public void CGenTest(Reg ret, CGenState state) {
// test Cond
switch (ret) {
case Reg.EAX:
state.TESTL(Reg.EAX, Reg.EAX);
break;
case Reg.ST0:
/// Compare Expr with 0.0
/// < see cref = "BinaryComparisonOp.OperateFloat(CGenState)" />
state.FLDZ();
state.FUCOMIP();
state.FSTP(Reg.ST0);
break;
default:
throw new InvalidProgramException();
}
}
public override Reg CGenValue(CGenState state) {
Reg ret = this.Expr.CGenValue(state);
switch (ret) {
case Reg.EAX:
state.TESTL(Reg.EAX, Reg.EAX);
state.SETE(Reg.AL);
state.MOVZBL(Reg.AL, Reg.EAX);
return Reg.EAX;
case Reg.ST0:
/// Compare Expr with 0.0
/// < see cref = "BinaryComparisonOp.OperateFloat(CGenState)" />
state.FLDZ();
state.FUCOMIP();
state.FSTP(Reg.ST0);
state.SETE(Reg.AL);
state.MOVZBL(Reg.AL, Reg.EAX);
return Reg.EAX;
default:
throw new InvalidProgramException();
}
}
//
// test Cond
// jz false ---+
// true_expr |
// +------- jmp finish |
// | false: <--------+
// | false_expr
// +--> finish:
//
public override Reg CGenValue(CGenState state) {
Int32 stack_size = state.StackSize;
Reg ret = this.Cond.CGenValue(state);
state.CGenForceStackSizeTo(stack_size);
// test Cond
switch (ret) {
case Reg.EAX:
state.TESTL(Reg.EAX, Reg.EAX);
break;
case Reg.ST0:
/// Compare Expr with 0.0
/// < see cref = "BinaryComparisonOp.OperateFloat(CGenState)" />
state.FLDZ();
state.FUCOMIP();
state.FSTP(Reg.ST0);
break;
default:
throw new InvalidProgramException();
}
Int32 false_label = state.RequestLabel();
Int32 finish_label = state.RequestLabel();
state.JZ(false_label);
this.TrueExpr.CGenValue(state);
state.JMP(finish_label);
state.CGenLabel(false_label);
ret = this.FalseExpr.CGenValue(state);
state.CGenLabel(finish_label);
return ret;
}
public override Reg CGenValue(CGenState state) {
Int32 label_set = state.label_idx;
state.label_idx++;
Int32 label_finish = state.label_idx;
state.label_idx++;
Reg ret = this.Left.CGenValue(state);
switch (ret) {
case Reg.EAX:
state.TESTL(Reg.EAX, Reg.EAX);
state.JNZ(label_set);
break;
case Reg.ST0:
state.FLDZ();
state.FUCOMIP();
state.FSTP(Reg.ST0);
state.JNZ(label_set);
break;
default:
throw new InvalidProgramException();
}
ret = this.Right.CGenValue(state);
switch (ret) {
case Reg.EAX:
state.TESTL(Reg.EAX, Reg.EAX);
state.JNZ(label_set);
break;
case Reg.ST0:
state.FLDZ();
state.FUCOMIP();
state.FSTP(Reg.ST0);
state.JNZ(label_set);
break;
default:
throw new InvalidProgramException();
}
state.MOVL(0, Reg.EAX);
state.JMP(label_finish);
state.CGenLabel(label_set);
state.MOVL(1, Reg.EAX);
state.CGenLabel(label_finish);
return Reg.EAX;
}
/// <summary>
/// Before: %st(0) = left, %st(1) = right, stack unchanged.
/// After: with SetDouble, %eax = left op right, stack unchanged.
/// </summary>
public override sealed void OperateDouble(CGenState state) {
// In the beginning, %st(0) = Left, %st(1) = Right.
//
// float stack:
// +-----+
// | rhs | <- %st(1)
// +-----+
// | lhs | <- %st(0)
// +-----+
//
// 1. Do comparison between %st(0) and %st(1).
// Pop one Value from FPU stack.
//
// float stack:
// +-----+
// | rhs | <- %st(0)
// +-----+
//
state.FUCOMIP();
// 2. Pop another Value from FPU stack.
//
// float stack:
// +-----+ empty
//
state.FSTP(Reg.ST0);
// 3. Set bit based on comparison result.
SetDouble(state);
state.MOVZBL(Reg.AL, Reg.EAX);
}