llvm-6502/lib/VMCore/ConstantFolding.h
Chris Lattner 5d5a714b24 Implement == and != correctly. Before they would incorrectly return !=
for some constant exprs when they could really be the same value


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10058 91177308-0d34-0410-b5e6-96231b3b80d8
2003-11-17 20:19:35 +00:00

243 lines
9.9 KiB
C++

//===-- ConstantHandling.h - Stuff for manipulating constants ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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"
namespace llvm {
class PointerType;
//===----------------------------------------------------------------------===//
// Implement all other operators indirectly through TypeRules system
//===----------------------------------------------------------------------===//
struct ConstRules {
ConstRules() {}
// 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;
virtual ConstantBool *equalto(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 Constant *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, reinterpret_cast<const PointerType*>(Ty));
default: return 0;
}
}
// ConstRules::get - Return an instance of ConstRules for the specified
// constant operands.
//
static ConstRules &get(const Constant &V1, const Constant &V2);
private:
ConstRules(const ConstRules &); // Do not implement
ConstRules &operator=(const ConstRules &); // Do not implement
};
// Unary operators...
inline Constant *operator~(const Constant &V) {
assert(V.getType()->isIntegral() && "Cannot invert non-integral constant!");
return ConstRules::get(V, V).op_xor(&V,
ConstantInt::getAllOnesValue(V.getType()));
}
inline Constant *operator-(const Constant &V) {
return ConstRules::get(V, V).sub(Constant::getNullValue(V.getType()), &V);
}
// 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, V2).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, V2).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, V2).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, V2).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, V2).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, V2).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, V2).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, V2).op_xor(&V1, &V2);
}
// Shift Instructions...
inline Constant *operator<<(const Constant &V1, const Constant &V2) {
assert(V1.getType()->isInteger() && V2.getType() == Type::UByteTy);
return ConstRules::get(V1, V2).shl(&V1, &V2);
}
inline Constant *operator>>(const Constant &V1, const Constant &V2) {
assert(V1.getType()->isInteger() && V2.getType() == Type::UByteTy);
return ConstRules::get(V1, V2).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, V2).lessthan(&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, V2).equalto(&V1, &V2);
}
//===----------------------------------------------------------------------===//
// Implement 'derived' operators based on what we already have...
//===----------------------------------------------------------------------===//
inline ConstantBool *operator!=(const Constant &V1, const Constant &V2) {
if (ConstantBool *V = (V1 == V2))
return V->inverted(); // !(V1 == V2)
return 0;
}
inline ConstantBool *operator>(const Constant &V1,
const Constant &V2) {
return V2 < V1;
}
inline ConstantBool *operator>=(const Constant &V1,
const Constant &V2) {
if (ConstantBool *V = (V1 < V2))
return V->inverted(); // !(V1 < V2)
return 0;
}
inline ConstantBool *operator<=(const Constant &V1,
const Constant &V2) {
if (ConstantBool *V = (V1 > V2))
return V->inverted(); // !(V1 > V2)
return 0;
}
//===----------------------------------------------------------------------===//
// 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);
Constant *ConstantFoldGetElementPtr(const Constant *C,
const std::vector<Constant*> &IdxList);
} // End llvm namespace
#endif