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)"
}
else if (SemanticHelper.IsPure(inst.Right.Flags))
{
context.Step("Replace bit.and with logic.and", inst);
var expr = IfInstruction.LogicAnd(inst.Left, inst.Right);
inst.ReplaceWith(expr);
expr.AcceptVisitor(this);
}
}
break;
}
}
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 (IsBoolean(inst.Left) && IsBoolean(inst.Right) && SemanticHelper.IsPure(inst.Right.Flags))
{
context.Step("Replace bit.and with logic.and", inst);
var expr = IfInstruction.LogicAnd(inst.Left, inst.Right);
inst.ReplaceWith(expr);
expr.AcceptVisitor(this);
}
break;
}
}
/// <code>
/// stloc s(binary(callvirt(getter), value))
/// callvirt (setter, ldloc s)
/// (followed by single usage of s in next instruction)
/// -->
/// stloc s(compound.op.new(callvirt(getter), value))
/// </code>
bool TransformInlineCompoundAssignmentCall(Block block, int i)
{
var mainStLoc = block.Instructions[i] as StLoc;
// in some cases it can be a compiler-generated local
if (mainStLoc == null || (mainStLoc.Variable.Kind != VariableKind.StackSlot && mainStLoc.Variable.Kind != VariableKind.Local))
{
return(false);
}
BinaryNumericInstruction binary = mainStLoc.Value as BinaryNumericInstruction;
ILVariable localVariable = mainStLoc.Variable;
if (!localVariable.IsSingleDefinition)
{
return(false);
}
if (localVariable.LoadCount != 2)
{
return(false);
}
var getterCall = binary?.Left as CallInstruction;
var setterCall = block.Instructions.ElementAtOrDefault(i + 1) as CallInstruction;
if (!MatchingGetterAndSetterCalls(getterCall, setterCall))
{
return(false);
}
if (!setterCall.Arguments.Last().MatchLdLoc(localVariable))
{
return(false);
}
var next = block.Instructions.ElementAtOrDefault(i + 2);
if (next == null)
{
return(false);
}
if (next.Descendants.Where(d => d.MatchLdLoc(localVariable)).Count() != 1)
{
return(false);
}
if (!CompoundAssignmentInstruction.IsBinaryCompatibleWithType(binary, getterCall.Method.ReturnType))
{
return(false);
}
context.Step($"Inline compound assignment to '{getterCall.Method.AccessorOwner.Name}'", setterCall);
block.Instructions.RemoveAt(i + 1); // remove setter call
binary.ReplaceWith(new CompoundAssignmentInstruction(
binary, getterCall, binary.Right,
getterCall.Method.ReturnType, CompoundAssignmentType.EvaluatesToNewValue));
return(true);
}
/// <summary>
/// VS2017.8 / Roslyn 2.9 started optimizing some cases of
/// "a.GetValueOrDefault() == b.GetValueOrDefault() && (a.HasValue & b.HasValue)"
/// to
/// "(a.GetValueOrDefault() == b.GetValueOrDefault()) & (a.HasValue & b.HasValue)"
/// so this secondary entry point analyses logic.and as-if it was a short-circuiting &&.
/// </summary>
public bool Run(BinaryNumericInstruction bni)
{
Debug.Assert(!bni.IsLifted && bni.Operator == BinaryNumericOperator.BitAnd);
// caller ensures that bni.Left/bni.Right are booleans
var lifted = Lift(bni, bni.Left, bni.Right, new LdcI4(0));
if (lifted != null)
{
bni.ReplaceWith(lifted);
return(true);
}
return(false);
}