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//===--- LiveRangeEdit.cpp - Basic tools for editing a register live range --===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// The LiveRangeEdit class represents changes done to a virtual register when it
// is spilled or split.
//===----------------------------------------------------------------------===//
#include "LiveRangeEdit.h"
#include "VirtRegMap.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
using namespace llvm;
int LiveRangeEdit::assignStackSlot(VirtRegMap &vrm) {
int ss = vrm.getStackSlot(getReg());
if (ss != VirtRegMap::NO_STACK_SLOT)
return ss;
return vrm.assignVirt2StackSlot(getReg());
}
LiveInterval &LiveRangeEdit::create(MachineRegisterInfo &mri,
LiveIntervals &lis,
VirtRegMap &vrm) {
const TargetRegisterClass *RC = mri.getRegClass(parent_.reg);
unsigned VReg = mri.createVirtualRegister(RC);
vrm.grow();
// Immediately assign to the same stack slot as parent.
vrm.assignVirt2StackSlot(VReg, assignStackSlot(vrm));
LiveInterval &li = lis.getOrCreateInterval(VReg);
newRegs_.push_back(&li);
return li;
}
/// allUsesAvailableAt - Return true if all registers used by OrigMI at
/// OrigIdx are also available with the same value at UseIdx.
bool LiveRangeEdit::allUsesAvailableAt(const MachineInstr *OrigMI,
SlotIndex OrigIdx,
SlotIndex UseIdx,
LiveIntervals &lis) {
OrigIdx = OrigIdx.getUseIndex();
UseIdx = UseIdx.getUseIndex();
for (unsigned i = 0, e = OrigMI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = OrigMI->getOperand(i);
if (!MO.isReg() || !MO.getReg() || MO.getReg() == getReg())
continue;
// Reserved registers are OK.
if (MO.isUndef() || !lis.hasInterval(MO.getReg()))
continue;
// We don't want to move any defs.
if (MO.isDef())
return false;
// We cannot depend on virtual registers in uselessRegs_.
for (unsigned ui = 0, ue = uselessRegs_.size(); ui != ue; ++ui)
if (uselessRegs_[ui]->reg == MO.getReg())
return false;
LiveInterval &li = lis.getInterval(MO.getReg());
const VNInfo *OVNI = li.getVNInfoAt(OrigIdx);
if (!OVNI)
continue;
if (OVNI != li.getVNInfoAt(UseIdx))
return false;
}
return true;
}
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