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ILSpy/ICSharpCode.Decompiler/ILAst/PeepholeTransform.cs

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// Copyright (c) 2011 AlphaSierraPapa for the SharpDevelop Team
//
// 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 ICSharpCode.NRefactory.Utils;
using Mono.Cecil;
namespace ICSharpCode.Decompiler.ILAst
{
public partial class ILAstOptimizer
{
#region TypeConversionSimplifications
static bool TypeConversionSimplifications(List<ILNode> body, ILExpression expr, int pos)
{
bool modified = false;
modified |= TransformDecimalCtorToConstant(expr);
modified |= SimplifyLdcI4ConvI8(expr);
modified |= RemoveConvIFromArrayCreation(expr);
foreach(ILExpression arg in expr.Arguments) {
modified |= TypeConversionSimplifications(null, arg, -1);
}
return modified;
}
static bool TransformDecimalCtorToConstant(ILExpression expr)
{
MethodReference r;
List<ILExpression> args;
if (expr.Match(ILCode.Newobj, out r, out args) &&
r.DeclaringType.Namespace == "System" &&
r.DeclaringType.Name == "Decimal")
{
if (args.Count == 1) {
int val;
if (args[0].Match(ILCode.Ldc_I4, out val)) {
expr.Code = ILCode.Ldc_Decimal;
expr.Operand = new decimal(val);
expr.InferredType = r.DeclaringType;
expr.Arguments.Clear();
return true;
}
} else if (args.Count == 5) {
int lo, mid, hi, isNegative, scale;
if (expr.Arguments[0].Match(ILCode.Ldc_I4, out lo) &&
expr.Arguments[1].Match(ILCode.Ldc_I4, out mid) &&
expr.Arguments[2].Match(ILCode.Ldc_I4, out hi) &&
expr.Arguments[3].Match(ILCode.Ldc_I4, out isNegative) &&
expr.Arguments[4].Match(ILCode.Ldc_I4, out scale))
{
expr.Code = ILCode.Ldc_Decimal;
expr.Operand = new decimal(lo, mid, hi, isNegative != 0, (byte)scale);
expr.InferredType = r.DeclaringType;
expr.Arguments.Clear();
return true;
}
}
}
return false;
}
static bool SimplifyLdcI4ConvI8(ILExpression expr)
{
ILExpression ldc;
int val;
if (expr.Match(ILCode.Conv_I8, out ldc) && ldc.Match(ILCode.Ldc_I4, out val)) {
expr.Code = ILCode.Ldc_I8;
expr.Operand = (long)val;
expr.Arguments.Clear();
return true;
}
return false;
}
static bool RemoveConvIFromArrayCreation(ILExpression expr)
{
TypeReference typeRef;
ILExpression length;
ILExpression input;
if (expr.Match(ILCode.Newarr, out typeRef, out length)) {
if (length.Match(ILCode.Conv_Ovf_I, out input) || length.Match(ILCode.Conv_I, out input)
|| length.Match(ILCode.Conv_Ovf_I_Un, out input) || length.Match(ILCode.Conv_U, out input))
{
expr.Arguments[0] = input;
return true;
}
}
return false;
}
#endregion
#region SimplifyLdObjAndStObj
static bool SimplifyLdObjAndStObj(List<ILNode> body, ILExpression expr, int pos)
{
bool modified = false;
expr = SimplifyLdObjAndStObj(expr, ref modified);
if (modified && body != null)
body[pos] = expr;
for (int i = 0; i < expr.Arguments.Count; i++) {
expr.Arguments[i] = SimplifyLdObjAndStObj(expr.Arguments[i], ref modified);
modified |= SimplifyLdObjAndStObj(null, expr.Arguments[i], -1);
}
return modified;
}
static ILExpression SimplifyLdObjAndStObj(ILExpression expr, ref bool modified)
{
if (expr.Code == ILCode.Initobj) {
expr.Code = ILCode.Stobj;
expr.Arguments.Add(new ILExpression(ILCode.DefaultValue, expr.Operand));
modified = true;
} else if (expr.Code == ILCode.Cpobj) {
expr.Code = ILCode.Stobj;
expr.Arguments[1] = new ILExpression(ILCode.Ldobj, expr.Operand, expr.Arguments[1]);
modified = true;
}
ILExpression arg, arg2;
TypeReference type;
ILCode? newCode = null;
if (expr.Match(ILCode.Stobj, out type, out arg, out arg2)) {
switch (arg.Code) {
case ILCode.Ldelema: newCode = ILCode.Stelem_Any; break;
case ILCode.Ldloca: newCode = ILCode.Stloc; break;
case ILCode.Ldflda: newCode = ILCode.Stfld; break;
case ILCode.Ldsflda: newCode = ILCode.Stsfld; break;
}
} else if (expr.Match(ILCode.Ldobj, out type, out arg)) {
switch (arg.Code) {
case ILCode.Ldelema: newCode = ILCode.Ldelem_Any; break;
case ILCode.Ldloca: newCode = ILCode.Ldloc; break;
case ILCode.Ldflda: newCode = ILCode.Ldfld; break;
case ILCode.Ldsflda: newCode = ILCode.Ldsfld; break;
}
}
if (newCode != null) {
arg.Code = newCode.Value;
if (expr.Code == ILCode.Stobj) {
arg.InferredType = expr.InferredType;
arg.ExpectedType = expr.ExpectedType;
arg.Arguments.Add(arg2);
}
arg.ILRanges.AddRange(expr.ILRanges);
modified = true;
return arg;
} else {
return expr;
}
}
#endregion
#region CachedDelegateInitialization
void CachedDelegateInitializationWithField(ILBlock block, ref int i)
{
// if (logicnot(ldsfld(field))) {
// stsfld(field, newobj(Action::.ctor, ldnull(), ldftn(method)))
// } else {
// }
// ...(..., ldsfld(field), ...)
ILCondition c = block.Body[i] as ILCondition;
if (c == null || c.Condition == null && c.TrueBlock == null || c.FalseBlock == null)
return;
if (!(c.TrueBlock.Body.Count == 1 && c.FalseBlock.Body.Count == 0))
return;
if (!c.Condition.Match(ILCode.LogicNot))
return;
ILExpression condition = c.Condition.Arguments.Single() as ILExpression;
if (condition == null || condition.Code != ILCode.Ldsfld)
return;
FieldDefinition field = ((FieldReference)condition.Operand).ResolveWithinSameModule(); // field is defined in current assembly
if (field == null || !field.IsCompilerGeneratedOrIsInCompilerGeneratedClass())
return;
ILExpression stsfld = c.TrueBlock.Body[0] as ILExpression;
if (!(stsfld != null && stsfld.Code == ILCode.Stsfld && ((FieldReference)stsfld.Operand).ResolveWithinSameModule() == field))
return;
ILExpression newObj = stsfld.Arguments[0];
if (!(newObj.Code == ILCode.Newobj && newObj.Arguments.Count == 2))
return;
if (newObj.Arguments[0].Code != ILCode.Ldnull)
return;
if (newObj.Arguments[1].Code != ILCode.Ldftn)
return;
MethodDefinition anonymousMethod = ((MethodReference)newObj.Arguments[1].Operand).ResolveWithinSameModule(); // method is defined in current assembly
if (!Ast.Transforms.DelegateConstruction.IsAnonymousMethod(context, anonymousMethod))
return;
ILNode followingNode = block.Body.ElementAtOrDefault(i + 1);
if (followingNode != null && followingNode.GetSelfAndChildrenRecursive<ILExpression>().Count(
e => e.Code == ILCode.Ldsfld && ((FieldReference)e.Operand).ResolveWithinSameModule() == field) == 1)
{
foreach (ILExpression parent in followingNode.GetSelfAndChildrenRecursive<ILExpression>()) {
for (int j = 0; j < parent.Arguments.Count; j++) {
if (parent.Arguments[j].Code == ILCode.Ldsfld && ((FieldReference)parent.Arguments[j].Operand).ResolveWithinSameModule() == field) {
parent.Arguments[j] = newObj;
block.Body.RemoveAt(i);
i -= new ILInlining(method).InlineInto(block.Body, i, aggressive: false);
return;
}
}
}
}
}
void CachedDelegateInitializationWithLocal(ILBlock block, ref int i)
{
// if (logicnot(ldloc(v))) {
// stloc(v, newobj(Action::.ctor, ldloc(displayClass), ldftn(method)))
// } else {
// }
// ...(..., ldloc(v), ...)
ILCondition c = block.Body[i] as ILCondition;
if (c == null || c.Condition == null && c.TrueBlock == null || c.FalseBlock == null)
return;
if (!(c.TrueBlock.Body.Count == 1 && c.FalseBlock.Body.Count == 0))
return;
if (!c.Condition.Match(ILCode.LogicNot))
return;
ILExpression condition = c.Condition.Arguments.Single() as ILExpression;
if (condition == null || condition.Code != ILCode.Ldloc)
return;
ILVariable v = (ILVariable)condition.Operand;
ILExpression stloc = c.TrueBlock.Body[0] as ILExpression;
if (!(stloc != null && stloc.Code == ILCode.Stloc && (ILVariable)stloc.Operand == v))
return;
ILExpression newObj = stloc.Arguments[0];
if (!(newObj.Code == ILCode.Newobj && newObj.Arguments.Count == 2))
return;
if (newObj.Arguments[0].Code != ILCode.Ldloc)
return;
if (newObj.Arguments[1].Code != ILCode.Ldftn)
return;
MethodDefinition anonymousMethod = ((MethodReference)newObj.Arguments[1].Operand).ResolveWithinSameModule(); // method is defined in current assembly
if (!Ast.Transforms.DelegateConstruction.IsAnonymousMethod(context, anonymousMethod))
return;
ILNode followingNode = block.Body.ElementAtOrDefault(i + 1);
if (followingNode != null && followingNode.GetSelfAndChildrenRecursive<ILExpression>().Count(
e => e.Code == ILCode.Ldloc && (ILVariable)e.Operand == v) == 1)
{
ILInlining inlining = new ILInlining(method);
if (!(inlining.numLdloc.GetOrDefault(v) == 2 && inlining.numStloc.GetOrDefault(v) == 2 && inlining.numLdloca.GetOrDefault(v) == 0))
return;
// Find the store instruction that initializes the local to null:
foreach (ILBlock storeBlock in method.GetSelfAndChildrenRecursive<ILBlock>()) {
for (int j = 0; j < storeBlock.Body.Count; j++) {
ILVariable storedVar;
ILExpression storedExpr;
if (storeBlock.Body[j].Match(ILCode.Stloc, out storedVar, out storedExpr) && storedVar == v && storedExpr.Match(ILCode.Ldnull)) {
// Remove the instruction
storeBlock.Body.RemoveAt(j);
if (storeBlock == block && j < i)
i--;
break;
}
}
}
block.Body[i] = stloc; // remove the 'if (v==null)'
inlining = new ILInlining(method);
inlining.InlineIfPossible(block.Body, ref i);
}
}
#endregion
#region MakeAssignmentExpression
bool MakeAssignmentExpression(List<ILNode> body, ILExpression expr, int pos)
{
// exprVar = ...
// stloc(v, exprVar)
// ->
// exprVar = stloc(v, ...))
ILVariable exprVar;
ILExpression initializer;
if (!(expr.Match(ILCode.Stloc, out exprVar, out initializer) && exprVar.IsGenerated))
return false;
ILExpression nextExpr = body.ElementAtOrDefault(pos + 1) as ILExpression;
ILVariable v;
ILExpression stLocArg;
if (nextExpr.Match(ILCode.Stloc, out v, out stLocArg) && stLocArg.MatchLdloc(exprVar)) {
ILExpression store2 = body.ElementAtOrDefault(pos + 2) as ILExpression;
if (StoreCanBeConvertedToAssignment(store2, exprVar)) {
// expr_44 = ...
// stloc(v1, expr_44)
// anystore(v2, expr_44)
// ->
// stloc(v1, anystore(v2, ...))
ILInlining inlining = new ILInlining(method);
if (inlining.numLdloc.GetOrDefault(exprVar) == 2 && inlining.numStloc.GetOrDefault(exprVar) == 1) {
body.RemoveAt(pos + 2); // remove store2
body.RemoveAt(pos); // remove expr = ...
nextExpr.Arguments[0] = store2;
store2.Arguments[store2.Arguments.Count - 1] = initializer;
inlining.InlineIfPossible(body, ref pos);
return true;
}
}
body.RemoveAt(pos + 1); // remove stloc
nextExpr.Arguments[0] = initializer;
((ILExpression)body[pos]).Arguments[0] = nextExpr;
return true;
} else if ((nextExpr.Code == ILCode.Stsfld || nextExpr.Code == ILCode.CallSetter || nextExpr.Code == ILCode.CallvirtSetter) && nextExpr.Arguments.Count == 1) {
// exprVar = ...
// stsfld(fld, exprVar)
// ->
// exprVar = stsfld(fld, ...))
if (nextExpr.Arguments[0].MatchLdloc(exprVar)) {
body.RemoveAt(pos + 1); // remove stsfld
nextExpr.Arguments[0] = initializer;
((ILExpression)body[pos]).Arguments[0] = nextExpr;
return true;
}
}
return false;
}
bool StoreCanBeConvertedToAssignment(ILExpression store, ILVariable exprVar)
{
if (store == null)
return false;
switch (store.Code) {
case ILCode.Stloc:
case ILCode.Stfld:
case ILCode.Stsfld:
case ILCode.Stobj:
case ILCode.CallSetter:
case ILCode.CallvirtSetter:
break;
default:
if (!store.Code.IsStoreToArray())
return false;
break;
}
return store.Arguments.Last().Code == ILCode.Ldloc && store.Arguments.Last().Operand == exprVar;
}
#endregion
#region MakeCompoundAssignments
bool MakeCompoundAssignments(List<ILNode> body, ILExpression expr, int pos)
{
bool modified = false;
modified |= MakeCompoundAssignment(expr);
// Static fields and local variables are not handled here - those are expressions without side effects
// and get handled by ReplaceMethodCallsWithOperators
// (which does a reversible transform to the short operator form, as the introduction of checked/unchecked might have to revert to the long form).
foreach (ILExpression arg in expr.Arguments) {
modified |= MakeCompoundAssignments(null, arg, -1);
}
if (modified && body != null)
new ILInlining(method).InlineInto(body, pos, aggressive: false);
return modified;
}
bool MakeCompoundAssignment(ILExpression expr)
{
// stelem.any(T, ldloc(array), ldloc(pos), <OP>(ldelem.any(T, ldloc(array), ldloc(pos)), <RIGHT>))
// or
// stobj(T, ldloc(ptr), <OP>(ldobj(T, ldloc(ptr)), <RIGHT>))
ILCode expectedLdelemCode;
switch (expr.Code) {
case ILCode.Stelem_Any:
expectedLdelemCode = ILCode.Ldelem_Any;
break;
case ILCode.Stfld:
expectedLdelemCode = ILCode.Ldfld;
break;
case ILCode.Stobj:
expectedLdelemCode = ILCode.Ldobj;
break;
case ILCode.CallSetter:
expectedLdelemCode = ILCode.CallGetter;
break;
case ILCode.CallvirtSetter:
expectedLdelemCode = ILCode.CallvirtGetter;
break;
default:
return false;
}
// all arguments except the last (so either array+pos, or ptr):
bool hasGeneratedVar = false;
for (int i = 0; i < expr.Arguments.Count - 1; i++) {
ILVariable inputVar;
if (!expr.Arguments[i].Match(ILCode.Ldloc, out inputVar))
return false;
hasGeneratedVar |= inputVar.IsGenerated;
}
// At least one of the variables must be generated; otherwise we just keep the expanded form.
// We do this because we want compound assignments to be represented in ILAst only when strictly necessary;
// other compound assignments will be introduced by ReplaceMethodCallsWithOperator
// (which uses a reversible transformation, see ReplaceMethodCallsWithOperator.RestoreOriginalAssignOperatorAnnotation)
if (!hasGeneratedVar)
return false;
ILExpression op = expr.Arguments.Last();
// in case of compound assignments with a lifted operator the result is inside NullableOf and the operand is inside ValueOf
bool liftedOperator = false;
if (op.Code == ILCode.NullableOf) {
op = op.Arguments[0];
liftedOperator = true;
}
if (!CanBeRepresentedAsCompoundAssignment(op))
return false;
ILExpression ldelem = op.Arguments[0];
if (liftedOperator) {
if (ldelem.Code != ILCode.ValueOf)
return false;
ldelem = ldelem.Arguments[0];
}
if (ldelem.Code != expectedLdelemCode)
return false;
Debug.Assert(ldelem.Arguments.Count == expr.Arguments.Count - 1);
for (int i = 0; i < ldelem.Arguments.Count; i++) {
if (!ldelem.Arguments[i].MatchLdloc((ILVariable)expr.Arguments[i].Operand))
return false;
}
expr.Code = ILCode.CompoundAssignment;
expr.Operand = null;
expr.Arguments.RemoveRange(0, ldelem.Arguments.Count);
// result is "CompoundAssignment(<OP>(ldelem.any(...), <RIGHT>))"
return true;
}
static bool CanBeRepresentedAsCompoundAssignment(ILExpression expr)
{
switch (expr.Code) {
case ILCode.Add:
case ILCode.Add_Ovf:
case ILCode.Add_Ovf_Un:
case ILCode.Sub:
case ILCode.Sub_Ovf:
case ILCode.Sub_Ovf_Un:
case ILCode.Mul:
case ILCode.Mul_Ovf:
case ILCode.Mul_Ovf_Un:
case ILCode.Div:
case ILCode.Div_Un:
case ILCode.Rem:
case ILCode.Rem_Un:
case ILCode.And:
case ILCode.Or:
case ILCode.Xor:
case ILCode.Shl:
case ILCode.Shr:
case ILCode.Shr_Un:
return true;
case ILCode.Call:
var m = expr.Operand as MethodReference;
if (m == null || m.HasThis || expr.Arguments.Count != 2) return false;
switch (m.Name) {
case "op_Addition":
case "op_Subtraction":
case "op_Multiply":
case "op_Division":
case "op_Modulus":
case "op_BitwiseAnd":
case "op_BitwiseOr":
case "op_ExclusiveOr":
case "op_LeftShift":
case "op_RightShift":
return true;
default:
return false;
}
default:
return false;
}
}
#endregion
#region IntroducePostIncrement
bool IntroducePostIncrement(List<ILNode> body, ILExpression expr, int pos)
{
bool modified = IntroducePostIncrementForVariables(body, expr, pos);
Debug.Assert(body[pos] == expr); // IntroducePostIncrementForVariables shouldn't change the expression reference
ILExpression newExpr = IntroducePostIncrementForInstanceFields(expr);
if (newExpr != null) {
modified = true;
body[pos] = newExpr;
new ILInlining(method).InlineIfPossible(body, ref pos);
}
return modified;
}
bool IntroducePostIncrementForVariables(List<ILNode> body, ILExpression expr, int pos)
{
// Works for variables and static fields/properties
// expr = ldloc(i)
// stloc(i, add(expr, ldc.i4(1)))
// ->
// expr = postincrement(1, ldloca(i))
ILVariable exprVar;
ILExpression exprInit;
if (!(expr.Match(ILCode.Stloc, out exprVar, out exprInit) && exprVar.IsGenerated))
return false;
//The next expression
ILExpression nextExpr = body.ElementAtOrDefault(pos + 1) as ILExpression;
if (nextExpr == null)
return false;
ILCode loadInstruction = exprInit.Code;
ILCode storeInstruction = nextExpr.Code;
bool recombineVariable = false;
// We only recognise local variables, static fields, and static getters with no arguments
switch (loadInstruction) {
case ILCode.Ldloc:
//Must be a matching store type
if (storeInstruction != ILCode.Stloc)
return false;
ILVariable loadVar = (ILVariable)exprInit.Operand;
ILVariable storeVar = (ILVariable)nextExpr.Operand;
if (loadVar != storeVar) {
if (loadVar.OriginalVariable != null && loadVar.OriginalVariable == storeVar.OriginalVariable)
recombineVariable = true;
else
return false;
}
break;
case ILCode.Ldsfld:
if (storeInstruction != ILCode.Stsfld)
return false;
if (exprInit.Operand != nextExpr.Operand)
return false;
break;
case ILCode.CallGetter:
// non-static getters would have the 'this' argument
if (exprInit.Arguments.Count != 0)
return false;
if (storeInstruction != ILCode.CallSetter)
return false;
if (!IsGetterSetterPair(exprInit.Operand, nextExpr.Operand))
return false;
break;
default:
return false;
}
ILExpression addExpr = nextExpr.Arguments[0];
int incrementAmount;
ILCode incrementCode = GetIncrementCode(addExpr, out incrementAmount);
if (!(incrementAmount != 0 && addExpr.Arguments[0].MatchLdloc(exprVar)))
return false;
if (recombineVariable) {
// Split local variable, unsplit these two instances
// replace nextExpr.Operand with exprInit.Operand
ReplaceVariables(method, oldVar => oldVar == nextExpr.Operand ? (ILVariable)exprInit.Operand : oldVar);
}
switch (loadInstruction) {
case ILCode.Ldloc:
exprInit.Code = ILCode.Ldloca;
break;
case ILCode.Ldsfld:
exprInit.Code = ILCode.Ldsflda;
break;
case ILCode.CallGetter:
exprInit = new ILExpression(ILCode.AddressOf, null, exprInit);
break;
}
expr.Arguments[0] = new ILExpression(incrementCode, incrementAmount, exprInit);
body.RemoveAt(pos + 1); // TODO ILRanges
return true;
}
static bool IsGetterSetterPair(object getterOperand, object setterOperand)
{
MethodReference getter = getterOperand as MethodReference;
MethodReference setter = setterOperand as MethodReference;
if (getter == null || setter == null)
return false;
if (!TypeAnalysis.IsSameType(getter.DeclaringType, setter.DeclaringType))
return false;
MethodDefinition getterDef = getter.Resolve();
MethodDefinition setterDef = setter.Resolve();
if (getterDef == null || setterDef == null)
return false;
foreach (PropertyDefinition prop in getterDef.DeclaringType.Properties) {
if (prop.GetMethod == getterDef)
return prop.SetMethod == setterDef;
}
return false;
}
ILExpression IntroducePostIncrementForInstanceFields(ILExpression expr)
{
// stfld(field, ldloc(instance), add(stloc(helperVar, ldfld(field, ldloc(instance))), ldc.i4(1)))
// -> stloc(helperVar, postincrement(1, ldflda(field, ldloc(instance))))
// Also works for array elements and pointers:
// stelem.any(T, ldloc(instance), ldloc(pos), add(stloc(helperVar, ldelem.any(T, ldloc(instance), ldloc(pos))), ldc.i4(1)))
// -> stloc(helperVar, postincrement(1, ldelema(ldloc(instance), ldloc(pos))))
// stobj(T, ldloc(ptr), add(stloc(helperVar, ldobj(T, ldloc(ptr)), ldc.i4(1))))
// -> stloc(helperVar, postIncrement(1, ldloc(ptr)))
// callsetter(set_P, ldloc(instance), add(stloc(helperVar, callgetter(get_P, ldloc(instance))), ldc.i4(1)))
// -> stloc(helperVar, postIncrement(1, propertyaddress. callgetter(get_P, ldloc(instance))))
if (!(expr.Code == ILCode.Stfld || expr.Code.IsStoreToArray() || expr.Code == ILCode.Stobj || expr.Code == ILCode.CallSetter || expr.Code == ILCode.CallvirtSetter))
return null;
// Test that all arguments except the last are ldloc (1 arg for fields and pointers, 2 args for arrays)
for (int i = 0; i < expr.Arguments.Count - 1; i++) {
if (expr.Arguments[i].Code != ILCode.Ldloc)
return null;
}
ILExpression addExpr = expr.Arguments[expr.Arguments.Count - 1];
int incrementAmount;
ILCode incrementCode = GetIncrementCode(addExpr, out incrementAmount);
ILVariable helperVar;
ILExpression initialValue;
if (!(incrementAmount != 0 && addExpr.Arguments[0].Match(ILCode.Stloc, out helperVar, out initialValue)))
return null;
if (expr.Code == ILCode.Stfld) {
if (initialValue.Code != ILCode.Ldfld)
return null;
// There might be two different FieldReference instances, so we compare the field's signatures:
FieldReference getField = (FieldReference)initialValue.Operand;
FieldReference setField = (FieldReference)expr.Operand;
if (!(TypeAnalysis.IsSameType(getField.DeclaringType, setField.DeclaringType)
&& getField.Name == setField.Name && TypeAnalysis.IsSameType(getField.FieldType, setField.FieldType)))
{
return null;
}
} else if (expr.Code == ILCode.Stobj) {
if (!(initialValue.Code == ILCode.Ldobj && initialValue.Operand == expr.Operand))
return null;
} else if (expr.Code == ILCode.CallSetter) {
if (!(initialValue.Code == ILCode.CallGetter && IsGetterSetterPair(initialValue.Operand, expr.Operand)))
return null;
} else if (expr.Code == ILCode.CallvirtSetter) {
if (!(initialValue.Code == ILCode.CallvirtGetter && IsGetterSetterPair(initialValue.Operand, expr.Operand)))
return null;
} else {
if (!initialValue.Code.IsLoadFromArray())
return null;
}
Debug.Assert(expr.Arguments.Count - 1 == initialValue.Arguments.Count);
for (int i = 0; i < initialValue.Arguments.Count; i++) {
if (!initialValue.Arguments[i].MatchLdloc((ILVariable)expr.Arguments[i].Operand))
return null;
}
ILExpression stloc = addExpr.Arguments[0];
if (expr.Code == ILCode.Stobj) {
stloc.Arguments[0] = new ILExpression(ILCode.PostIncrement, incrementAmount, initialValue.Arguments[0]);
} else if (expr.Code == ILCode.CallSetter || expr.Code == ILCode.CallvirtSetter) {
initialValue = new ILExpression(ILCode.AddressOf, null, initialValue);
stloc.Arguments[0] = new ILExpression(ILCode.PostIncrement, incrementAmount, initialValue);
} else {
stloc.Arguments[0] = new ILExpression(ILCode.PostIncrement, incrementAmount, initialValue);
initialValue.Code = (expr.Code == ILCode.Stfld ? ILCode.Ldflda : ILCode.Ldelema);
}
// TODO: ILRanges?
return stloc;
}
ILCode GetIncrementCode(ILExpression addExpr, out int incrementAmount)
{
ILCode incrementCode;
bool decrement = false;
switch (addExpr.Code) {
case ILCode.Add:
incrementCode = ILCode.PostIncrement;
break;
case ILCode.Add_Ovf:
incrementCode = ILCode.PostIncrement_Ovf;
break;
case ILCode.Add_Ovf_Un:
incrementCode = ILCode.PostIncrement_Ovf_Un;
break;
case ILCode.Sub:
incrementCode = ILCode.PostIncrement;
decrement = true;
break;
case ILCode.Sub_Ovf:
incrementCode = ILCode.PostIncrement_Ovf;
decrement = true;
break;
case ILCode.Sub_Ovf_Un:
incrementCode = ILCode.PostIncrement_Ovf_Un;
decrement = true;
break;
default:
incrementAmount = 0;
return ILCode.Nop;
}
if (addExpr.Arguments[1].Match(ILCode.Ldc_I4, out incrementAmount)) {
if (incrementAmount == -1 || incrementAmount == 1) { // TODO pointer increment?
if (decrement)
incrementAmount = -incrementAmount;
return incrementCode;
}
}
incrementAmount = 0;
return ILCode.Nop;
}
#endregion
#region IntroduceFixedStatements
bool IntroduceFixedStatements(List<ILNode> body, int i)
{
ILExpression initValue;
ILVariable pinnedVar;
int initEndPos;
if (!MatchFixedInitializer(body, i, out pinnedVar, out initValue, out initEndPos))
return false;
ILFixedStatement fixedStmt = body.ElementAtOrDefault(initEndPos) as ILFixedStatement;
if (fixedStmt != null) {
ILExpression expr = fixedStmt.BodyBlock.Body.LastOrDefault() as ILExpression;
if (expr != null && expr.Code == ILCode.Stloc && expr.Operand == pinnedVar && IsNullOrZero(expr.Arguments[0])) {
// we found a second initializer for the existing fixed statement
fixedStmt.Initializers.Insert(0, initValue);
body.RemoveRange(i, initEndPos - i);
fixedStmt.BodyBlock.Body.RemoveAt(fixedStmt.BodyBlock.Body.Count - 1);
if (pinnedVar.Type.IsByReference)
pinnedVar.Type = new PointerType(((ByReferenceType)pinnedVar.Type).ElementType);
return true;
}
}
// find where pinnedVar is reset to 0:
int j;
for (j = initEndPos; j < body.Count; j++) {
ILVariable v2;
ILExpression storedVal;
// stloc(pinned_Var, conv.u(ldc.i4(0)))
if (body[j].Match(ILCode.Stloc, out v2, out storedVal) && v2 == pinnedVar) {
if (IsNullOrZero(storedVal)) {
break;
}
}
}
// Create fixed statement from i to j
fixedStmt = new ILFixedStatement();
fixedStmt.Initializers.Add(initValue);
fixedStmt.BodyBlock = new ILBlock(body.GetRange(initEndPos, j - initEndPos)); // from initEndPos to j-1 (inclusive)
body.RemoveRange(i + 1, Math.Min(j, body.Count - 1) - i); // from i+1 to j (inclusive)
body[i] = fixedStmt;
if (pinnedVar.Type.IsByReference)
pinnedVar.Type = new PointerType(((ByReferenceType)pinnedVar.Type).ElementType);
return true;
}
bool IsNullOrZero(ILExpression expr)
{
if (expr.Code == ILCode.Conv_U || expr.Code == ILCode.Conv_I)
expr = expr.Arguments[0];
return (expr.Code == ILCode.Ldc_I4 && (int)expr.Operand == 0) || expr.Code == ILCode.Ldnull;
}
bool MatchFixedInitializer(List<ILNode> body, int i, out ILVariable pinnedVar, out ILExpression initValue, out int nextPos)
{
if (body[i].Match(ILCode.Stloc, out pinnedVar, out initValue) && pinnedVar.IsPinned && !IsNullOrZero(initValue)) {
initValue = (ILExpression)body[i];
nextPos = i + 1;
HandleStringFixing(pinnedVar, body, ref nextPos, ref initValue);
return true;
}
ILCondition ifStmt = body[i] as ILCondition;
ILExpression arrayLoadingExpr;
if (ifStmt != null && MatchFixedArrayInitializerCondition(ifStmt.Condition, out arrayLoadingExpr)) {
ILVariable arrayVariable = (ILVariable)arrayLoadingExpr.Operand;
ILExpression trueValue;
if (ifStmt.TrueBlock != null && ifStmt.TrueBlock.Body.Count == 1
&& ifStmt.TrueBlock.Body[0].Match(ILCode.Stloc, out pinnedVar, out trueValue)
&& pinnedVar.IsPinned && IsNullOrZero(trueValue))
{
if (ifStmt.FalseBlock != null && ifStmt.FalseBlock.Body.Count == 1 && ifStmt.FalseBlock.Body[0] is ILFixedStatement) {
ILFixedStatement fixedStmt = (ILFixedStatement)ifStmt.FalseBlock.Body[0];
ILVariable stlocVar;
ILExpression falseValue;
if (fixedStmt.Initializers.Count == 1 && fixedStmt.BodyBlock.Body.Count == 0
&& fixedStmt.Initializers[0].Match(ILCode.Stloc, out stlocVar, out falseValue) && stlocVar == pinnedVar)
{
ILVariable loadedVariable;
if (falseValue.Code == ILCode.Ldelema
&& falseValue.Arguments[0].Match(ILCode.Ldloc, out loadedVariable) && loadedVariable == arrayVariable
&& IsNullOrZero(falseValue.Arguments[1]))
{
// OK, we detected the pattern for fixing an array.
// Now check whether the loading expression was a store ot a temp. var
// that can be eliminated.
if (arrayLoadingExpr.Code == ILCode.Stloc) {
ILInlining inlining = new ILInlining(method);
if (inlining.numLdloc.GetOrDefault(arrayVariable) == 2 &&
inlining.numStloc.GetOrDefault(arrayVariable) == 1 && inlining.numLdloca.GetOrDefault(arrayVariable) == 0)
{
arrayLoadingExpr = arrayLoadingExpr.Arguments[0];
}
}
initValue = new ILExpression(ILCode.Stloc, pinnedVar, arrayLoadingExpr);
nextPos = i + 1;
return true;
}
}
}
}
}
initValue = null;
nextPos = -1;
return false;
}
bool MatchFixedArrayInitializerCondition(ILExpression condition, out ILExpression initValue)
{
ILExpression logicAnd;
ILVariable arrayVar;
if (condition.Match(ILCode.LogicNot, out logicAnd) && logicAnd.Code == ILCode.LogicAnd) {
initValue = UnpackDoubleNegation(logicAnd.Arguments[0]);
ILExpression arrayVarInitializer;
if (initValue.Match(ILCode.Ldloc, out arrayVar)
|| initValue.Match(ILCode.Stloc, out arrayVar, out arrayVarInitializer))
{
ILExpression arrayLength = logicAnd.Arguments[1];
if (arrayLength.Code == ILCode.Conv_I4)
arrayLength = arrayLength.Arguments[0];
return arrayLength.Code == ILCode.Ldlen && arrayLength.Arguments[0].MatchLdloc(arrayVar);
}
}
initValue = null;
return false;
}
ILExpression UnpackDoubleNegation(ILExpression expr)
{
ILExpression negated;
if (expr.Match(ILCode.LogicNot, out negated) && negated.Match(ILCode.LogicNot, out negated))
return negated;
else
return expr;
}
bool HandleStringFixing(ILVariable pinnedVar, List<ILNode> body, ref int pos, ref ILExpression fixedStmtInitializer)
{
// fixed (stloc(pinnedVar, ldloc(text))) {
// var1 = var2 = conv.i(ldloc(pinnedVar))
// if (logicnot(logicnot(var1))) {
// var2 = add(var1, call(RuntimeHelpers::get_OffsetToStringData))
// }
// stloc(ptrVar, var2)
// ...
if (pos >= body.Count)
return false;
ILVariable var1, var2;
ILExpression varAssignment, ptrInitialization;
if (!(body[pos].Match(ILCode.Stloc, out var1, out varAssignment) && varAssignment.Match(ILCode.Stloc, out var2, out ptrInitialization)))
return false;
if (!(var1.IsGenerated && var2.IsGenerated))
return false;
if (ptrInitialization.Code == ILCode.Conv_I || ptrInitialization.Code == ILCode.Conv_U)
ptrInitialization = ptrInitialization.Arguments[0];
if (!ptrInitialization.MatchLdloc(pinnedVar))
return false;
ILCondition ifStmt = body[pos + 1] as ILCondition;
if (!(ifStmt != null && ifStmt.TrueBlock != null && ifStmt.TrueBlock.Body.Count == 1 && (ifStmt.FalseBlock == null || ifStmt.FalseBlock.Body.Count == 0)))
return false;
if (!UnpackDoubleNegation(ifStmt.Condition).MatchLdloc(var1))
return false;
ILVariable assignedVar;
ILExpression assignedExpr;
if (!(ifStmt.TrueBlock.Body[0].Match(ILCode.Stloc, out assignedVar, out assignedExpr) && assignedVar == var2 && assignedExpr.Code == ILCode.Add))
return false;
MethodReference calledMethod;
if (!(assignedExpr.Arguments[0].MatchLdloc(var1)))
return false;
if (!(assignedExpr.Arguments[1].Match(ILCode.Call, out calledMethod) || assignedExpr.Arguments[1].Match(ILCode.CallGetter, out calledMethod)))
return false;
if (!(calledMethod.Name == "get_OffsetToStringData" && calledMethod.DeclaringType.FullName == "System.Runtime.CompilerServices.RuntimeHelpers"))
return false;
ILVariable pointerVar;
if (body[pos + 2].Match(ILCode.Stloc, out pointerVar, out assignedExpr) && assignedExpr.MatchLdloc(var2)) {
pos += 3;
fixedStmtInitializer.Operand = pointerVar;
return true;
}
return false;
}
#endregion
#region SimplifyLogicNot
static bool SimplifyLogicNot(List<ILNode> body, ILExpression expr, int pos)
{
bool modified = false;
expr = SimplifyLogicNot(expr, ref modified);
Debug.Assert(expr == null);
return modified;
}
static ILExpression SimplifyLogicNot(ILExpression expr, ref bool modified)
{
ILExpression a;
// "ceq(a, ldc.i4.0)" becomes "logicnot(a)" if the inferred type for expression "a" is boolean
if (expr.Code == ILCode.Ceq && TypeAnalysis.IsBoolean(expr.Arguments[0].InferredType) && (a = expr.Arguments[1]).Code == ILCode.Ldc_I4 && (int)a.Operand == 0) {
expr.Code = ILCode.LogicNot;
expr.ILRanges.AddRange(a.ILRanges);
expr.Arguments.RemoveAt(1);
modified = true;
}
ILExpression res = null;
while (expr.Code == ILCode.LogicNot) {
a = expr.Arguments[0];
// remove double negation
if (a.Code == ILCode.LogicNot) {
res = a.Arguments[0];
res.ILRanges.AddRange(expr.ILRanges);
res.ILRanges.AddRange(a.ILRanges);
expr = res;
} else {
if (SimplifyLogicNotArgument(expr)) res = expr = a;
break;
}
}
for (int i = 0; i < expr.Arguments.Count; i++) {
a = SimplifyLogicNot(expr.Arguments[i], ref modified);
if (a != null) {
expr.Arguments[i] = a;
modified = true;
}
}
return res;
}
/// <summary>
/// If the argument is a binary comparison operation then the negation is pushed through it
/// </summary>
static bool SimplifyLogicNotArgument(ILExpression expr)
{
var a = expr.Arguments[0];
ILCode c;
switch (a.Code) {
case ILCode.Ceq: c = ILCode.Cne; break;
case ILCode.Cne: c = ILCode.Ceq; break;
case ILCode.Cgt: c = ILCode.Cle; break;
case ILCode.Cgt_Un: c = ILCode.Cle_Un; break;
case ILCode.Cge: c = ILCode.Clt; break;
case ILCode.Cge_Un: c = ILCode.Clt_Un; break;
case ILCode.Clt: c = ILCode.Cge; break;
case ILCode.Clt_Un: c = ILCode.Cge_Un; break;
case ILCode.Cle: c = ILCode.Cgt; break;
case ILCode.Cle_Un: c = ILCode.Cgt_Un; break;
default: return false;
}
a.Code = c;
a.ILRanges.AddRange(expr.ILRanges);
return true;
}
#endregion
#region SimplifyShiftOperators
static bool SimplifyShiftOperators(List<ILNode> body, ILExpression expr, int pos)
{
// C# compiles "a << b" to "a << (b & 31)", so we will remove the "& 31" if possible.
bool modified = false;
SimplifyShiftOperators(expr, ref modified);
return modified;
}
static void SimplifyShiftOperators(ILExpression expr, ref bool modified)
{
for (int i = 0; i < expr.Arguments.Count; i++)
SimplifyShiftOperators(expr.Arguments[i], ref modified);
if (expr.Code != ILCode.Shl && expr.Code != ILCode.Shr && expr.Code != ILCode.Shr_Un)
return;
var a = expr.Arguments[1];
if (a.Code != ILCode.And || a.Arguments[1].Code != ILCode.Ldc_I4 || expr.InferredType == null)
return;
int mask;
switch (expr.InferredType.MetadataType) {
case MetadataType.Int32:
case MetadataType.UInt32: mask = 31; break;
case MetadataType.Int64:
case MetadataType.UInt64: mask = 63; break;
default: return;
}
if ((int)a.Arguments[1].Operand != mask) return;
var res = a.Arguments[0];
res.ILRanges.AddRange(a.ILRanges);
res.ILRanges.AddRange(a.Arguments[1].ILRanges);
expr.Arguments[1] = res;
modified = true;
}
#endregion
#region InlineExpressionTreeParameterDeclarations
bool InlineExpressionTreeParameterDeclarations(List<ILNode> body, ILExpression expr, int pos)
{
// When there is a Expression.Lambda() call, and the parameters are declared in the
// IL statement immediately prior to the one containing the Lambda() call,
// using this code for the3 declaration:
// stloc(v, call(Expression::Parameter, call(Type::GetTypeFromHandle, ldtoken(...)), ldstr(...)))
// and the variables v are assigned only once (in that statements), and read only in a Expression::Lambda
// call that immediately follows the assignment statements, then we will inline those assignments
// into the Lambda call using ILCode.ExpressionTreeParameterDeclarations.
// This is sufficient to allow inlining over the expression tree construction. The remaining translation
// of expression trees into C# will be performed by a C# AST transformer.
for (int i = expr.Arguments.Count - 1; i >= 0; i--) {
if (InlineExpressionTreeParameterDeclarations(body, expr.Arguments[i], pos))
return true;
}
MethodReference mr;
ILExpression lambdaBodyExpr, parameterArray;
if (!(expr.Match(ILCode.Call, out mr, out lambdaBodyExpr, out parameterArray) && mr.Name == "Lambda"))
return false;
if (!(parameterArray.Code == ILCode.InitArray && mr.DeclaringType.FullName == "System.Linq.Expressions.Expression"))
return false;
int firstParameterPos = pos - parameterArray.Arguments.Count;
if (firstParameterPos < 0)
return false;
ILExpression[] parameterInitExpressions = new ILExpression[parameterArray.Arguments.Count + 1];
for (int i = 0; i < parameterArray.Arguments.Count; i++) {
parameterInitExpressions[i] = body[firstParameterPos + i] as ILExpression;
if (!MatchParameterVariableAssignment(parameterInitExpressions[i]))
return false;
ILVariable v = (ILVariable)parameterInitExpressions[i].Operand;
if (!parameterArray.Arguments[i].MatchLdloc(v))
return false;
// TODO: validate that the variable is only used here and within 'body'
}
parameterInitExpressions[parameterInitExpressions.Length - 1] = lambdaBodyExpr;
Debug.Assert(expr.Arguments[0] == lambdaBodyExpr);
expr.Arguments[0] = new ILExpression(ILCode.ExpressionTreeParameterDeclarations, null, parameterInitExpressions);
body.RemoveRange(firstParameterPos, parameterArray.Arguments.Count);
return true;
}
bool MatchParameterVariableAssignment(ILExpression expr)
{
// stloc(v, call(Expression::Parameter, call(Type::GetTypeFromHandle, ldtoken(...)), ldstr(...)))
ILVariable v;
ILExpression init;
if (!expr.Match(ILCode.Stloc, out v, out init))
return false;
if (v.IsGenerated || v.IsParameter || v.IsPinned)
return false;
if (v.Type == null || v.Type.FullName != "System.Linq.Expressions.ParameterExpression")
return false;
MethodReference parameterMethod;
ILExpression typeArg, nameArg;
if (!init.Match(ILCode.Call, out parameterMethod, out typeArg, out nameArg))
return false;
if (!(parameterMethod.Name == "Parameter" && parameterMethod.DeclaringType.FullName == "System.Linq.Expressions.Expression"))
return false;
MethodReference getTypeFromHandle;
ILExpression typeToken;
if (!typeArg.Match(ILCode.Call, out getTypeFromHandle, out typeToken))
return false;
if (!(getTypeFromHandle.Name == "GetTypeFromHandle" && getTypeFromHandle.DeclaringType.FullName == "System.Type"))
return false;
return typeToken.Code == ILCode.Ldtoken && nameArg.Code == ILCode.Ldstr;
}
#endregion
}
}