/// <summary>
/// Matches Roslyn C# switch on nullable.
/// </summary>
bool MatchRoslynSwitchOnNullable(InstructionCollection <ILInstruction> instructions, int i, out SwitchInstruction newSwitch)
{
newSwitch = null;
// match first block:
// if (logic.not(call get_HasValue(target))) br nullCaseBlock
// br switchBlock
if (!instructions[i].MatchIfInstruction(out var condition, out var trueInst))
{
return(false);
}
if (!instructions[i + 1].MatchBranch(out var switchBlock) || !trueInst.MatchBranch(out var nullCaseBlock))
{
return(false);
}
if (!condition.MatchLogicNot(out var getHasValue) || !NullableLiftingTransform.MatchHasValueCall(getHasValue, out ILInstruction target) || !SemanticHelper.IsPure(target.Flags))
{
return(false);
}
// match second block: switchBlock
// note: I have seen cases where switchVar is inlined into the switch.
// stloc switchVar(call GetValueOrDefault(ldloca tmp))
// switch (ldloc switchVar) {
// case [0..1): br caseBlock1
// ... more cases ...
// case [long.MinValue..0),[1..5),[6..10),[11..long.MaxValue]: br defaultBlock
// }
if (switchBlock.IncomingEdgeCount != 1)
{
return(false);
}
SwitchInstruction switchInst;
switch (switchBlock.Instructions.Count)
{
case 2: {
// this is the normal case described by the pattern above
if (!switchBlock.Instructions[0].MatchStLoc(out var switchVar, out var getValueOrDefault))
{
return(false);
}
if (!switchVar.IsSingleDefinition || switchVar.LoadCount != 1)
{
return(false);
}
if (!(NullableLiftingTransform.MatchGetValueOrDefault(getValueOrDefault, out ILInstruction target2) && target2.Match(target).Success))
{
return(false);
}
if (!(switchBlock.Instructions[1] is SwitchInstruction si))
{
return(false);
}
switchInst = si;
break;
}
case 1: {
// this is the special case where `call GetValueOrDefault(ldloca tmp)` is inlined into the switch.
if (!(switchBlock.Instructions[0] is SwitchInstruction si))
{
return(false);
}
if (!(NullableLiftingTransform.MatchGetValueOrDefault(si.Value, out ILInstruction target2) && target2.Match(target).Success))
{
return(false);
}
switchInst = si;
break;
}
default: {
return(false);
}
}
ILInstruction switchValue;
if (target.MatchLdLoca(out var v))
{
switchValue = new LdLoc(v).WithILRange(target);
}
else
{
switchValue = new LdObj(target, ((CallInstruction)getHasValue).Method.DeclaringType);
}
newSwitch = BuildLiftedSwitch(nullCaseBlock, switchInst, switchValue);
return(true);
}
/// <summary>
/// Matches legacy C# switch on nullable.
/// </summary>
bool MatchSwitchOnNullable(InstructionCollection <ILInstruction> instructions, int i, out SwitchInstruction newSwitch)
{
newSwitch = null;
// match first block:
// stloc tmp(ldloca switchValueVar)
// stloc switchVariable(call GetValueOrDefault(ldloc tmp))
// if (logic.not(call get_HasValue(ldloc tmp))) br nullCaseBlock
// br switchBlock
if (i < 2)
{
return(false);
}
if (!instructions[i - 2].MatchStLoc(out var tmp, out var ldloca) ||
!instructions[i - 1].MatchStLoc(out var switchVariable, out var getValueOrDefault) ||
!instructions[i].MatchIfInstruction(out var condition, out var trueInst))
{
return(false);
}
if (!tmp.IsSingleDefinition || tmp.LoadCount != 2)
{
return(false);
}
if (!switchVariable.IsSingleDefinition || switchVariable.LoadCount != 1)
{
return(false);
}
if (!instructions[i + 1].MatchBranch(out var switchBlock) || !trueInst.MatchBranch(out var nullCaseBlock))
{
return(false);
}
if (!ldloca.MatchLdLoca(out var switchValueVar))
{
return(false);
}
if (!condition.MatchLogicNot(out var getHasValue))
{
return(false);
}
if (!NullableLiftingTransform.MatchGetValueOrDefault(getValueOrDefault, out ILInstruction getValueOrDefaultArg))
{
return(false);
}
if (!NullableLiftingTransform.MatchHasValueCall(getHasValue, out ILInstruction getHasValueArg))
{
return(false);
}
if (!(getHasValueArg.MatchLdLoc(tmp) && getValueOrDefaultArg.MatchLdLoc(tmp)))
{
return(false);
}
// match second block: switchBlock
// switch (ldloc switchVariable) {
// case [0..1): br caseBlock1
// ... more cases ...
// case [long.MinValue..0),[1..5),[6..10),[11..long.MaxValue]: br defaultBlock
// }
if (switchBlock.Instructions.Count != 1 || switchBlock.IncomingEdgeCount != 1)
{
return(false);
}
if (!(switchBlock.Instructions[0] is SwitchInstruction switchInst))
{
return(false);
}
newSwitch = BuildLiftedSwitch(nullCaseBlock, switchInst, new LdLoc(switchValueVar));
return(true);
}
bool MatchDisposeCheck(ILVariable objVar, ILInstruction checkInst, bool isReference, bool usingNull, out int numObjVarLoadsInCheck)
{
numObjVarLoadsInCheck = 2;
CallVirt callVirt;
if (objVar.Type.IsKnownType(KnownTypeCode.NullableOfT))
{
if (checkInst.MatchIfInstruction(out var condition, out var disposeInst))
{
if (!NullableLiftingTransform.MatchHasValueCall(condition, objVar))
{
return(false);
}
if (!(disposeInst is Block disposeBlock) || disposeBlock.Instructions.Count != 1)
{
return(false);
}
callVirt = disposeBlock.Instructions[0] as CallVirt;
}
else if (checkInst.MatchNullableRewrap(out disposeInst))
{
callVirt = disposeInst as CallVirt;
}
else
{
return(false);
}
if (callVirt == null)
{
return(false);
}
if (callVirt.Method.FullName != "System.IDisposable.Dispose")
{
return(false);
}
if (callVirt.Method.Parameters.Count > 0)
{
return(false);
}
if (callVirt.Arguments.Count != 1)
{
return(false);
}
var firstArg = callVirt.Arguments.FirstOrDefault();
if (!(firstArg.MatchUnboxAny(out var innerArg1, out var unboxType) && unboxType.IsKnownType(KnownTypeCode.IDisposable)))
{
if (!firstArg.MatchAddressOf(out var innerArg2))
{
return(false);
}
return(NullableLiftingTransform.MatchGetValueOrDefault(innerArg2, objVar) ||
(innerArg2 is NullableUnwrap unwrap &&
unwrap.Argument.MatchLdLoc(objVar)));
}
else
{
if (!(innerArg1.MatchBox(out firstArg, out var boxType) && boxType.IsKnownType(KnownTypeCode.NullableOfT) &&
NullableType.GetUnderlyingType(boxType).Equals(NullableType.GetUnderlyingType(objVar.Type))))
{
return(false);
}
return(firstArg.MatchLdLoc(objVar));
}
}