1 //===--- LiveRangeEdit.cpp - Basic tools for editing a register live range --===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // The LiveRangeEdit class represents changes done to a virtual register when it
11 // is spilled or split.
12 //===----------------------------------------------------------------------===//
14 #include "LiveRangeEdit.h"
15 #include "VirtRegMap.h"
16 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
17 #include "llvm/CodeGen/MachineRegisterInfo.h"
18 #include "llvm/Target/TargetInstrInfo.h"
22 LiveInterval &LiveRangeEdit::create(MachineRegisterInfo &mri,
25 const TargetRegisterClass *RC = mri.getRegClass(getReg());
26 unsigned VReg = mri.createVirtualRegister(RC);
28 vrm.setIsSplitFromReg(VReg, vrm.getOriginal(getReg()));
29 LiveInterval &li = lis.getOrCreateInterval(VReg);
30 newRegs_.push_back(&li);
34 void LiveRangeEdit::scanRemattable(LiveIntervals &lis,
35 const TargetInstrInfo &tii,
37 for (LiveInterval::vni_iterator I = parent_.vni_begin(),
38 E = parent_.vni_end(); I != E; ++I) {
42 MachineInstr *DefMI = lis.getInstructionFromIndex(VNI->def);
45 if (tii.isTriviallyReMaterializable(DefMI, aa))
46 remattable_.insert(VNI);
48 scannedRemattable_ = true;
51 bool LiveRangeEdit::anyRematerializable(LiveIntervals &lis,
52 const TargetInstrInfo &tii,
54 if (!scannedRemattable_)
55 scanRemattable(lis, tii, aa);
56 return !remattable_.empty();
59 /// allUsesAvailableAt - Return true if all registers used by OrigMI at
60 /// OrigIdx are also available with the same value at UseIdx.
61 bool LiveRangeEdit::allUsesAvailableAt(const MachineInstr *OrigMI,
65 OrigIdx = OrigIdx.getUseIndex();
66 UseIdx = UseIdx.getUseIndex();
67 for (unsigned i = 0, e = OrigMI->getNumOperands(); i != e; ++i) {
68 const MachineOperand &MO = OrigMI->getOperand(i);
69 if (!MO.isReg() || !MO.getReg() || MO.getReg() == getReg())
71 // Reserved registers are OK.
72 if (MO.isUndef() || !lis.hasInterval(MO.getReg()))
74 // We don't want to move any defs.
77 // We cannot depend on virtual registers in uselessRegs_.
79 for (unsigned ui = 0, ue = uselessRegs_->size(); ui != ue; ++ui)
80 if ((*uselessRegs_)[ui]->reg == MO.getReg())
83 LiveInterval &li = lis.getInterval(MO.getReg());
84 const VNInfo *OVNI = li.getVNInfoAt(OrigIdx);
87 if (OVNI != li.getVNInfoAt(UseIdx))
93 bool LiveRangeEdit::canRematerializeAt(Remat &RM,
97 assert(scannedRemattable_ && "Call anyRematerializable first");
99 // Use scanRemattable info.
100 if (!remattable_.count(RM.ParentVNI))
103 // No defining instruction.
104 RM.OrigMI = lis.getInstructionFromIndex(RM.ParentVNI->def);
105 assert(RM.OrigMI && "Defining instruction for remattable value disappeared");
107 // If only cheap remats were requested, bail out early.
108 if (cheapAsAMove && !RM.OrigMI->getDesc().isAsCheapAsAMove())
111 // Verify that all used registers are available with the same values.
112 if (!allUsesAvailableAt(RM.OrigMI, RM.ParentVNI->def, UseIdx, lis))
118 SlotIndex LiveRangeEdit::rematerializeAt(MachineBasicBlock &MBB,
119 MachineBasicBlock::iterator MI,
123 const TargetInstrInfo &tii,
124 const TargetRegisterInfo &tri) {
125 assert(RM.OrigMI && "Invalid remat");
126 tii.reMaterialize(MBB, MI, DestReg, 0, RM.OrigMI, tri);
127 rematted_.insert(RM.ParentVNI);
128 return lis.InsertMachineInstrInMaps(--MI).getDefIndex();