SlotIndexes.cpp revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338 
1//===-- SlotIndexes.cpp - Slot Indexes Pass  ------------------------------===//
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 "slotindexes"
11
12#include "llvm/CodeGen/SlotIndexes.h"
13#include "llvm/ADT/Statistic.h"
14#include "llvm/CodeGen/MachineFunction.h"
15#include "llvm/Support/Debug.h"
16#include "llvm/Support/raw_ostream.h"
17#include "llvm/Target/TargetInstrInfo.h"
18
19using namespace llvm;
20
21char SlotIndexes::ID = 0;
22INITIALIZE_PASS(SlotIndexes, "slotindexes",
23                "Slot index numbering", false, false)
24
25STATISTIC(NumLocalRenum,  "Number of local renumberings");
26STATISTIC(NumGlobalRenum, "Number of global renumberings");
27
28void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
29  au.setPreservesAll();
30  MachineFunctionPass::getAnalysisUsage(au);
31}
32
33void SlotIndexes::releaseMemory() {
34  mi2iMap.clear();
35  MBBRanges.clear();
36  idx2MBBMap.clear();
37  indexList.clear();
38  ileAllocator.Reset();
39}
40
41bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
42
43  // Compute numbering as follows:
44  // Grab an iterator to the start of the index list.
45  // Iterate over all MBBs, and within each MBB all MIs, keeping the MI
46  // iterator in lock-step (though skipping it over indexes which have
47  // null pointers in the instruction field).
48  // At each iteration assert that the instruction pointed to in the index
49  // is the same one pointed to by the MI iterator. This
50
51  // FIXME: This can be simplified. The mi2iMap_, Idx2MBBMap, etc. should
52  // only need to be set up once after the first numbering is computed.
53
54  mf = &fn;
55
56  // Check that the list contains only the sentinal.
57  assert(indexList.empty() && "Index list non-empty at initial numbering?");
58  assert(idx2MBBMap.empty() &&
59         "Index -> MBB mapping non-empty at initial numbering?");
60  assert(MBBRanges.empty() &&
61         "MBB -> Index mapping non-empty at initial numbering?");
62  assert(mi2iMap.empty() &&
63         "MachineInstr -> Index mapping non-empty at initial numbering?");
64
65  unsigned index = 0;
66  MBBRanges.resize(mf->getNumBlockIDs());
67  idx2MBBMap.reserve(mf->size());
68
69  indexList.push_back(createEntry(0, index));
70
71  // Iterate over the function.
72  for (MachineFunction::iterator mbbItr = mf->begin(), mbbEnd = mf->end();
73       mbbItr != mbbEnd; ++mbbItr) {
74    MachineBasicBlock *mbb = &*mbbItr;
75
76    // Insert an index for the MBB start.
77    SlotIndex blockStartIndex(&indexList.back(), SlotIndex::Slot_Block);
78
79    for (MachineBasicBlock::iterator miItr = mbb->begin(), miEnd = mbb->end();
80         miItr != miEnd; ++miItr) {
81      MachineInstr *mi = miItr;
82      if (mi->isDebugValue())
83        continue;
84
85      // Insert a store index for the instr.
86      indexList.push_back(createEntry(mi, index += SlotIndex::InstrDist));
87
88      // Save this base index in the maps.
89      mi2iMap.insert(std::make_pair(mi, SlotIndex(&indexList.back(),
90                                                  SlotIndex::Slot_Block)));
91    }
92
93    // We insert one blank instructions between basic blocks.
94    indexList.push_back(createEntry(0, index += SlotIndex::InstrDist));
95
96    MBBRanges[mbb->getNumber()].first = blockStartIndex;
97    MBBRanges[mbb->getNumber()].second = SlotIndex(&indexList.back(),
98                                                   SlotIndex::Slot_Block);
99    idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, mbb));
100  }
101
102  // Sort the Idx2MBBMap
103  std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
104
105  DEBUG(mf->print(dbgs(), this));
106
107  // And we're done!
108  return false;
109}
110
111void SlotIndexes::renumberIndexes() {
112  // Renumber updates the index of every element of the index list.
113  DEBUG(dbgs() << "\n*** Renumbering SlotIndexes ***\n");
114  ++NumGlobalRenum;
115
116  unsigned index = 0;
117
118  for (IndexList::iterator I = indexList.begin(), E = indexList.end();
119       I != E; ++I) {
120    I->setIndex(index);
121    index += SlotIndex::InstrDist;
122  }
123}
124
125// Renumber indexes locally after curItr was inserted, but failed to get a new
126// index.
127void SlotIndexes::renumberIndexes(IndexList::iterator curItr) {
128  // Number indexes with half the default spacing so we can catch up quickly.
129  const unsigned Space = SlotIndex::InstrDist/2;
130  assert((Space & 3) == 0 && "InstrDist must be a multiple of 2*NUM");
131
132  IndexList::iterator startItr = std::prev(curItr);
133  unsigned index = startItr->getIndex();
134  do {
135    curItr->setIndex(index += Space);
136    ++curItr;
137    // If the next index is bigger, we have caught up.
138  } while (curItr != indexList.end() && curItr->getIndex() <= index);
139
140  DEBUG(dbgs() << "\n*** Renumbered SlotIndexes " << startItr->getIndex() << '-'
141               << index << " ***\n");
142  ++NumLocalRenum;
143}
144
145// Repair indexes after adding and removing instructions.
146void SlotIndexes::repairIndexesInRange(MachineBasicBlock *MBB,
147                                       MachineBasicBlock::iterator Begin,
148                                       MachineBasicBlock::iterator End) {
149  // FIXME: Is this really necessary? The only caller repairIntervalsForRange()
150  // does the same thing.
151  // Find anchor points, which are at the beginning/end of blocks or at
152  // instructions that already have indexes.
153  while (Begin != MBB->begin() && !hasIndex(Begin))
154    --Begin;
155  while (End != MBB->end() && !hasIndex(End))
156    ++End;
157
158  bool includeStart = (Begin == MBB->begin());
159  SlotIndex startIdx;
160  if (includeStart)
161    startIdx = getMBBStartIdx(MBB);
162  else
163    startIdx = getInstructionIndex(Begin);
164
165  SlotIndex endIdx;
166  if (End == MBB->end())
167    endIdx = getMBBEndIdx(MBB);
168  else
169    endIdx = getInstructionIndex(End);
170
171  // FIXME: Conceptually, this code is implementing an iterator on MBB that
172  // optionally includes an additional position prior to MBB->begin(), indicated
173  // by the includeStart flag. This is done so that we can iterate MIs in a MBB
174  // in parallel with SlotIndexes, but there should be a better way to do this.
175  IndexList::iterator ListB = startIdx.listEntry();
176  IndexList::iterator ListI = endIdx.listEntry();
177  MachineBasicBlock::iterator MBBI = End;
178  bool pastStart = false;
179  while (ListI != ListB || MBBI != Begin || (includeStart && !pastStart)) {
180    assert(ListI->getIndex() >= startIdx.getIndex() &&
181           (includeStart || !pastStart) &&
182           "Decremented past the beginning of region to repair.");
183
184    MachineInstr *SlotMI = ListI->getInstr();
185    MachineInstr *MI = (MBBI != MBB->end() && !pastStart) ? MBBI : 0;
186    bool MBBIAtBegin = MBBI == Begin && (!includeStart || pastStart);
187
188    if (SlotMI == MI && !MBBIAtBegin) {
189      --ListI;
190      if (MBBI != Begin)
191        --MBBI;
192      else
193        pastStart = true;
194    } else if (MI && mi2iMap.find(MI) == mi2iMap.end()) {
195      if (MBBI != Begin)
196        --MBBI;
197      else
198        pastStart = true;
199    } else {
200      --ListI;
201      if (SlotMI)
202        removeMachineInstrFromMaps(SlotMI);
203    }
204  }
205
206  // In theory this could be combined with the previous loop, but it is tricky
207  // to update the IndexList while we are iterating it.
208  for (MachineBasicBlock::iterator I = End; I != Begin;) {
209    --I;
210    MachineInstr *MI = I;
211    if (!MI->isDebugValue() && mi2iMap.find(MI) == mi2iMap.end())
212      insertMachineInstrInMaps(MI);
213  }
214}
215
216#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
217void SlotIndexes::dump() const {
218  for (IndexList::const_iterator itr = indexList.begin();
219       itr != indexList.end(); ++itr) {
220    dbgs() << itr->getIndex() << " ";
221
222    if (itr->getInstr() != 0) {
223      dbgs() << *itr->getInstr();
224    } else {
225      dbgs() << "\n";
226    }
227  }
228
229  for (unsigned i = 0, e = MBBRanges.size(); i != e; ++i)
230    dbgs() << "BB#" << i << "\t[" << MBBRanges[i].first << ';'
231           << MBBRanges[i].second << ")\n";
232}
233#endif
234
235// Print a SlotIndex to a raw_ostream.
236void SlotIndex::print(raw_ostream &os) const {
237  if (isValid())
238    os << listEntry()->getIndex() << "Berd"[getSlot()];
239  else
240    os << "invalid";
241}
242
243#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
244// Dump a SlotIndex to stderr.
245void SlotIndex::dump() const {
246  print(dbgs());
247  dbgs() << "\n";
248}
249#endif
250
251