llvm/lib/CodeGen/AllocationOrder.h
Jakob Stoklund Olesen c9672cb8be Add an AllocationOrder class that can iterate over the allocatable physical
registers for a given virtual register.

Reserved registers are filtered from the allocation order, and any valid hint is
returned as the first suggestion.

For target dependent hints, a number of arcane target hooks are invoked.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121497 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-10 18:36:02 +00:00

55 lines
1.7 KiB
C++

//===-- llvm/CodeGen/AllocationOrder.h - Allocation Order -*- C++ -*-------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements an allocation order for virtual registers.
//
// The preferred allocation order for a virtual register depends on allocation
// hints and target hooks. The AllocationOrder class encapsulates all of that.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_ALLOCATIONORDER_H
#define LLVM_CODEGEN_ALLOCATIONORDER_H
namespace llvm {
class BitVector;
class VirtRegMap;
class AllocationOrder {
const unsigned *Begin;
const unsigned *End;
const unsigned *Pos;
const BitVector &Reserved;
unsigned Hint;
public:
/// AllocationOrder - Create a new AllocationOrder for VirtReg.
/// @param VirtReg Virtual register to allocate for.
/// @param VRM Virtual register map for function.
/// @param ReservedRegs Set of reserved registers as returned by
/// TargetRegisterInfo::getReservedRegs().
AllocationOrder(unsigned VirtReg,
const VirtRegMap &VRM,
const BitVector &ReservedRegs);
/// next - Return the next physical register in the allocation order, or 0.
/// It is safe to call next again after it returned 0.
/// It will keep returning 0 until rewind() is called.
unsigned next();
/// rewind - Start over from the beginning.
void rewind() { Pos = 0; }
};
} // end namespace llvm
#endif