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This transform interleaves statement-combining transforms so that nested structures can be detected better.pull/881/merge
Daniel Grunwald
8 years ago
15 changed files with 264 additions and 113 deletions
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// Copyright (c) 2017 Daniel Grunwald
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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.Diagnostics; |
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namespace ICSharpCode.Decompiler.IL.Transforms |
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{ |
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/// <summary>
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/// IL transform that runs on a sequence of statements within a block.
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/// </summary>
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/// <remarks>
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/// Interleaving different statement-combining transforms on a per-statement level
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/// improves detection of nested constructs.
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/// For example, array initializers can assume that each element assignment was already
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/// reduced to a single statement, even if the element contains a high-level construct
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/// detected by a different transform (e.g. object initializer).
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/// </remarks>
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public interface IStatementTransform |
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{ |
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/// <summary>
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/// Runs the transform on the statements within a block.
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///
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/// Note: the transform may only modify block.Instructions[pos..].
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/// The transform will be called repeatedly for pos=block.Instructions.Count-1, pos=block.Instructions.Count-2, ..., pos=0.
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/// </summary>
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/// <param name="block">The current block.</param>
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/// <param name="pos">The starting position where the transform is allowed to work.</param>
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/// <param name="context">Additional parameters.</param>
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/// <remarks>
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/// Instructions prior to block.Instructions[pos] must not be modified.
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/// It is valid to read such instructions, but not recommended as those have not been transformed yet.
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/// </remarks>
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void Run(Block block, int pos, StatementTransformContext context); |
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} |
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/// <summary>
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/// Parameter class holding various arguments for <see cref="IStatementTransform.Run"/>.
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/// </summary>
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public class StatementTransformContext : ILTransformContext |
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{ |
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public BlockTransformContext BlockContext { get; } |
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public StatementTransformContext(BlockTransformContext blockContext) : base(blockContext) |
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{ |
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this.BlockContext = blockContext ?? throw new ArgumentNullException(nameof(blockContext)); |
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} |
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/// <summary>
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/// Gets the block on which the transform is running.
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/// </summary>
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public Block Block => BlockContext.Block; |
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internal bool rerunCurrentPosition; |
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internal int? rerunPosition; |
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/// <summary>
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/// After the current statement transform has completed,
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/// do not continue with the next statement transform at the same position.
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/// Instead, re-run all statement transforms (including the current transform) starting at the specified position.
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/// </summary>
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public void RequestRerun(int pos) |
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{ |
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if (rerunPosition == null || pos > rerunPosition) { |
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rerunPosition = pos; |
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} |
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} |
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/// <summary>
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/// After the current statement transform has completed,
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/// repeat all statement transforms on the current position.
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/// </summary>
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public void RequestRerun() |
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{ |
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rerunCurrentPosition = true; |
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} |
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} |
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/// <summary>
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/// Block transform that runs a list of statement transforms.
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/// </summary>
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public class StatementTransform : IBlockTransform |
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{ |
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readonly IStatementTransform[] children; |
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public StatementTransform(params IStatementTransform[] children) |
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{ |
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this.children = children; |
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} |
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public void Run(Block block, BlockTransformContext context) |
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{ |
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var ctx = new StatementTransformContext(context); |
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int pos = 0; |
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ctx.rerunPosition = block.Instructions.Count - 1; |
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while (pos >= 0) { |
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if (ctx.rerunPosition != null) { |
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Debug.Assert(ctx.rerunPosition >= pos); |
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#if DEBUG
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for (; pos < ctx.rerunPosition; ++pos) { |
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block.Instructions[pos].ResetDirty(); |
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} |
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#else
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pos = ctx.rerunPosition.Value; |
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#endif
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Debug.Assert(pos == ctx.rerunPosition); |
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ctx.rerunPosition = null; |
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} |
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foreach (var transform in children) { |
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transform.Run(block, pos, ctx); |
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block.CheckInvariant(ILPhase.Normal); |
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#if DEBUG
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for (int i = 0; i < pos; ++i) { |
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Debug.Assert(!block.Instructions[i].IsDirty, $"{transform.GetType().Name} modified an instruction before pos"); |
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} |
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#endif
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if (ctx.rerunCurrentPosition) { |
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ctx.rerunCurrentPosition = false; |
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ctx.RequestRerun(pos); |
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} |
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if (ctx.rerunPosition != null) { |
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break; |
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} |
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} |
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if (ctx.rerunPosition == null) { |
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pos--; |
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} |
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} |
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} |
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} |
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} |
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