mirror of
https://github.com/icsharpcode/ILSpy.git
synced 2026-10-12 02:15:58 +00:00
Daniel Grunwald
5526400b17
Change InferType() to an abstract method and implement for every ILInstruction. With this change, we now always have enough information to create a variable of an appropriate type to store the result of evaluating the instruction. This previously was not the case for instructions producing "other value type", for which the stacktype-based fallback incorrectly produced `object`.
79 lines
3.1 KiB
C#
79 lines
3.1 KiB
C#
// Copyright (c) 2019 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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namespace ICSharpCode.Decompiler.IL.Transforms
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{
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class CombineExitsTransform : IILTransform
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{
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public void Run(ILFunction function, ILTransformContext context)
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{
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if (!(function.Body is BlockContainer container && container.Blocks.Count == 1))
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return;
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var combinedExit = CombineExits(container.EntryPoint);
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if (combinedExit == null)
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return;
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ExpressionTransforms.RunOnSingleStatement(combinedExit, context);
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}
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static Leave CombineExits(Block block)
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{
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if (!(block.Instructions.SecondToLastOrDefault() is IfInstruction ifInst && block.Instructions.LastOrDefault() is Leave leaveElse))
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return null;
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if (!ifInst.FalseInst.MatchNop())
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return null;
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// try to unwrap true branch to single instruction:
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var trueInstruction = Block.Unwrap(ifInst.TrueInst);
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// if the true branch is a block with multiple instructions:
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// try to apply the combine exits transform to the nested block
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// and then continue on that transformed block.
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// Example:
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// if (cond) {
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// if (cond2) {
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// leave (value)
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// }
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// leave (value2)
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// }
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// leave (value3)
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// =>
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// leave (if (cond) value else if (cond2) value2 else value3)
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if (trueInstruction is Block nestedBlock && nestedBlock.Instructions.Count == 2)
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trueInstruction = CombineExits(nestedBlock);
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if (!(trueInstruction is Leave leave))
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return null;
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if (!(leave.IsLeavingFunction && leaveElse.IsLeavingFunction))
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return null;
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if (leave.Value.MatchNop() || leaveElse.Value.MatchNop())
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return null;
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// if (cond) {
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// leave (value)
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// }
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// leave (elseValue)
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// =>
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// leave (if (cond) value else elseValue)
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IfInstruction value = new IfInstruction(ifInst.Condition, leave.Value, leaveElse.Value, leave.TargetContainer.ExpectedResultType);
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value.AddILRange(ifInst);
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Leave combinedLeave = new Leave(leave.TargetContainer, value);
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combinedLeave.AddILRange(leaveElse);
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combinedLeave.AddILRange(leave);
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ifInst.ReplaceWith(combinedLeave);
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block.Instructions.RemoveAt(combinedLeave.ChildIndex + 1);
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return combinedLeave;
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}
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}
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}
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