public override void GenerateMSIL(ILGenerator ilGenerator, TypeBuilder typeBuilder)
{
Condition.GenerateMSIL(ilGenerator, typeBuilder);
ilGenerator.Emit(OpCodes.Ldc_I4_0);
ilGenerator.Emit(OpCodes.Ceq);
if (ElsePart == null)
{
Label labelAfterIf = ilGenerator.DefineLabel();
ilGenerator.Emit(OpCodes.Brtrue, labelAfterIf);
ThenPart.GenerateMSIL(ilGenerator, typeBuilder);
ilGenerator.MarkLabel(labelAfterIf);
}
else
{
Label labelForFalse = ilGenerator.DefineLabel();
Label labelAfterIf = ilGenerator.DefineLabel();
ilGenerator.Emit(OpCodes.Brtrue, labelForFalse);
ThenPart.GenerateMSIL(ilGenerator, typeBuilder);
ilGenerator.Emit(OpCodes.Br_S, labelAfterIf);
ilGenerator.MarkLabel(labelForFalse);
ElsePart.GenerateMSIL(ilGenerator, typeBuilder);
ilGenerator.MarkLabel(labelAfterIf);
}
}
public override bool HasExternalLibraryCall()
{
if (ElsePart != null)
{
return(Condition.HasExternalLibraryCall() || ThenPart.HasExternalLibraryCall() ||
ElsePart.HasExternalLibraryCall());
}
else
{
return(Condition.HasExternalLibraryCall() || ThenPart.HasExternalLibraryCall());
}
}
public override Expression ClearConstant(Dictionary <string, Expression> constMapping)
{
return(new If(Condition.ClearConstant(constMapping), ThenPart.ClearConstant(constMapping), ElsePart == null ? null : ElsePart.ClearConstant(constMapping)));
}
protected override void GenerateCode(CodeGenContext context)
{
var target = ThenPart.GetBranchTarget();
if (target.HasValue)
{
//
// Normally, we evaluate
// if ( a ) { b = 1; }
// such that if "a" evaluates to false, then we branch around the then-part
// and if "a" evaluates to true, we fall-thru to the then-part
// But when the then-part is itself a goto statement of some sort:
// if ( a ) { goto L; }
// if ( a ) { break; }
// if ( a ) { continue; }
// Then instead of branching around a branch instruction,
// we reverse the evaluation condition and supply the control flow target:
// so that if "a" evaluates to true, then we branch (goto/break/continue),
// and if "a" evaluates to false, we don't branch
//
context.SetPrettyPrintProlog("If-Goto\t");
Condition.GenerateCodeForConditionalBranchWithPrettyPrint(context, target.Value, true);
Dump.WriteLine("<then part branch incorporated into preceding condition>");
context.SetPrettyPrintProlog("ElsePart\t");
ElsePart?.GenerateCodeWithPrettyPrint(context);
}
else if (ElsePart == null)
{
context.SetPrettyPrintProlog("Condition\t");
var joinPoint = context.CreateLabel();
Condition.GenerateCodeForConditionalBranchWithPrettyPrint(context, joinPoint, false);
context.SetPrettyPrintProlog("ThenPart");
ThenPart.GenerateCodeWithPrettyPrint(context);
context.InsertComment("if-then rejoin");
context.PlaceLabelHere(joinPoint);
}
/* else if ( ElsePart.IsBranchStatement () { }*/
else
{
var elsePartLabel = context.CreateLabel();
context.SetPrettyPrintProlog("Condition\t");
Condition.GenerateCodeForConditionalBranchWithPrettyPrint(context, elsePartLabel, false);
context.SetPrettyPrintProlog("ThenPart\t");
ThenPart.GenerateCodeWithPrettyPrint(context);
var joinPoint = context.CreateLabel();
context.InsertComment("end of ThenPart");
context.GenerateUnconditionalBranch(joinPoint);
context.SetPrettyPrintProlog("ElsePart\t");
context.PlaceLabelHere(elsePartLabel);
context.InsertComment("start of ElsePart");
ElsePart.GenerateCodeWithPrettyPrint(context);
context.InsertComment("if-then-else rejoin");
context.PlaceLabelHere(joinPoint);
}
}
