SlotIndexes.cpp revision 10c5f2dad5e11e2502ebc0b9e9ea56e449f42d16 
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(NumRenumPasses, "Number of slot index renumber passes");
26
27void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
28  au.setPreservesAll();
29  MachineFunctionPass::getAnalysisUsage(au);
30}
31
32void SlotIndexes::releaseMemory() {
33  mi2iMap.clear();
34  mbb2IdxMap.clear();
35  idx2MBBMap.clear();
36  clearList();
37}
38
39bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
40
41  // Compute numbering as follows:
42  // Grab an iterator to the start of the index list.
43  // Iterate over all MBBs, and within each MBB all MIs, keeping the MI
44  // iterator in lock-step (though skipping it over indexes which have
45  // null pointers in the instruction field).
46  // At each iteration assert that the instruction pointed to in the index
47  // is the same one pointed to by the MI iterator. This
48
49  // FIXME: This can be simplified. The mi2iMap_, Idx2MBBMap, etc. should
50  // only need to be set up once after the first numbering is computed.
51
52  mf = &fn;
53  initList();
54
55  // Check that the list contains only the sentinal.
56  assert(indexListHead->getNext() == 0 &&
57         "Index list non-empty at initial numbering?");
58  assert(idx2MBBMap.empty() &&
59         "Index -> MBB mapping non-empty at initial numbering?");
60  assert(mbb2IdxMap.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
68  push_back(createEntry(0, index));
69
70  // Iterate over the function.
71  for (MachineFunction::iterator mbbItr = mf->begin(), mbbEnd = mf->end();
72       mbbItr != mbbEnd; ++mbbItr) {
73    MachineBasicBlock *mbb = &*mbbItr;
74
75    // Insert an index for the MBB start.
76    SlotIndex blockStartIndex(back(), SlotIndex::LOAD);
77
78    index += SlotIndex::NUM;
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      push_back(createEntry(mi, index));
88
89      // Save this base index in the maps.
90      mi2iMap.insert(
91        std::make_pair(mi, SlotIndex(back(), SlotIndex::LOAD)));
92
93      ++functionSize;
94
95      unsigned Slots = mi->getDesc().getNumDefs();
96      if (Slots == 0)
97        Slots = 1;
98
99      index += (Slots + 1) * SlotIndex::NUM;
100    }
101
102    // We insert two blank instructions between basic blocks.
103    // One to represent live-out registers and one to represent live-ins.
104    push_back(createEntry(0, index));
105    index += SlotIndex::NUM;
106
107    push_back(createEntry(0, index));
108
109    SlotIndex blockEndIndex(back(), SlotIndex::LOAD);
110    mbb2IdxMap.insert(
111      std::make_pair(mbb, std::make_pair(blockStartIndex, blockEndIndex)));
112
113    idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, mbb));
114  }
115
116  // Sort the Idx2MBBMap
117  std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
118
119  DEBUG(dump());
120
121  // And we're done!
122  return false;
123}
124
125void SlotIndexes::renumberIndexes() {
126
127  // Renumber updates the index of every element of the index list.
128  // If all instrs in the function have been allocated an index (which has been
129  // placed in the index list in the order of instruction iteration) then the
130  // resulting numbering will match what would have been generated by the
131  // pass during the initial numbering of the function if the new instructions
132  // had been present.
133  DEBUG(dbgs() << "\n*** Renumbering SlotIndexes ***\n");
134  ++NumRenumPasses;
135
136  unsigned index = 0;
137
138  for (IndexListEntry *curEntry = front(); curEntry != getTail();
139       curEntry = curEntry->getNext()) {
140    curEntry->setIndex(index);
141    index += 4*SlotIndex::NUM;
142  }
143}
144
145void SlotIndexes::dump() const {
146  for (const IndexListEntry *itr = front(); itr != getTail();
147       itr = itr->getNext()) {
148    dbgs() << itr->getIndex() << " ";
149
150    if (itr->getInstr() != 0) {
151      dbgs() << *itr->getInstr();
152    } else {
153      dbgs() << "\n";
154    }
155  }
156
157  for (MBB2IdxMap::const_iterator itr = mbb2IdxMap.begin();
158       itr != mbb2IdxMap.end(); ++itr) {
159    dbgs() << "MBB " << itr->first->getNumber() << " (" << itr->first << ") - ["
160           << itr->second.first << ", " << itr->second.second << "]\n";
161  }
162}
163
164// Print a SlotIndex to a raw_ostream.
165void SlotIndex::print(raw_ostream &os) const {
166  if (isValid())
167    os << entry().getIndex() << "LudS"[getSlot()];
168  else
169    os << "invalid";
170}
171
172// Dump a SlotIndex to stderr.
173void SlotIndex::dump() const {
174  print(dbgs());
175  dbgs() << "\n";
176}
177
178