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231 lines
10 KiB
231 lines
10 KiB
// Copyright (c) 2017 Siegfried Pammer |
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// |
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// Permission is hereby granted, free of charge, to any person obtaining a copy of this |
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// software and associated documentation files (the "Software"), to deal in the Software |
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// without restriction, including without limitation the rights to use, copy, modify, merge, |
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// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons |
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// to whom the Software is furnished to do so, subject to the following conditions: |
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// |
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// The above copyright notice and this permission notice shall be included in all copies or |
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// substantial portions of the Software. |
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// |
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, |
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// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR |
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE |
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// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR |
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// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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// DEALINGS IN THE SOFTWARE. |
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using System; |
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using System.Collections.Generic; |
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using System.Linq; |
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using System.Text; |
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using ICSharpCode.Decompiler.TypeSystem; |
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namespace ICSharpCode.Decompiler.IL.Transforms |
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{ |
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class SwitchOnStringTransform : IILTransform |
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{ |
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public void Run(ILFunction function, ILTransformContext context) |
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{ |
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HashSet<BlockContainer> changedContainers = new HashSet<BlockContainer>(); |
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foreach (var block in function.Descendants.OfType<Block>()) { |
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for (int i = block.Instructions.Count - 1; i >= 0; i--) { |
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SwitchInstruction newSwitch; |
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Block blockAfterSwitch = null; |
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if (!MatchLegacySwitchOnString(block.Instructions, i, out newSwitch, out blockAfterSwitch) && |
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!MatchRoslynSwitchOnString(block.Instructions, i, out newSwitch)) |
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continue; |
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if (i + 1 < block.Instructions.Count && block.Instructions[i + 1] is Branch b && blockAfterSwitch != null) { |
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block.Instructions[i + 1].ReplaceWith(new Branch(blockAfterSwitch)); |
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} |
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block.Instructions[i].ReplaceWith(newSwitch); |
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block.Instructions.RemoveAt(i - 1); |
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i--; |
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// This happens in some cases: |
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// Use correct index after transformation. |
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if (i >= block.Instructions.Count) |
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i = block.Instructions.Count; |
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} |
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if (block.Parent is BlockContainer container) |
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changedContainers.Add(container); |
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} |
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foreach (var container in changedContainers) |
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container.SortBlocks(deleteUnreachableBlocks: true); |
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} |
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bool MatchLegacySwitchOnString(InstructionCollection<ILInstruction> instructions, int i, out SwitchInstruction inst, out Block blockAfterSwitch) |
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{ |
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inst = null; |
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blockAfterSwitch = null; |
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if (i < 1) return false; |
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// match first block: checking switch-value for null |
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if (!(instructions[i].MatchIfInstruction(out var condition, out var exitBlockJump) && |
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instructions[i - 1].MatchStLoc(out var switchValueVar, out var switchValue) && switchValueVar.Type.IsKnownType(KnownTypeCode.String))) |
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return false; |
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if (!exitBlockJump.MatchBranch(out var exitBlock)) |
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return false; |
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if (!(condition.MatchCompEquals(out var left, out var right) && right.MatchLdNull() && left.Match(switchValue).Success)) |
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return false; |
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var nextBlockJump = instructions.ElementAtOrDefault(i + 1) as Branch; |
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if (nextBlockJump == null || nextBlockJump.TargetBlock.IncomingEdgeCount != 1) |
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return false; |
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// match second block: checking compiler-generated Dictionary<string, int> for null |
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var nextBlock = nextBlockJump.TargetBlock; |
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if (nextBlock.Instructions.Count != 2 || !nextBlock.Instructions[0].MatchIfInstruction(out condition, out var tryGetValueBlockJump)) |
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return false; |
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if (!tryGetValueBlockJump.MatchBranch(out var tryGetValueBlock)) |
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return false; |
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if (!nextBlock.Instructions[1].MatchBranch(out var dictInitBlock) || dictInitBlock.IncomingEdgeCount != 1) |
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return false; |
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if (!(condition.MatchCompNotEquals(out left, out right) && right.MatchLdNull() && |
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MatchDictionaryFieldLoad(left, out var dictField, out var dictionaryType))) |
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return false; |
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// match third block: initialization of compiler-generated Dictionary<string, int> |
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if (dictInitBlock.IncomingEdgeCount != 1 || dictInitBlock.Instructions.Count < 3) |
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return false; |
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if (!ExtractStringValuesFromDictionaryInitBlock(dictInitBlock, out var stringValues, tryGetValueBlock, dictionaryType, dictField)) |
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return false; |
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// match fourth block: TryGetValue on compiler-generated Dictionary<string, int> |
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if (tryGetValueBlock.IncomingEdgeCount != 2 || tryGetValueBlock.Instructions.Count != 2) |
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return false; |
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if (!tryGetValueBlock.Instructions[0].MatchIfInstruction(out condition, out var defaultBlockJump)) |
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return false; |
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if (!defaultBlockJump.MatchBranch(out var defaultBlock)) |
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return false; |
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if (!(condition.MatchLogicNot(out var arg) && arg is Call c && c.Method.Name == "TryGetValue" && |
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MatchDictionaryFieldLoad(c.Arguments[0], out var dictField2, out _) && dictField2.Equals(dictField))) |
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return false; |
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if (!c.Arguments[1].MatchLdLoc(switchValueVar) || !c.Arguments[2].MatchLdLoca(out var switchIndexVar)) |
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return false; |
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if (!tryGetValueBlock.Instructions[1].MatchBranch(out var switchBlock)) |
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return false; |
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// match fifth block: switch-instruction block |
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if (switchBlock.IncomingEdgeCount != 1 || switchBlock.Instructions.Count != 2) |
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return false; |
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if (!(switchBlock.Instructions[0] is SwitchInstruction switchInst && switchInst.Value.MatchLdLoc(switchIndexVar))) |
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return false; |
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if (!switchBlock.Instructions[1].MatchBranch(defaultBlock)) |
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return false; |
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// switch contains case null: |
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var sections = new List<SwitchSection>(switchInst.Sections); |
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if (exitBlock != defaultBlock) { |
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stringValues.Add(null); |
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sections.Add(new SwitchSection() { Labels = new Util.LongSet(stringValues.Count - 1), Body = new Branch(exitBlock) }); |
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} |
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var stringToInt = new StringToInt(switchValue.Clone(), stringValues.ToArray()); |
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inst = new SwitchInstruction(stringToInt); |
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inst.DefaultBody = switchInst.DefaultBody; |
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inst.Sections.AddRange(sections); |
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blockAfterSwitch = defaultBlock; |
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return true; |
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} |
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bool MatchDictionaryFieldLoad(ILInstruction inst, out IField dictField, out IType dictionaryType) |
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{ |
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dictField = null; |
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dictionaryType = null; |
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return inst.MatchLdObj(out var dictionaryFieldLoad, out dictionaryType) && |
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IsStringToIntDictionary(dictionaryType) && |
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dictionaryFieldLoad.MatchLdsFlda(out dictField) && |
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dictField.IsCompilerGeneratedOrIsInCompilerGeneratedClass(); |
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} |
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bool ExtractStringValuesFromDictionaryInitBlock(Block block, out List<string> values, Block targetBlock, IType dictionaryType, IField dictionaryField) |
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{ |
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values = null; |
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if (!(block.Instructions[0].MatchStLoc(out var dictVar, out var newObjDict) && |
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newObjDict is NewObj newObj && newObj.Arguments.Count == 1 && newObj.Arguments[0].MatchLdcI4(out var valuesLength))) |
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return false; |
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if (block.Instructions.Count != valuesLength + 3) |
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return false; |
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values = new List<string>(valuesLength); |
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for (int i = 0; i < valuesLength; i++) { |
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if (!(block.Instructions[i + 1] is Call c && c.Method.Name == "Add" && c.Arguments.Count == 3 && |
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c.Arguments[0].MatchLdLoc(dictVar) && c.Arguments[1].MatchLdStr(out var value) && c.Arguments[2].MatchLdcI4(i))) |
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return false; |
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values.Add(value); |
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} |
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if (!(block.Instructions[valuesLength + 1].MatchStObj(out var loadField, out var dictVarLoad, out var dictType) && |
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dictType.Equals(dictionaryType) && loadField.MatchLdsFlda(out var dictField) && dictField.Equals(dictionaryField)) && |
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dictVarLoad.MatchLdLoc(dictVar)) |
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return false; |
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return block.Instructions[valuesLength + 2].MatchBranch(targetBlock); |
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} |
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bool IsStringToIntDictionary(IType dictionaryType) |
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{ |
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if (dictionaryType.FullName != "System.Collections.Generic.Dictionary") |
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return false; |
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if (dictionaryType.TypeArguments.Count != 2) |
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return false; |
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return dictionaryType.TypeArguments[0].IsKnownType(KnownTypeCode.String) && |
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dictionaryType.TypeArguments[1].IsKnownType(KnownTypeCode.Int32); |
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} |
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bool MatchRoslynSwitchOnString(InstructionCollection<ILInstruction> instructions, int i, out SwitchInstruction inst) |
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{ |
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inst = null; |
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if (i < 1) return false; |
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if (!(instructions[i] is SwitchInstruction switchInst && switchInst.Value.MatchLdLoc(out var targetVar) && |
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MatchComputeStringHashCall(instructions[i - 1], targetVar, out var switchValue))) |
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return false; |
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var stringValues = new List<(int, string, Block)>(); |
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int index = 0; |
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foreach (var section in switchInst.Sections) { |
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if (!section.Body.MatchBranch(out Block target)) |
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return false; |
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if (target.IncomingEdgeCount != 1 || target.Instructions.Count == 0) |
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return false; |
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if (!target.Instructions[0].MatchIfInstruction(out var condition, out var bodyBranch)) |
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return false; |
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if (!MatchStringEqualityComparison(condition, switchValue.Variable, out string stringValue)) |
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return false; |
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if (!bodyBranch.MatchBranch(out Block body)) |
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return false; |
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stringValues.Add((index++, stringValue, body)); |
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} |
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var value = new StringToInt(switchValue.Clone(), stringValues.Select(item => item.Item2).ToArray()); |
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inst = new SwitchInstruction(value); |
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inst.Sections.AddRange(stringValues.Select(section => new SwitchSection { Labels = new Util.LongSet(section.Item1), Body = new Branch(section.Item3) })); |
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return true; |
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} |
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bool MatchComputeStringHashCall(ILInstruction inst, ILVariable targetVar, out LdLoc switchValue) |
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{ |
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switchValue = null; |
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if (!inst.MatchStLoc(targetVar, out var value)) |
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return false; |
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if (!(value is Call c && c.Arguments.Count == 1 && c.Method.Name == "ComputeStringHash" && c.Method.IsCompilerGeneratedOrIsInCompilerGeneratedClass())) |
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return false; |
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if (!(c.Arguments[0] is LdLoc)) |
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return false; |
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switchValue = (LdLoc)c.Arguments[0]; |
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return true; |
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} |
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bool MatchStringEqualityComparison(ILInstruction condition, ILVariable variable, out string stringValue) |
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{ |
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stringValue = null; |
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ILInstruction left, right; |
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if (condition is Call c && c.Method.IsOperator && c.Method.Name == "op_Equality" && c.Arguments.Count == 2) { |
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left = c.Arguments[0]; |
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right = c.Arguments[1]; |
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if (!right.MatchLdStr(out stringValue)) |
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return false; |
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} else if (condition.MatchCompEquals(out left, out right) && right.MatchLdNull()) { |
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} else return false; |
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return left.MatchLdLoc(variable); |
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} |
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} |
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}
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