Spiller.cpp revision 1485455be0310c6b24f096823029e08867531016 
1//===-- llvm/CodeGen/Spiller.cpp -  Spiller -------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#define DEBUG_TYPE "spiller"
11
12#include "Spiller.h"
13#include "VirtRegMap.h"
14#include "LiveRangeEdit.h"
15#include "llvm/CodeGen/LiveIntervalAnalysis.h"
16#include "llvm/CodeGen/LiveStackAnalysis.h"
17#include "llvm/CodeGen/MachineFrameInfo.h"
18#include "llvm/CodeGen/MachineFunction.h"
19#include "llvm/CodeGen/MachineInstrBuilder.h"
20#include "llvm/CodeGen/MachineLoopInfo.h"
21#include "llvm/CodeGen/MachineRegisterInfo.h"
22#include "llvm/Target/TargetMachine.h"
23#include "llvm/Target/TargetInstrInfo.h"
24#include "llvm/Support/CommandLine.h"
25#include "llvm/Support/Debug.h"
26#include "llvm/Support/ErrorHandling.h"
27#include "llvm/Support/raw_ostream.h"
28
29using namespace llvm;
30
31namespace {
32  enum SpillerName { trivial, inline_ };
33}
34
35static cl::opt<SpillerName>
36spillerOpt("spiller",
37           cl::desc("Spiller to use: (default: standard)"),
38           cl::Prefix,
39           cl::values(clEnumVal(trivial,   "trivial spiller"),
40                      clEnumValN(inline_,  "inline", "inline spiller"),
41                      clEnumValEnd),
42           cl::init(trivial));
43
44// Spiller virtual destructor implementation.
45Spiller::~Spiller() {}
46
47namespace {
48
49/// Utility class for spillers.
50class SpillerBase : public Spiller {
51protected:
52  MachineFunctionPass *pass;
53  MachineFunction *mf;
54  VirtRegMap *vrm;
55  LiveIntervals *lis;
56  MachineFrameInfo *mfi;
57  MachineRegisterInfo *mri;
58  const TargetInstrInfo *tii;
59  const TargetRegisterInfo *tri;
60
61  /// Construct a spiller base.
62  SpillerBase(MachineFunctionPass &pass, MachineFunction &mf, VirtRegMap &vrm)
63    : pass(&pass), mf(&mf), vrm(&vrm)
64  {
65    lis = &pass.getAnalysis<LiveIntervals>();
66    mfi = mf.getFrameInfo();
67    mri = &mf.getRegInfo();
68    tii = mf.getTarget().getInstrInfo();
69    tri = mf.getTarget().getRegisterInfo();
70  }
71
72  /// Add spill ranges for every use/def of the live interval, inserting loads
73  /// immediately before each use, and stores after each def. No folding or
74  /// remat is attempted.
75  void trivialSpillEverywhere(LiveRangeEdit& LRE) {
76    LiveInterval* li = &LRE.getParent();
77
78    DEBUG(dbgs() << "Spilling everywhere " << *li << "\n");
79
80    assert(li->weight != HUGE_VALF &&
81           "Attempting to spill already spilled value.");
82
83    assert(!TargetRegisterInfo::isStackSlot(li->reg) &&
84           "Trying to spill a stack slot.");
85
86    DEBUG(dbgs() << "Trivial spill everywhere of reg" << li->reg << "\n");
87
88    const TargetRegisterClass *trc = mri->getRegClass(li->reg);
89    unsigned ss = vrm->assignVirt2StackSlot(li->reg);
90
91    // Iterate over reg uses/defs.
92    for (MachineRegisterInfo::reg_iterator
93         regItr = mri->reg_begin(li->reg); regItr != mri->reg_end();) {
94
95      // Grab the use/def instr.
96      MachineInstr *mi = &*regItr;
97
98      DEBUG(dbgs() << "  Processing " << *mi);
99
100      // Step regItr to the next use/def instr.
101      do {
102        ++regItr;
103      } while (regItr != mri->reg_end() && (&*regItr == mi));
104
105      // Collect uses & defs for this instr.
106      SmallVector<unsigned, 2> indices;
107      bool hasUse = false;
108      bool hasDef = false;
109      for (unsigned i = 0; i != mi->getNumOperands(); ++i) {
110        MachineOperand &op = mi->getOperand(i);
111        if (!op.isReg() || op.getReg() != li->reg)
112          continue;
113        hasUse |= mi->getOperand(i).isUse();
114        hasDef |= mi->getOperand(i).isDef();
115        indices.push_back(i);
116      }
117
118      // Create a new vreg & interval for this instr.
119      LiveInterval *newLI = &LRE.create(*lis, *vrm);
120      newLI->weight = HUGE_VALF;
121
122      // Update the reg operands & kill flags.
123      for (unsigned i = 0; i < indices.size(); ++i) {
124        unsigned mopIdx = indices[i];
125        MachineOperand &mop = mi->getOperand(mopIdx);
126        mop.setReg(newLI->reg);
127        if (mop.isUse() && !mi->isRegTiedToDefOperand(mopIdx)) {
128          mop.setIsKill(true);
129        }
130      }
131      assert(hasUse || hasDef);
132
133      // Insert reload if necessary.
134      MachineBasicBlock::iterator miItr(mi);
135      if (hasUse) {
136        tii->loadRegFromStackSlot(*mi->getParent(), miItr, newLI->reg, ss, trc,
137                                  tri);
138        MachineInstr *loadInstr(prior(miItr));
139        SlotIndex loadIndex =
140          lis->InsertMachineInstrInMaps(loadInstr).getRegSlot();
141        SlotIndex endIndex = loadIndex.getNextIndex();
142        VNInfo *loadVNI =
143          newLI->getNextValue(loadIndex, lis->getVNInfoAllocator());
144        newLI->addRange(LiveRange(loadIndex, endIndex, loadVNI));
145      }
146
147      // Insert store if necessary.
148      if (hasDef) {
149        tii->storeRegToStackSlot(*mi->getParent(), llvm::next(miItr),newLI->reg,
150                                 true, ss, trc, tri);
151        MachineInstr *storeInstr(llvm::next(miItr));
152        SlotIndex storeIndex =
153          lis->InsertMachineInstrInMaps(storeInstr).getRegSlot();
154        SlotIndex beginIndex = storeIndex.getPrevIndex();
155        VNInfo *storeVNI =
156          newLI->getNextValue(beginIndex, lis->getVNInfoAllocator());
157        newLI->addRange(LiveRange(beginIndex, storeIndex, storeVNI));
158      }
159    }
160  }
161};
162
163} // end anonymous namespace
164
165namespace {
166
167/// Spills any live range using the spill-everywhere method with no attempt at
168/// folding.
169class TrivialSpiller : public SpillerBase {
170public:
171
172  TrivialSpiller(MachineFunctionPass &pass, MachineFunction &mf,
173                 VirtRegMap &vrm)
174    : SpillerBase(pass, mf, vrm) {}
175
176  void spill(LiveRangeEdit &LRE) {
177    // Ignore spillIs - we don't use it.
178    trivialSpillEverywhere(LRE);
179  }
180};
181
182} // end anonymous namespace
183
184void Spiller::anchor() { }
185
186llvm::Spiller* llvm::createSpiller(MachineFunctionPass &pass,
187                                   MachineFunction &mf,
188                                   VirtRegMap &vrm) {
189  switch (spillerOpt) {
190  case trivial: return new TrivialSpiller(pass, mf, vrm);
191  case inline_: return createInlineSpiller(pass, mf, vrm);
192  }
193  llvm_unreachable("Invalid spiller optimization");
194}
195