mirror of https://github.com/icsharpcode/ILSpy.git
Daniel Grunwald
9 years ago
3 changed files with 0 additions and 239 deletions
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@@ -1,237 +0,0 @@
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// Copyright (c) 2014 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.Collections.Generic; |
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using System.Diagnostics; |
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using System.Linq; |
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using Mono.Cecil; |
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namespace ICSharpCode.Decompiler.IL |
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{ |
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/// <summary>
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/// Visitor that applies a list of transformations to the IL Ast.
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/// TODO: do we still need this, now that inlining is reverted back to the old ILInlining?
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/// </summary>
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/// <remarks>
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/// The base class performs:
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/// - variable inlining
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/// - cleanup after branch inlining
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/// - removal of unnecessary blocks and block containers
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/// </remarks>
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public class TransformingVisitor : ILVisitor<ILInstruction>, IILTransform |
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{ |
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public void Run(ILFunction function, ILTransformContext context) |
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{ |
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function.AcceptVisitor(this); |
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} |
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protected override ILInstruction Default(ILInstruction inst) |
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{ |
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foreach (var child in inst.Children) { |
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child.ReplaceWith(child.AcceptVisitor(this)); |
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} |
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return inst; |
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} |
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/* |
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protected internal override ILInstruction VisitBranch(Branch inst) |
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{ |
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// If this branch is the only edge to the target block, we can inline the target block here:
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if (inst.TargetBlock.IncomingEdgeCount == 1 && inst.PopCount == 0) { |
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return inst.TargetBlock; |
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} |
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return base.VisitBranch(inst); |
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} |
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*/ |
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protected bool removeNops = true; |
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/* |
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sealed class InliningStack : Stack<ILInstruction>, IInlineContext |
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{ |
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/// <summary>
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/// Indicates whether inlining was success for at least one
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/// peek or pop instruction.
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/// </summary>
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internal bool didInline; |
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/// <summary>
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/// Indicates whether inlining encountered a peek or pop instruction
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/// that could not be inlined.
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/// </summary>
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internal bool error; |
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ILInstruction IInlineContext.Peek(InstructionFlags flagsBefore) |
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{ |
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error = true; |
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return null; |
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} |
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ILInstruction IInlineContext.Pop(InstructionFlags flagsBefore) |
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{ |
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if (error) |
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return null; |
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if (base.Count > 0 && SemanticHelper.MayReorder(flagsBefore, base.Peek().Flags)) { |
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didInline = true; |
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return base.Pop(); |
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} |
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error = true; |
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return null; |
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} |
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} |
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ILInstruction DoInline(InliningStack stack, ILInstruction inst) |
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{ |
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do { |
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inst = inst.AcceptVisitor(this); |
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stack.didInline = false; |
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stack.error = false; |
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inst = inst.Inline(InstructionFlags.None, stack); |
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// An error implies that a peek or pop instruction wasn't replaced
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// But even if we replaced all peek/pop instructions, we might have replaced them with
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// another peek or pop instruction, so MayPeek/MayPop might still be set after
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// we finish without error!
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Debug.Assert(!stack.error || inst.HasFlag(InstructionFlags.MayPeek | InstructionFlags.MayPop)); |
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} while (stack.didInline); // repeat transformations when something was inlined
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return inst; |
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} |
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protected internal override ILInstruction VisitBlock(Block block) |
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{ |
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var stack = new InliningStack(); |
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List<ILInstruction> output = new List<ILInstruction>(); |
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for (int i = 0; i < block.Instructions.Count; i++) { |
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var inst = block.Instructions[i]; |
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if (removeNops && inst.OpCode == OpCode.Nop) |
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continue; |
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inst = DoInline(stack, inst); |
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if (inst.HasFlag(InstructionFlags.MayBranch | InstructionFlags.MayPop |
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| InstructionFlags.MayReadEvaluationStack | InstructionFlags.MayWriteEvaluationStack)) { |
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// Values currently on the stack might be used on both sides of the branch,
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// so we can't inline them.
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// We also have to flush the stack if the instruction still accesses the evaluation stack,
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// no matter whether in phase-1 or phase-2.
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FlushInstructionStack(stack, output); |
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} else if (inst.ResultType == StackType.Void && stack.Count > 0) { |
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// For void instructions on non-empty stack, we can create a new inline block (or add to an existing one)
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// This works even when inst involves Peek.
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// ILInstruction headInst = stack.Pop();
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// Block inlineBlock = headInst as Block;
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// if (inlineBlock == null || inlineBlock.FinalInstruction.OpCode != OpCode.Pop) {
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// inlineBlock = new Block {
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// Instructions = { headInst },
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// ILRange = new Interval(headInst.ILRange.Start, headInst.ILRange.Start),
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// FinalInstruction = new Pop(headInst.ResultType)
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// };
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// }
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// inlineBlock.Instructions.Add(inst);
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// inst = inlineBlock;
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} |
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if (inst.HasFlag(InstructionFlags.MayPeek)) { |
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// Prevent instruction from being inlined if it was peeked at.
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FlushInstructionStack(stack, output); |
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} |
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if (inst.ResultType == StackType.Void) { |
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// We can't add void instructions to the stack, so flush the stack
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// and directly add the instruction to the output.
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FlushInstructionStack(stack, output); |
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output.Add(inst); |
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} else { |
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// Instruction has a result, so we can push it on the stack normally
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stack.Push(inst); |
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} |
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} |
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// Allow inlining into the final instruction
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if (block.FinalInstruction.OpCode == OpCode.Pop && stack.Count > 0 && IsInlineBlock(stack.Peek())) { |
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// Don't inline an inline block into the final pop instruction:
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// doing so would result in infinite recursion.
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} else { |
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// regular inlining into the final instruction
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block.FinalInstruction = DoInline(stack, block.FinalInstruction); |
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} |
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FlushInstructionStack(stack, output); |
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block.Instructions.ReplaceList(output); |
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if (!(block.Parent is BlockContainer)) { |
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return TrySimplifyBlock(block); |
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} |
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return block; |
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} |
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bool IsInlineBlock(ILInstruction inst) |
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{ |
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Block block = inst as Block; |
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return block != null && block.FinalInstruction.OpCode == OpCode.Pop; |
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} |
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void FlushInstructionStack(Stack<ILInstruction> stack, List<ILInstruction> output) |
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{ |
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foreach (var inst in stack.Reverse()) { |
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AddToOutput(inst, output); |
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} |
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stack.Clear(); |
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} |
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void AddToOutput(ILInstruction inst, List<ILInstruction> output) |
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{ |
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// Unpack inline blocks that would become direct children of the parent block
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if (IsInlineBlock(inst)) { |
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foreach (var nestedInst in ((Block)inst).Instructions) { |
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AddToOutput(nestedInst, output); |
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} |
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} else { |
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output.Add(inst); |
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} |
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} |
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*/ |
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protected internal override ILInstruction VisitBlockContainer(BlockContainer container) |
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{ |
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foreach (var block in container.Blocks) { |
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block.ReplaceWith(block.AcceptVisitor(this)); |
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} |
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// VisitBranch() 'steals' blocks from containers. Remove all blocks that were stolen from the block list:
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// Debug.Assert(container.EntryPoint.IncomingEdgeCount > 0);
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// container.Blocks.RemoveAll(b => b.IncomingEdgeCount == 0);
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// If the container only contains a single block, and the block contents do not jump back to the block start,
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// we can remove the container.
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if (container.Blocks.Count == 1 && container.LeaveCount == 0 && container.EntryPoint.IncomingEdgeCount == 1) { |
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return TrySimplifyBlock(container.EntryPoint); |
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} |
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return container; |
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} |
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/// <summary>
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/// If a block has only one instruction, replace it with that instruction.
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/// </summary>
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ILInstruction TrySimplifyBlock(Block block) |
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{ |
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// If the block has only one instruction, we can remove the block too
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// (but only if this doesn't change the pop-order in the phase 1 evaluation of the parent block)
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if (block.Instructions.Count == 0) { |
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return block.FinalInstruction; |
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} else if (block.Instructions.Count == 1 && block.FinalInstruction.OpCode == OpCode.Nop) { |
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if (block.Instructions[0].ResultType == StackType.Void) |
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return block.Instructions[0]; |
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} |
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return block; |
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} |
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} |
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} |
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