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//===-- CodeGen/MachineConstantPool.h - Abstract Constant Pool --*- 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.
//
//===----------------------------------------------------------------------===//
//
// The MachineConstantPool class keeps track of constants referenced by a
// function which must be spilled to memory. This is used for constants which
// are unable to be used directly as operands to instructions, which typically
// include floating point and large integer constants.
//
// Instructions reference the address of these constant pool constants through
// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
// code, these virtual address references are converted to refer to the
// address of the function constant pool values.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_MACHINECONSTANTPOOL_H
#define LLVM_CODEGEN_MACHINECONSTANTPOOL_H
#include <vector>
#include <iosfwd>
#include <cassert>
namespace llvm {
class Constant;
/// MachineConstantPoolEntry - One entry in the constant pool.
///
struct MachineConstantPoolEntry {
/// Val - The constant itself.
Constant *Val;
/// Alignment - The alignment of the constant.
unsigned Alignment;
MachineConstantPoolEntry(Constant *V, unsigned A) : Val(V), Alignment(A) {}
};
class MachineConstantPool {
std::vector<MachineConstantPoolEntry> Constants;
public:
/// getConstantPoolIndex - Create a new entry in the constant pool or return
/// an existing one. User must specify an alignment in bytes for the object.
///
unsigned getConstantPoolIndex(Constant *C, unsigned Alignment) {
assert(Alignment && "Alignment must be specified!");
// Check to see if we already have this constant.
//
// FIXME, this could be made much more efficient for large constant pools.
for (unsigned i = 0, e = Constants.size(); i != e; ++i)
if (Constants[i].Val == C && Constants[i].Alignment >= Alignment)
return i;
Constants.push_back(MachineConstantPoolEntry(C, Alignment));
return Constants.size()-1;
}
/// isEmpty - Return true if this constant pool contains no constants.
///
bool isEmpty() const { return Constants.empty(); }
const std::vector<MachineConstantPoolEntry> &getConstants() const {
return Constants;
}
/// print - Used by the MachineFunction printer to print information about
/// stack objects. Implemented in MachineFunction.cpp
///
void print(std::ostream &OS) const;
/// dump - Call print(std::cerr) to be called from the debugger.
void dump() const;
};
} // End llvm namespace
#endif
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