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 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 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]))
{
initValue = new ILExpression(ILCode.Stloc, pinnedVar, arrayLoadingExpr);
nextPos = i + 1;
return(true);
}
}
}
}
}
initValue = null;
nextPos = -1;
return(false);
}
