// Copyright (c) 2014-2017 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;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Linq.Expressions;
using ICSharpCode.Decompiler.TypeSystem;
using ICSharpCode.Decompiler.Util;
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, IStatementTransform
{
internal StatementTransformContext context;
public static void RunOnSingleStatement(ILInstruction statement, ILTransformContext context)
{
if (statement == null)
throw new ArgumentNullException(nameof(statement));
if (!(statement.Parent is Block parent))
throw new ArgumentException("ILInstruction must be a statement, i.e., direct child of a block.");
new ExpressionTransforms().Run(parent, statement.ChildIndex, new StatementTransformContext(new BlockTransformContext(context)));
}
public void Run(Block block, int pos, StatementTransformContext context)
{
this.context = context;
context.StepStartGroup($"ExpressionTransforms ({block.Label}:{pos})", block.Instructions[pos]);
block.Instructions[pos].AcceptVisitor(this);
context.StepEndGroup(keepIfEmpty: true);
}
protected override void Default(ILInstruction inst)
{
foreach (var child in inst.Children) {
child.AcceptVisitor(this);
}
}
protected internal override void VisitBlockContainer(BlockContainer container)
{
if (container.Kind == ContainerKind.Switch) {
// Special case for switch: Only visit the switch condition block.
var switchInst = (SwitchInstruction)container.EntryPoint.Instructions[0];
switchInst.Value.AcceptVisitor(this);
}
// No need to call base.VisitBlockContainer, see comment in VisitBlock.
}
protected internal override void VisitBlock(Block block)
{
if (block.Kind == BlockKind.ControlFlow) {
// Don't visit child control flow blocks;
// since this is a block transform
// we know those were already handled previously.
return;
}
base.VisitBlock(block);
}
protected internal override void VisitComp(Comp inst)
{
// "logic.not(arg)" is sugar for "comp(arg != ldc.i4 0)"
if (inst.MatchLogicNot(out var arg)) {
VisitLogicNot(inst, arg);
return;
} else if (inst.Kind == ComparisonKind.Inequality && inst.LiftingKind == ComparisonLiftingKind.None
&& inst.Right.MatchLdcI4(0) && (IfInstruction.IsInConditionSlot(inst) || inst.Left is Comp)
) {
// if (comp(x != 0)) ==> if (x)
// comp(comp(...) != 0) => comp(...)
context.Step("Remove redundant comp(... != 0)", inst);
inst.Left.AddILRange(inst);
inst.ReplaceWith(inst.Left);
inst.Left.AcceptVisitor(this);
return;
}
base.VisitComp(inst);
if (inst.IsLifted) {
return;
}
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))
{
if (inst.Kind == ComparisonKind.GreaterThan) {
context.Step("comp.unsigned(left > ldc.i4 0) => comp(left != ldc.i4 0)", inst);
inst.Kind = ComparisonKind.Inequality;
VisitComp(inst);
return;
} else if (inst.Kind == ComparisonKind.LessThanOrEqual) {
context.Step("comp.unsigned(left <= ldc.i4 0) => comp(left == ldc.i4 0)", inst);
inst.Kind = ComparisonKind.Equality;
VisitComp(inst);
return;
}
} else if (rightWithoutConv.MatchLdcI4(0) && inst.Kind.IsEqualityOrInequality()) {
if (inst.Left.MatchLdLen(StackType.I, out ILInstruction 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.InputType = StackType.I4;
inst.Left.ReplaceWith(new LdLen(StackType.I4, array).WithILRange(inst.Left));
inst.Right = rightWithoutConv;
} else if (inst.Left is Conv conv && conv.TargetType == PrimitiveType.I && conv.Argument.ResultType == StackType.O) {
// C++/CLI sometimes uses this weird comparison with null:
context.Step("comp(conv o->i (ldloc obj) == conv i4->i <sign extend>(ldc.i4 0))", inst);
// -> comp(ldloc obj == ldnull)
inst.InputType = StackType.O;
inst.Left = conv.Argument;
inst.Right = new LdNull().WithILRange(inst.Right);
inst.Right.AddILRange(rightWithoutConv);
}
}
if (inst.Right.MatchLdNull() && inst.Left.MatchBox(out arg, out var type) && type.Kind == TypeKind.TypeParameter) {
if (inst.Kind == ComparisonKind.Equality) {
context.Step("comp(box T(..) == ldnull) -> comp(.. == ldnull)", inst);
inst.Left = arg;
}
if (inst.Kind == ComparisonKind.Inequality) {
context.Step("comp(box T(..) != ldnull) -> comp(.. != ldnull)", inst);
inst.Left = arg;
}
}
}
protected internal override void VisitConv(Conv inst)
{
inst.Argument.AcceptVisitor(this);
if (inst.Argument.MatchLdLen(StackType.I, out ILInstruction array) && inst.TargetType.IsIntegerType()
&& (!inst.CheckForOverflow || context.Settings.AssumeArrayLengthFitsIntoInt32))
{
context.Step("conv.i4(ldlen array) => ldlen.i4(array)", inst);
inst.AddILRange(inst.Argument);
inst.ReplaceWith(new LdLen(inst.TargetType.GetStackType(), array).WithILRange(inst));
return;
}
if (inst.TargetType.IsFloatType() && inst.Argument is Conv conv
&& conv.Kind == ConversionKind.IntToFloat && conv.TargetType == PrimitiveType.R)
{
// IL conv.r.un does not indicate whether to convert the target type to R4 or R8,
// so the C# compiler usually follows it with an explicit conv.r4 or conv.r8.
// To avoid emitting '(float)(double)val', we combine these two conversions:
context.Step("conv.rN(conv.r.un(...)) => conv.rN.un(...)", inst);
inst.ReplaceWith(new Conv(conv.Argument, conv.InputType, conv.InputSign, inst.TargetType, inst.CheckForOverflow, inst.IsLifted | conv.IsLifted));
return;
}
}
protected internal override void VisitBox(Box inst)
{
inst.Argument.AcceptVisitor(this);
if (inst.Type.IsReferenceType == true && inst.Argument.ResultType == inst.ResultType) {
// For reference types, box is a no-op.
context.Step("box ref-type(arg) => arg", inst);
inst.Argument.AddILRange(inst);
inst.ReplaceWith(inst.Argument);
}
}
protected internal override void VisitLdElema(LdElema inst)
{
base.VisitLdElema(inst);
CleanUpArrayIndices(inst.Indices);
if (IndexRangeTransform.HandleLdElema(inst, context))
return;
}
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);
}
}
}
void VisitLogicNot(Comp inst, ILInstruction arg)
{
ILInstruction lhs, rhs;
if (arg is Comp comp) {
if ((!comp.InputType.IsFloatType() && !comp.IsLifted) || comp.Kind.IsEqualityOrInequality()) {
context.Step("push negation into comparison", inst);
comp.Kind = comp.Kind.Negate();
comp.AddILRange(inst);
inst.ReplaceWith(comp);
}
comp.AcceptVisitor(this);
} else if (arg.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)arg;
var ldc0 = ifInst.FalseInst;
Debug.Assert(ldc0.MatchLdcI4(0));
ifInst.Condition = Comp.LogicNot(lhs).WithILRange(inst);
ifInst.TrueInst = new LdcI4(1).WithILRange(ldc0);
ifInst.FalseInst = Comp.LogicNot(rhs).WithILRange(inst);
inst.ReplaceWith(ifInst);
ifInst.AcceptVisitor(this);
} else if (arg.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)arg;
var ldc1 = ifInst.TrueInst;
Debug.Assert(ldc1.MatchLdcI4(1));
ifInst.Condition = Comp.LogicNot(lhs).WithILRange(inst);
ifInst.TrueInst = Comp.LogicNot(rhs).WithILRange(inst);
ifInst.FalseInst = new LdcI4(0).WithILRange(ldc1);
inst.ReplaceWith(ifInst);
ifInst.AcceptVisitor(this);
} else {
arg.AcceptVisitor(this);
}
}
protected internal override void VisitCall(Call inst)
{
var expr = EarlyExpressionTransforms.HandleCall(inst, context);
if (expr != null) {
// The resulting expression may trigger further rules, so continue visiting the replacement:
expr.AcceptVisitor(this);
} else {
base.VisitCall(inst);
TransformAssignment.HandleCompoundAssign(inst, context);
}
}
protected internal override void VisitCallVirt(CallVirt inst)
{
base.VisitCallVirt(inst);
TransformAssignment.HandleCompoundAssign(inst, context);
}
protected internal override void VisitNewObj(NewObj inst)
{
if (TransformDecimalCtorToConstant(inst, out LdcDecimal decimalConstant)) {
context.Step("TransformDecimalCtorToConstant", inst);
inst.ReplaceWith(decimalConstant);
return;
}
Block block;
if (TransformSpanTCtorContainingStackAlloc(inst, out ILInstruction locallocSpan)) {
context.Step("new Span<T>(stackalloc) -> stackalloc Span<T>", inst);
inst.ReplaceWith(locallocSpan);
block = null;
ILInstruction stmt = locallocSpan;
while (stmt.Parent != null) {
if (stmt.Parent is Block b) {
block = b;
break;
}
stmt = stmt.Parent;
}
// Special case to eliminate extra store
if (stmt.GetNextSibling() is StLoc storeStmt && storeStmt.Value is LdLoc)
ILInlining.InlineIfPossible(block, stmt.ChildIndex, context);
return;
}
if (TransformArrayInitializers.TransformSpanTArrayInitialization(inst, context, out block)) {
context.Step("TransformSpanTArrayInitialization: single-dim", inst);
inst.ReplaceWith(block);
return;
}
if (TransformDelegateCtorLdVirtFtnToLdVirtDelegate(inst, out LdVirtDelegate ldVirtDelegate)) {
context.Step("new Delegate(target, ldvirtftn Method) -> ldvirtdelegate Delegate Method(target)", inst);
inst.ReplaceWith(ldVirtDelegate);
return;
}
base.VisitNewObj(inst);
}
/// <summary>
/// newobj Delegate..ctor(target, ldvirtftn TargetMethod(target))
/// =>
/// ldvirtdelegate System.Delegate TargetMethod(target)
/// </summary>
bool TransformDelegateCtorLdVirtFtnToLdVirtDelegate(NewObj inst, out LdVirtDelegate ldVirtDelegate)
{
ldVirtDelegate = null;
if (inst.Method.DeclaringType.Kind != TypeKind.Delegate)
return false;
if (inst.Arguments.Count != 2)
return false;
if (!(inst.Arguments[1] is LdVirtFtn ldVirtFtn))
return false;
if (!SemanticHelper.IsPure(inst.Arguments[0].Flags))
return false;
if (!inst.Arguments[0].Match(ldVirtFtn.Argument).Success)
return false;
ldVirtDelegate = new LdVirtDelegate(inst.Arguments[0], inst.Method.DeclaringType, ldVirtFtn.Method)
.WithILRange(inst).WithILRange(ldVirtFtn).WithILRange(ldVirtFtn.Argument);
return true;
}
/// <summary>
/// newobj Span..ctor(localloc(conv i4->u <zero extend>(ldc.i4 sizeInBytes)), numberOfElementsExpr)
/// =>
/// localloc.span T(numberOfElementsExpr)
///
/// -or-
///
/// newobj Span..ctor(Block IL_0000 (StackAllocInitializer) {
/// stloc I_0(localloc(conv i4->u<zero extend>(ldc.i4 sizeInBytes)))
/// ...
/// final: ldloc I_0
/// }, numberOfElementsExpr)
/// =>
/// Block IL_0000 (StackAllocInitializer) {
/// stloc I_0(localloc.span T(numberOfElementsExpr))
/// ...
/// final: ldloc I_0
/// }
/// </summary>
bool TransformSpanTCtorContainingStackAlloc(NewObj newObj, out ILInstruction locallocSpan)
{
locallocSpan = null;
IType type = newObj.Method.DeclaringType;
if (!type.IsKnownType(KnownTypeCode.SpanOfT) && !type.IsKnownType(KnownTypeCode.ReadOnlySpanOfT))
return false;
if (newObj.Arguments.Count != 2 || type.TypeArguments.Count != 1)
return false;
IType elementType = type.TypeArguments[0];
if (newObj.Arguments[0].MatchLocAlloc(out var sizeInBytes) && MatchesElementCount(sizeInBytes, elementType, newObj.Arguments[1])) {
locallocSpan = new LocAllocSpan(newObj.Arguments[1], type);
return true;
}
if (newObj.Arguments[0] is Block initializer && initializer.Kind == BlockKind.StackAllocInitializer) {
if (!initializer.Instructions[0].MatchStLoc(out var initializerVariable, out var value))
return false;
if (!(value.MatchLocAlloc(out sizeInBytes) && MatchesElementCount(sizeInBytes, elementType, newObj.Arguments[1])))
return false;
var newVariable = initializerVariable.Function.RegisterVariable(VariableKind.InitializerTarget, type);
foreach (var load in initializerVariable.LoadInstructions.ToArray()) {
ILInstruction newInst = new LdLoc(newVariable);
newInst.AddILRange(load);
if (load.Parent != initializer)
newInst = new Conv(newInst, PrimitiveType.I, false, Sign.None);
load.ReplaceWith(newInst);
}
foreach (var store in initializerVariable.StoreInstructions.ToArray()) {
store.Variable = newVariable;
}
value.ReplaceWith(new LocAllocSpan(newObj.Arguments[1], type));
locallocSpan = initializer;
return true;
}
return false;
}
bool MatchesElementCount(ILInstruction sizeInBytesInstr, IType elementType, ILInstruction elementCountInstr2)
{
var pointerType = new PointerType(elementType);
var elementCountInstr = PointerArithmeticOffset.Detect(sizeInBytesInstr, pointerType.ElementType, checkForOverflow: true, unwrapZeroExtension: true);
if (elementCountInstr == null || !elementCountInstr.Match(elementCountInstr2).Success)
return false;
return true;
}
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;
}
bool TransformDecimalFieldToConstant(LdObj inst, out LdcDecimal result)
{
if (inst.MatchLdsFld(out var field) && field.DeclaringType.IsKnownType(KnownTypeCode.Decimal)) {
decimal? value = null;
if (field.Name == "One") {
value = decimal.One;
} else if (field.Name == "MinusOne") {
value = decimal.MinusOne;
} else if (field.Name == "Zero") {
value = decimal.Zero;
}
if (value != null) {
result = new LdcDecimal(value.Value).WithILRange(inst).WithILRange(inst.Target);
return true;
}
}
result = null;
return false;
}
protected internal override void VisitLdObj(LdObj inst)
{
base.VisitLdObj(inst);
EarlyExpressionTransforms.AddressOfLdLocToLdLoca(inst, context);
if (EarlyExpressionTransforms.LdObjToLdLoc(inst, context))
return;
if (TransformDecimalFieldToConstant(inst, out LdcDecimal decimalConstant)) {
context.Step("TransformDecimalFieldToConstant", inst);
inst.ReplaceWith(decimalConstant);
return;
}
}
protected internal override void VisitStObj(StObj inst)
{
base.VisitStObj(inst);
if (EarlyExpressionTransforms.StObjToStLoc(inst, context)) {
context.RequestRerun();
return;
}
TransformAssignment.HandleCompoundAssign(inst, context);
}
protected internal override void VisitStLoc(StLoc inst)
{
base.VisitStLoc(inst);
TransformAssignment.HandleCompoundAssign(inst, context);
}
protected internal override void VisitIfInstruction(IfInstruction inst)
{
inst.TrueInst.AcceptVisitor(this);
inst.FalseInst.AcceptVisitor(this);
inst = HandleConditionalOperator(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 = Comp.LogicNot(inst.Condition);
}
// Process condition after our potential modifications.
inst.Condition.AcceptVisitor(this);
if (new NullableLiftingTransform(context).Run(inst))
return;
if (TransformDynamicAddAssignOrRemoveAssign(inst))
return;
if (inst.MatchIfInstructionPositiveCondition(out var condition, out var trueInst, out var falseInst)) {
ILInstruction transformed = UserDefinedLogicTransform.Transform(condition, trueInst, falseInst);
if (transformed == null) {
transformed = UserDefinedLogicTransform.TransformDynamic(condition, trueInst, falseInst);
}
if (transformed != null) {
context.Step("User-defined short-circuiting logic operator (roslyn pattern)", condition);
transformed.AddILRange(inst);
inst.ReplaceWith(transformed);
return;
}
}
}
/// <summary>
/// op is either add or remove/subtract:
/// if (dynamic.isevent (target)) {
/// dynamic.invokemember.invokespecial.discard op_Name(target, value)
/// } else {
/// dynamic.compound.op (dynamic.getmember Name(target), value)
/// }
/// =>
/// dynamic.compound.op (dynamic.getmember Name(target), value)
/// </summary>
bool TransformDynamicAddAssignOrRemoveAssign(IfInstruction inst)
{
if (!inst.MatchIfInstructionPositiveCondition(out var condition, out var trueInst, out var falseInst))
return false;
if (!(condition is DynamicIsEventInstruction isEvent))
return false;
trueInst = Block.Unwrap(trueInst);
falseInst = Block.Unwrap(falseInst);
if (!(falseInst is DynamicCompoundAssign dynamicCompoundAssign))
return false;
if (!(dynamicCompoundAssign.Target is DynamicGetMemberInstruction getMember))
return false;
if (!SemanticHelper.IsPure(isEvent.Argument.Flags))
return false;
if (!isEvent.Argument.Match(getMember.Target).Success)
return false;
if (!(trueInst is DynamicInvokeMemberInstruction invokeMember))
return false;
if (!(invokeMember.BinderFlags.HasFlag(CSharpBinderFlags.InvokeSpecialName) && invokeMember.BinderFlags.HasFlag(CSharpBinderFlags.ResultDiscarded)))
return false;
switch (dynamicCompoundAssign.Operation) {
case ExpressionType.AddAssign:
if (invokeMember.Name != "add_" + getMember.Name)
return false;
break;
case ExpressionType.SubtractAssign:
if (invokeMember.Name != "remove_" + getMember.Name)
return false;
break;
default:
return false;
}
if (!dynamicCompoundAssign.Value.Match(invokeMember.Arguments[1]).Success)
return false;
if (!invokeMember.Arguments[0].Match(getMember.Target).Success)
return false;
context.Step("+= / -= dynamic.isevent pattern -> dynamic.compound.op", inst);
inst.ReplaceWith(dynamicCompoundAssign);
return true;
}
/// <summary>
/// dynamic.setmember.compound Name(target, dynamic.binary.operator op(dynamic.getmember Name(target), value))
/// =>
/// dynamic.compound.op (dynamic.getmember Name(target), value)
/// </summary>
protected internal override void VisitDynamicSetMemberInstruction(DynamicSetMemberInstruction inst)
{
base.VisitDynamicSetMemberInstruction(inst);
TransformDynamicSetMemberInstruction(inst, context);
}
internal static void TransformDynamicSetMemberInstruction(DynamicSetMemberInstruction inst, StatementTransformContext context)
{
if (!inst.BinderFlags.HasFlag(CSharpBinderFlags.ValueFromCompoundAssignment))
return;
if (!(inst.Value is DynamicBinaryOperatorInstruction binaryOp))
return;
if (!(binaryOp.Left is DynamicGetMemberInstruction dynamicGetMember))
return;
if (!dynamicGetMember.Target.Match(inst.Target).Success)
return;
if (!SemanticHelper.IsPure(dynamicGetMember.Target.Flags))
return;
if (inst.Name != dynamicGetMember.Name || !DynamicCompoundAssign.IsExpressionTypeSupported(binaryOp.Operation))
return;
context.Step("dynamic.setmember.compound -> dynamic.compound.op", inst);
inst.ReplaceWith(new DynamicCompoundAssign(binaryOp.Operation, binaryOp.BinderFlags, binaryOp.Left, binaryOp.LeftArgumentInfo, binaryOp.Right, binaryOp.RightArgumentInfo));
}
/// <summary>
/// dynamic.setindex.compound(target, index, dynamic.binary.operator op(dynamic.getindex(target, index), value))
/// =>
/// dynamic.compound.op (dynamic.getindex(target, index), value)
/// </summary>
protected internal override void VisitDynamicSetIndexInstruction(DynamicSetIndexInstruction inst)
{
base.VisitDynamicSetIndexInstruction(inst);
if (!inst.BinderFlags.HasFlag(CSharpBinderFlags.ValueFromCompoundAssignment))
return;
if (!(inst.Arguments.LastOrDefault() is DynamicBinaryOperatorInstruction binaryOp))
return;
if (!(binaryOp.Left is DynamicGetIndexInstruction dynamicGetIndex))
return;
if (inst.Arguments.Count != dynamicGetIndex.Arguments.Count + 1)
return;
// Ensure that same arguments are passed to dynamicGetIndex and inst:
for (int j = 0; j < dynamicGetIndex.Arguments.Count; j++) {
if (!SemanticHelper.IsPure(dynamicGetIndex.Arguments[j].Flags))
return;
if (!dynamicGetIndex.Arguments[j].Match(inst.Arguments[j]).Success)
return;
}
if (!DynamicCompoundAssign.IsExpressionTypeSupported(binaryOp.Operation))
return;
context.Step("dynamic.setindex.compound -> dynamic.compound.op", inst);
inst.ReplaceWith(new DynamicCompoundAssign(binaryOp.Operation, binaryOp.BinderFlags, binaryOp.Left, binaryOp.LeftArgumentInfo, binaryOp.Right, binaryOp.RightArgumentInfo));
}
IfInstruction HandleConditionalOperator(IfInstruction 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 inst;
Block falseInst = inst.FalseInst as Block;
if (falseInst == null || falseInst.Instructions.Count != 1)
return inst;
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);
var newIf = new IfInstruction(Comp.LogicNot(inst.Condition), value2, value1);
newIf.AddILRange(inst);
inst.ReplaceWith(new StLoc(v, newIf));
context.RequestRerun(); // trigger potential inlining of the newly created StLoc
return newIf;
}
return inst;
}
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;
case BinaryNumericOperator.BitAnd:
if (inst.Left.InferType(context.TypeSystem).IsKnownType(KnownTypeCode.Boolean)
&& inst.Right.InferType(context.TypeSystem).IsKnownType(KnownTypeCode.Boolean))
{
if (new NullableLiftingTransform(context).Run(inst)) {
// e.g. "(a.GetValueOrDefault() == b.GetValueOrDefault()) & (a.HasValue & b.HasValue)"
}
}
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, isCatchBlock: true);
}
/// <summary>
/// catch ex : TException when (...) BlockContainer {
/// Block entryPoint (incoming: 1) {
/// stloc v(ldloc ex)
/// ...
/// }
/// }
/// =>
/// catch v : TException when (...) BlockContainer {
/// Block entryPoint (incoming: 1) {
/// ...
/// }
/// }
/// </summary>
void TransformCatchVariable(TryCatchHandler handler, Block entryPoint, bool isCatchBlock)
{
if (!handler.Variable.IsSingleDefinition || handler.Variable.LoadCount != 1)
return; // handle.Variable already has non-trivial uses
if (!entryPoint.Instructions[0].MatchStLoc(out var exceptionVar, out var exceptionSlotLoad)) {
// Not the pattern with a second exceptionVar.
// However, it is still possible that we need to remove a pointless UnboxAny:
if (handler.Variable.LoadInstructions.Single().Parent is UnboxAny inlinedUnboxAny) {
if (inlinedUnboxAny.Type.Equals(handler.Variable.Type)) {
context.Step("TransformCatchVariable - remove inlined UnboxAny", inlinedUnboxAny);
inlinedUnboxAny.ReplaceWith(inlinedUnboxAny.Argument);
foreach (var range in inlinedUnboxAny.ILRanges)
handler.AddExceptionSpecifierILRange(range);
}
}
return;
}
if (exceptionVar.Kind != VariableKind.Local && exceptionVar.Kind != VariableKind.StackSlot)
return;
if (exceptionSlotLoad is UnboxAny unboxAny) {
// When catching a type parameter, csc emits an unbox.any instruction
if (!unboxAny.Type.Equals(handler.Variable.Type))
return;
exceptionSlotLoad = unboxAny.Argument;
}
if (!exceptionSlotLoad.MatchLdLoc(handler.Variable))
return;
// Check that exceptionVar is only used within the catch block:
var allUses = exceptionVar.LoadInstructions
.Concat(exceptionVar.StoreInstructions.Cast<ILInstruction>())
.Concat(exceptionVar.AddressInstructions);
foreach (var inst in allUses) {
if (!inst.IsDescendantOf(handler))
return;
}
context.Step("TransformCatchVariable", entryPoint.Instructions[0]);
exceptionVar.Kind = VariableKind.ExceptionLocal;
exceptionVar.Type = handler.Variable.Type;
handler.Variable = exceptionVar;
if (isCatchBlock) {
foreach (var offset in entryPoint.Instructions[0].Descendants.SelectMany(o => o.ILRanges))
handler.AddExceptionSpecifierILRange(offset);
}
entryPoint.Instructions.RemoveAt(0);
}
/// <summary>
/// Inline condition from catch-when condition BlockContainer, if possible.
/// </summary>
void TransformCatchWhen(TryCatchHandler handler, Block entryPoint)
{
TransformCatchVariable(handler, entryPoint, isCatchBlock: false);
if (entryPoint.Instructions.Count == 1 && entryPoint.Instructions[0].MatchLeave(out _, out var condition)) {
context.Step("TransformCatchWhen", entryPoint.Instructions[0]);
handler.Filter = condition;
}
}
}
}