SlotIndexes.cpp revision 16dcaf59960d699735a57b1623092d561c18a165 
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/CodeGen/MachineFunction.h"
14#include "llvm/Support/Debug.h"
15#include "llvm/Support/raw_ostream.h"
16#include "llvm/Support/ManagedStatic.h"
17
18using namespace llvm;
19
20
21// Yep - these are thread safe. See the header for details.
22namespace {
23
24
25  class EmptyIndexListEntry : public IndexListEntry {
26  public:
27    EmptyIndexListEntry() : IndexListEntry(EMPTY_KEY) {}
28  };
29
30  class TombstoneIndexListEntry : public IndexListEntry {
31  public:
32    TombstoneIndexListEntry() : IndexListEntry(TOMBSTONE_KEY) {}
33  };
34
35  // The following statics are thread safe. They're read only, and you
36  // can't step from them to any other list entries.
37  ManagedStatic<EmptyIndexListEntry> IndexListEntryEmptyKey;
38  ManagedStatic<TombstoneIndexListEntry> IndexListEntryTombstoneKey;
39}
40
41char SlotIndexes::ID = 0;
42static RegisterPass<SlotIndexes> X("slotindexes", "Slot index numbering");
43
44IndexListEntry* IndexListEntry::getEmptyKeyEntry() {
45  return &*IndexListEntryEmptyKey;
46}
47
48IndexListEntry* IndexListEntry::getTombstoneKeyEntry() {
49  return &*IndexListEntryTombstoneKey;
50}
51
52
53void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
54  au.setPreservesAll();
55  MachineFunctionPass::getAnalysisUsage(au);
56}
57
58void SlotIndexes::releaseMemory() {
59  mi2iMap.clear();
60  mbb2IdxMap.clear();
61  idx2MBBMap.clear();
62  terminatorGaps.clear();
63  clearList();
64}
65
66bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
67
68  // Compute numbering as follows:
69  // Grab an iterator to the start of the index list.
70  // Iterate over all MBBs, and within each MBB all MIs, keeping the MI
71  // iterator in lock-step (though skipping it over indexes which have
72  // null pointers in the instruction field).
73  // At each iteration assert that the instruction pointed to in the index
74  // is the same one pointed to by the MI iterator. This
75
76  // FIXME: This can be simplified. The mi2iMap_, Idx2MBBMap, etc. should
77  // only need to be set up once after the first numbering is computed.
78
79  mf = &fn;
80  initList();
81
82  // Check that the list contains only the sentinal.
83  assert(indexListHead->getNext() == 0 &&
84         "Index list non-empty at initial numbering?");
85  assert(idx2MBBMap.empty() &&
86         "Index -> MBB mapping non-empty at initial numbering?");
87  assert(mbb2IdxMap.empty() &&
88         "MBB -> Index mapping non-empty at initial numbering?");
89  assert(mi2iMap.empty() &&
90         "MachineInstr -> Index mapping non-empty at initial numbering?");
91
92  functionSize = 0;
93  unsigned index = 0;
94
95  // Iterate over the the function.
96  for (MachineFunction::iterator mbbItr = mf->begin(), mbbEnd = mf->end();
97       mbbItr != mbbEnd; ++mbbItr) {
98    MachineBasicBlock *mbb = &*mbbItr;
99
100    // Insert an index for the MBB start.
101    push_back(createEntry(0, index));
102    SlotIndex blockStartIndex(back(), SlotIndex::LOAD);
103
104    index += SlotIndex::NUM;
105
106    for (MachineBasicBlock::iterator miItr = mbb->begin(), miEnd = mbb->end();
107         miItr != miEnd; ++miItr) {
108      MachineInstr *mi = &*miItr;
109
110      if (miItr == mbb->getFirstTerminator()) {
111        push_back(createEntry(0, index));
112        terminatorGaps.insert(
113          std::make_pair(mbb, SlotIndex(back(), SlotIndex::PHI_BIT)));
114        index += SlotIndex::NUM;
115      }
116
117      // Insert a store index for the instr.
118      push_back(createEntry(mi, index));
119
120      // Save this base index in the maps.
121      mi2iMap.insert(
122        std::make_pair(mi, SlotIndex(back(), SlotIndex::LOAD)));
123
124      ++functionSize;
125
126      unsigned Slots = mi->getDesc().getNumDefs();
127      if (Slots == 0)
128        Slots = 1;
129
130      index += (Slots + 1) * SlotIndex::NUM;
131    }
132
133    if (mbb->getFirstTerminator() == mbb->end()) {
134      push_back(createEntry(0, index));
135      terminatorGaps.insert(
136        std::make_pair(mbb, SlotIndex(back(), SlotIndex::PHI_BIT)));
137      index += SlotIndex::NUM;
138    }
139
140    SlotIndex blockEndIndex(back(), SlotIndex::STORE);
141    mbb2IdxMap.insert(
142      std::make_pair(mbb, std::make_pair(blockStartIndex, blockEndIndex)));
143
144    idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, mbb));
145  }
146
147  // One blank instruction at the end.
148  push_back(createEntry(0, index));
149
150  // Sort the Idx2MBBMap
151  std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
152
153  DEBUG(dump());
154
155  // And we're done!
156  return false;
157}
158
159void SlotIndexes::renumber() {
160
161  // Renumber updates the index of every element of the index list.
162  // If all instrs in the function have been allocated an index (which has been
163  // placed in the index list in the order of instruction iteration) then the
164  // resulting numbering will match what would have been generated by the
165  // pass during the initial numbering of the function if the new instructions
166  // had been present.
167
168  functionSize = 0;
169  unsigned index = 0;
170
171  for (IndexListEntry *curEntry = front(); curEntry != getTail();
172       curEntry = curEntry->getNext()) {
173
174    curEntry->setIndex(index);
175
176    if (curEntry->getInstr() == 0) {
177      // MBB start entry or terminator gap. Just step index by 1.
178      index += SlotIndex::NUM;
179    }
180    else {
181      ++functionSize;
182      unsigned Slots = curEntry->getInstr()->getDesc().getNumDefs();
183      if (Slots == 0)
184        Slots = 1;
185
186      index += (Slots + 1) * SlotIndex::NUM;
187
188    }
189  }
190}
191
192void SlotIndexes::dump() const {
193  for (const IndexListEntry *itr = front(); itr != getTail();
194       itr = itr->getNext()) {
195    errs() << itr->getIndex() << " ";
196
197    if (itr->getInstr() != 0) {
198      errs() << *itr->getInstr();
199    } else {
200      errs() << "\n";
201    }
202  }
203
204  for (MBB2IdxMap::iterator itr = mbb2IdxMap.begin();
205       itr != mbb2IdxMap.end(); ++itr) {
206    errs() << "MBB " << itr->first->getNumber() << " (" << itr->first << ") - ["
207           << itr->second.first << ", " << itr->second.second << "]\n";
208  }
209}
210
211// Print a SlotIndex to a raw_ostream.
212void SlotIndex::print(raw_ostream &os) const {
213  os << getIndex();
214  if (isPHI())
215    os << "*";
216}
217
218// Dump a SlotIndex to stderr.
219void SlotIndex::dump() const {
220  print(errs());
221  errs() << "\n";
222}
223
224