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  functionSize = 0;
66  unsigned index = 0;
67  MBBRanges.resize(mf->getNumBlockIDs());
68  idx2MBBMap.reserve(mf->size());
69
70  indexList.push_back(createEntry(0, index));
71
72  // Iterate over the function.
73  for (MachineFunction::iterator mbbItr = mf->begin(), mbbEnd = mf->end();
74       mbbItr != mbbEnd; ++mbbItr) {
75    MachineBasicBlock *mbb = &*mbbItr;
76
77    // Insert an index for the MBB start.
78    SlotIndex blockStartIndex(&indexList.back(), SlotIndex::Slot_Block);
79
80    for (MachineBasicBlock::iterator miItr = mbb->begin(), miEnd = mbb->end();
81         miItr != miEnd; ++miItr) {
82      MachineInstr *mi = miItr;
83      if (mi->isDebugValue())
84        continue;
85
86      // Insert a store index for the instr.
87      indexList.push_back(createEntry(mi, index += SlotIndex::InstrDist));
88
89      // Save this base index in the maps.
90      mi2iMap.insert(std::make_pair(mi, SlotIndex(&indexList.back(),
91                                                  SlotIndex::Slot_Block)));
92
93      ++functionSize;
94    }
95
96    // We insert one blank instructions between basic blocks.
97    indexList.push_back(createEntry(0, index += SlotIndex::InstrDist));
98
99    MBBRanges[mbb->getNumber()].first = blockStartIndex;
100    MBBRanges[mbb->getNumber()].second = SlotIndex(&indexList.back(),
101                                                   SlotIndex::Slot_Block);
102    idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, mbb));
103  }
104
105  // Sort the Idx2MBBMap
106  std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
107
108  DEBUG(mf->print(dbgs(), this));
109
110  // And we're done!
111  return false;
112}
113
114void SlotIndexes::renumberIndexes() {
115  // Renumber updates the index of every element of the index list.
116  DEBUG(dbgs() << "\n*** Renumbering SlotIndexes ***\n");
117  ++NumGlobalRenum;
118
119  unsigned index = 0;
120
121  for (IndexList::iterator I = indexList.begin(), E = indexList.end();
122       I != E; ++I) {
123    I->setIndex(index);
124    index += SlotIndex::InstrDist;
125  }
126}
127
128// Renumber indexes locally after curItr was inserted, but failed to get a new
129// index.
130void SlotIndexes::renumberIndexes(IndexList::iterator curItr) {
131  // Number indexes with half the default spacing so we can catch up quickly.
132  const unsigned Space = SlotIndex::InstrDist/2;
133  assert((Space & 3) == 0 && "InstrDist must be a multiple of 2*NUM");
134
135  IndexList::iterator startItr = prior(curItr);
136  unsigned index = startItr->getIndex();
137  do {
138    curItr->setIndex(index += Space);
139    ++curItr;
140    // If the next index is bigger, we have caught up.
141  } while (curItr != indexList.end() && curItr->getIndex() <= index);
142
143  DEBUG(dbgs() << "\n*** Renumbered SlotIndexes " << startItr->getIndex() << '-'
144               << index << " ***\n");
145  ++NumLocalRenum;
146}
147
148
149void SlotIndexes::dump() const {
150  for (IndexList::const_iterator itr = indexList.begin();
151       itr != indexList.end(); ++itr) {
152    dbgs() << itr->getIndex() << " ";
153
154    if (itr->getInstr() != 0) {
155      dbgs() << *itr->getInstr();
156    } else {
157      dbgs() << "\n";
158    }
159  }
160
161  for (unsigned i = 0, e = MBBRanges.size(); i != e; ++i)
162    dbgs() << "BB#" << i << "\t[" << MBBRanges[i].first << ';'
163           << MBBRanges[i].second << ")\n";
164}
165
166// Print a SlotIndex to a raw_ostream.
167void SlotIndex::print(raw_ostream &os) const {
168  if (isValid())
169    os << listEntry()->getIndex() << "Berd"[getSlot()];
170  else
171    os << "invalid";
172}
173
174// Dump a SlotIndex to stderr.
175void SlotIndex::dump() const {
176  print(dbgs());
177  dbgs() << "\n";
178}
179
180