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548 lines
22 KiB
548 lines
22 KiB
// Copyright (c) 2015 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; |
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using System.Diagnostics; |
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using System.Linq; |
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using ICSharpCode.Decompiler.TypeSystem; |
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using ICSharpCode.Decompiler.TypeSystem.Implementation; |
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using ICSharpCode.Decompiler.Util; |
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namespace ICSharpCode.Decompiler.IL.Transforms |
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{ |
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/// <summary> |
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/// Constructs compound assignments and inline assignments. |
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/// </summary> |
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public class TransformAssignment : IStatementTransform |
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{ |
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StatementTransformContext context; |
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void IStatementTransform.Run(Block block, int pos, StatementTransformContext context) |
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{ |
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this.context = context; |
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if (TransformInlineAssignmentStObjOrCall(block, pos) || TransformInlineAssignmentLocal(block, pos)) { |
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// both inline assignments create a top-level stloc which might affect inlining |
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context.RequestRerun(); |
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return; |
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} |
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if (TransformPostIncDecOperatorWithInlineStore(block, pos) |
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|| TransformPostIncDecOperator(block, pos) |
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|| TransformPostIncDecOperatorLocal(block, pos)) |
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{ |
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// again, new top-level stloc might need inlining: |
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context.RequestRerun(); |
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return; |
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} |
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} |
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/// <code> |
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/// stloc s(value) |
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/// stloc l(ldloc s) |
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/// stobj(..., ldloc s) |
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/// where ... is pure and does not use s or l, |
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/// and where neither the 'stloc s' nor the 'stobj' truncates |
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/// --> |
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/// stloc l(stobj (..., value)) |
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/// </code> |
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/// e.g. used for inline assignment to instance field |
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/// |
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/// -or- |
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/// |
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/// <code> |
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/// stloc s(value) |
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/// stobj (..., ldloc s) |
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/// where ... is pure and does not use s, and where the 'stobj' does not truncate |
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/// --> |
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/// stloc s(stobj (..., value)) |
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/// </code> |
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/// e.g. used for inline assignment to static field |
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/// |
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/// -or- |
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/// |
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/// <code> |
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/// stloc s(value) |
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/// call set_Property(..., ldloc s) |
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/// where the '...' arguments are pure and not using 's' |
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/// --> |
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/// stloc s(Block InlineAssign { call set_Property(..., stloc i(value)); final: ldloc i }) |
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/// new temporary 'i' has type of the property; transform only valid if 'stloc i' doesn't truncate |
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/// </code> |
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bool TransformInlineAssignmentStObjOrCall(Block block, int pos) |
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{ |
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var inst = block.Instructions[pos] as StLoc; |
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// in some cases it can be a compiler-generated local |
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if (inst == null || (inst.Variable.Kind != VariableKind.StackSlot && inst.Variable.Kind != VariableKind.Local)) |
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return false; |
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if (IsImplicitTruncation(inst.Value, inst.Variable.Type)) { |
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// 'stloc s' is implicitly truncating the value |
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return false; |
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} |
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ILVariable local; |
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int nextPos; |
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if (block.Instructions[pos + 1] is StLoc localStore) { // with extra local |
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if (localStore.Variable.Kind != VariableKind.Local || !localStore.Value.MatchLdLoc(inst.Variable)) |
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return false; |
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// if we're using an extra local, we'll delete "s", so check that that doesn't have any additional uses |
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if (!(inst.Variable.IsSingleDefinition && inst.Variable.LoadCount == 2)) |
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return false; |
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local = localStore.Variable; |
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nextPos = pos + 2; |
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} else { |
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local = inst.Variable; |
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localStore = null; |
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nextPos = pos + 1; |
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} |
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if (block.Instructions[nextPos] is StObj stobj) { |
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if (!stobj.Value.MatchLdLoc(inst.Variable)) |
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return false; |
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if (!SemanticHelper.IsPure(stobj.Target.Flags) || inst.Variable.IsUsedWithin(stobj.Target)) |
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return false; |
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if (IsImplicitTruncation(inst.Value, stobj.Type)) { |
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// 'stobj' is implicitly truncating the value |
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return false; |
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} |
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context.Step("Inline assignment stobj", stobj); |
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block.Instructions.Remove(localStore); |
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block.Instructions.Remove(stobj); |
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stobj.Value = inst.Value; |
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inst.ReplaceWith(new StLoc(local, stobj)); |
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// note: our caller will trigger a re-run, which will call HandleStObjCompoundAssign if applicable |
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return true; |
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} else if (block.Instructions[nextPos] is CallInstruction call) { |
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// call must be a setter call: |
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if (!(call.OpCode == OpCode.Call || call.OpCode == OpCode.CallVirt)) |
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return false; |
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if (call.ResultType != StackType.Void || call.Arguments.Count == 0) |
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return false; |
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if (!call.Method.Equals((call.Method.AccessorOwner as IProperty)?.Setter)) |
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return false; |
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if (!call.Arguments.Last().MatchLdLoc(inst.Variable)) |
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return false; |
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foreach (var arg in call.Arguments.SkipLast(1)) { |
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if (!SemanticHelper.IsPure(arg.Flags) || inst.Variable.IsUsedWithin(arg)) |
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return false; |
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} |
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if (IsImplicitTruncation(inst.Value, call.Method.Parameters.Last().Type)) { |
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// setter call is implicitly truncating the value |
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return false; |
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} |
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// stloc s(Block InlineAssign { call set_Property(..., stloc i(value)); final: ldloc i }) |
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context.Step("Inline assignment call", call); |
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block.Instructions.Remove(localStore); |
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block.Instructions.Remove(call); |
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var newVar = context.Function.RegisterVariable(VariableKind.StackSlot, call.Method.Parameters.Last().Type); |
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call.Arguments[call.Arguments.Count - 1] = new StLoc(newVar, inst.Value); |
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var inlineBlock = new Block(BlockKind.CallInlineAssign) { |
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Instructions = { call }, |
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FinalInstruction = new LdLoc(newVar) |
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}; |
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inst.ReplaceWith(new StLoc(local, inlineBlock)); |
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// because the ExpressionTransforms don't look into inline blocks, manually trigger HandleCallCompoundAssign |
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if (HandleCallCompoundAssign(call, context)) { |
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// if we did construct a compound assignment, it should have made our inline block redundant: |
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if (inlineBlock.Instructions.Single().MatchStLoc(newVar, out var compoundAssign)) { |
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Debug.Assert(newVar.IsSingleDefinition && newVar.LoadCount == 1); |
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inlineBlock.ReplaceWith(compoundAssign); |
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} |
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} |
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return true; |
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} else { |
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return false; |
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} |
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} |
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static ILInstruction UnwrapSmallIntegerConv(ILInstruction inst, out Conv conv) |
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{ |
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conv = inst as Conv; |
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if (conv != null && conv.Kind == ConversionKind.Truncate && conv.TargetType.IsSmallIntegerType()) { |
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// for compound assignments to small integers, the compiler emits a "conv" instruction |
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return conv.Argument; |
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} else { |
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return inst; |
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} |
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} |
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static bool ValidateCompoundAssign(BinaryNumericInstruction binary, Conv conv, IType targetType) |
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{ |
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if (!CompoundAssignmentInstruction.IsBinaryCompatibleWithType(binary, targetType)) |
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return false; |
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if (conv != null && !(conv.TargetType == targetType.ToPrimitiveType() && conv.CheckForOverflow == binary.CheckForOverflow)) |
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return false; // conv does not match binary operation |
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return true; |
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} |
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static bool MatchingGetterAndSetterCalls(CallInstruction getterCall, CallInstruction setterCall) |
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{ |
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if (getterCall == null || setterCall == null || !IsSameMember(getterCall.Method.AccessorOwner, setterCall.Method.AccessorOwner)) |
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return false; |
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var owner = getterCall.Method.AccessorOwner as IProperty; |
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if (owner == null || !IsSameMember(getterCall.Method, owner.Getter) || !IsSameMember(setterCall.Method, owner.Setter)) |
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return false; |
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if (setterCall.Arguments.Count != getterCall.Arguments.Count + 1) |
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return false; |
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// Ensure that same arguments are passed to getterCall and setterCall: |
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for (int j = 0; j < getterCall.Arguments.Count; j++) { |
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if (!SemanticHelper.IsPure(getterCall.Arguments[j].Flags)) |
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return false; |
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if (!getterCall.Arguments[j].Match(setterCall.Arguments[j]).Success) |
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return false; |
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} |
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return true; |
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} |
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/// <summary> |
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/// Transform compound assignments where the return value is not being used, |
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/// or where there's an inlined assignment within the setter call. |
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/// </summary> |
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/// <remarks> |
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/// Called by ExpressionTransforms. |
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/// </remarks> |
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internal static bool HandleCallCompoundAssign(CallInstruction setterCall, StatementTransformContext context) |
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{ |
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// callvirt set_Property(ldloc S_1, binary.op(callvirt get_Property(ldloc S_1), value)) |
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// ==> compound.op.new(callvirt get_Property(ldloc S_1), value) |
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var setterValue = setterCall.Arguments.LastOrDefault(); |
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var storeInSetter = setterValue as StLoc; |
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if (storeInSetter != null) { |
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// callvirt set_Property(ldloc S_1, stloc v(binary.op(callvirt get_Property(ldloc S_1), value))) |
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// ==> stloc v(compound.op.new(callvirt get_Property(ldloc S_1), value)) |
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setterValue = storeInSetter.Value; |
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} |
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setterValue = UnwrapSmallIntegerConv(setterValue, out var conv); |
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if (!(setterValue is BinaryNumericInstruction binary)) |
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return false; |
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var getterCall = binary.Left as CallInstruction; |
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if (!MatchingGetterAndSetterCalls(getterCall, setterCall)) |
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return false; |
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IType targetType = getterCall.Method.ReturnType; |
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if (!ValidateCompoundAssign(binary, conv, targetType)) |
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return false; |
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if (storeInSetter != null && storeInSetter.Variable.Type.IsSmallIntegerType()) { |
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// 'stloc v' implicitly truncates. |
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// Ensure that type of 'v' must match type of the property: |
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if (storeInSetter.Variable.Type.GetSize() != targetType.GetSize()) |
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return false; |
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if (storeInSetter.Variable.Type.GetSign() != targetType.GetSign()) |
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return false; |
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} |
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context.Step($"Compound assignment to '{getterCall.Method.AccessorOwner.Name}'", setterCall); |
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ILInstruction newInst = new CompoundAssignmentInstruction( |
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binary, getterCall, binary.Right, |
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getterCall.Method.ReturnType, CompoundAssignmentType.EvaluatesToNewValue); |
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if (storeInSetter != null) { |
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storeInSetter.Value = newInst; |
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newInst = storeInSetter; |
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context.RequestRerun(); // moving stloc to top-level might trigger inlining |
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} |
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setterCall.ReplaceWith(newInst); |
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return true; |
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} |
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/// <summary> |
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/// stobj(target, binary.op(ldobj(target), ...)) |
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/// where target is pure |
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/// => compound.op(target, ...) |
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/// </summary> |
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/// <remarks> |
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/// Called by ExpressionTransforms. |
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/// </remarks> |
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internal static bool HandleStObjCompoundAssign(StObj inst, ILTransformContext context) |
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{ |
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if (!(UnwrapSmallIntegerConv(inst.Value, out var conv) is BinaryNumericInstruction binary)) |
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return false; |
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if (!(binary.Left is LdObj ldobj)) |
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return false; |
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if (!inst.Target.Match(ldobj.Target).Success) |
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return false; |
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if (!SemanticHelper.IsPure(ldobj.Target.Flags)) |
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return false; |
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// ldobj.Type may just be 'int' (due to ldind.i4) when we're actually operating on a 'ref MyEnum'. |
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// Try to determine the real type of the object we're modifying: |
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IType targetType = ldobj.Target.InferType(); |
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if (targetType.Kind == TypeKind.Pointer || targetType.Kind == TypeKind.ByReference) { |
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targetType = ((TypeWithElementType)targetType).ElementType; |
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if (targetType.Kind == TypeKind.Unknown || targetType.GetSize() != ldobj.Type.GetSize()) { |
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targetType = ldobj.Type; |
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} |
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} else { |
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targetType = ldobj.Type; |
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} |
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if (!ValidateCompoundAssign(binary, conv, targetType)) |
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return false; |
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context.Step("compound assignment", inst); |
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inst.ReplaceWith(new CompoundAssignmentInstruction( |
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binary, binary.Left, binary.Right, |
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targetType, CompoundAssignmentType.EvaluatesToNewValue)); |
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return true; |
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} |
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/// <code> |
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/// stloc s(value) |
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/// stloc l(ldloc s) |
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/// where neither 'stloc s' nor 'stloc l' truncates the value |
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/// --> |
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/// stloc s(stloc l(value)) |
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/// </code> |
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bool TransformInlineAssignmentLocal(Block block, int pos) |
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{ |
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var inst = block.Instructions[pos] as StLoc; |
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var nextInst = block.Instructions.ElementAtOrDefault(pos + 1) as StLoc; |
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if (inst == null || nextInst == null) |
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return false; |
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if (inst.Variable.Kind != VariableKind.StackSlot) |
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return false; |
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Debug.Assert(!inst.Variable.Type.IsSmallIntegerType()); |
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if (!(nextInst.Variable.Kind == VariableKind.Local || nextInst.Variable.Kind == VariableKind.Parameter)) |
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return false; |
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if (!nextInst.Value.MatchLdLoc(inst.Variable)) |
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return false; |
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if (IsImplicitTruncation(inst.Value, inst.Variable.Type)) { |
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// 'stloc s' is implicitly truncating the stack value |
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return false; |
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} |
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if (IsImplicitTruncation(inst.Value, nextInst.Variable.Type)) { |
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// 'stloc l' is implicitly truncating the stack value |
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return false; |
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} |
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context.Step("Inline assignment to local variable", inst); |
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var value = inst.Value; |
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var var = nextInst.Variable; |
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var stackVar = inst.Variable; |
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block.Instructions.RemoveAt(pos); |
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nextInst.ReplaceWith(new StLoc(stackVar, new StLoc(var, value))); |
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return true; |
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} |
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/// <summary> |
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/// Gets whether 'stobj type(..., value)' would evaluate to a different value than 'value' |
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/// due to implicit truncation. |
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/// </summary> |
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bool IsImplicitTruncation(ILInstruction value, IType type) |
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{ |
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if (!type.IsSmallIntegerType()) { |
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// Implicit truncation in ILAst only happens for small integer types; |
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// other types of implicit truncation in IL cause the ILReader to insert |
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// conv instructions. |
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return false; |
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} |
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// With small integer types, test whether the value might be changed by |
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// truncation (based on type.GetSize()) followed by sign/zero extension (based on type.GetSign()). |
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// (it's OK to have false-positives here if we're unsure) |
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if (value.MatchLdcI4(out int val)) { |
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switch (type.GetEnumUnderlyingType().GetDefinition()?.KnownTypeCode) { |
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case KnownTypeCode.Boolean: |
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return !(val == 0 || val == 1); |
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case KnownTypeCode.Byte: |
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return !(val >= byte.MinValue && val <= byte.MaxValue); |
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case KnownTypeCode.SByte: |
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return !(val >= sbyte.MinValue && val <= sbyte.MaxValue); |
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case KnownTypeCode.Int16: |
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return !(val >= short.MinValue && val <= short.MaxValue); |
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case KnownTypeCode.UInt16: |
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case KnownTypeCode.Char: |
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return !(val >= ushort.MinValue && val <= ushort.MaxValue); |
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} |
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} else if (value is Conv conv) { |
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return conv.TargetType != type.ToPrimitiveType(); |
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} else if (value is Comp) { |
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return false; // comp returns 0 or 1, which always fits |
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} else { |
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IType inferredType = value.InferType(); |
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if (inferredType.Kind != TypeKind.Unknown) { |
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return !(inferredType.GetSize() <= type.GetSize() && inferredType.GetSign() == type.GetSign()); |
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} |
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} |
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return true; |
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} |
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/// <code> |
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/// stloc s(ldloc l) |
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/// stloc l(binary.op(ldloc s, ldc.i4 1)) |
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/// --> |
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/// stloc s(block { |
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/// stloc s2(ldloc l) |
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/// stloc l(binary.op(ldloc s2, ldc.i4 1)) |
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/// final: ldloc s2 |
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/// }) |
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/// </code> |
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bool TransformPostIncDecOperatorLocal(Block block, int pos) |
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{ |
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var inst = block.Instructions[pos] as StLoc; |
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var nextInst = block.Instructions.ElementAtOrDefault(pos + 1) as StLoc; |
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if (inst == null || nextInst == null || !inst.Value.MatchLdLoc(out var loadVar) || !ILVariableEqualityComparer.Instance.Equals(loadVar, nextInst.Variable)) |
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return false; |
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var binary = nextInst.Value as BinaryNumericInstruction; |
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if (inst.Variable.Kind != VariableKind.StackSlot || nextInst.Variable.Kind == VariableKind.StackSlot || binary == null) |
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return false; |
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if (binary.IsLifted) |
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return false; |
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if ((binary.Operator != BinaryNumericOperator.Add && binary.Operator != BinaryNumericOperator.Sub) || !binary.Left.MatchLdLoc(inst.Variable) || !binary.Right.MatchLdcI4(1)) |
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return false; |
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context.Step($"TransformPostIncDecOperatorLocal", inst); |
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if (loadVar != nextInst.Variable) { |
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// load and store are two different variables, that were split from the same variable |
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context.Function.RecombineVariables(loadVar, nextInst.Variable); |
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} |
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var tempStore = context.Function.RegisterVariable(VariableKind.StackSlot, inst.Variable.Type); |
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var assignment = new Block(BlockKind.PostfixOperator); |
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assignment.Instructions.Add(new StLoc(tempStore, new LdLoc(loadVar))); |
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assignment.Instructions.Add(new StLoc(loadVar, new BinaryNumericInstruction(binary.Operator, new LdLoc(tempStore), new LdcI4(1), binary.CheckForOverflow, binary.Sign))); |
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assignment.FinalInstruction = new LdLoc(tempStore); |
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inst.Value = assignment; |
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block.Instructions.RemoveAt(pos + 1); // remove nextInst |
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return true; |
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} |
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|
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/// <summary> |
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/// Gets whether 'inst' is a possible store for use as a compound store. |
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/// </summary> |
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bool IsCompoundStore(ILInstruction inst, out IType storeType, out ILInstruction value) |
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{ |
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value = null; |
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storeType = null; |
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if (inst is StObj stobj) { |
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storeType = stobj.Type; |
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value = stobj.Value; |
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return SemanticHelper.IsPure(stobj.Target.Flags); |
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} else if (inst is CallInstruction call && (call.OpCode == OpCode.Call || call.OpCode == OpCode.CallVirt)) { |
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if (call.Method.Parameters.Count == 0) { |
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return false; |
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} |
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foreach (var arg in call.Arguments.SkipLast(1)) { |
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if (!SemanticHelper.IsPure(arg.Flags)) { |
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return false; |
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} |
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} |
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storeType = call.Method.Parameters.Last().Type; |
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value = call.Arguments.Last(); |
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return IsSameMember(call.Method, (call.Method.AccessorOwner as IProperty)?.Setter); |
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} else { |
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return false; |
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} |
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} |
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|
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bool IsMatchingCompoundLoad(ILInstruction load, ILInstruction store, ILVariable forbiddenVariable) |
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{ |
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if (load is LdObj ldobj && store is StObj stobj) { |
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Debug.Assert(SemanticHelper.IsPure(stobj.Target.Flags)); |
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if (!SemanticHelper.IsPure(ldobj.Target.Flags)) |
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return false; |
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if (forbiddenVariable.IsUsedWithin(ldobj.Target)) |
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return false; |
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return ldobj.Target.Match(stobj.Target).Success; |
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} else if (MatchingGetterAndSetterCalls(load as CallInstruction, store as CallInstruction)) { |
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if (forbiddenVariable.IsUsedWithin(load)) |
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return false; |
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return true; |
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} else { |
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return false; |
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} |
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} |
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|
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/// <code> |
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/// stobj(target, binary.add(stloc l(ldobj(target)), ldc.i4 1)) |
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/// where target is pure and does not use 'l', and the 'stloc l' does not truncate |
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/// --> |
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/// stloc l(compound.op.old(ldobj(target), ldc.i4 1)) |
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/// |
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/// -or- |
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/// |
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/// call set_Prop(args..., binary.add(stloc l(call get_Prop(args...)), ldc.i4 1)) |
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/// where args.. are pure and do not use 'l', and the 'stloc l' does not truncate |
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/// --> |
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/// stloc l(compound.op.old(call get_Prop(target), ldc.i4 1)) |
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/// </code> |
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/// <remarks> |
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/// Even though this transform operates only on a single expression, it's not an expression transform |
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/// as the result value of the expression changes (this is OK only for statements in a block). |
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/// </remarks> |
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bool TransformPostIncDecOperatorWithInlineStore(Block block, int pos) |
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{ |
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var store = block.Instructions[pos]; |
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if (!IsCompoundStore(store, out var targetType, out var value)) |
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return false; |
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var binary = UnwrapSmallIntegerConv(value, out var conv) as BinaryNumericInstruction; |
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if (binary == null || !binary.Right.MatchLdcI4(1)) |
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return false; |
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if (!(binary.Operator == BinaryNumericOperator.Add || binary.Operator == BinaryNumericOperator.Sub)) |
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return false; |
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if (!(binary.Left is StLoc stloc)) |
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return false; |
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if (!(stloc.Variable.Kind == VariableKind.Local || stloc.Variable.Kind == VariableKind.StackSlot)) |
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return false; |
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if (!IsMatchingCompoundLoad(stloc.Value, store, stloc.Variable)) |
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return false; |
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if (!ValidateCompoundAssign(binary, conv, targetType)) |
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return false; |
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if (IsImplicitTruncation(stloc.Value, stloc.Variable.Type)) |
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return false; |
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context.Step("TransformPostIncDecOperatorWithInlineStore", store); |
|
block.Instructions[pos] = new StLoc(stloc.Variable, new CompoundAssignmentInstruction( |
|
binary, stloc.Value, binary.Right, targetType, CompoundAssignmentType.EvaluatesToOldValue)); |
|
return true; |
|
} |
|
|
|
/// <code> |
|
/// stloc l(ldobj(target)) |
|
/// stobj(target, binary.op(ldloc l, ldc.i4 1)) |
|
/// target is pure and does not use 'l', 'stloc does not truncate' |
|
/// --> |
|
/// stloc l(compound.op.old(ldobj(target), ldc.i4 1)) |
|
/// </code> |
|
/// <remarks> |
|
/// This pattern occurs with legacy csc for static fields, and with Roslyn for most post-increments. |
|
/// </remarks> |
|
bool TransformPostIncDecOperator(Block block, int i) |
|
{ |
|
var inst = block.Instructions[i] as StLoc; |
|
var store = block.Instructions.ElementAtOrDefault(i + 1); |
|
if (inst == null || store == null) |
|
return false; |
|
if (!IsCompoundStore(store, out var targetType, out var value)) |
|
return false; |
|
if (!IsMatchingCompoundLoad(inst.Value, store, inst.Variable)) |
|
return false; |
|
var binary = UnwrapSmallIntegerConv(value, out var conv) as BinaryNumericInstruction; |
|
if (binary == null || !binary.Left.MatchLdLoc(inst.Variable) || !binary.Right.MatchLdcI4(1)) |
|
return false; |
|
if (!(binary.Operator == BinaryNumericOperator.Add || binary.Operator == BinaryNumericOperator.Sub)) |
|
return false; |
|
if (!ValidateCompoundAssign(binary, conv, targetType)) |
|
return false; |
|
if (IsImplicitTruncation(value, targetType)) |
|
return false; |
|
context.Step("TransformPostIncDecOperator", inst); |
|
inst.Value = new CompoundAssignmentInstruction(binary, inst.Value, binary.Right, targetType, CompoundAssignmentType.EvaluatesToOldValue); |
|
block.Instructions.RemoveAt(i + 1); |
|
if (inst.Variable.IsSingleDefinition && inst.Variable.LoadCount == 0) { |
|
// dead store -> it was a statement-level post-increment |
|
inst.ReplaceWith(inst.Value); |
|
} |
|
return true; |
|
} |
|
|
|
static bool IsSameMember(IMember a, IMember b) |
|
{ |
|
if (a == null || b == null) |
|
return false; |
|
a = a.MemberDefinition; |
|
b = b.MemberDefinition; |
|
return a.Equals(b); |
|
} |
|
} |
|
}
|
|
|