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
19 using namespace llvm;
20
21 char SlotIndexes::ID = 0;
22 INITIALIZE_PASS(SlotIndexes, "slotindexes",
23 "Slot index numbering", false, false)
24
25 STATISTIC(NumLocalRenum, "Number of local renumberings");
26 STATISTIC(NumGlobalRenum, "Number of global renumberings");
27
getAnalysisUsage(AnalysisUsage & au) const28 void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
29 au.setPreservesAll();
30 MachineFunctionPass::getAnalysisUsage(au);
31 }
32
releaseMemory()33 void SlotIndexes::releaseMemory() {
34 mi2iMap.clear();
35 MBBRanges.clear();
36 idx2MBBMap.clear();
37 indexList.clear();
38 ileAllocator.Reset();
39 }
40
runOnMachineFunction(MachineFunction & fn)41 bool 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
renumberIndexes()114 void 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.
renumberIndexes(IndexList::iterator curItr)130 void 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
dump() const149 void 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.
print(raw_ostream & os) const167 void 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.
dump() const175 void SlotIndex::dump() const {
176 print(dbgs());
177 dbgs() << "\n";
178 }
179
180