llvm/lib/VMCore/ConstantFolding.h
2002-08-14 18:17:07 +00:00

225 lines
9.4 KiB
C++

//===-- ConstantHandling.h - Stuff for manipulating constants ----*- C++ -*--=//
//
// This file contains the declarations of some cool operators that allow you
// to do natural things with constant pool values.
//
// Unfortunately we can't overload operators on pointer types (like this:)
//
// inline bool operator==(const Constant *V1, const Constant *V2)
//
// so we must make due with references, even though it leads to some butt ugly
// looking code downstream. *sigh* (ex: Constant *Result = *V1 + *v2; )
//
//===----------------------------------------------------------------------===//
//
// WARNING: These operators may return a null object if I don't know how to
// perform the specified operation on the specified constant types.
//
//===----------------------------------------------------------------------===//
//
// Implementation notes:
// This library is implemented this way for a reason: In most cases, we do
// not want to have to link the constant mucking code into an executable.
// We do, however want to tie some of this into the main type system, as an
// optional component. By using a mutable cache member in the Type class, we
// get exactly the kind of behavior we want.
//
// In the end, we get performance almost exactly the same as having a virtual
// function dispatch, but we don't have to put our virtual functions into the
// "Type" class, and we can implement functionality with templates. Good deal.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CONSTANTHANDLING_H
#define LLVM_CONSTANTHANDLING_H
#include "llvm/Constants.h"
#include "llvm/Type.h"
class PointerType;
//===----------------------------------------------------------------------===//
// Implement == and != directly...
//===----------------------------------------------------------------------===//
inline ConstantBool *operator==(const Constant &V1,
const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstantBool::get(&V1 == &V2);
}
inline ConstantBool *operator!=(const Constant &V1,
const Constant &V2) {
return ConstantBool::get(&V1 != &V2);
}
//===----------------------------------------------------------------------===//
// Implement all other operators indirectly through TypeRules system
//===----------------------------------------------------------------------===//
class ConstRules : public Annotation {
protected:
inline ConstRules() : Annotation(AID) {} // Can only be subclassed...
public:
static AnnotationID AID; // AnnotationID for this class
// Binary Operators...
virtual Constant *add(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *mul(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *div(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *rem(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0;
virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *shr(const Constant *V1, const Constant *V2) const = 0;
virtual ConstantBool *lessthan(const Constant *V1,
const Constant *V2) const = 0;
// Casting operators. ick
virtual ConstantBool *castToBool (const Constant *V) const = 0;
virtual ConstantSInt *castToSByte (const Constant *V) const = 0;
virtual ConstantUInt *castToUByte (const Constant *V) const = 0;
virtual ConstantSInt *castToShort (const Constant *V) const = 0;
virtual ConstantUInt *castToUShort(const Constant *V) const = 0;
virtual ConstantSInt *castToInt (const Constant *V) const = 0;
virtual ConstantUInt *castToUInt (const Constant *V) const = 0;
virtual ConstantSInt *castToLong (const Constant *V) const = 0;
virtual ConstantUInt *castToULong (const Constant *V) const = 0;
virtual ConstantFP *castToFloat (const Constant *V) const = 0;
virtual ConstantFP *castToDouble(const Constant *V) const = 0;
virtual ConstantPointer *castToPointer(const Constant *V,
const PointerType *Ty) const = 0;
inline Constant *castTo(const Constant *V, const Type *Ty) const {
switch (Ty->getPrimitiveID()) {
case Type::BoolTyID: return castToBool(V);
case Type::UByteTyID: return castToUByte(V);
case Type::SByteTyID: return castToSByte(V);
case Type::UShortTyID: return castToUShort(V);
case Type::ShortTyID: return castToShort(V);
case Type::UIntTyID: return castToUInt(V);
case Type::IntTyID: return castToInt(V);
case Type::ULongTyID: return castToULong(V);
case Type::LongTyID: return castToLong(V);
case Type::FloatTyID: return castToFloat(V);
case Type::DoubleTyID: return castToDouble(V);
case Type::PointerTyID:return castToPointer(V, (PointerType*)Ty);
default: return 0;
}
}
// ConstRules::get - A type will cache its own type rules if one is needed...
// we just want to make sure to hit the cache instead of doing it indirectly,
// if possible...
//
static inline ConstRules *get(const Constant &V) {
return (ConstRules*)V.getType()->getOrCreateAnnotation(AID);
}
private :
static Annotation *find(AnnotationID AID, const Annotable *Ty, void *);
ConstRules(const ConstRules &); // Do not implement
ConstRules &operator=(const ConstRules &); // Do not implement
};
// Standard binary operators...
inline Constant *operator+(const Constant &V1, const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->add(&V1, &V2);
}
inline Constant *operator-(const Constant &V1, const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->sub(&V1, &V2);
}
inline Constant *operator*(const Constant &V1, const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->mul(&V1, &V2);
}
inline Constant *operator/(const Constant &V1, const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->div(&V1, &V2);
}
inline Constant *operator%(const Constant &V1, const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->rem(&V1, &V2);
}
// Logical Operators...
inline Constant *operator&(const Constant &V1, const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->op_and(&V1, &V2);
}
inline Constant *operator|(const Constant &V1, const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->op_or(&V1, &V2);
}
inline Constant *operator^(const Constant &V1, const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->op_xor(&V1, &V2);
}
// Shift Instructions...
inline Constant *operator<<(const Constant &V1, const Constant &V2) {
assert(V1.getType()->isIntegral() && V2.getType() == Type::UByteTy);
return ConstRules::get(V1)->shl(&V1, &V2);
}
inline Constant *operator>>(const Constant &V1, const Constant &V2) {
assert(V1.getType()->isIntegral() && V2.getType() == Type::UByteTy);
return ConstRules::get(V1)->shr(&V1, &V2);
}
inline ConstantBool *operator<(const Constant &V1,
const Constant &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->lessthan(&V1, &V2);
}
//===----------------------------------------------------------------------===//
// Implement 'derived' operators based on what we already have...
//===----------------------------------------------------------------------===//
inline ConstantBool *operator>(const Constant &V1,
const Constant &V2) {
return V2 < V1;
}
inline ConstantBool *operator>=(const Constant &V1,
const Constant &V2) {
return (V1 < V2)->inverted(); // !(V1 < V2)
}
inline ConstantBool *operator<=(const Constant &V1,
const Constant &V2) {
return (V1 > V2)->inverted(); // !(V1 > V2)
}
//===----------------------------------------------------------------------===//
// Implement higher level instruction folding type instructions
//===----------------------------------------------------------------------===//
// ConstantFoldInstruction - Attempt to constant fold the specified instruction.
// If successful, the constant result is returned, if not, null is returned.
//
Constant *ConstantFoldInstruction(Instruction *I);
// Constant fold various types of instruction...
Constant *ConstantFoldCastInstruction(const Constant *V, const Type *DestTy);
Constant *ConstantFoldBinaryInstruction(unsigned Opcode, const Constant *V1,
const Constant *V2);
Constant *ConstantFoldShiftInstruction(unsigned Opcode, const Constant *V1,
const Constant *V2);
#endif