LLVM  14.0.0git
SlotIndexes.cpp
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1 //===-- SlotIndexes.cpp - Slot Indexes Pass ------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
10 #include "llvm/ADT/Statistic.h"
12 #include "llvm/Config/llvm-config.h"
13 #include "llvm/InitializePasses.h"
14 #include "llvm/Support/Debug.h"
16 
17 using namespace llvm;
18 
19 #define DEBUG_TYPE "slotindexes"
20 
21 char SlotIndexes::ID = 0;
22 
25 }
26 
28  // The indexList's nodes are all allocated in the BumpPtrAllocator.
29  indexList.clearAndLeakNodesUnsafely();
30 }
31 
33  "Slot index numbering", false, false)
34 
35 STATISTIC(NumLocalRenum, "Number of local renumberings");
36 
37 void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
38  au.setPreservesAll();
40 }
41 
43  mi2iMap.clear();
44  MBBRanges.clear();
45  idx2MBBMap.clear();
46  indexList.clear();
47  ileAllocator.Reset();
48 }
49 
51 
52  // Compute numbering as follows:
53  // Grab an iterator to the start of the index list.
54  // Iterate over all MBBs, and within each MBB all MIs, keeping the MI
55  // iterator in lock-step (though skipping it over indexes which have
56  // null pointers in the instruction field).
57  // At each iteration assert that the instruction pointed to in the index
58  // is the same one pointed to by the MI iterator. This
59 
60  // FIXME: This can be simplified. The mi2iMap_, Idx2MBBMap, etc. should
61  // only need to be set up once after the first numbering is computed.
62 
63  mf = &fn;
64 
65  // Check that the list contains only the sentinal.
66  assert(indexList.empty() && "Index list non-empty at initial numbering?");
67  assert(idx2MBBMap.empty() &&
68  "Index -> MBB mapping non-empty at initial numbering?");
69  assert(MBBRanges.empty() &&
70  "MBB -> Index mapping non-empty at initial numbering?");
71  assert(mi2iMap.empty() &&
72  "MachineInstr -> Index mapping non-empty at initial numbering?");
73 
74  unsigned index = 0;
75  MBBRanges.resize(mf->getNumBlockIDs());
76  idx2MBBMap.reserve(mf->size());
77 
78  indexList.push_back(createEntry(nullptr, index));
79 
80  // Iterate over the function.
81  for (MachineBasicBlock &MBB : *mf) {
82  // Insert an index for the MBB start.
83  SlotIndex blockStartIndex(&indexList.back(), SlotIndex::Slot_Block);
84 
85  for (MachineInstr &MI : MBB) {
86  if (MI.isDebugOrPseudoInstr())
87  continue;
88 
89  // Insert a store index for the instr.
90  indexList.push_back(createEntry(&MI, index += SlotIndex::InstrDist));
91 
92  // Save this base index in the maps.
93  mi2iMap.insert(std::make_pair(
94  &MI, SlotIndex(&indexList.back(), SlotIndex::Slot_Block)));
95  }
96 
97  // We insert one blank instructions between basic blocks.
98  indexList.push_back(createEntry(nullptr, index += SlotIndex::InstrDist));
99 
100  MBBRanges[MBB.getNumber()].first = blockStartIndex;
101  MBBRanges[MBB.getNumber()].second = SlotIndex(&indexList.back(),
102  SlotIndex::Slot_Block);
103  idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, &MBB));
104  }
105 
106  // Sort the Idx2MBBMap
107  llvm::sort(idx2MBBMap, less_first());
108 
109  LLVM_DEBUG(mf->print(dbgs(), this));
110 
111  // And we're done!
112  return false;
113 }
114 
116  bool AllowBundled) {
117  assert((AllowBundled || !MI.isBundledWithPred()) &&
118  "Use removeSingleMachineInstrFromMaps() instead");
119  Mi2IndexMap::iterator mi2iItr = mi2iMap.find(&MI);
120  if (mi2iItr == mi2iMap.end())
121  return;
122 
123  SlotIndex MIIndex = mi2iItr->second;
124  IndexListEntry &MIEntry = *MIIndex.listEntry();
125  assert(MIEntry.getInstr() == &MI && "Instruction indexes broken.");
126  mi2iMap.erase(mi2iItr);
127  // FIXME: Eventually we want to actually delete these indexes.
128  MIEntry.setInstr(nullptr);
129 }
130 
132  Mi2IndexMap::iterator mi2iItr = mi2iMap.find(&MI);
133  if (mi2iItr == mi2iMap.end())
134  return;
135 
136  SlotIndex MIIndex = mi2iItr->second;
137  IndexListEntry &MIEntry = *MIIndex.listEntry();
138  assert(MIEntry.getInstr() == &MI && "Instruction indexes broken.");
139  mi2iMap.erase(mi2iItr);
140 
141  // When removing the first instruction of a bundle update mapping to next
142  // instruction.
143  if (MI.isBundledWithSucc()) {
144  // Only the first instruction of a bundle should have an index assigned.
145  assert(!MI.isBundledWithPred() && "Should be first bundle instruction");
146 
147  MachineBasicBlock::instr_iterator Next = std::next(MI.getIterator());
148  MachineInstr &NextMI = *Next;
149  MIEntry.setInstr(&NextMI);
150  mi2iMap.insert(std::make_pair(&NextMI, MIIndex));
151  return;
152  } else {
153  // FIXME: Eventually we want to actually delete these indexes.
154  MIEntry.setInstr(nullptr);
155  }
156 }
157 
158 // Renumber indexes locally after curItr was inserted, but failed to get a new
159 // index.
160 void SlotIndexes::renumberIndexes(IndexList::iterator curItr) {
161  // Number indexes with half the default spacing so we can catch up quickly.
162  const unsigned Space = SlotIndex::InstrDist/2;
163  static_assert((Space & 3) == 0, "InstrDist must be a multiple of 2*NUM");
164 
165  IndexList::iterator startItr = std::prev(curItr);
166  unsigned index = startItr->getIndex();
167  do {
168  curItr->setIndex(index += Space);
169  ++curItr;
170  // If the next index is bigger, we have caught up.
171  } while (curItr != indexList.end() && curItr->getIndex() <= index);
172 
173  LLVM_DEBUG(dbgs() << "\n*** Renumbered SlotIndexes " << startItr->getIndex()
174  << '-' << index << " ***\n");
175  ++NumLocalRenum;
176 }
177 
178 // Repair indexes after adding and removing instructions.
182  // FIXME: Is this really necessary? The only caller repairIntervalsForRange()
183  // does the same thing.
184  // Find anchor points, which are at the beginning/end of blocks or at
185  // instructions that already have indexes.
186  while (Begin != MBB->begin() && !hasIndex(*Begin))
187  --Begin;
188  while (End != MBB->end() && !hasIndex(*End))
189  ++End;
190 
191  bool includeStart = (Begin == MBB->begin());
192  SlotIndex startIdx;
193  if (includeStart)
194  startIdx = getMBBStartIdx(MBB);
195  else
196  startIdx = getInstructionIndex(*Begin);
197 
198  SlotIndex endIdx;
199  if (End == MBB->end())
200  endIdx = getMBBEndIdx(MBB);
201  else
202  endIdx = getInstructionIndex(*End);
203 
204  // FIXME: Conceptually, this code is implementing an iterator on MBB that
205  // optionally includes an additional position prior to MBB->begin(), indicated
206  // by the includeStart flag. This is done so that we can iterate MIs in a MBB
207  // in parallel with SlotIndexes, but there should be a better way to do this.
208  IndexList::iterator ListB = startIdx.listEntry()->getIterator();
209  IndexList::iterator ListI = endIdx.listEntry()->getIterator();
211  bool pastStart = false;
212  while (ListI != ListB || MBBI != Begin || (includeStart && !pastStart)) {
213  assert(ListI->getIndex() >= startIdx.getIndex() &&
214  (includeStart || !pastStart) &&
215  "Decremented past the beginning of region to repair.");
216 
217  MachineInstr *SlotMI = ListI->getInstr();
218  MachineInstr *MI = (MBBI != MBB->end() && !pastStart) ? &*MBBI : nullptr;
219  bool MBBIAtBegin = MBBI == Begin && (!includeStart || pastStart);
220 
221  if (SlotMI == MI && !MBBIAtBegin) {
222  --ListI;
223  if (MBBI != Begin)
224  --MBBI;
225  else
226  pastStart = true;
227  } else if (MI && mi2iMap.find(MI) == mi2iMap.end()) {
228  if (MBBI != Begin)
229  --MBBI;
230  else
231  pastStart = true;
232  } else {
233  --ListI;
234  if (SlotMI)
236  }
237  }
238 
239  // In theory this could be combined with the previous loop, but it is tricky
240  // to update the IndexList while we are iterating it.
241  for (MachineBasicBlock::iterator I = End; I != Begin;) {
242  --I;
243  MachineInstr &MI = *I;
244  if (!MI.isDebugOrPseudoInstr() && mi2iMap.find(&MI) == mi2iMap.end())
246  }
247 }
248 
249 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
251  for (const IndexListEntry &ILE : indexList) {
252  dbgs() << ILE.getIndex() << " ";
253 
254  if (ILE.getInstr()) {
255  dbgs() << *ILE.getInstr();
256  } else {
257  dbgs() << "\n";
258  }
259  }
260 
261  for (unsigned i = 0, e = MBBRanges.size(); i != e; ++i)
262  dbgs() << "%bb." << i << "\t[" << MBBRanges[i].first << ';'
263  << MBBRanges[i].second << ")\n";
264 }
265 #endif
266 
267 // Print a SlotIndex to a raw_ostream.
268 void SlotIndex::print(raw_ostream &os) const {
269  if (isValid())
270  os << listEntry()->getIndex() << "Berd"[getSlot()];
271  else
272  os << "invalid";
273 }
274 
275 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
276 // Dump a SlotIndex to stderr.
278  print(dbgs());
279  dbgs() << "\n";
280 }
281 #endif
i
i
Definition: README.txt:29
llvm::iplist_impl::clear
void clear()
Definition: ilist.h:309
llvm::SlotIndex::dump
void dump() const
Dump this index to stderr.
Definition: SlotIndexes.cpp:277
MI
IRTranslator LLVM IR MI
Definition: IRTranslator.cpp:103
LLVM_DUMP_METHOD
#define LLVM_DUMP_METHOD
Mark debug helper function definitions like dump() that should not be stripped from debug builds.
Definition: Compiler.h:491
llvm::SlotIndexes::releaseMemory
void releaseMemory() override
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memo...
Definition: SlotIndexes.cpp:42
llvm
---------------------— PointerInfo ------------------------------------—
Definition: AllocatorList.h:23
llvm::BumpPtrAllocatorImpl::Reset
void Reset()
Deallocate all but the current slab and reset the current pointer to the beginning of it,...
Definition: Allocator.h:125
llvm::SlotIndex::InstrDist
@ InstrDist
The default distance between instructions as returned by distance().
Definition: SlotIndexes.h:137
llvm::iplist_impl::push_back
void push_back(pointer val)
Definition: ilist.h:313
llvm::SlotIndex::isValid
bool isValid() const
Returns true if this is a valid index.
Definition: SlotIndexes.h:151
llvm::SlotIndexes::~SlotIndexes
~SlotIndexes() override
Definition: SlotIndexes.cpp:27
llvm::IndexListEntry::setInstr
void setInstr(MachineInstr *mi)
Definition: SlotIndexes.h:54
llvm::iplist_impl::clearAndLeakNodesUnsafely
void clearAndLeakNodesUnsafely()
Remove all nodes from the list like clear(), but do not call removeNodeFromList() or deleteNode().
Definition: ilist.h:280
llvm::IndexListEntry::getInstr
MachineInstr * getInstr() const
Definition: SlotIndexes.h:53
Statistic.h
llvm::MachineFunctionPass
MachineFunctionPass - This class adapts the FunctionPass interface to allow convenient creation of pa...
Definition: MachineFunctionPass.h:30
llvm::DenseMapBase::erase
bool erase(const KeyT &Val)
Definition: DenseMap.h:302
llvm::MachineFunction::getNumBlockIDs
unsigned getNumBlockIDs() const
getNumBlockIDs - Return the number of MBB ID's allocated.
Definition: MachineFunction.h:753
llvm::DenseMapIterator
Definition: DenseMap.h:56
llvm::SlotIndexes::repairIndexesInRange
void repairIndexesInRange(MachineBasicBlock *MBB, MachineBasicBlock::iterator Begin, MachineBasicBlock::iterator End)
Repair indexes after adding and removing instructions.
Definition: SlotIndexes.cpp:179
llvm::SlotIndexes::getMBBEndIdx
SlotIndex getMBBEndIdx(unsigned Num) const
Returns the last index in the given basic block number.
Definition: SlotIndexes.h:476
llvm::initializeSlotIndexesPass
void initializeSlotIndexesPass(PassRegistry &)
llvm::MachineFunctionPass::getAnalysisUsage
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - Subclasses that override getAnalysisUsage must call this.
Definition: MachineFunctionPass.cpp:102
LLVM_DEBUG
#define LLVM_DEBUG(X)
Definition: Debug.h:101
DEBUG_TYPE
#define DEBUG_TYPE
Definition: SlotIndexes.cpp:19
llvm::dbgs
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:163
INITIALIZE_PASS
INITIALIZE_PASS(SlotIndexes, DEBUG_TYPE, "Slot index numbering", false, false) STATISTIC(NumLocalRenum
llvm::SlotIndexes::hasIndex
bool hasIndex(const MachineInstr &instr) const
Returns true if the given machine instr is mapped to an index, otherwise returns false.
Definition: SlotIndexes.h:380
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static PassRegistry * getPassRegistry()
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Definition: PassRegistry.cpp:31
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Definition: STLExtras.h:1274
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Represent the analysis usage information of a pass.
Definition: PassAnalysisSupport.h:47
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unsigned size() const
Definition: MachineFunction.h:818
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llvm::raw_ostream
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:53
llvm::SlotIndexes::getInstructionIndex
SlotIndex getInstructionIndex(const MachineInstr &MI, bool IgnoreBundle=false) const
Returns the base index for the given instruction.
Definition: SlotIndexes.h:385
llvm::IndexListEntry
This class represents an entry in the slot index list held in the SlotIndexes pass.
Definition: SlotIndexes.h:46
llvm::SlotIndexes::dump
void dump() const
Dump the indexes.
Definition: SlotIndexes.cpp:250
llvm::SlotIndexes
SlotIndexes pass.
Definition: SlotIndexes.h:314
llvm::SlotIndexes::removeSingleMachineInstrFromMaps
void removeSingleMachineInstrFromMaps(MachineInstr &MI)
Removes a single machine instruction MI from the mapping.
Definition: SlotIndexes.cpp:131
llvm::SlotIndex
SlotIndex - An opaque wrapper around machine indexes.
Definition: SlotIndexes.h:83
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Definition: MachineBasicBlock.h:95
llvm::SlotIndexes::insertMachineInstrInMaps
SlotIndex insertMachineInstrInMaps(MachineInstr &MI, bool Late=false)
Insert the given machine instruction into the mapping.
Definition: SlotIndexes.h:535
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SlotIndex getMBBStartIdx(unsigned Num) const
Returns the first index in the given basic block number.
Definition: SlotIndexes.h:466
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Definition: DenseMap.h:111
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Definition: MachineInstr.h:64
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Print this index to the given raw_ostream.
Definition: SlotIndexes.cpp:268
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Definition: AArch64SLSHardening.cpp:74
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Definition: DenseMap.h:83
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Definition: SlotIndexes.cpp:35
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Definition: SlotIndexes.h:348
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Definition: SlotIndexes.cpp:23
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Definition: SlotIndexes.cpp:50
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Definition: SlotIndexes.cpp:115
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