mirror of https://github.com/icsharpcode/ILSpy.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
361 lines
14 KiB
361 lines
14 KiB
// Copyright (c) 2014 Daniel Grunwald |
|
// |
|
// Permission is hereby granted, free of charge, to any person obtaining a copy of this |
|
// software and associated documentation files (the "Software"), to deal in the Software |
|
// without restriction, including without limitation the rights to use, copy, modify, merge, |
|
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons |
|
// to whom the Software is furnished to do so, subject to the following conditions: |
|
// |
|
// The above copyright notice and this permission notice shall be included in all copies or |
|
// substantial portions of the Software. |
|
// |
|
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, |
|
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR |
|
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE |
|
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR |
|
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
|
// DEALINGS IN THE SOFTWARE. |
|
|
|
using System.Diagnostics; |
|
using System.Linq; |
|
using ICSharpCode.Decompiler.TypeSystem; |
|
|
|
namespace ICSharpCode.Decompiler.IL.Transforms |
|
{ |
|
/// <summary> |
|
/// Collection of transforms that detect simple expression patterns |
|
/// (e.g. 'cgt.un(..., ld.null)') and replace them with different instructions. |
|
/// </summary> |
|
/// <remarks> |
|
/// Should run after inlining so that the expression patterns can be detected. |
|
/// </remarks> |
|
public class ExpressionTransforms : ILVisitor, IBlockTransform |
|
{ |
|
internal ILTransformContext context; |
|
|
|
public void Run(Block block, BlockTransformContext context) |
|
{ |
|
this.context = context; |
|
Default(block); |
|
} |
|
|
|
protected override void Default(ILInstruction inst) |
|
{ |
|
foreach (var child in inst.Children) { |
|
child.AcceptVisitor(this); |
|
} |
|
} |
|
|
|
protected internal override void VisitBlock(Block block) |
|
{ |
|
// Don't visit child blocks; since this is a block transform |
|
// we know those were already handled previously. |
|
} |
|
|
|
protected internal override void VisitComp(Comp inst) |
|
{ |
|
base.VisitComp(inst); |
|
if (inst.Right.MatchLdNull()) { |
|
if (inst.Kind == ComparisonKind.GreaterThan) { |
|
context.Step("comp(left > ldnull) => comp(left != ldnull)", inst); |
|
inst.Kind = ComparisonKind.Inequality; |
|
} else if (inst.Kind == ComparisonKind.LessThanOrEqual) { |
|
context.Step("comp(left <= ldnull) => comp(left == ldnull)", inst); |
|
inst.Kind = ComparisonKind.Equality; |
|
} |
|
} else if (inst.Left.MatchLdNull()) { |
|
if (inst.Kind == ComparisonKind.LessThan) { |
|
context.Step("comp(ldnull < right) => comp(ldnull != right)", inst); |
|
inst.Kind = ComparisonKind.Inequality; |
|
} else if (inst.Kind == ComparisonKind.GreaterThanOrEqual) { |
|
context.Step("comp(ldnull >= right) => comp(ldnull == right)", inst); |
|
inst.Kind = ComparisonKind.Equality; |
|
} |
|
} |
|
|
|
var rightWithoutConv = inst.Right.UnwrapConv(ConversionKind.SignExtend).UnwrapConv(ConversionKind.ZeroExtend); |
|
if (rightWithoutConv.MatchLdcI4(0) |
|
&& inst.Sign == Sign.Unsigned |
|
&& (inst.Kind == ComparisonKind.GreaterThan || inst.Kind == ComparisonKind.LessThanOrEqual)) |
|
{ |
|
ILInstruction array; |
|
if (inst.Left.MatchLdLen(StackType.I, out array)) { |
|
// comp.unsigned(ldlen array > conv i4->i(ldc.i4 0)) |
|
// => comp(ldlen.i4 array > ldc.i4 0) |
|
// This is a special case where the C# compiler doesn't generate conv.i4 after ldlen. |
|
context.Step("comp(ldlen.i4 array > ldc.i4 0)", inst); |
|
inst.Left.ReplaceWith(new LdLen(StackType.I4, array) { ILRange = inst.Left.ILRange }); |
|
inst.Right = rightWithoutConv; |
|
} |
|
if (inst.Kind == ComparisonKind.GreaterThan) { |
|
context.Step("comp.unsigned(left > ldc.i4 0) => comp(left != ldc.i4 0)", inst); |
|
inst.Kind = ComparisonKind.Inequality; |
|
} else if (inst.Kind == ComparisonKind.LessThanOrEqual) { |
|
context.Step("comp.unsigned(left <= ldc.i4 0) => comp(left == ldc.i4 0)", inst); |
|
inst.Kind = ComparisonKind.Equality; |
|
} |
|
} |
|
} |
|
|
|
protected internal override void VisitConv(Conv inst) |
|
{ |
|
inst.Argument.AcceptVisitor(this); |
|
ILInstruction array; |
|
if (inst.Argument.MatchLdLen(StackType.I, out array) && inst.TargetType.IsIntegerType() && !inst.CheckForOverflow) { |
|
context.Step("conv.i4(ldlen array) => ldlen.i4(array)", inst); |
|
inst.AddILRange(inst.Argument.ILRange); |
|
inst.ReplaceWith(new LdLen(inst.TargetType.GetStackType(), array) { ILRange = inst.ILRange }); |
|
} |
|
} |
|
|
|
protected internal override void VisitLdElema(LdElema inst) |
|
{ |
|
base.VisitLdElema(inst); |
|
CleanUpArrayIndices(inst.Indices); |
|
} |
|
|
|
protected internal override void VisitNewArr(NewArr inst) |
|
{ |
|
base.VisitNewArr(inst); |
|
CleanUpArrayIndices(inst.Indices); |
|
} |
|
|
|
void CleanUpArrayIndices(InstructionCollection<ILInstruction> indices) |
|
{ |
|
foreach (ILInstruction index in indices) { |
|
if (index is Conv conv && conv.ResultType == StackType.I |
|
&& (conv.Kind == ConversionKind.Truncate && conv.CheckForOverflow |
|
|| conv.Kind == ConversionKind.ZeroExtend || conv.Kind == ConversionKind.SignExtend) |
|
) { |
|
context.Step("Remove conv.i from array index", index); |
|
index.ReplaceWith(conv.Argument); |
|
} |
|
} |
|
} |
|
|
|
protected internal override void VisitLogicNot(LogicNot inst) |
|
{ |
|
ILInstruction arg, lhs, rhs; |
|
if (inst.Argument.MatchLogicNot(out arg)) { |
|
context.Step("logic.not(logic.not(arg)) => arg", inst); |
|
Debug.Assert(arg.ResultType == StackType.I4); |
|
arg.AddILRange(inst.ILRange); |
|
arg.AddILRange(inst.Argument.ILRange); |
|
inst.ReplaceWith(arg); |
|
arg.AcceptVisitor(this); |
|
} else if (inst.Argument is Comp) { |
|
Comp comp = (Comp)inst.Argument; |
|
if (comp.InputType != StackType.F || comp.Kind.IsEqualityOrInequality()) { |
|
context.Step("push negation into comparison", inst); |
|
comp.Kind = comp.Kind.Negate(); |
|
comp.AddILRange(inst.ILRange); |
|
inst.ReplaceWith(comp); |
|
} |
|
comp.AcceptVisitor(this); |
|
} else if (inst.Argument.MatchLogicAnd(out lhs, out rhs)) { |
|
// logic.not(if (lhs) rhs else ldc.i4 0) |
|
// ==> if (logic.not(lhs)) ldc.i4 1 else logic.not(rhs) |
|
context.Step("push negation into logic.and", inst); |
|
IfInstruction ifInst = (IfInstruction)inst.Argument; |
|
var ldc0 = ifInst.FalseInst; |
|
Debug.Assert(ldc0.MatchLdcI4(0)); |
|
ifInst.Condition = new LogicNot(lhs) { ILRange = inst.ILRange }; |
|
ifInst.TrueInst = new LdcI4(1) { ILRange = ldc0.ILRange }; |
|
ifInst.FalseInst = new LogicNot(rhs) { ILRange = inst.ILRange }; |
|
inst.ReplaceWith(ifInst); |
|
ifInst.AcceptVisitor(this); |
|
} else if (inst.Argument.MatchLogicOr(out lhs, out rhs)) { |
|
// logic.not(if (lhs) ldc.i4 1 else rhs) |
|
// ==> if (logic.not(lhs)) logic.not(rhs) else ldc.i4 0) |
|
context.Step("push negation into logic.or", inst); |
|
IfInstruction ifInst = (IfInstruction)inst.Argument; |
|
var ldc1 = ifInst.TrueInst; |
|
Debug.Assert(ldc1.MatchLdcI4(1)); |
|
ifInst.Condition = new LogicNot(lhs) { ILRange = inst.ILRange }; |
|
ifInst.TrueInst = new LogicNot(rhs) { ILRange = inst.ILRange }; |
|
ifInst.FalseInst = new LdcI4(0) { ILRange = ldc1.ILRange }; |
|
inst.ReplaceWith(ifInst); |
|
ifInst.AcceptVisitor(this); |
|
} else { |
|
inst.Argument.AcceptVisitor(this); |
|
} |
|
} |
|
|
|
protected internal override void VisitCall(Call inst) |
|
{ |
|
if (inst.Method.IsConstructor && !inst.Method.IsStatic && inst.Method.DeclaringType.Kind == TypeKind.Struct) { |
|
Debug.Assert(inst.Arguments.Count == inst.Method.Parameters.Count + 1); |
|
context.Step("Transform call to struct constructor", inst); |
|
// call(ref, ...) |
|
// => stobj(ref, newobj(...)) |
|
var newObj = new NewObj(inst.Method); |
|
newObj.ILRange = inst.ILRange; |
|
newObj.Arguments.AddRange(inst.Arguments.Skip(1)); |
|
var expr = new StObj(inst.Arguments[0], newObj, inst.Method.DeclaringType); |
|
inst.ReplaceWith(expr); |
|
// Both the StObj and the NewObj may trigger further rules, so continue visiting the replacement: |
|
VisitStObj(expr); |
|
} else { |
|
base.VisitCall(inst); |
|
} |
|
} |
|
|
|
protected internal override void VisitNewObj(NewObj inst) |
|
{ |
|
LdcDecimal decimalConstant; |
|
if (TransformDecimalCtorToConstant(inst, out decimalConstant)) { |
|
context.Step("TransformDecimalCtorToConstant", inst); |
|
inst.ReplaceWith(decimalConstant); |
|
return; |
|
} |
|
base.VisitNewObj(inst); |
|
} |
|
|
|
bool TransformDecimalCtorToConstant(NewObj inst, out LdcDecimal result) |
|
{ |
|
IType t = inst.Method.DeclaringType; |
|
result = null; |
|
if (!t.IsKnownType(KnownTypeCode.Decimal)) |
|
return false; |
|
var args = inst.Arguments; |
|
if (args.Count == 1) { |
|
int val; |
|
if (args[0].MatchLdcI4(out val)) { |
|
result = new LdcDecimal(val); |
|
return true; |
|
} |
|
} else if (args.Count == 5) { |
|
int lo, mid, hi, isNegative, scale; |
|
if (args[0].MatchLdcI4(out lo) && args[1].MatchLdcI4(out mid) && |
|
args[2].MatchLdcI4(out hi) && args[3].MatchLdcI4(out isNegative) && |
|
args[4].MatchLdcI4(out scale)) |
|
{ |
|
result = new LdcDecimal(new decimal(lo, mid, hi, isNegative != 0, (byte)scale)); |
|
return true; |
|
} |
|
} |
|
return false; |
|
} |
|
|
|
// This transform is required because ILInlining only works with stloc/ldloc |
|
protected internal override void VisitStObj(StObj inst) |
|
{ |
|
base.VisitStObj(inst); |
|
if (StObjToStLoc(inst, context)) { |
|
return; |
|
} |
|
|
|
if (inst.Value is BinaryNumericInstruction binary |
|
&& binary.Left.MatchLdObj(out ILInstruction target, out IType t) |
|
&& inst.Target.Match(target).Success) |
|
{ |
|
context.Step("compound assignment", inst); |
|
// stobj(target, binary.op(ldobj(target), ...)) |
|
// => compound.op(target, ...) |
|
inst.ReplaceWith(new CompoundAssignmentInstruction(binary.Operator, binary.Left, binary.Right, t, binary.CheckForOverflow, binary.Sign, CompoundAssignmentType.EvaluatesToNewValue)); |
|
} |
|
} |
|
|
|
internal static bool StObjToStLoc(StObj inst, ILTransformContext context) |
|
{ |
|
if (inst.Target.MatchLdLoca(out ILVariable v) |
|
&& TypeUtils.IsCompatibleTypeForMemoryAccess(new ByReferenceType(v.Type), inst.Type) |
|
&& inst.UnalignedPrefix == 0 |
|
&& !inst.IsVolatile) { |
|
context.Step($"stobj(ldloca {v.Name}, ...) => stloc {v.Name}(...)", inst); |
|
inst.ReplaceWith(new StLoc(v, inst.Value)); |
|
return true; |
|
} |
|
return false; |
|
} |
|
|
|
protected internal override void VisitIfInstruction(IfInstruction inst) |
|
{ |
|
// Bring LogicAnd/LogicOr into their canonical forms: |
|
// if (cond) ldc.i4 0 else RHS --> if (!cond) RHS else ldc.i4 0 |
|
// if (cond) RHS else ldc.i4 1 --> if (!cond) ldc.i4 1 else RHS |
|
// Be careful: when both LHS and RHS are the constant 1, we must not |
|
// swap the arguments as it would lead to an infinite transform loop. |
|
if (inst.TrueInst.MatchLdcI4(0) && !inst.FalseInst.MatchLdcI4(0) |
|
|| inst.FalseInst.MatchLdcI4(1) && !inst.TrueInst.MatchLdcI4(1)) |
|
{ |
|
context.Step("canonicalize logic and/or", inst); |
|
var t = inst.TrueInst; |
|
inst.TrueInst = inst.FalseInst; |
|
inst.FalseInst = t; |
|
inst.Condition = new LogicNot(inst.Condition); |
|
} |
|
|
|
base.VisitIfInstruction(inst); |
|
|
|
// if (cond) stloc (A, V1) else stloc (A, V2) --> stloc (A, if (cond) V1 else V2) |
|
Block trueInst = inst.TrueInst as Block; |
|
if (trueInst == null || trueInst.Instructions.Count != 1) |
|
return; |
|
Block falseInst = inst.FalseInst as Block; |
|
if (falseInst == null || falseInst.Instructions.Count != 1) |
|
return; |
|
ILVariable v; |
|
ILInstruction value1, value2; |
|
if (trueInst.Instructions[0].MatchStLoc(out v, out value1) && falseInst.Instructions[0].MatchStLoc(v, out value2)) { |
|
context.Step("conditional operator", inst); |
|
inst.ReplaceWith(new StLoc(v, new IfInstruction(new LogicNot(inst.Condition), value2, value1))); |
|
} |
|
} |
|
|
|
protected internal override void VisitBinaryNumericInstruction(BinaryNumericInstruction inst) |
|
{ |
|
base.VisitBinaryNumericInstruction(inst); |
|
switch (inst.Operator) { |
|
case BinaryNumericOperator.ShiftLeft: |
|
case BinaryNumericOperator.ShiftRight: |
|
if (inst.Right.MatchBinaryNumericInstruction(BinaryNumericOperator.BitAnd, out var lhs, out var rhs) |
|
&& rhs.MatchLdcI4(inst.ResultType == StackType.I8 ? 63 : 31)) |
|
{ |
|
// a << (b & 31) => a << b |
|
context.Step("Combine bit.and into shift", inst); |
|
inst.Right = lhs; |
|
} |
|
break; |
|
} |
|
} |
|
} |
|
|
|
protected internal override void VisitTryCatchHandler(TryCatchHandler inst) |
|
{ |
|
base.VisitTryCatchHandler(inst); |
|
if (inst.Filter is BlockContainer filterContainer && filterContainer.Blocks.Count == 1) { |
|
TransformCatchWhen(inst, filterContainer.EntryPoint); |
|
} |
|
if (inst.Body is BlockContainer catchContainer) |
|
TransformCatchVariable(inst, catchContainer.EntryPoint); |
|
} |
|
|
|
/// <summary> |
|
/// Transform local exception variable. |
|
/// </summary> |
|
void TransformCatchVariable(TryCatchHandler handler, Block entryPoint) |
|
{ |
|
if (!entryPoint.Instructions[0].MatchStLoc(out var exceptionVar, out var exceptionSlotLoad)) |
|
return; |
|
if (!exceptionVar.IsSingleDefinition || exceptionVar.Kind != VariableKind.Local) |
|
return; |
|
if (!exceptionSlotLoad.MatchLdLoc(handler.Variable) || !handler.Variable.IsSingleDefinition || handler.Variable.LoadCount != 1) |
|
return; |
|
handler.Variable = exceptionVar; |
|
exceptionVar.Kind = VariableKind.Exception; |
|
entryPoint.Instructions.RemoveAt(0); |
|
} |
|
|
|
/// <summary> |
|
/// Inline condition from catch-when condition BlockContainer, if possible. |
|
/// </summary> |
|
void TransformCatchWhen(TryCatchHandler handler, Block entryPoint) |
|
{ |
|
TransformCatchVariable(handler, entryPoint); |
|
if (entryPoint.Instructions.Count == 1 && entryPoint.Instructions[0].MatchLeave(out _, out var condition)) { |
|
handler.Filter = condition; |
|
} |
|
} |
|
} |
|
}
|
|
|