LLVM  14.0.0git
JITLink.cpp
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1 //===------------- JITLink.cpp - Core Run-time JIT linker APIs ------------===//
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 
14 #include "llvm/Support/Format.h"
18 
19 using namespace llvm;
20 using namespace llvm::object;
21 
22 #define DEBUG_TYPE "jitlink"
23 
24 namespace {
25 
26 enum JITLinkErrorCode { GenericJITLinkError = 1 };
27 
28 // FIXME: This class is only here to support the transition to llvm::Error. It
29 // will be removed once this transition is complete. Clients should prefer to
30 // deal with the Error value directly, rather than converting to error_code.
31 class JITLinkerErrorCategory : public std::error_category {
32 public:
33  const char *name() const noexcept override { return "runtimedyld"; }
34 
35  std::string message(int Condition) const override {
36  switch (static_cast<JITLinkErrorCode>(Condition)) {
37  case GenericJITLinkError:
38  return "Generic JITLink error";
39  }
40  llvm_unreachable("Unrecognized JITLinkErrorCode");
41  }
42 };
43 
44 static ManagedStatic<JITLinkerErrorCategory> JITLinkerErrorCategory;
45 
46 } // namespace
47 
48 namespace llvm {
49 namespace jitlink {
50 
51 char JITLinkError::ID = 0;
52 
53 void JITLinkError::log(raw_ostream &OS) const { OS << ErrMsg; }
54 
55 std::error_code JITLinkError::convertToErrorCode() const {
56  return std::error_code(GenericJITLinkError, *JITLinkerErrorCategory);
57 }
58 
60  switch (K) {
61  case Edge::Invalid:
62  return "INVALID RELOCATION";
63  case Edge::KeepAlive:
64  return "Keep-Alive";
65  default:
66  return "<Unrecognized edge kind>";
67  }
68 }
69 
70 const char *getLinkageName(Linkage L) {
71  switch (L) {
72  case Linkage::Strong:
73  return "strong";
74  case Linkage::Weak:
75  return "weak";
76  }
77  llvm_unreachable("Unrecognized llvm.jitlink.Linkage enum");
78 }
79 
80 const char *getScopeName(Scope S) {
81  switch (S) {
82  case Scope::Default:
83  return "default";
84  case Scope::Hidden:
85  return "hidden";
86  case Scope::Local:
87  return "local";
88  }
89  llvm_unreachable("Unrecognized llvm.jitlink.Scope enum");
90 }
91 
93  return OS << formatv("{0:x16}", B.getAddress()) << " -- "
94  << formatv("{0:x8}", B.getAddress() + B.getSize()) << ": "
95  << "size = " << formatv("{0:x8}", B.getSize()) << ", "
96  << (B.isZeroFill() ? "zero-fill" : "content")
97  << ", align = " << B.getAlignment()
98  << ", align-ofs = " << B.getAlignmentOffset()
99  << ", section = " << B.getSection().getName();
100 }
101 
103  OS << formatv("{0:x16}", Sym.getAddress()) << " ("
104  << (Sym.isDefined() ? "block" : "addressable") << " + "
105  << formatv("{0:x8}", Sym.getOffset())
106  << "): size: " << formatv("{0:x8}", Sym.getSize())
107  << ", linkage: " << formatv("{0:6}", getLinkageName(Sym.getLinkage()))
108  << ", scope: " << formatv("{0:8}", getScopeName(Sym.getScope())) << ", "
109  << (Sym.isLive() ? "live" : "dead") << " - "
110  << (Sym.hasName() ? Sym.getName() : "<anonymous symbol>");
111  return OS;
112 }
113 
114 void printEdge(raw_ostream &OS, const Block &B, const Edge &E,
115  StringRef EdgeKindName) {
116  OS << "edge@" << formatv("{0:x16}", B.getAddress() + E.getOffset()) << ": "
117  << formatv("{0:x16}", B.getAddress()) << " + "
118  << formatv("{0:x}", E.getOffset()) << " -- " << EdgeKindName << " -> ";
119 
120  auto &TargetSym = E.getTarget();
121  if (TargetSym.hasName())
122  OS << TargetSym.getName();
123  else {
124  auto &TargetBlock = TargetSym.getBlock();
125  auto &TargetSec = TargetBlock.getSection();
126  JITTargetAddress SecAddress = ~JITTargetAddress(0);
127  for (auto *B : TargetSec.blocks())
128  if (B->getAddress() < SecAddress)
129  SecAddress = B->getAddress();
130 
131  JITTargetAddress SecDelta = TargetSym.getAddress() - SecAddress;
132  OS << formatv("{0:x16}", TargetSym.getAddress()) << " (section "
133  << TargetSec.getName();
134  if (SecDelta)
135  OS << " + " << formatv("{0:x}", SecDelta);
136  OS << " / block " << formatv("{0:x16}", TargetBlock.getAddress());
137  if (TargetSym.getOffset())
138  OS << " + " << formatv("{0:x}", TargetSym.getOffset());
139  OS << ")";
140  }
141 
142  if (E.getAddend() != 0)
143  OS << " + " << E.getAddend();
144 }
145 
146 Section::~Section() {
147  for (auto *Sym : Symbols)
148  Sym->~Symbol();
149  for (auto *B : Blocks)
150  B->~Block();
151 }
152 
153 Block &LinkGraph::splitBlock(Block &B, size_t SplitIndex,
154  SplitBlockCache *Cache) {
155 
156  assert(SplitIndex > 0 && "splitBlock can not be called with SplitIndex == 0");
157 
158  // If the split point covers all of B then just return B.
159  if (SplitIndex == B.getSize())
160  return B;
161 
162  assert(SplitIndex < B.getSize() && "SplitIndex out of range");
163 
164  // Create the new block covering [ 0, SplitIndex ).
165  auto &NewBlock =
166  B.isZeroFill()
167  ? createZeroFillBlock(B.getSection(), SplitIndex, B.getAddress(),
168  B.getAlignment(), B.getAlignmentOffset())
169  : createContentBlock(
170  B.getSection(), B.getContent().slice(0, SplitIndex),
171  B.getAddress(), B.getAlignment(), B.getAlignmentOffset());
172 
173  // Modify B to cover [ SplitIndex, B.size() ).
174  B.setAddress(B.getAddress() + SplitIndex);
175  B.setContent(B.getContent().slice(SplitIndex));
176  B.setAlignmentOffset((B.getAlignmentOffset() + SplitIndex) %
177  B.getAlignment());
178 
179  // Handle edge transfer/update.
180  {
181  // Copy edges to NewBlock (recording their iterators so that we can remove
182  // them from B), and update of Edges remaining on B.
183  std::vector<Block::edge_iterator> EdgesToRemove;
184  for (auto I = B.edges().begin(); I != B.edges().end();) {
185  if (I->getOffset() < SplitIndex) {
186  NewBlock.addEdge(*I);
187  I = B.removeEdge(I);
188  } else {
189  I->setOffset(I->getOffset() - SplitIndex);
190  ++I;
191  }
192  }
193  }
194 
195  // Handle symbol transfer/update.
196  {
197  // Initialize the symbols cache if necessary.
198  SplitBlockCache LocalBlockSymbolsCache;
199  if (!Cache)
200  Cache = &LocalBlockSymbolsCache;
201  if (*Cache == None) {
202  *Cache = SplitBlockCache::value_type();
203  for (auto *Sym : B.getSection().symbols())
204  if (&Sym->getBlock() == &B)
205  (*Cache)->push_back(Sym);
206 
207  llvm::sort(**Cache, [](const Symbol *LHS, const Symbol *RHS) {
208  return LHS->getOffset() > RHS->getOffset();
209  });
210  }
211  auto &BlockSymbols = **Cache;
212 
213  // Transfer all symbols with offset less than SplitIndex to NewBlock.
214  while (!BlockSymbols.empty() &&
215  BlockSymbols.back()->getOffset() < SplitIndex) {
216  BlockSymbols.back()->setBlock(NewBlock);
217  BlockSymbols.pop_back();
218  }
219 
220  // Update offsets for all remaining symbols in B.
221  for (auto *Sym : BlockSymbols)
222  Sym->setOffset(Sym->getOffset() - SplitIndex);
223  }
224 
225  return NewBlock;
226 }
227 
230 
231  // Map from blocks to the symbols pointing at them.
232  for (auto *Sym : defined_symbols())
233  BlockSymbols[&Sym->getBlock()].push_back(Sym);
234 
235  // For each block, sort its symbols by something approximating
236  // relevance.
237  for (auto &KV : BlockSymbols)
238  llvm::sort(KV.second, [](const Symbol *LHS, const Symbol *RHS) {
239  if (LHS->getOffset() != RHS->getOffset())
240  return LHS->getOffset() < RHS->getOffset();
241  if (LHS->getLinkage() != RHS->getLinkage())
242  return LHS->getLinkage() < RHS->getLinkage();
243  if (LHS->getScope() != RHS->getScope())
244  return LHS->getScope() < RHS->getScope();
245  if (LHS->hasName()) {
246  if (!RHS->hasName())
247  return true;
248  return LHS->getName() < RHS->getName();
249  }
250  return false;
251  });
252 
253  for (auto &Sec : sections()) {
254  OS << "section " << Sec.getName() << ":\n\n";
255 
256  std::vector<Block *> SortedBlocks;
257  llvm::copy(Sec.blocks(), std::back_inserter(SortedBlocks));
258  llvm::sort(SortedBlocks, [](const Block *LHS, const Block *RHS) {
259  return LHS->getAddress() < RHS->getAddress();
260  });
261 
262  for (auto *B : SortedBlocks) {
263  OS << " block " << formatv("{0:x16}", B->getAddress())
264  << " size = " << formatv("{0:x8}", B->getSize())
265  << ", align = " << B->getAlignment()
266  << ", alignment-offset = " << B->getAlignmentOffset();
267  if (B->isZeroFill())
268  OS << ", zero-fill";
269  OS << "\n";
270 
271  auto BlockSymsI = BlockSymbols.find(B);
272  if (BlockSymsI != BlockSymbols.end()) {
273  OS << " symbols:\n";
274  auto &Syms = BlockSymsI->second;
275  for (auto *Sym : Syms)
276  OS << " " << *Sym << "\n";
277  } else
278  OS << " no symbols\n";
279 
280  if (!B->edges_empty()) {
281  OS << " edges:\n";
282  std::vector<Edge> SortedEdges;
283  llvm::copy(B->edges(), std::back_inserter(SortedEdges));
284  llvm::sort(SortedEdges, [](const Edge &LHS, const Edge &RHS) {
285  return LHS.getOffset() < RHS.getOffset();
286  });
287  for (auto &E : SortedEdges) {
288  OS << " " << formatv("{0:x16}", B->getFixupAddress(E))
289  << " (block + " << formatv("{0:x8}", E.getOffset())
290  << "), addend = ";
291  if (E.getAddend() >= 0)
292  OS << formatv("+{0:x8}", E.getAddend());
293  else
294  OS << formatv("-{0:x8}", -E.getAddend());
295  OS << ", kind = " << getEdgeKindName(E.getKind()) << ", target = ";
296  if (E.getTarget().hasName())
297  OS << E.getTarget().getName();
298  else
299  OS << "addressable@"
300  << formatv("{0:x16}", E.getTarget().getAddress()) << "+"
301  << formatv("{0:x8}", E.getTarget().getOffset());
302  OS << "\n";
303  }
304  } else
305  OS << " no edges\n";
306  OS << "\n";
307  }
308  }
309 
310  OS << "Absolute symbols:\n";
311  if (!llvm::empty(absolute_symbols())) {
312  for (auto *Sym : absolute_symbols())
313  OS << " " << format("0x%016" PRIx64, Sym->getAddress()) << ": " << *Sym
314  << "\n";
315  } else
316  OS << " none\n";
317 
318  OS << "\nExternal symbols:\n";
319  if (!llvm::empty(external_symbols())) {
320  for (auto *Sym : external_symbols())
321  OS << " " << format("0x%016" PRIx64, Sym->getAddress()) << ": " << *Sym
322  << "\n";
323  } else
324  OS << " none\n";
325 }
326 
328  switch (LF) {
329  case SymbolLookupFlags::RequiredSymbol:
330  return OS << "RequiredSymbol";
331  case SymbolLookupFlags::WeaklyReferencedSymbol:
332  return OS << "WeaklyReferencedSymbol";
333  }
334  llvm_unreachable("Unrecognized lookup flags");
335 }
336 
337 void JITLinkAsyncLookupContinuation::anchor() {}
338 
339 JITLinkContext::~JITLinkContext() {}
340 
341 bool JITLinkContext::shouldAddDefaultTargetPasses(const Triple &TT) const {
342  return true;
343 }
344 
345 LinkGraphPassFunction JITLinkContext::getMarkLivePass(const Triple &TT) const {
346  return LinkGraphPassFunction();
347 }
348 
349 Error JITLinkContext::modifyPassConfig(LinkGraph &G,
350  PassConfiguration &Config) {
351  return Error::success();
352 }
353 
355  for (auto *Sym : G.defined_symbols())
356  Sym->setLive(true);
357  return Error::success();
358 }
359 
361  const Edge &E) {
362  std::string ErrMsg;
363  {
364  raw_string_ostream ErrStream(ErrMsg);
365  Section &Sec = B.getSection();
366  ErrStream << "In graph " << G.getName() << ", section " << Sec.getName()
367  << ": relocation target ";
368  if (E.getTarget().hasName())
369  ErrStream << "\"" << E.getTarget().getName() << "\" ";
370  ErrStream << "at address " << formatv("{0:x}", E.getTarget().getAddress());
371  ErrStream << " is out of range of " << G.getEdgeKindName(E.getKind())
372  << " fixup at " << formatv("{0:x}", B.getFixupAddress(E)) << " (";
373 
374  Symbol *BestSymbolForBlock = nullptr;
375  for (auto *Sym : Sec.symbols())
376  if (&Sym->getBlock() == &B && Sym->hasName() && Sym->getOffset() == 0 &&
377  (!BestSymbolForBlock ||
378  Sym->getScope() < BestSymbolForBlock->getScope() ||
379  Sym->getLinkage() < BestSymbolForBlock->getLinkage()))
380  BestSymbolForBlock = Sym;
381 
382  if (BestSymbolForBlock)
383  ErrStream << BestSymbolForBlock->getName() << ", ";
384  else
385  ErrStream << "<anonymous block> @ ";
386 
387  ErrStream << formatv("{0:x}", B.getAddress()) << " + "
388  << formatv("{0:x}", E.getOffset()) << ")";
389  }
390  return make_error<JITLinkError>(std::move(ErrMsg));
391 }
392 
395  auto Magic = identify_magic(ObjectBuffer.getBuffer());
396  switch (Magic) {
398  return createLinkGraphFromMachOObject(ObjectBuffer);
400  return createLinkGraphFromELFObject(ObjectBuffer);
401  default:
402  return make_error<JITLinkError>("Unsupported file format");
403  };
404 }
405 
406 void link(std::unique_ptr<LinkGraph> G, std::unique_ptr<JITLinkContext> Ctx) {
407  switch (G->getTargetTriple().getObjectFormat()) {
408  case Triple::MachO:
409  return link_MachO(std::move(G), std::move(Ctx));
410  case Triple::ELF:
411  return link_ELF(std::move(G), std::move(Ctx));
412  default:
413  Ctx->notifyFailed(make_error<JITLinkError>("Unsupported object format"));
414  };
415 }
416 
417 } // end namespace jitlink
418 } // end namespace llvm
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