llvm/lib/VMCore/ConstantFolding.h
Chris Lattner 009505452b Initial revision
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2 91177308-0d34-0410-b5e6-96231b3b80d8
2001-06-06 20:29:01 +00:00

146 lines
5.6 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 ConstPoolVal *V1, const ConstPoolVal *V2)
//
// so we must make due with references, even though it leads to some butt ugly
// looking code downstream. *sigh* (ex: ConstPoolVal *Result = *V1 + *v2; )
//
//===----------------------------------------------------------------------===//
//
// WARNING: These operators return pointers to newly 'new'd objects. You MUST
// make sure to free them if you don't want them hanging around. Also,
// note that these may return a null object if I don't know how to
// perform those operations 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_OPT_CONSTANTHANDLING_H
#define LLVM_OPT_CONSTANTHANDLING_H
#include "llvm/ConstPoolVals.h"
#include "llvm/Type.h"
//===----------------------------------------------------------------------===//
// Implement == directly...
//===----------------------------------------------------------------------===//
inline ConstPoolBool *operator==(const ConstPoolVal &V1,
const ConstPoolVal &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return new ConstPoolBool(V1.equals(&V2));
}
//===----------------------------------------------------------------------===//
// Implement all other operators indirectly through TypeRules system
//===----------------------------------------------------------------------===//
class ConstRules {
protected:
inline ConstRules() {} // Can only be subclassed...
public:
// Unary Operators...
virtual ConstPoolVal *neg(const ConstPoolVal *V) const = 0;
virtual ConstPoolVal *not(const ConstPoolVal *V) const = 0;
// Binary Operators...
virtual ConstPoolVal *add(const ConstPoolVal *V1,
const ConstPoolVal *V2) const = 0;
virtual ConstPoolVal *sub(const ConstPoolVal *V1,
const ConstPoolVal *V2) const = 0;
virtual ConstPoolBool *lessthan(const ConstPoolVal *V1,
const ConstPoolVal *V2) const = 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 const ConstRules *get(const ConstPoolVal &V) {
const ConstRules *Result = V.getType()->getConstRules();
return Result ? Result : find(V.getType());
}
private :
static const ConstRules *find(const Type *Ty);
ConstRules(const ConstRules &); // Do not implement
ConstRules &operator=(const ConstRules &); // Do not implement
};
inline ConstPoolVal *operator-(const ConstPoolVal &V) {
return ConstRules::get(V)->neg(&V);
}
inline ConstPoolVal *operator!(const ConstPoolVal &V) {
return ConstRules::get(V)->not(&V);
}
inline ConstPoolVal *operator+(const ConstPoolVal &V1, const ConstPoolVal &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->add(&V1, &V2);
}
inline ConstPoolVal *operator-(const ConstPoolVal &V1, const ConstPoolVal &V2) {
assert(V1.getType() == V2.getType() && "Constant types must be identical!");
return ConstRules::get(V1)->sub(&V1, &V2);
}
inline ConstPoolBool *operator<(const ConstPoolVal &V1,
const ConstPoolVal &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 ConstPoolBool *operator>(const ConstPoolVal &V1,
const ConstPoolVal &V2) {
return V2 < V1;
}
inline ConstPoolBool *operator!=(const ConstPoolVal &V1,
const ConstPoolVal &V2) {
ConstPoolBool *Result = V1 == V2;
Result->setValue(!Result->getValue()); // Invert value
return Result; // !(V1 == V2)
}
inline ConstPoolBool *operator>=(const ConstPoolVal &V1,
const ConstPoolVal &V2) {
ConstPoolBool *Result = V1 < V2;
Result->setValue(!Result->getValue()); // Invert value
return Result; // !(V1 < V2)
}
inline ConstPoolBool *operator<=(const ConstPoolVal &V1,
const ConstPoolVal &V2) {
ConstPoolBool *Result = V1 > V2;
Result->setValue(!Result->getValue()); // Invert value
return Result; // !(V1 > V2)
}
#endif