1 //===-- SlotIndexes.cpp - Slot Indexes Pass ------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 #include "llvm/CodeGen/SlotIndexes.h"
10 #include "llvm/ADT/Statistic.h"
11 #include "llvm/CodeGen/MachineFunction.h"
12 #include "llvm/Config/llvm-config.h"
13 #include "llvm/Support/Debug.h"
14 #include "llvm/Support/raw_ostream.h"
18 #define DEBUG_TYPE "slotindexes"
20 char SlotIndexes::ID = 0;
21 INITIALIZE_PASS(SlotIndexes, DEBUG_TYPE,
22 "Slot index numbering", false, false)
24 STATISTIC(NumLocalRenum, "Number of local renumberings");
26 void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
28 MachineFunctionPass::getAnalysisUsage(au);
31 void SlotIndexes::releaseMemory() {
39 bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
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
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.
54 // Check that the list contains only the sentinal.
55 assert(indexList.empty() && "Index list non-empty at initial numbering?");
56 assert(idx2MBBMap.empty() &&
57 "Index -> MBB mapping non-empty at initial numbering?");
58 assert(MBBRanges.empty() &&
59 "MBB -> Index mapping non-empty at initial numbering?");
60 assert(mi2iMap.empty() &&
61 "MachineInstr -> Index mapping non-empty at initial numbering?");
64 MBBRanges.resize(mf->getNumBlockIDs());
65 idx2MBBMap.reserve(mf->size());
67 indexList.push_back(createEntry(nullptr, index));
69 // Iterate over the function.
70 for (MachineBasicBlock &MBB : *mf) {
71 // Insert an index for the MBB start.
72 SlotIndex blockStartIndex(&indexList.back(), SlotIndex::Slot_Block);
74 for (MachineInstr &MI : MBB) {
75 if (MI.isDebugInstr())
78 // Insert a store index for the instr.
79 indexList.push_back(createEntry(&MI, index += SlotIndex::InstrDist));
81 // Save this base index in the maps.
82 mi2iMap.insert(std::make_pair(
83 &MI, SlotIndex(&indexList.back(), SlotIndex::Slot_Block)));
86 // We insert one blank instructions between basic blocks.
87 indexList.push_back(createEntry(nullptr, index += SlotIndex::InstrDist));
89 MBBRanges[MBB.getNumber()].first = blockStartIndex;
90 MBBRanges[MBB.getNumber()].second = SlotIndex(&indexList.back(),
91 SlotIndex::Slot_Block);
92 idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, &MBB));
95 // Sort the Idx2MBBMap
96 llvm::sort(idx2MBBMap, less_first());
98 LLVM_DEBUG(mf->print(dbgs(), this));
104 void SlotIndexes::removeMachineInstrFromMaps(MachineInstr &MI) {
105 assert(!MI.isBundledWithPred() &&
106 "Use removeSingleMachineInstrFromMaps() instread");
107 Mi2IndexMap::iterator mi2iItr = mi2iMap.find(&MI);
108 if (mi2iItr == mi2iMap.end())
111 SlotIndex MIIndex = mi2iItr->second;
112 IndexListEntry &MIEntry = *MIIndex.listEntry();
113 assert(MIEntry.getInstr() == &MI && "Instruction indexes broken.");
114 mi2iMap.erase(mi2iItr);
115 // FIXME: Eventually we want to actually delete these indexes.
116 MIEntry.setInstr(nullptr);
119 void SlotIndexes::removeSingleMachineInstrFromMaps(MachineInstr &MI) {
120 Mi2IndexMap::iterator mi2iItr = mi2iMap.find(&MI);
121 if (mi2iItr == mi2iMap.end())
124 SlotIndex MIIndex = mi2iItr->second;
125 IndexListEntry &MIEntry = *MIIndex.listEntry();
126 assert(MIEntry.getInstr() == &MI && "Instruction indexes broken.");
127 mi2iMap.erase(mi2iItr);
129 // When removing the first instruction of a bundle update mapping to next
131 if (MI.isBundledWithSucc()) {
132 // Only the first instruction of a bundle should have an index assigned.
133 assert(!MI.isBundledWithPred() && "Should have first bundle isntruction");
135 MachineBasicBlock::instr_iterator Next = std::next(MI.getIterator());
136 MachineInstr &NextMI = *Next;
137 MIEntry.setInstr(&NextMI);
138 mi2iMap.insert(std::make_pair(&NextMI, MIIndex));
141 // FIXME: Eventually we want to actually delete these indexes.
142 MIEntry.setInstr(nullptr);
146 // Renumber indexes locally after curItr was inserted, but failed to get a new
148 void SlotIndexes::renumberIndexes(IndexList::iterator curItr) {
149 // Number indexes with half the default spacing so we can catch up quickly.
150 const unsigned Space = SlotIndex::InstrDist/2;
151 static_assert((Space & 3) == 0, "InstrDist must be a multiple of 2*NUM");
153 IndexList::iterator startItr = std::prev(curItr);
154 unsigned index = startItr->getIndex();
156 curItr->setIndex(index += Space);
158 // If the next index is bigger, we have caught up.
159 } while (curItr != indexList.end() && curItr->getIndex() <= index);
161 LLVM_DEBUG(dbgs() << "\n*** Renumbered SlotIndexes " << startItr->getIndex()
162 << '-' << index << " ***\n");
166 // Repair indexes after adding and removing instructions.
167 void SlotIndexes::repairIndexesInRange(MachineBasicBlock *MBB,
168 MachineBasicBlock::iterator Begin,
169 MachineBasicBlock::iterator End) {
170 // FIXME: Is this really necessary? The only caller repairIntervalsForRange()
171 // does the same thing.
172 // Find anchor points, which are at the beginning/end of blocks or at
173 // instructions that already have indexes.
174 while (Begin != MBB->begin() && !hasIndex(*Begin))
176 while (End != MBB->end() && !hasIndex(*End))
179 bool includeStart = (Begin == MBB->begin());
182 startIdx = getMBBStartIdx(MBB);
184 startIdx = getInstructionIndex(*Begin);
187 if (End == MBB->end())
188 endIdx = getMBBEndIdx(MBB);
190 endIdx = getInstructionIndex(*End);
192 // FIXME: Conceptually, this code is implementing an iterator on MBB that
193 // optionally includes an additional position prior to MBB->begin(), indicated
194 // by the includeStart flag. This is done so that we can iterate MIs in a MBB
195 // in parallel with SlotIndexes, but there should be a better way to do this.
196 IndexList::iterator ListB = startIdx.listEntry()->getIterator();
197 IndexList::iterator ListI = endIdx.listEntry()->getIterator();
198 MachineBasicBlock::iterator MBBI = End;
199 bool pastStart = false;
200 while (ListI != ListB || MBBI != Begin || (includeStart && !pastStart)) {
201 assert(ListI->getIndex() >= startIdx.getIndex() &&
202 (includeStart || !pastStart) &&
203 "Decremented past the beginning of region to repair.");
205 MachineInstr *SlotMI = ListI->getInstr();
206 MachineInstr *MI = (MBBI != MBB->end() && !pastStart) ? &*MBBI : nullptr;
207 bool MBBIAtBegin = MBBI == Begin && (!includeStart || pastStart);
209 if (SlotMI == MI && !MBBIAtBegin) {
215 } else if (MI && mi2iMap.find(MI) == mi2iMap.end()) {
223 removeMachineInstrFromMaps(*SlotMI);
227 // In theory this could be combined with the previous loop, but it is tricky
228 // to update the IndexList while we are iterating it.
229 for (MachineBasicBlock::iterator I = End; I != Begin;) {
231 MachineInstr &MI = *I;
232 if (!MI.isDebugInstr() && mi2iMap.find(&MI) == mi2iMap.end())
233 insertMachineInstrInMaps(MI);
237 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
238 LLVM_DUMP_METHOD void SlotIndexes::dump() const {
239 for (IndexList::const_iterator itr = indexList.begin();
240 itr != indexList.end(); ++itr) {
241 dbgs() << itr->getIndex() << " ";
243 if (itr->getInstr()) {
244 dbgs() << *itr->getInstr();
250 for (unsigned i = 0, e = MBBRanges.size(); i != e; ++i)
251 dbgs() << "%bb." << i << "\t[" << MBBRanges[i].first << ';'
252 << MBBRanges[i].second << ")\n";
256 // Print a SlotIndex to a raw_ostream.
257 void SlotIndex::print(raw_ostream &os) const {
259 os << listEntry()->getIndex() << "Berd"[getSlot()];
264 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
265 // Dump a SlotIndex to stderr.
266 LLVM_DUMP_METHOD void SlotIndex::dump() const {