLength);
mapper.SetReadExec(NativeCodePage, codeLength);
}
#endregion
#endregion

/// <summary>
/// Given a newly allocated Python type object and a managed Type that
Expand Down Expand Up @@ -745,21 +713,40 @@ internal static void InitializeSlots(IntPtr type, Type impl)
impl = impl.BaseType;
}

// See the TestDomainReload test: there was a crash related to
// the gc-related slots. They always return 0 or 1 because we don't
// really support gc:
var native = NativeCode.Active;

// The garbage collection related slots always have to return 1 or 0
// since .NET objects don't take part in Python's gc:
// tp_traverse (returns 0)
// tp_clear (returns 0)
// tp_is_gc (returns 1)
// We can't do without: python really wants those slots to exist.
// We can't implement those in C# because the application domain
// can be shut down and the memory released.
InitializeNativeCodePage();
InitializeSlot(type, NativeCodePage + NativeCode.Active.Return0, "tp_traverse");
InitializeSlot(type, NativeCodePage + NativeCode.Active.Return0, "tp_clear");
InitializeSlot(type, NativeCodePage + NativeCode.Active.Return1, "tp_is_gc");
// These have to be defined, though, so by default we fill these with
// static C# functions from this class.

var ret0 = Interop.GetThunk(((Func<IntPtr, int>)Return0).Method);
var ret1 = Interop.GetThunk(((Func<IntPtr, int>)Return1).Method);

if (native != null)
{
// If we want to support domain reload, the C# implementation
// cannot be used as the assembly may get released before
// CPython calls these functions. Instead, for amd64 and x86 we
// load them into a separate code page that is leaked
// intentionally.
InitializeNativeCodePage();
ret1 = NativeCodePage + native.Return1;
ret0 = NativeCodePage + native.Return0;
}

InitializeSlot(type, ret0, "tp_traverse");
InitializeSlot(type, ret0, "tp_clear");
InitializeSlot(type, ret1, "tp_is_gc");
}

static int Return1(IntPtr _) => 1;

static int Return0(IntPtr _) => 0;

/// <summary>
/// Helper for InitializeSlots.
///
Expand Down