Copyright (C) 1994, Digital Equipment Corp.
File: ModExpr.m3
MODULE ModExpr;
IMPORT CG, Expr, ExprRep, Type, Int, IntegerExpr, Target;
IMPORT Reel, LReel, EReel, ReelExpr, DivExpr, TInt;
TYPE
Class = { cINT, cREAL, cLONG, cEXTND, cERR };
CONST
CGType = ARRAY Class OF CG.Type {
CG.Type.Int, CG.Type.Reel, CG.Type.LReel,
CG.Type.XReel, CG.Type.Word };
TYPE
P = ExprRep.Tab BRANDED "ModExpr.P" OBJECT
class: Class;
tmp1 : CG.Var;
tmp2 : CG.Var;
OVERRIDES
typeOf := ExprRep.NoType;
check := Check;
need_addr := ExprRep.NotAddressable;
prep := Prep;
compile := Compile;
prepLV := ExprRep.NotLValue;
compileLV := ExprRep.NotLValue;
prepBR := ExprRep.NotBoolean;
compileBR := ExprRep.NotBoolean;
evaluate := Fold;
isEqual := ExprRep.EqCheckAB;
getBounds := ExprRep.NoBounds;
isWritable := ExprRep.IsNever;
isDesignator := ExprRep.IsNever;
isZeroes := ExprRep.IsNever;
genFPLiteral := ExprRep.NoFPLiteral;
prepLiteral := ExprRep.NoPrepLiteral;
genLiteral := ExprRep.NoLiteral;
note_write := ExprRep.NotWritable;
END;
PROCEDURE New (a, b: Expr.T): Expr.T =
VAR p: P;
BEGIN
p := NEW (P);
ExprRep.Init (p);
p.a := a;
p.b := b;
p.type := Int.T;
p.tmp1 := NIL;
p.tmp2 := NIL;
RETURN p;
END New;
PROCEDURE Check (p: P; VAR cs: Expr.CheckState) =
VAR ta, tb: Type.T;
BEGIN
Expr.TypeCheck (p.a, cs);
Expr.TypeCheck (p.b, cs);
ta := Type.Base (Expr.TypeOf (p.a));
tb := Type.Base (Expr.TypeOf (p.b));
IF (ta = Int.T) AND (tb = Int.T) THEN
p.class := Class.cINT; INC (cs.div_ops);
ELSIF (ta = Reel.T) AND (tb = Reel.T) THEN
p.class := Class.cREAL; INC (cs.fp_ops);
ELSIF (ta = LReel.T) AND (tb = LReel.T) THEN
p.class := Class.cLONG; INC (cs.fp_ops);
ELSIF (ta = EReel.T) AND (tb = EReel.T) THEN
p.class := Class.cEXTND; INC (cs.fp_ops);
ELSE p.class := Class.cERR; ta := Int.T;
ta := Expr.BadOperands ("MOD", ta, tb);
END;
p.type := ta;
END Check;
PROCEDURE Prep (p: P) =
VAR cg_type: CG.Type; sz, align: INTEGER; info: Type.Info;
BEGIN
Expr.Prep (p.a);
Expr.Prep (p.b);
IF (p.class # Class.cINT) THEN
(* floating point: x MOD y == x - y * FLOOR (x / y) *)
EVAL Type.CheckInfo (p.a.type, info);
sz := info.size;
align := info.alignment;
cg_type := CGType [p.class];
Expr.Compile (p.a);
p.tmp1 := CG.Declare_temp (sz, align, cg_type, in_memory := FALSE);
CG.Store (p.tmp1, 0, sz, align, cg_type);
Expr.Compile (p.b);
p.tmp2 := CG.Declare_temp (sz, align, cg_type, in_memory := FALSE);
CG.Store (p.tmp2, 0, sz, align, cg_type);
END;
END Prep;
PROCEDURE Compile (p: P) =
VAR
cg_type: CG.Type;
info: Type.Info;
sz, align: INTEGER;
e1, e2, e3: Expr.T;
divisor, mask: Target.Int;
log: INTEGER;
BEGIN
IF (p.class = Class.cINT) THEN
e1 := Expr.ConstValue (p.a);
e2 := Expr.ConstValue (p.b);
e3 := NIL;
IF (e1 # NIL) AND (e2 # NIL) AND IntegerExpr.Mod (e1, e2, e3) THEN
Expr.Compile (e3);
ELSIF (e2 # NIL)
AND IntegerExpr.Split (e2, divisor)
AND DivExpr.SmallPowerOfTwo (divisor, log) THEN
IF (e1 = NIL) THEN e1 := p.a; END;
IF (log = 0) THEN
(* mod 1 => zero *)
Expr.Compile (e1);
CG.Discard (CG.Type.Int);
CG.Load_integer (TInt.Zero);
ELSE
EVAL TInt.Subtract (divisor, TInt.One, mask);
Expr.Compile (e1);
CG.Load_integer (mask);
CG.And ();
END;
ELSE
IF (e1 = NIL) THEN e1 := p.a; END;
IF (e2 = NIL) THEN e2 := p.b; END;
Expr.Compile (e1);
Expr.Compile (e2);
CG.Mod (CG.Type.Int, Expr.GetSign (e1), Expr.GetSign (e2));
END;
ELSE
(* floating point: x MOD y == x - y * FLOOR (x / y) *)
EVAL Type.CheckInfo (p.a.type, info);
sz := info.size;
align := info.alignment;
cg_type := CGType [p.class];
CG.Load (p.tmp1, 0, sz, align, cg_type);
CG.Load (p.tmp2, 0, sz, align, cg_type);
CG.Divide (cg_type);
CG.Floor (cg_type);
CG.Cvt_float (CG.Type.Int, cg_type);
CG.Load (p.tmp2, 0, sz, align, cg_type);
CG.Multiply (cg_type);
CG.Load (p.tmp1, 0, sz, align, cg_type);
CG.Swap ();
CG.Subtract (cg_type);
CG.Free_temp (p.tmp1);
CG.Free_temp (p.tmp2);
p.tmp1 := NIL;
p.tmp2 := NIL;
END;
END Compile;
PROCEDURE Fold (p: P): Expr.T =
VAR e1, e2, e3: Expr.T;
BEGIN
e1 := Expr.ConstValue (p.a);
e2 := Expr.ConstValue (p.b);
e3 := NIL;
IF (e1 = NIL) OR (e2 = NIL) THEN
ELSIF IntegerExpr.Mod (e1, e2, e3) THEN
ELSIF ReelExpr.Mod (e1, e2, e3) THEN
END;
RETURN e3;
END Fold;
BEGIN
END ModExpr.