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Replace LightExpression TryEmit parent flags plumbing with compiler-context emit stack #524

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Replace LightExpression TryEmit parent flags plumbing with compiler-context emit stack #524

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1df252d
Initial plan
Copilot Apr 20, 2026
811844d
feat: track TryEmit expression stack in compiler context
Copilot Apr 20, 2026
a0eff69
test: cover TryEmit expression stack context
Copilot Apr 20, 2026
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44 changes: 22 additions & 22 deletions src/FastExpressionCompiler.LightExpression/Expression.cs
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Expand Up @@ -74,7 +74,7 @@ public abstract class Expression
/// and available in the `closure` structure. Find the expression examples below by searching `IsIntrinsic => true`.</summary>
[RequiresUnreferencedCode(Trimming.Message)]

public virtual bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1) => false;
public virtual bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1) => false;

public virtual bool IsCustomToCSharpString => false;

Expand Down Expand Up @@ -3337,9 +3337,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
ExpressionCompiler.TryCollectInfo(ref context, Operand, nestedLambda, ref rootNestedLambdas);

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
if (!EmittingVisitor.TryEmit(Operand, il, ref context, parent, byRefIndex))
if (!EmittingVisitor.TryEmit(Operand, il, ref context, context.CurrentParentFlags, byRefIndex))
return false;
il.Demit(OpCodes.Ldftn, Operand.Type.FindDelegateInvokeMethod());
il.Demit(OpCodes.Newobj, Type.GetConstructors()[0]);
Expand Down Expand Up @@ -3379,9 +3379,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
ExpressionCompiler.TryCollectInfo(ref context, Operand, nestedLambda, ref rootNestedLambdas);

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
if (!EmittingVisitor.TryEmit(Operand, il, ref context, parent, byRefIndex))
if (!EmittingVisitor.TryEmit(Operand, il, ref context, context.CurrentParentFlags, byRefIndex))
return false;
if (Type == typeof(object))
{
Expand Down Expand Up @@ -3930,7 +3930,7 @@ internal NoArgsNewClassIntrinsicExpression(ConstructorInfo constructor) : base(c
public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaInfo nestedLambda, ref SmallList<NestedLambdaInfo> rootNestedLambdas) => 0;

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
il.Demit(OpCodes.Newobj, Constructor);
return true;
Expand All @@ -3957,9 +3957,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
ExpressionCompiler.TryCollectInfo(ref context, Argument, nestedLambda, ref rootNestedLambdas);

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
var ok = EmittingVisitor.TryEmit(Argument, il, ref context, parent | ParentFlags.CtorCall, -1);
var ok = EmittingVisitor.TryEmit(Argument, il, ref context, context.CurrentParentFlags | ParentFlags.CtorCall, -1);
il.Demit(OpCodes.Newobj, Constructor);
return ok;
}
Expand Down Expand Up @@ -3993,9 +3993,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
}

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
var f = parent | ParentFlags.CtorCall;
var f = context.CurrentParentFlags | ParentFlags.CtorCall;
var ok =
EmittingVisitor.TryEmit(Argument0, il, ref context, f, -1) &&
EmittingVisitor.TryEmit(Argument1, il, ref context, f, -1);
Expand Down Expand Up @@ -4036,9 +4036,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
}

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
var f = parent | ParentFlags.CtorCall;
var f = context.CurrentParentFlags | ParentFlags.CtorCall;
var ok =
EmittingVisitor.TryEmit(Argument0, il, ref context, f, -1) &&
EmittingVisitor.TryEmit(Argument1, il, ref context, f, -1) &&
Expand Down Expand Up @@ -4082,9 +4082,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
}

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
var f = parent | ParentFlags.CtorCall;
var f = context.CurrentParentFlags | ParentFlags.CtorCall;
var ok =
EmittingVisitor.TryEmit(Argument0, il, ref context, f, -1) &&
EmittingVisitor.TryEmit(Argument1, il, ref context, f, -1) &&
Expand Down Expand Up @@ -4132,9 +4132,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
}

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
var f = parent | ParentFlags.CtorCall;
var f = context.CurrentParentFlags | ParentFlags.CtorCall;
var ok =
EmittingVisitor.TryEmit(Argument0, il, ref context, f, -1) &&
EmittingVisitor.TryEmit(Argument1, il, ref context, f, -1) &&
Expand Down Expand Up @@ -4186,9 +4186,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
}

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
var f = parent | ParentFlags.CtorCall;
var f = context.CurrentParentFlags | ParentFlags.CtorCall;
var ok =
EmittingVisitor.TryEmit(Argument0, il, ref context, f, -1) &&
EmittingVisitor.TryEmit(Argument1, il, ref context, f, -1) &&
Expand Down Expand Up @@ -4243,9 +4243,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
}

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
var f = parent | ParentFlags.CtorCall;
var f = context.CurrentParentFlags | ParentFlags.CtorCall;
var ok =
EmittingVisitor.TryEmit(Argument0, il, ref context, f, -1) &&
EmittingVisitor.TryEmit(Argument1, il, ref context, f, -1) &&
Expand Down Expand Up @@ -4285,9 +4285,9 @@ public override Result TryCollectInfo(ref CompilerContext context, NestedLambdaI
}

[RequiresUnreferencedCode(Trimming.Message)]
public override bool TryEmit(ref CompilerContext context, ILGenerator il, ParentFlags parent, int byRefIndex = -1)
public override bool TryEmit(ref CompilerContext context, ILGenerator il, int byRefIndex = -1)
{
var f = parent | ParentFlags.CtorCall;
var f = context.CurrentParentFlags | ParentFlags.CtorCall;
var args = Args;
for (var i = 0; i < args.Count; i++)
if (!EmittingVisitor.TryEmit(args[i], il, ref context, f, -1))
Expand Down
4 changes: 4 additions & 0 deletions src/FastExpressionCompiler.LightExpression/Properties/AssemblyInfo.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
using System.Runtime.CompilerServices;

// Reuse the repository signing key so the signed LightExpression issue-tests assembly can override internal LightExpression members.
[assembly: InternalsVisibleTo("FastExpressionCompiler.LightExpression.IssueTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100C3EE5DD15505AED491F6EFFE157E3EC3694E4EC3A532D3C16E497AB1B0C3CA9FB2959D870E24831B600B576E66B82DDA14F0FD88860D8EA05547454B7FC77201D2082FB320D5E609BBAF853A16D5AC459A9585AF6B48C796B22EBB70472C5412C997F68D6E5A044DE3B0DE7B95D1569EE57BF72469F23C748F5879E50A8D50B2")]
148 changes: 102 additions & 46 deletions src/FastExpressionCompiler/FastExpressionCompiler.cs
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Expand Up @@ -611,13 +611,19 @@ public struct LabelInfo
}

/// <summary>Track the info required to build a closure object + some context information not directly related to closure.</summary>
public struct CompilerContext
{
/// <summary>Tracks that the last emit was an address</summary>
public bool LastEmitIsAddress;

// Tracks the current block nesting count in the stack of blocks in Collect and Emit phase
private ushort _blockCount;
public struct CompilerContext
{
/// <summary>Tracks that the last emit was an address</summary>
public bool LastEmitIsAddress;

/// <summary>Tracks the expressions currently being emitted; the most recently entered expression is at the end.</summary>
internal SmallList<Expression, Stack16<Expression>, NoArrayPool<Expression>> EmitExpressions;

/// <summary>Tracks the parent flags for the corresponding entries in <see cref="EmitExpressions"/>.</summary>
internal SmallList<ParentFlags, Stack16<ParentFlags>, NoArrayPool<ParentFlags>> EmitParentFlags;

// Tracks the current block nesting count in the stack of blocks in Collect and Emit phase
private ushort _blockCount;

/// <summary>Tracks the use of the variables in the blocks stack per variable,
/// (uint) contains (ushort) BlockIndex in the upper bits and (ushort) VarIndex in the lower bits.
Expand Down Expand Up @@ -666,20 +672,63 @@ public struct CompilerContext
public CompilerFlags CompilerFlags;

/// <summary>Populates the info</summary>
public CompilerContext(ClosureStatus status, ParamExprs paramExprs, CompilerFlags compilerFlags)
{
Status = status;
Constants = new SmallList<object>();
LastEmitIsAddress = false;
public CompilerContext(ClosureStatus status, ParamExprs paramExprs, CompilerFlags compilerFlags)
{
Status = status;
Constants = new SmallList<object>();
LastEmitIsAddress = false;
CurrentInlinedLambdaInvokeIndex = -1;
ParamExprs = paramExprs;
CompilerFlags = compilerFlags;
}

/// <summary>Populates info directly with provided closure object and constants.</summary>
public CompilerContext(ClosureStatus status, object[] constValues, ParamExprs paramExprs, CompilerFlags compilerFlags)
{
Status = status;
ParamExprs = paramExprs;
CompilerFlags = compilerFlags;
}

/// <summary>The number of expressions in the current emit stack.</summary>
public int EmitExpressionCount
{
[MethodImpl((MethodImplOptions)256)]
get => EmitExpressions.Count;
}

/// <summary>The currently emitted expression or <c>null</c> when the emit stack is empty.</summary>
public Expression CurrentEmitExpression
{
[MethodImpl((MethodImplOptions)256)]
get => EmitExpressions.Count != 0 ? EmitExpressions.GetLastSurePresentItem() : null;
}

/// <summary>The parent flags for the currently emitted expression.</summary>
public ParentFlags CurrentParentFlags
{
[MethodImpl((MethodImplOptions)256)]
get => EmitParentFlags.Count != 0 ? EmitParentFlags.GetLastSurePresentItem() : ParentFlags.Empty;
}

/// <summary>Gets the current expression or its parent by zero-based distance from the current expression.</summary>
[MethodImpl((MethodImplOptions)256)]
public Expression GetEmitExpression(int indexFromCurrent = 0)
{
var exprIndex = EmitExpressions.Count - 1 - indexFromCurrent;
return exprIndex >= 0 ? EmitExpressions.GetSurePresentRef(exprIndex) : null;
}

[MethodImpl((MethodImplOptions)256)]
internal void PushEmitContext(Expression expr, ParentFlags parent)
{
EmitExpressions.Add(expr);
EmitParentFlags.Add(parent);
}

[MethodImpl((MethodImplOptions)256)]
internal void PopEmitContext()
{
EmitExpressions.RemoveLastSurePresentItem();
EmitParentFlags.RemoveLastSurePresentItem();
}

/// <summary>Populates info directly with provided closure object and constants.</summary>
public CompilerContext(ClosureStatus status, object[] constValues, ParamExprs paramExprs, CompilerFlags compilerFlags)
{
Status = status;

Constants = new SmallList<object>(constValues ?? Tools.Empty<object>());
if (constValues != null)
Expand All @@ -688,9 +737,9 @@ public CompilerContext(ClosureStatus status, object[] constValues, ParamExprs pa
LastEmitIsAddress = false;
CurrentInlinedLambdaInvokeIndex = -1;

ParamExprs = paramExprs;
CompilerFlags = compilerFlags;
}
ParamExprs = paramExprs;
CompilerFlags = compilerFlags;
}

[MethodImpl((MethodImplOptions)256)]
public bool ContainsConstantsOrNestedLambdas() => Constants.Count != 0 | NestedLambdas.Count != 0;
Expand Down Expand Up @@ -1890,22 +1939,25 @@ public static class EmittingVisitor
private static readonly MethodInfo _objectEqualsMethod =
((Func<object, object, bool>)object.Equals).Method;

public static bool TryEmit(Expression expr, ILGenerator il, ref CompilerContext context, ParentFlags parent, int byRefIndex = -1)
{
var exprType = expr.Type;
while (true)
{
context.LastEmitIsAddress = false;
#if LIGHT_EXPRESSION
if (expr.IsIntrinsic)
return expr.TryEmit(ref context, il, parent, byRefIndex);
#endif
var nodeType = expr.NodeType;
switch (nodeType)
{
case ExpressionType.Parameter:
return (parent & ParentFlags.IgnoreResult) != 0 ||
TryEmitParameter((ParameterExpression)expr, il, ref context, parent, byRefIndex);
public static bool TryEmit(Expression expr, ILGenerator il, ref CompilerContext context, ParentFlags parent, int byRefIndex = -1)
{
context.PushEmitContext(expr, parent);
try
{
var exprType = expr.Type;
while (true)
{
context.LastEmitIsAddress = false;
#if LIGHT_EXPRESSION
if (expr.IsIntrinsic)
return expr.TryEmit(ref context, il, byRefIndex);
#endif
var nodeType = expr.NodeType;
switch (nodeType)
{
case ExpressionType.Parameter:
return (parent & ParentFlags.IgnoreResult) != 0 ||
TryEmitParameter((ParameterExpression)expr, il, ref context, parent, byRefIndex);

case ExpressionType.TypeAs:
case ExpressionType.IsTrue:
Expand Down Expand Up @@ -2236,13 +2288,17 @@ public static bool TryEmit(Expression expr, ILGenerator il, ref CompilerContext
case ExpressionType.DebugInfo: // todo: @feature - is not supported yet
return true; // todo: @unclear - just ignoring the info for now

case ExpressionType.Quote: // todo: @feature - is not supported yet
default:
return false;

}
}
}
case ExpressionType.Quote: // todo: @feature - is not supported yet
default:
return false;
}
}
}
finally
{
context.PopEmitContext();
}
}

private static bool TryEmitNew(Expression expr, ILGenerator il, ref CompilerContext context, ParentFlags parent)
{
Expand Down
14 changes: 8 additions & 6 deletions ...piler.LightExpression.IssueTests/FastExpressionCompiler.LightExpression.IssueTests.csproj
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@@ -1,10 +1,12 @@
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFrameworks Condition="'$(DevMode)' != 'true'">net472;net6.0;net8.0;net9.0</TargetFrameworks>
<TargetFrameworks Condition="'$(DevMode)' == 'true'">net472;net9.0</TargetFrameworks>

<DefineConstants>LIGHT_EXPRESSION</DefineConstants>
</PropertyGroup>
<PropertyGroup>
<TargetFrameworks Condition="'$(DevMode)' != 'true'">net472;net6.0;net8.0;net9.0</TargetFrameworks>
<TargetFrameworks Condition="'$(DevMode)' == 'true'">net472;net9.0</TargetFrameworks>

<DefineConstants>LIGHT_EXPRESSION</DefineConstants>
<SignAssembly>true</SignAssembly>
<AssemblyOriginatorKeyFile>..\..\FastExpressionCompiler.snk</AssemblyOriginatorKeyFile>
</PropertyGroup>

<ItemGroup>
<None Remove="*.ncrunchproject"/>
Expand Down
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