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Fix bugs in preinitialization #134173

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Merged
MichalStrehovsky merged 6 commits into from
Sep 24, 2026
+374 −25
Merged

Fix bugs in preinitialization #134173

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e430ad5
Fix NativeAOT preinitialization typed-store representations
MichalStrehovsky Sep 11, 2026
5c88895
Fix NativeAOT preinitialization reference-containing type checks
MichalStrehovsky Sep 11, 2026
7b5b3fc
Fix NativeAOT preinitialization duplicated value ownership
MichalStrehovsky Sep 11, 2026
ec917de
Fix NativeAOT preinitialization span assignment aliases
MichalStrehovsky Sep 11, 2026
4a01243
Fix NativeAOT preinitialization RVA span identity
MichalStrehovsky Sep 11, 2026
9111a5b
Reject NativeAOT preinitialization of boxes containing GC pointers
MichalStrehovsky Sep 18, 2026
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59 changes: 34 additions & 25 deletions src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/TypePreinit.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -313,12 +313,19 @@ private Status TryScanMethod(MethodIL methodIL, Value[] parameters, Stack<Method
break;

case ILOpcode.dup:
{
if (stack.Count == 0)
{
ThrowHelper.ThrowInvalidProgramException();
}
stack.Push(stack.Peek());

StackEntry entry = stack.Peek();
if (entry.ValueKind is not StackValueKind.ByRef and not StackValueKind.ObjRef)
entry = new StackEntry(entry.ValueKind, entry.Value.Clone());

stack.Push(entry);
break;
}

case ILOpcode.pop:
{
Expand Down Expand Up @@ -1690,6 +1697,9 @@ private Status TryScanMethod(MethodIL methodIL, Value[] parameters, Stack<Method
if (type.IsNullable)
return Status.Fail(methodIL.OwningMethod, opcode);

if (((DefType)type).ContainsGCPointers)
return Status.Fail(methodIL.OwningMethod, opcode, "GC pointers");
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if (type.RequiresAlign8())
return Status.Fail(methodIL.OwningMethod, opcode, "Align8");

Expand Down Expand Up @@ -1766,29 +1776,16 @@ private Status TryScanMethod(MethodIL methodIL, Value[] parameters, Stack<Method
case ILOpcode.stind_i4:
case ILOpcode.stind_i8:
{
if (opcode == ILOpcode.stobj)
{
TypeDesc type = methodIL.GetObject(reader.ReadILToken()) as TypeDesc;
opcode = type.Category switch
{
TypeFlags.SByte or TypeFlags.Boolean or TypeFlags.Byte => ILOpcode.stind_i1,
TypeFlags.Int16 or TypeFlags.Char or TypeFlags.UInt16 => ILOpcode.stind_i2,
TypeFlags.Int32 or TypeFlags.UInt32 => ILOpcode.stind_i4,
TypeFlags.Int64 or TypeFlags.UInt64 => ILOpcode.stind_i8,
TypeFlags.IntPtr or TypeFlags.UIntPtr => ILOpcode.stind_i,
_ => ILOpcode.stobj,
};
}

Value val = opcode switch
TypeDesc type = opcode switch
{
ILOpcode.stind_i1 => stack.PopIntoLocation(context.GetWellKnownType(WellKnownType.Byte)),
ILOpcode.stind_i2 => stack.PopIntoLocation(context.GetWellKnownType(WellKnownType.UInt16)),
ILOpcode.stind_i4 => stack.PopIntoLocation(context.GetWellKnownType(WellKnownType.UInt32)),
ILOpcode.stind_i8 => stack.PopIntoLocation(context.GetWellKnownType(WellKnownType.UInt64)),
ILOpcode.stind_i => stack.PopIntoLocation(context.GetWellKnownType(WellKnownType.UIntPtr)),
_ => stack.Pop().Value
ILOpcode.stind_i1 => context.GetWellKnownType(WellKnownType.Byte),
ILOpcode.stind_i2 => context.GetWellKnownType(WellKnownType.UInt16),
ILOpcode.stind_i4 => context.GetWellKnownType(WellKnownType.UInt32),
ILOpcode.stind_i8 => context.GetWellKnownType(WellKnownType.UInt64),
ILOpcode.stind_i => context.GetWellKnownType(WellKnownType.UIntPtr),
_ /* stobj */ => (TypeDesc)methodIL.GetObject(reader.ReadILToken()),
};
Value val = stack.PopIntoLocation(type);

StackEntry location = stack.Pop();
if (location.ValueKind != StackValueKind.ByRef && location.ValueKind != StackValueKind.NativeInt)
Expand Down Expand Up @@ -1918,7 +1915,7 @@ private bool TryHandleIntrinsicCall(MethodDesc method, Value[] parameters, out V
{
var elementType = (MetadataType)method.Instantiation[0];
int elementSize = elementType.InstanceFieldSize.AsInt;
byte[] rvaData = Internal.TypeSystem.Ecma.EcmaFieldExtensions.GetFieldRvaData(createSpanEcmaField);
byte[] rvaData = GetFieldRvaData(createSpanEcmaField);
if (rvaData.Length % elementSize != 0)
return false;
retVal = new SpanValue(elementType, rvaData, 0, rvaData.Length);
Expand Down Expand Up @@ -1952,7 +1949,8 @@ private bool TryHandleIntrinsicCall(MethodDesc method, Value[] parameters, out V
&& isReferenceOrContainsReferencesType.Name == "RuntimeHelpers"u8 && isReferenceOrContainsReferencesType.Namespace == "System.Runtime.CompilerServices"u8
&& isReferenceOrContainsReferencesType.Module == method.Context.SystemModule:
{
bool result = method.Instantiation[0].IsGCPointer || (method.Instantiation[0] is DefType defType && defType.ContainsGCPointers);
bool result = method.Instantiation[0].IsGCPointer
|| (method.Instantiation[0] is DefType defType && (defType.ContainsGCPointers || defType.ContainsByRefs));
retVal = ValueTypeValue.FromSByte(result ? (sbyte)1 : (sbyte)0);
return true;
}
Expand Down Expand Up @@ -2910,7 +2908,7 @@ public override void WriteFieldData(ref ObjectDataBuilder builder, NodeFactory f
}
}

private sealed class SpanValue : BaseValueTypeValue, IInternalModelingOnlyValue
private sealed class SpanValue : BaseValueTypeValue, IInternalModelingOnlyValue, IAssignableValue
{
private readonly MetadataType _elementType;
private byte[] _bytes;
Expand Down Expand Up @@ -2957,6 +2955,17 @@ public override bool TryCreateByRef(out Value value)
return true;
}

bool IAssignableValue.TryAssign(Value value)
{
if (value is not SpanValue other || other._elementType != _elementType)
return false;

_bytes = other._bytes;
_index = other._index;
_length = other._length;
return true;
}

private sealed class SpanReferenceValue : ByRefValueBase, IHasInstanceFields
{
private readonly SpanValue _value;
Expand Down
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