mirror of https://github.com/icsharpcode/ILSpy.git
Siegfried Pammer
6 years ago
3 changed files with 243 additions and 220 deletions
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// Copyright (c) 2018 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.Collections.Generic; |
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using System.Linq; |
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using ICSharpCode.Decompiler.FlowAnalysis; |
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using ICSharpCode.Decompiler.IL.Transforms; |
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using ICSharpCode.Decompiler.TypeSystem; |
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namespace ICSharpCode.Decompiler.IL.ControlFlow |
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{ |
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class AwaitInFinallyTransform |
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{ |
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public static void Run(ILFunction function, ILTransformContext context) |
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{ |
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if (!context.Settings.AwaitInCatchFinally) |
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return; |
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HashSet<BlockContainer> changedContainers = new HashSet<BlockContainer>(); |
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// analyze all try-catch statements in the function
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foreach (var tryCatch in function.Descendants.OfType<TryCatch>().ToArray()) { |
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if (!(tryCatch.Parent?.Parent is BlockContainer container)) |
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continue; |
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// await in finally uses a single catch block with catch-type object
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if (tryCatch.Handlers.Count != 1 || !(tryCatch.Handlers[0].Body is BlockContainer catchBlockContainer) || !tryCatch.Handlers[0].Variable.Type.IsKnownType(KnownTypeCode.Object)) |
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continue; |
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// and consists of an assignment to a temporary that is used outside the catch block
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// and a jump to the finally block
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var block = catchBlockContainer.EntryPoint; |
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if (block.Instructions.Count < 2 || !block.Instructions[0].MatchStLoc(out var globalCopyVar, out var value) || !value.MatchLdLoc(tryCatch.Handlers[0].Variable)) |
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continue; |
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if (block.Instructions.Count == 3) { |
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if (!block.Instructions[1].MatchStLoc(out var globalCopyVarTemp, out value) || !value.MatchLdLoc(globalCopyVar)) |
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continue; |
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globalCopyVar = globalCopyVarTemp; |
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} |
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if (!block.Instructions[block.Instructions.Count - 1].MatchBranch(out var entryPointOfFinally)) |
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continue; |
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// globalCopyVar should only be used once, at the end of the finally-block
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if (globalCopyVar.LoadCount != 1 || globalCopyVar.StoreCount > 2) |
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continue; |
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var tempStore = globalCopyVar.LoadInstructions[0].Parent as StLoc; |
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if (tempStore == null || !MatchExceptionCaptureBlock(tempStore, out var exitOfFinally, out var afterFinally, out var blocksToRemove)) |
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continue; |
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if (!MatchAfterFinallyBlock(ref afterFinally, blocksToRemove, out bool removeFirstInstructionInAfterFinally)) |
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continue; |
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var cfg = new ControlFlowGraph(container, context.CancellationToken); |
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var exitOfFinallyNode = cfg.GetNode(exitOfFinally); |
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var entryPointOfFinallyNode = cfg.GetNode(entryPointOfFinally); |
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var additionalBlocksInFinally = new HashSet<Block>(); |
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var invalidExits = new List<ControlFlowNode>(); |
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TraverseDominatorTree(entryPointOfFinallyNode); |
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void TraverseDominatorTree(ControlFlowNode node) |
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{ |
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if (entryPointOfFinallyNode != node) { |
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if (entryPointOfFinallyNode.Dominates(node)) |
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additionalBlocksInFinally.Add((Block)node.UserData); |
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else |
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invalidExits.Add(node); |
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} |
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if (node == exitOfFinallyNode) |
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return; |
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foreach (var child in node.DominatorTreeChildren) { |
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TraverseDominatorTree(child); |
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} |
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} |
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if (invalidExits.Any()) |
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continue; |
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context.Step("Inline finally block with await", tryCatch.Handlers[0]); |
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foreach (var blockToRemove in blocksToRemove) { |
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blockToRemove.Remove(); |
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} |
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var finallyContainer = new BlockContainer(); |
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entryPointOfFinally.Remove(); |
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if (removeFirstInstructionInAfterFinally) |
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afterFinally.Instructions.RemoveAt(0); |
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changedContainers.Add(container); |
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var outer = BlockContainer.FindClosestContainer(container.Parent); |
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if (outer != null) changedContainers.Add(outer); |
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finallyContainer.Blocks.Add(entryPointOfFinally); |
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finallyContainer.AddILRange(entryPointOfFinally); |
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exitOfFinally.Instructions.RemoveRange(tempStore.ChildIndex, 3); |
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exitOfFinally.Instructions.Add(new Leave(finallyContainer)); |
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foreach (var branchToFinally in container.Descendants.OfType<Branch>()) { |
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if (branchToFinally.TargetBlock == entryPointOfFinally) |
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branchToFinally.ReplaceWith(new Branch(afterFinally)); |
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} |
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foreach (var newBlock in additionalBlocksInFinally) { |
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newBlock.Remove(); |
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finallyContainer.Blocks.Add(newBlock); |
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finallyContainer.AddILRange(newBlock); |
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} |
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tryCatch.ReplaceWith(new TryFinally(tryCatch.TryBlock, finallyContainer).WithILRange(tryCatch.TryBlock)); |
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} |
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// clean up all modified containers
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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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/// <summary>
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/// Block finallyHead (incoming: 2) {
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/// [body of finally]
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/// stloc V_4(ldloc V_1)
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/// if (comp(ldloc V_4 == ldnull)) br afterFinally
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/// br typeCheckBlock
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/// }
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///
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/// Block typeCheckBlock (incoming: 1) {
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/// stloc S_110(isinst System.Exception(ldloc V_4))
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/// if (comp(ldloc S_110 != ldnull)) br captureBlock
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/// br throwBlock
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/// }
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///
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/// Block throwBlock (incoming: 1) {
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/// throw(ldloc V_4)
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/// }
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///
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/// Block captureBlock (incoming: 1) {
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/// callvirt Throw(call Capture(ldloc S_110))
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/// br afterFinally
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/// }
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///
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/// Block afterFinally (incoming: 2) {
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/// stloc V_1(ldnull)
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/// [after finally]
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/// }
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/// </summary>
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static bool MatchExceptionCaptureBlock(StLoc tempStore, out Block endOfFinally, out Block afterFinally, out List<Block> blocksToRemove) |
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{ |
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afterFinally = null; |
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endOfFinally = (Block)tempStore.Parent; |
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blocksToRemove = new List<Block>(); |
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int count = endOfFinally.Instructions.Count; |
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if (tempStore.ChildIndex != count - 3) |
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return false; |
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if (!(endOfFinally.Instructions[count - 2] is IfInstruction ifInst)) |
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return false; |
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if (!endOfFinally.Instructions.Last().MatchBranch(out var typeCheckBlock)) |
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return false; |
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if (!ifInst.TrueInst.MatchBranch(out afterFinally)) |
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return false; |
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// match typeCheckBlock
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if (typeCheckBlock.Instructions.Count != 3) |
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return false; |
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if (!typeCheckBlock.Instructions[0].MatchStLoc(out var castStore, out var cast) |
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|| !cast.MatchIsInst(out var arg, out var type) || !type.IsKnownType(KnownTypeCode.Exception) || !arg.MatchLdLoc(tempStore.Variable)) |
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return false; |
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if (!typeCheckBlock.Instructions[1].MatchIfInstruction(out var cond, out var jumpToCaptureBlock)) |
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return false; |
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if (!cond.MatchCompNotEqualsNull(out arg) || !arg.MatchLdLoc(castStore)) |
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return false; |
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if (!typeCheckBlock.Instructions[2].MatchBranch(out var throwBlock)) |
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return false; |
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if (!jumpToCaptureBlock.MatchBranch(out var captureBlock)) |
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return false; |
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// match throwBlock
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if (throwBlock.Instructions.Count != 1 || !throwBlock.Instructions[0].MatchThrow(out arg) || !arg.MatchLdLoc(tempStore.Variable)) |
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return false; |
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// match captureBlock
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if (captureBlock.Instructions.Count != 2) |
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return false; |
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if (!captureBlock.Instructions[1].MatchBranch(afterFinally)) |
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return false; |
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if (!(captureBlock.Instructions[0] is CallVirt callVirt) || callVirt.Method.FullName != "System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw" || callVirt.Arguments.Count != 1) |
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return false; |
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if (!(callVirt.Arguments[0] is Call call) || call.Method.FullName != "System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture" || call.Arguments.Count != 1) |
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return false; |
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if (!call.Arguments[0].MatchLdLoc(castStore)) |
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return false; |
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blocksToRemove.Add(typeCheckBlock); |
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blocksToRemove.Add(throwBlock); |
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blocksToRemove.Add(captureBlock); |
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return true; |
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} |
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static bool MatchAfterFinallyBlock(ref Block afterFinally, List<Block> blocksToRemove, out bool removeFirstInstructionInAfterFinally) |
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{ |
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removeFirstInstructionInAfterFinally = false; |
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if (afterFinally.Instructions.Count < 2) |
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return false; |
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ILVariable globalCopyVarSplitted; |
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switch (afterFinally.Instructions[0]) { |
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case IfInstruction ifInst: |
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if (ifInst.Condition.MatchCompEquals(out var load, out var ldone) && ldone.MatchLdcI4(1) && load.MatchLdLoc(out var variable)) { |
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if (!ifInst.TrueInst.MatchBranch(out var targetBlock)) |
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return false; |
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blocksToRemove.Add(afterFinally); |
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afterFinally = targetBlock; |
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return true; |
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} else if (ifInst.Condition.MatchCompNotEquals(out load, out ldone) && ldone.MatchLdcI4(1) && load.MatchLdLoc(out variable)) { |
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if (!afterFinally.Instructions[1].MatchBranch(out var targetBlock)) |
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return false; |
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blocksToRemove.Add(afterFinally); |
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afterFinally = targetBlock; |
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return true; |
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} |
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return false; |
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case LdLoc ldLoc: |
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if (ldLoc.Variable.LoadCount != 1 || ldLoc.Variable.StoreCount != 1) |
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return false; |
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if (!afterFinally.Instructions[1].MatchStLoc(out globalCopyVarSplitted, out var ldnull) || !ldnull.MatchLdNull()) |
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return false; |
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removeFirstInstructionInAfterFinally = true; |
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break; |
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case StLoc stloc: |
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globalCopyVarSplitted = stloc.Variable; |
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if (!stloc.Value.MatchLdNull()) |
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return false; |
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break; |
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default: |
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return false; |
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} |
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if (globalCopyVarSplitted.StoreCount != 1 || globalCopyVarSplitted.LoadCount != 0) |
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return false; |
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return true; |
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} |
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} |
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} |
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