mirror of https://github.com/icsharpcode/ILSpy.git
Daniel Grunwald
8 years ago
11 changed files with 430 additions and 44 deletions
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@@ -0,0 +1,159 @@
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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 System.Text; |
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using System.Threading.Tasks; |
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using ICSharpCode.Decompiler.TypeSystem; |
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namespace ICSharpCode.Decompiler.IL.Transforms |
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{ |
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class NullableLiftingTransform |
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{ |
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public static void Run(IfInstruction inst, ILTransformContext context) |
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{ |
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// if (call Nullable<inputUType>.get_HasValue(ldloca v))
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// newobj Nullable<utype>.ctor(...)
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// else
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// default.value System.Nullable<utype>[[System.Int32]]
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if (MatchHasValueCall(inst.Condition, out var v) |
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&& MatchNullableCtor(inst.TrueInst, out var utype, out var arg) |
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&& MatchNull(inst.FalseInst, utype)) |
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{ |
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ILInstruction lifted; |
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if (MatchGetValueOrDefault(arg, v)) { |
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// v != null ? call GetValueOrDefault(ldloca v) : null
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// => conv.nop.lifted(ldloc v)
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// This case is handled separately from LiftUnary() because
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// that doesn't introduce nop-conversions.
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context.Step("if => conv.nop.lifted", inst); |
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var inputUType = NullableType.GetUnderlyingType(v.Type); |
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lifted = new Conv(new LdLoc(v), inputUType.GetStackType(), inputUType.GetSign(), utype.ToPrimitiveType(), false) { |
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IsLifted = true, |
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ILRange = inst.ILRange |
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}; |
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} else { |
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lifted = LiftUnary(arg, v, context); |
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} |
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if (lifted != null) { |
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Debug.Assert(IsLifted(lifted)); |
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inst.ReplaceWith(lifted); |
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} |
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} |
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} |
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/// <summary>
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/// Lifting for unary expressions.
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/// Recurses into the instruction and checks that everything can be lifted,
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/// and that the chain ends with `call GetValueOrDefault(ldloca inputVar)`.
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/// </summary>
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static ILInstruction LiftUnary(ILInstruction inst, ILVariable inputVar, ILTransformContext context) |
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{ |
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if (MatchGetValueOrDefault(inst, inputVar)) { |
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// We found the end: the whole chain can be lifted.
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context.Step("NullableLiftingTransform.LiftUnary", inst); |
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return new LdLoc(inputVar) { ILRange = inst.ILRange }; |
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} else if (inst is Conv conv) { |
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var arg = LiftUnary(conv.Argument, inputVar, context); |
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if (arg != null) { |
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conv.Argument = arg; |
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conv.IsLifted = true; |
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return conv; |
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} |
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} |
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return null; |
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} |
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static bool IsLifted(ILInstruction inst) |
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{ |
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return inst is ILiftableInstruction liftable && liftable.IsLifted; |
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} |
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#region Match...Call
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/// <summary>
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/// Matches 'call get_HasValue(ldloca v)'
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/// </summary>
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static bool MatchHasValueCall(ILInstruction inst, out ILVariable v) |
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{ |
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v = null; |
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if (!(inst is Call call)) |
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return false; |
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if (call.Arguments.Count != 1) |
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return false; |
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if (call.Method.Name != "get_HasValue") |
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return false; |
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if (call.Method.DeclaringTypeDefinition?.KnownTypeCode != KnownTypeCode.NullableOfT) |
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return false; |
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return call.Arguments[0].MatchLdLoca(out v); |
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} |
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/// <summary>
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/// Matches 'newobj Nullable{underlyingType}.ctor(arg)'
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/// </summary>
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static bool MatchNullableCtor(ILInstruction inst, out IType underlyingType, out ILInstruction arg) |
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{ |
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underlyingType = null; |
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arg = null; |
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if (!(inst is NewObj newobj)) |
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return false; |
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if (!newobj.Method.IsConstructor || newobj.Arguments.Count != 1) |
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return false; |
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if (newobj.Method.DeclaringTypeDefinition?.KnownTypeCode != KnownTypeCode.NullableOfT) |
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return false; |
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arg = newobj.Arguments[0]; |
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underlyingType = NullableType.GetUnderlyingType(newobj.Method.DeclaringType); |
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return true; |
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} |
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/// <summary>
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/// Matches 'call Nullable{T}.GetValueOrDefault(arg)'
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/// </summary>
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static bool MatchGetValueOrDefault(ILInstruction inst, out ILInstruction arg) |
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{ |
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arg = null; |
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if (!(inst is Call call)) |
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return false; |
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if (call.Method.Name != "GetValueOrDefault" || call.Arguments.Count != 1) |
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return false; |
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if (call.Method.DeclaringTypeDefinition?.KnownTypeCode != KnownTypeCode.NullableOfT) |
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return false; |
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arg = call.Arguments[0]; |
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return true; |
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} |
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/// <summary>
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/// Matches 'call Nullable{T}.GetValueOrDefault(ldloca v)'
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/// </summary>
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static bool MatchGetValueOrDefault(ILInstruction inst, out ILVariable v) |
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{ |
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v = null; |
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return MatchGetValueOrDefault(inst, out ILInstruction arg) |
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&& arg.MatchLdLoca(out v); |
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} |
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/// <summary>
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/// Matches 'call Nullable{T}.GetValueOrDefault(ldloca v)'
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/// </summary>
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static bool MatchGetValueOrDefault(ILInstruction inst, ILVariable v) |
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{ |
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return MatchGetValueOrDefault(inst, out ILVariable v2) && v == v2; |
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} |
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static bool MatchNull(ILInstruction inst, out IType underlyingType) |
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{ |
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underlyingType = null; |
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if (inst.MatchDefaultValue(out IType type)) { |
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underlyingType = NullableType.GetUnderlyingType(type); |
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return NullableType.IsNullable(type); |
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} |
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underlyingType = null; |
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return false; |
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} |
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static bool MatchNull(ILInstruction inst, IType underlyingType) |
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{ |
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return MatchNull(inst, out var utype) && utype.Equals(underlyingType); |
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} |
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#endregion
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} |
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} |
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