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
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/InitializePasses.h"
14#include "llvm/Support/Debug.h"
15#include "llvm/Support/raw_ostream.h"
16
17using namespace llvm;
18
19#define DEBUG_TYPE "slotindexes"
20
21char SlotIndexes::ID = 0;
22
23SlotIndexes::SlotIndexes() : MachineFunctionPass(ID) {
24 initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
25}
26
27SlotIndexes::~SlotIndexes() {
28 // The indexList's nodes are all allocated in the BumpPtrAllocator.
29 indexList.clearAndLeakNodesUnsafely();
30}
31
32INITIALIZE_PASS(SlotIndexes, DEBUG_TYPE,
33 "Slot index numbering", false, false)
34
35STATISTIC(NumLocalRenum, "Number of local renumberings");
36
37void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
38 au.setPreservesAll();
39 MachineFunctionPass::getAnalysisUsage(AU&: au);
40}
41
42void SlotIndexes::releaseMemory() {
43 mi2iMap.clear();
44 MBBRanges.clear();
45 idx2MBBMap.clear();
46 indexList.clear();
47 ileAllocator.Reset();
48}
49
50bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
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 sentinel.
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(N: mf->getNumBlockIDs());
76 idx2MBBMap.reserve(N: mf->size());
77
78 indexList.push_back(val: createEntry(mi: 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(val: createEntry(mi: &MI, index: index += SlotIndex::InstrDist));
91
92 // Save this base index in the maps.
93 mi2iMap.insert(KV: std::make_pair(
94 x: &MI, y: SlotIndex(&indexList.back(), SlotIndex::Slot_Block)));
95 }
96
97 // We insert one blank instructions between basic blocks.
98 indexList.push_back(val: createEntry(mi: nullptr, index: 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(Elt: IdxMBBPair(blockStartIndex, &MBB));
104 }
105
106 // Sort the Idx2MBBMap
107 llvm::sort(C&: idx2MBBMap, Comp: less_first());
108
109 LLVM_DEBUG(mf->print(dbgs(), this));
110
111 // And we're done!
112 return false;
113}
114
115void SlotIndexes::removeMachineInstrFromMaps(MachineInstr &MI,
116 bool AllowBundled) {
117 assert((AllowBundled || !MI.isBundledWithPred()) &&
118 "Use removeSingleMachineInstrFromMaps() instead");
119 Mi2IndexMap::iterator mi2iItr = mi2iMap.find(Val: &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(I: mi2iItr);
127 // FIXME: Eventually we want to actually delete these indexes.
128 MIEntry.setInstr(nullptr);
129}
130
131void SlotIndexes::removeSingleMachineInstrFromMaps(MachineInstr &MI) {
132 Mi2IndexMap::iterator mi2iItr = mi2iMap.find(Val: &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(I: 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(x: MI.getIterator());
148 MachineInstr &NextMI = *Next;
149 MIEntry.setInstr(&NextMI);
150 mi2iMap.insert(KV: std::make_pair(x: &NextMI, y&: 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.
160void 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(x: 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.
179void SlotIndexes::repairIndexesInRange(MachineBasicBlock *MBB,
180 MachineBasicBlock::iterator Begin,
181 MachineBasicBlock::iterator End) {
182 bool includeStart = (Begin == MBB->begin());
183 SlotIndex startIdx;
184 if (includeStart)
185 startIdx = getMBBStartIdx(mbb: MBB);
186 else
187 startIdx = getInstructionIndex(MI: *--Begin);
188
189 SlotIndex endIdx;
190 if (End == MBB->end())
191 endIdx = getMBBEndIdx(mbb: MBB);
192 else
193 endIdx = getInstructionIndex(MI: *End);
194
195 // FIXME: Conceptually, this code is implementing an iterator on MBB that
196 // optionally includes an additional position prior to MBB->begin(), indicated
197 // by the includeStart flag. This is done so that we can iterate MIs in a MBB
198 // in parallel with SlotIndexes, but there should be a better way to do this.
199 IndexList::iterator ListB = startIdx.listEntry()->getIterator();
200 IndexList::iterator ListI = endIdx.listEntry()->getIterator();
201 MachineBasicBlock::iterator MBBI = End;
202 bool pastStart = false;
203 while (ListI != ListB || MBBI != Begin || (includeStart && !pastStart)) {
204 assert(ListI->getIndex() >= startIdx.getIndex() &&
205 (includeStart || !pastStart) &&
206 "Decremented past the beginning of region to repair.");
207
208 MachineInstr *SlotMI = ListI->getInstr();
209 MachineInstr *MI = (MBBI != MBB->end() && !pastStart) ? &*MBBI : nullptr;
210 bool MBBIAtBegin = MBBI == Begin && (!includeStart || pastStart);
211
212 if (SlotMI == MI && !MBBIAtBegin) {
213 --ListI;
214 if (MBBI != Begin)
215 --MBBI;
216 else
217 pastStart = true;
218 } else if (MI && !mi2iMap.contains(Val: MI)) {
219 if (MBBI != Begin)
220 --MBBI;
221 else
222 pastStart = true;
223 } else {
224 --ListI;
225 if (SlotMI)
226 removeMachineInstrFromMaps(MI&: *SlotMI);
227 }
228 }
229
230 // In theory this could be combined with the previous loop, but it is tricky
231 // to update the IndexList while we are iterating it.
232 for (MachineBasicBlock::iterator I = End; I != Begin;) {
233 --I;
234 MachineInstr &MI = *I;
235 if (!MI.isDebugOrPseudoInstr() && !mi2iMap.contains(Val: &MI))
236 insertMachineInstrInMaps(MI);
237 }
238}
239
240void SlotIndexes::packIndexes() {
241 for (auto [Index, Entry] : enumerate(First&: indexList))
242 Entry.setIndex(Index * SlotIndex::InstrDist);
243}
244
245#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
246LLVM_DUMP_METHOD void SlotIndexes::dump() const {
247 for (const IndexListEntry &ILE : indexList) {
248 dbgs() << ILE.getIndex() << " ";
249
250 if (ILE.getInstr()) {
251 dbgs() << *ILE.getInstr();
252 } else {
253 dbgs() << "\n";
254 }
255 }
256
257 for (unsigned i = 0, e = MBBRanges.size(); i != e; ++i)
258 dbgs() << "%bb." << i << "\t[" << MBBRanges[i].first << ';'
259 << MBBRanges[i].second << ")\n";
260}
261#endif
262
263// Print a SlotIndex to a raw_ostream.
264void SlotIndex::print(raw_ostream &os) const {
265 if (isValid())
266 os << listEntry()->getIndex() << "Berd"[getSlot()];
267 else
268 os << "invalid";
269}
270
271#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
272// Dump a SlotIndex to stderr.
273LLVM_DUMP_METHOD void SlotIndex::dump() const {
274 print(os&: dbgs());
275 dbgs() << "\n";
276}
277#endif
278

source code of llvm/lib/CodeGen/SlotIndexes.cpp