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Fix #1638: identify renamed yield state machine members via method impls 

Obfuscators may rename the members of compiler-generated iterator
classes while keeping the MethodImpl (.override) rows intact. Since
b110d5c2d (first shipped in ILSpy 8.0), Dispose, get_Current and
GetEnumerator are identified by name or method impl; MoveNext was still
looked up by name only, so such a state machine was rejected with
"Method not found". The pre-Roslyn "yield break" handling likewise
matched the Dispose call by name; it now compares against the already
resolved Dispose handle. The new ILPretty fixture models the obfuscated
shape from the issue's assemblies, against which the fix was verified;
the rest of the issue was already resolved by b110d5c2d and 81e702f84.

Assisted-by: Claude:claude-fable-5:Claude Code
pull/3906/head
Siegfried Pammer 2 months ago committed by Siegfried Pammer
parent
2e617a38c0
commit
cac1209014
4 changed files with 340 additions and 2 deletions
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  1. 6
      ICSharpCode.Decompiler.Tests/ILPrettyTestRunner.cs
  2. 23
      ICSharpCode.Decompiler.Tests/TestCases/ILPretty/Issue1638.cs
  3. 309
      ICSharpCode.Decompiler.Tests/TestCases/ILPretty/Issue1638.il
  4. 4
      ICSharpCode.Decompiler/IL/ControlFlow/YieldReturnDecompiler.cs

6
ICSharpCode.Decompiler.Tests/ILPrettyTestRunner.cs
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@ -201,6 +201,12 @@ namespace ICSharpCode.Decompiler.Tests @@ -201,6 +201,12 @@ namespace ICSharpCode.Decompiler.Tests
await Run();
}
[Test]
public async Task Issue1638()
{
await Run();
}
[Test]
public async Task Issue2104()
{

23
ICSharpCode.Decompiler.Tests/TestCases/ILPretty/Issue1638.cs
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@ -0,0 +1,23 @@ @@ -0,0 +1,23 @@
using System.Collections;
namespace ICSharpCode.Decompiler.Tests.TestCases.ILPretty
{
public class Issue1638
{
private int state;
public IEnumerator Test(object arg1, object arg2)
{
try
{
yield return arg1;
yield return state;
}
finally
{
state = 0;
}
yield return arg2;
}
}
}

309
ICSharpCode.Decompiler.Tests/TestCases/ILPretty/Issue1638.il
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@ -0,0 +1,309 @@ @@ -0,0 +1,309 @@
// Regression fixture for issue #1638: yield-return state machine with obfuscated names.
//
// This is Roslyn /optimize codegen for
// public IEnumerator Test(object arg1, object arg2)
// {
// try { yield return arg1; yield return state; }
// finally { state = 0; }
// yield return arg2;
// }
// with an obfuscator-style rename pass applied: the state machine class, its fields,
// 'System.IDisposable.Dispose' and 'MoveNext' all carry meaningless names, and
// [IteratorStateMachine] is stripped. The MethodImpl (.override) rows are kept intact,
// so the decompiler must identify Dispose and MoveNext through them instead of by name.
.assembly extern System.Runtime
{
.publickeytoken = (B0 3F 5F 7F 11 D5 0A 3A )
.ver 4:0:0:0
}
.assembly Issue1638
{
.ver 0:0:0:0
}
.module Issue1638.dll
.class private auto ansi '<Module>'
{
} // end of class <Module>
.class public auto ansi beforefieldinit ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638
extends [System.Runtime]System.Object
{
// Nested Types
.class nested private auto ansi sealed beforefieldinit ObfuscatedIterator
extends [System.Runtime]System.Object
implements class [System.Runtime]System.Collections.Generic.IEnumerator`1<object>,
[System.Runtime]System.Collections.IEnumerator,
[System.Runtime]System.IDisposable
{
.custom instance void [System.Runtime]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = (
01 00 00 00
)
// Fields
.field private int32 m_state
.field private object m_current
.field public object m_1
.field public class ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638 m_owner
.field public object m_2
// Methods
.method public hidebysig specialname rtspecialname
instance void .ctor (
int32 initialState
) cil managed
{
.custom instance void [System.Runtime]System.Diagnostics.DebuggerHiddenAttribute::.ctor() = (
01 00 00 00
)
.maxstack 8
IL_0000: ldarg.0
IL_0001: call instance void [System.Runtime]System.Object::.ctor()
IL_0006: ldarg.0
IL_0007: ldarg.1
IL_0008: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_000d: ret
} // end of method ObfuscatedIterator::.ctor
.method private final hidebysig newslot virtual
instance void ObfuscatedDispose () cil managed
{
.custom instance void [System.Runtime]System.Diagnostics.DebuggerHiddenAttribute::.ctor() = (
01 00 00 00
)
.override method instance void [System.Runtime]System.IDisposable::Dispose()
.maxstack 2
.locals init (
[0] int32
)
IL_0000: ldarg.0
IL_0001: ldfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_0006: stloc.0
IL_0007: ldloc.0
IL_0008: ldc.i4.s -3
IL_000a: beq.s IL_0012
IL_000c: ldloc.0
IL_000d: ldc.i4.1
IL_000e: sub
IL_000f: ldc.i4.1
IL_0010: bgt.un.s IL_001c
IL_0012: nop
.try
{
IL_0013: leave.s IL_001c
} // end .try
finally
{
IL_0015: ldarg.0
IL_0016: call instance void ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::ObfuscatedFinally()
IL_001b: endfinally
} // end handler
IL_001c: ldarg.0
IL_001d: ldc.i4.s -2
IL_001f: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_0024: ret
} // end of method ObfuscatedIterator::ObfuscatedDispose
.method private final hidebysig newslot virtual
instance bool ObfuscatedMoveNext () cil managed
{
.override method instance bool [System.Runtime]System.Collections.IEnumerator::MoveNext()
.maxstack 2
.locals init (
[0] bool,
[1] int32,
[2] class ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638
)
.try
{
IL_0000: ldarg.0
IL_0001: ldfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_0006: stloc.1
IL_0007: ldarg.0
IL_0008: ldfld class ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_owner
IL_000d: stloc.2
IL_000e: ldloc.1
IL_000f: switch (IL_002b, IL_0051, IL_0075, IL_009a)
IL_0024: ldc.i4.0
IL_0025: stloc.0
IL_0026: leave IL_00ac
IL_002b: ldarg.0
IL_002c: ldc.i4.m1
IL_002d: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_0032: ldarg.0
IL_0033: ldc.i4.s -3
IL_0035: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_003a: ldarg.0
IL_003b: ldarg.0
IL_003c: ldfld object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_1
IL_0041: stfld object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_current
IL_0046: ldarg.0
IL_0047: ldc.i4.1
IL_0048: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_004d: ldc.i4.1
IL_004e: stloc.0
IL_004f: leave.s IL_00ac
IL_0051: ldarg.0
IL_0052: ldc.i4.s -3
IL_0054: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_0059: ldarg.0
IL_005a: ldloc.2
IL_005b: ldfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638::state
IL_0060: box [System.Runtime]System.Int32
IL_0065: stfld object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_current
IL_006a: ldarg.0
IL_006b: ldc.i4.2
IL_006c: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_0071: ldc.i4.1
IL_0072: stloc.0
IL_0073: leave.s IL_00ac
IL_0075: ldarg.0
IL_0076: ldc.i4.s -3
IL_0078: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_007d: ldarg.0
IL_007e: call instance void ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::ObfuscatedFinally()
IL_0083: ldarg.0
IL_0084: ldarg.0
IL_0085: ldfld object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_2
IL_008a: stfld object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_current
IL_008f: ldarg.0
IL_0090: ldc.i4.3
IL_0091: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_0096: ldc.i4.1
IL_0097: stloc.0
IL_0098: leave.s IL_00ac
IL_009a: ldarg.0
IL_009b: ldc.i4.m1
IL_009c: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_00a1: ldc.i4.0
IL_00a2: stloc.0
IL_00a3: leave.s IL_00ac
} // end .try
fault
{
IL_00a5: ldarg.0
IL_00a6: call instance void ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::ObfuscatedDispose()
IL_00ab: endfinally
} // end handler
IL_00ac: ldloc.0
IL_00ad: ret
} // end of method ObfuscatedIterator::ObfuscatedMoveNext
.method private hidebysig
instance void ObfuscatedFinally () cil managed
{
.maxstack 8
IL_0000: ldarg.0
IL_0001: ldc.i4.m1
IL_0002: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_state
IL_0007: ldarg.0
IL_0008: ldfld class ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_owner
IL_000d: ldc.i4.0
IL_000e: stfld int32 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638::state
IL_0013: ret
} // end of method ObfuscatedIterator::ObfuscatedFinally
.method private final hidebysig specialname newslot virtual
instance object 'System.Collections.Generic.IEnumerator<System.Object>.get_Current' () cil managed
{
.custom instance void [System.Runtime]System.Diagnostics.DebuggerHiddenAttribute::.ctor() = (
01 00 00 00
)
.override method instance !0 class [System.Runtime]System.Collections.Generic.IEnumerator`1<object>::get_Current()
.maxstack 8
IL_0000: ldarg.0
IL_0001: ldfld object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_current
IL_0006: ret
} // end of method ObfuscatedIterator::'System.Collections.Generic.IEnumerator<System.Object>.get_Current'
.method private final hidebysig newslot virtual
instance void System.Collections.IEnumerator.Reset () cil managed
{
.custom instance void [System.Runtime]System.Diagnostics.DebuggerHiddenAttribute::.ctor() = (
01 00 00 00
)
.override method instance void [System.Runtime]System.Collections.IEnumerator::Reset()
.maxstack 8
IL_0000: newobj instance void [System.Runtime]System.NotSupportedException::.ctor()
IL_0005: throw
} // end of method ObfuscatedIterator::System.Collections.IEnumerator.Reset
.method private final hidebysig specialname newslot virtual
instance object System.Collections.IEnumerator.get_Current () cil managed
{
.custom instance void [System.Runtime]System.Diagnostics.DebuggerHiddenAttribute::.ctor() = (
01 00 00 00
)
.override method instance object [System.Runtime]System.Collections.IEnumerator::get_Current()
.maxstack 8
IL_0000: ldarg.0
IL_0001: ldfld object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_current
IL_0006: ret
} // end of method ObfuscatedIterator::System.Collections.IEnumerator.get_Current
// Properties
.property instance object 'System.Collections.Generic.IEnumerator<System.Object>.Current'()
{
.get instance object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::'System.Collections.Generic.IEnumerator<System.Object>.get_Current'()
}
.property instance object System.Collections.IEnumerator.Current()
{
.get instance object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::System.Collections.IEnumerator.get_Current()
}
} // end of class ObfuscatedIterator
// Fields
.field private int32 state
// Methods
.method public hidebysig
instance class [System.Runtime]System.Collections.IEnumerator Test (
object arg1,
object arg2
) cil managed
{
.maxstack 8
IL_0000: ldc.i4.0
IL_0001: newobj instance void ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::.ctor(int32)
IL_0006: dup
IL_0007: ldarg.0
IL_0008: stfld class ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638 ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_owner
IL_000d: dup
IL_000e: ldarg.1
IL_000f: stfld object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_1
IL_0014: dup
IL_0015: ldarg.2
IL_0016: stfld object ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638/ObfuscatedIterator::m_2
IL_001b: ret
} // end of method Issue1638::Test
.method public hidebysig specialname rtspecialname
instance void .ctor () cil managed
{
.maxstack 8
IL_0000: ldarg.0
IL_0001: call instance void [System.Runtime]System.Object::.ctor()
IL_0006: ret
} // end of method Issue1638::.ctor
} // end of class ICSharpCode.Decompiler.Tests.TestCases.ILPretty.Issue1638

4
ICSharpCode.Decompiler/IL/ControlFlow/YieldReturnDecompiler.cs
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@ -650,7 +650,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow @@ -650,7 +650,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
BlockContainer AnalyzeMoveNext(ILFunction function)
{
context.StepStartGroup("AnalyzeMoveNext");
MethodDefinitionHandle moveNextMethod = metadata.GetTypeDefinition(enumeratorType).GetMethods().FirstOrDefault(m => metadata.GetString(metadata.GetMethodDefinition(m).Name) == "MoveNext");
MethodDefinitionHandle moveNextMethod = metadata.GetTypeDefinition(enumeratorType).GetMethods().FirstOrDefault(m => IsMethod(m, "MoveNext"));
ILFunction moveNextFunction = CreateILAst(moveNextMethod, context);
function.MoveNextMethod = moveNextFunction.Method;
@ -1303,7 +1303,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow @@ -1303,7 +1303,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
int stateAfterBranch = newState;
if (Block.GetPredecessor(branch) is Call call
&& call.Arguments.Count == 1 && call.Arguments[0].MatchLdThis()
&& call.Method.Name == "System.IDisposable.Dispose")
&& call.Method.MetadataToken == disposeMethod)
{
// pre-roslyn compiles "yield break;" into "Dispose(); goto return_false;",
// so convert the dispose call into a state transition to the final state

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