mirror of https://github.com/icsharpcode/ILSpy.git
Siegfried Pammer
8 years ago
3 changed files with 180 additions and 101 deletions
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// 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 ICSharpCode.Decompiler.Util; |
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namespace ICSharpCode.Decompiler.IL |
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{ |
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public enum LoopKind { While, DoWhile, For } |
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public class DetectedLoop |
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{ |
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public BlockContainer Container { get; } |
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public LoopKind Kind { get; private set; } |
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public ILInstruction Condition { get; private set; } |
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public Block IncrementBlock { get; private set; } |
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public Block ContinueJumpTarget { get; private set; } // jumps to this block are "continue;" jumps
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public ILInstruction Body { get; private set; } // null in case of DoWhile
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public Block[] AdditionalBlocks { get; private set; } // blocks to be merged into the loop body
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private DetectedLoop(BlockContainer container) |
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{ |
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this.Container = container; |
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} |
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/// <summary>
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/// Gets whether the statement is 'simple' (usable as for loop iterator):
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/// Currently we only accept calls and assignments.
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/// </summary>
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private static bool IsSimpleStatement(ILInstruction inst) |
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{ |
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switch (inst.OpCode) { |
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case OpCode.Call: |
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case OpCode.CallVirt: |
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case OpCode.NewObj: |
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case OpCode.StLoc: |
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case OpCode.StObj: |
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case OpCode.CompoundAssignmentInstruction: |
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return true; |
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default: |
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return false; |
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} |
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} |
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public static DetectedLoop DetectLoop(BlockContainer container) |
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{ |
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return new DetectedLoop(container).DetectLoopInternal(); |
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} |
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private static Block FindDoWhileConditionBlock(BlockContainer container, out ILInstruction condition) |
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{ |
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condition = null; |
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foreach (var b in container.Blocks) { |
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if (b.Instructions.Last().MatchBranch(container.EntryPoint)) { |
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// potentially the do-while-condition block
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int i = b.Instructions.Count - 2; |
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while (i >= 0 && b.Instructions[i] is IfInstruction ifInst |
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&& ifInst.TrueInst.MatchLeave(container) && ifInst.FalseInst.MatchNop()) { |
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if (condition == null) |
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condition = new LogicNot(ifInst.Condition); |
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else |
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condition = IfInstruction.LogicAnd(new LogicNot(ifInst.Condition), condition); |
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i--; |
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} |
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if (i == -1) { |
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return b; |
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} |
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} |
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} |
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return null; |
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} |
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private DetectedLoop DetectLoopInternal() |
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{ |
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Kind = LoopKind.While; |
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ContinueJumpTarget = Container.EntryPoint; |
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if (Container.EntryPoint.Instructions.Count == 2 |
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&& Container.EntryPoint.Instructions[0].MatchIfInstruction(out var conditionInst, out var trueInst) |
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&& Container.EntryPoint.Instructions[1].MatchLeave(Container)) { |
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// detected while(condition)-loop or for-loop
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// we have to check if there's an increment block before converting the loop body using ConvertAsBlock(trueInst)
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// and set the continueJumpTarget to correctly convert 'br incrementBlock' instructions to continue;
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IncrementBlock = null; |
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if (Container.EntryPoint.IncomingEdgeCount == 2) { |
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IncrementBlock = Container.Blocks.SingleOrDefault( |
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b => b.Instructions.Last().MatchBranch(Container.EntryPoint) |
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&& b.Instructions.SkipLast(1).All(IsSimpleStatement)); |
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if (IncrementBlock != null) |
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ContinueJumpTarget = IncrementBlock; |
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} |
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Condition = conditionInst; |
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Body = trueInst; |
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if (IncrementBlock != null) { |
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// for-loop
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Kind = LoopKind.For; |
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AdditionalBlocks = Container.Blocks.Skip(1).Where(b => b != IncrementBlock).ToArray(); |
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} else { |
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AdditionalBlocks = Container.Blocks.Skip(1).ToArray(); |
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} |
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} else { |
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// do-while or while(true)-loop
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if (Container.EntryPoint.IncomingEdgeCount == 2) { |
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Block conditionBlock = FindDoWhileConditionBlock(Container, out var conditionInst2); |
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if (conditionBlock != null) { |
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Kind = LoopKind.DoWhile; |
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ContinueJumpTarget = conditionBlock; |
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Body = null; |
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Condition = conditionInst2; |
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AdditionalBlocks = Container.Blocks.Where(b => b != conditionBlock).ToArray(); |
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} |
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} |
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} |
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return this; |
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} |
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} |
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} |
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