llvm-6502/lib/CodeGen/AllocationOrder.cpp

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//===-- llvm/CodeGen/AllocationOrder.cpp - Allocation Order ---------------===//
//
// 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.
//
//===----------------------------------------------------------------------===//
#include "AllocationOrder.h"
#include "VirtRegMap.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
using namespace llvm;
// Compare VirtRegMap::getRegAllocPref().
AllocationOrder::AllocationOrder(unsigned VirtReg,
const VirtRegMap &VRM,
const BitVector &ReservedRegs)
: Pos(0), Reserved(ReservedRegs) {
const TargetRegisterClass *RC = VRM.getRegInfo().getRegClass(VirtReg);
std::pair<unsigned, unsigned> HintPair =
VRM.getRegInfo().getRegAllocationHint(VirtReg);
// HintPair.second is a register, phys or virt.
Hint = HintPair.second;
// Translate to physreg, or 0 if not assigned yet.
if (Hint && TargetRegisterInfo::isVirtualRegister(Hint))
Hint = VRM.getPhys(Hint);
// The remaining allocation order may depend on the hint.
tie(Begin, End) = VRM.getTargetRegInfo()
.getAllocationOrder(RC, HintPair.first, Hint, VRM.getMachineFunction());
// Target-dependent hints require resolution.
if (HintPair.first)
Hint = VRM.getTargetRegInfo().ResolveRegAllocHint(HintPair.first, Hint,
VRM.getMachineFunction());
// The hint must be a valid physreg for allocation.
if (Hint && (!TargetRegisterInfo::isPhysicalRegister(Hint) ||
!RC->contains(Hint) || ReservedRegs.test(Hint)))
Hint = 0;
}
unsigned AllocationOrder::next() {
// First take the hint.
if (!Pos) {
Pos = Begin;
if (Hint)
return Hint;
}
// Then look at the order from TRI.
while(Pos != End) {
unsigned Reg = *Pos++;
if (Reg != Hint && !Reserved.test(Reg))
return Reg;
}
return 0;
}