From 1d1b29e24a903817138893155f94ebac72692994 Mon Sep 17 00:00:00 2001 From: Daniel Beaupre Date: Fri, 29 May 2026 16:28:31 -0400 Subject: [PATCH] Add opt-in SortSwitchSections setting (#3749). When enabled, switch sections are ordered by their case label value instead of by the underlying branch's IL offset. Default is false to keep existing output unchanged. Useful when diffing decompiler output across rebuilds of obfuscated assemblies, where IL block layout is unstable but the case-to-value mapping is not. Includes an ILPretty test that exercises a hand-written switch whose table targets are placed at non-monotonic IL offsets (simulating obfuscator block shuffling) and verifies the cases come out in label-value order with the setting enabled. Also adds the Resources.resx / Resources.Designer.cs entry so the WPF settings UI shows a proper label instead of the raw key. Co-Authored-By: Claude Opus 4.7 (1M context) --- .../ILPrettyTestRunner.cs | 6 ++ .../TestCases/ILPretty/SortSwitchSections.cs | 35 ++++++++++ .../TestCases/ILPretty/SortSwitchSections.il | 64 +++++++++++++++++++ ICSharpCode.Decompiler/DecompilerSettings.cs | 20 ++++++ .../IL/ControlFlow/SwitchDetection.cs | 23 ++++--- ILSpy/Properties/Resources.Designer.cs | 11 +++- ILSpy/Properties/Resources.resx | 3 + 7 files changed, 153 insertions(+), 9 deletions(-) create mode 100644 ICSharpCode.Decompiler.Tests/TestCases/ILPretty/SortSwitchSections.cs create mode 100644 ICSharpCode.Decompiler.Tests/TestCases/ILPretty/SortSwitchSections.il diff --git a/ICSharpCode.Decompiler.Tests/ILPrettyTestRunner.cs b/ICSharpCode.Decompiler.Tests/ILPrettyTestRunner.cs index 6ffefade4c..1d6c29e16e 100644 --- a/ICSharpCode.Decompiler.Tests/ILPrettyTestRunner.cs +++ b/ICSharpCode.Decompiler.Tests/ILPrettyTestRunner.cs @@ -339,6 +339,12 @@ public async Task ExtensionEncodingV2() await Run(); } + [Test] + public async Task SortSwitchSections() + { + await Run(settings: new DecompilerSettings { SortSwitchSections = true, FileScopedNamespaces = false }); + } + async Task Run([CallerMemberName] string testName = null, DecompilerSettings settings = null, AssemblerOptions assemblerOptions = AssemblerOptions.Library) { diff --git a/ICSharpCode.Decompiler.Tests/TestCases/ILPretty/SortSwitchSections.cs b/ICSharpCode.Decompiler.Tests/TestCases/ILPretty/SortSwitchSections.cs new file mode 100644 index 0000000000..2b0c1b0b72 --- /dev/null +++ b/ICSharpCode.Decompiler.Tests/TestCases/ILPretty/SortSwitchSections.cs @@ -0,0 +1,35 @@ +// Copyright (c) AlphaSierraPapa for the SharpDevelop Team +// +// Permission is hereby granted, free of charge, to any person obtaining a copy of this +// software and associated documentation files (the "Software"), to deal in the Software +// without restriction, including without limitation the rights to use, copy, modify, merge, +// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons +// to whom the Software is furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in all copies or +// substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, +// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR +// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE +// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR +// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +// DEALINGS IN THE SOFTWARE. + +namespace ICSharpCode.Decompiler.Tests.TestCases.ILPretty +{ + public static class SortSwitchSections + { + public static int PickValue(int n) + { + return n switch { + 0 => 100, + 1 => 200, + 2 => 300, + 3 => 400, + 4 => 500, + _ => -1, + }; + } + } +} diff --git a/ICSharpCode.Decompiler.Tests/TestCases/ILPretty/SortSwitchSections.il b/ICSharpCode.Decompiler.Tests/TestCases/ILPretty/SortSwitchSections.il new file mode 100644 index 0000000000..a76bf07598 --- /dev/null +++ b/ICSharpCode.Decompiler.Tests/TestCases/ILPretty/SortSwitchSections.il @@ -0,0 +1,64 @@ +// Test fixture for the SortSwitchSections decompiler setting. +// +// The IL `switch` table targets are placed at non-monotonic offsets, +// simulating obfuscator block-reordering. With SortSwitchSections=false +// (default) the decompiler would emit cases in IL-offset order (3, 0, 4, 1, 2); +// with the setting enabled they are emitted in label-value order (0..4). +// The matching .cs file is the expected output with the setting enabled. + +.assembly extern mscorlib +{ + .publickeytoken = (B7 7A 5C 56 19 34 E0 89 ) + .ver 4:0:0:0 +} +.assembly SortSwitchSections +{ + .ver 1:0:0:0 +} +.module SortSwitchSections.dll +.imagebase 0x10000000 +.file alignment 0x00000200 +.stackreserve 0x00100000 +.subsystem 0x0003 // WINDOWS_CUI +.corflags 0x00000001 // ILONLY + +.class public auto ansi abstract sealed beforefieldinit ICSharpCode.Decompiler.Tests.TestCases.ILPretty.SortSwitchSections + extends [mscorlib]System.Object +{ + .method public hidebysig static int32 PickValue(int32 n) cil managed + { + .maxstack 1 + IL_0000: ldarg.0 + IL_0001: switch ( + LBL_0, + LBL_1, + LBL_2, + LBL_3, + LBL_4) + IL_001a: br.s LBL_DEFAULT + + LBL_3: + IL_001c: ldc.i4 400 + IL_0021: ret + + LBL_0: + IL_0022: ldc.i4 100 + IL_0027: ret + + LBL_4: + IL_0028: ldc.i4 500 + IL_002d: ret + + LBL_1: + IL_002e: ldc.i4 200 + IL_0033: ret + + LBL_2: + IL_0034: ldc.i4 300 + IL_0039: ret + + LBL_DEFAULT: + IL_003a: ldc.i4.m1 + IL_003b: ret + } +} diff --git a/ICSharpCode.Decompiler/DecompilerSettings.cs b/ICSharpCode.Decompiler/DecompilerSettings.cs index e9aeefb733..c9da954d68 100644 --- a/ICSharpCode.Decompiler/DecompilerSettings.cs +++ b/ICSharpCode.Decompiler/DecompilerSettings.cs @@ -2375,6 +2375,26 @@ public bool SortCustomAttributes { } } + bool sortSwitchSections = false; + + /// + /// Sort switch sections by their label value instead of by IL offset. + /// Useful when diffing decompiler output across rebuilds of obfuscated assemblies, + /// where IL block layout is unstable but the case-to-value mapping is not. + /// + [Category("DecompilerSettings.Other")] + [Description("DecompilerSettings.SortSwitchSections")] + public bool SortSwitchSections { + get { return sortSwitchSections; } + set { + if (sortSwitchSections != value) + { + sortSwitchSections = value; + OnPropertyChanged(); + } + } + } + bool checkForOverflowUnderflow = false; /// diff --git a/ICSharpCode.Decompiler/IL/ControlFlow/SwitchDetection.cs b/ICSharpCode.Decompiler/IL/ControlFlow/SwitchDetection.cs index 29d16e1ccf..edc2d43b93 100644 --- a/ICSharpCode.Decompiler/IL/ControlFlow/SwitchDetection.cs +++ b/ICSharpCode.Decompiler/IL/ControlFlow/SwitchDetection.cs @@ -208,7 +208,7 @@ void ProcessBlock(Block block, ref bool blockContainerNeedsCleanup) controlFlowGraph = null; // control flow graph is no-longer valid blockContainerNeedsCleanup = true; - SortSwitchSections(sw); + SortSwitchSections(sw, context); } else { @@ -249,16 +249,23 @@ internal static void SimplifySwitchInstruction(Block block, ILTransformContext c return false; }); AdjustLabels(sw, context); - SortSwitchSections(sw); + SortSwitchSections(sw, context); } - static void SortSwitchSections(SwitchInstruction sw) + static void SortSwitchSections(SwitchInstruction sw, ILTransformContext context) { - sw.Sections.ReplaceList(sw.Sections.OrderBy(s => s.Body switch { - Branch b => b.TargetILOffset, - Leave l => l.StartILOffset, - _ => (int?)null - }).ThenBy(s => s.Labels.Values.FirstOrDefault())); + if (context.Settings.SortSwitchSections) + { + sw.Sections.ReplaceList(sw.Sections.OrderBy(s => s.Labels.Values.FirstOrDefault())); + } + else + { + sw.Sections.ReplaceList(sw.Sections.OrderBy(s => s.Body switch { + Branch b => b.TargetILOffset, + Leave l => l.StartILOffset, + _ => (int?)null + }).ThenBy(s => s.Labels.Values.FirstOrDefault())); + } } static void AdjustLabels(SwitchInstruction sw, ILTransformContext context) diff --git a/ILSpy/Properties/Resources.Designer.cs b/ILSpy/Properties/Resources.Designer.cs index ba7df50e34..a3f3f8f0f3 100644 --- a/ILSpy/Properties/Resources.Designer.cs +++ b/ILSpy/Properties/Resources.Designer.cs @@ -1405,7 +1405,16 @@ public static string DecompilerSettings_SortCustomAttributes { return ResourceManager.GetString("DecompilerSettings.SortCustomAttributes", resourceCulture); } } - + + /// + /// Looks up a localized string similar to Sort switch sections by case label value. + /// + public static string DecompilerSettings_SortSwitchSections { + get { + return ResourceManager.GetString("DecompilerSettings.SortSwitchSections", resourceCulture); + } + } + /// /// Looks up a localized string similar to Detect switch on integer even if IL code does not use a jump table. /// diff --git a/ILSpy/Properties/Resources.resx b/ILSpy/Properties/Resources.resx index 5accafe41c..3b94c69b85 100644 --- a/ILSpy/Properties/Resources.resx +++ b/ILSpy/Properties/Resources.resx @@ -489,6 +489,9 @@ Are you sure you want to continue? Sort custom attributes + + Sort switch sections by case label value + Detect switch on integer even if IL code does not use a jump table