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  auto *Sym = BlockSymbols.back();
217  // If the symbol extends beyond the split, update the size to be within
218  // the new block.
219  if (Sym->getOffset() + Sym->getSize() > SplitIndex)
220  Sym->setSize(SplitIndex - Sym->getOffset());
221  Sym->setBlock(NewBlock);
222  BlockSymbols.pop_back();
223  }
224 
225  // Update offsets for all remaining symbols in B.
226  for (auto *Sym : BlockSymbols)
227  Sym->setOffset(Sym->getOffset() - SplitIndex);
228  }
229 
230  return NewBlock;
231 }
232 
235 
236  // Map from blocks to the symbols pointing at them.
237  for (auto *Sym : defined_symbols())
238  BlockSymbols[&Sym->getBlock()].push_back(Sym);
239 
240  // For each block, sort its symbols by something approximating
241  // relevance.
242  for (auto &KV : BlockSymbols)
243  llvm::sort(KV.second, [](const Symbol *LHS, const Symbol *RHS) {
244  if (LHS->getOffset() != RHS->getOffset())
245  return LHS->getOffset() < RHS->getOffset();
246  if (LHS->getLinkage() != RHS->getLinkage())
247  return LHS->getLinkage() < RHS->getLinkage();
248  if (LHS->getScope() != RHS->getScope())
249  return LHS->getScope() < RHS->getScope();
250  if (LHS->hasName()) {
251  if (!RHS->hasName())
252  return true;
253  return LHS->getName() < RHS->getName();
254  }
255  return false;
256  });
257 
258  for (auto &Sec : sections()) {
259  OS << "section " << Sec.getName() << ":\n\n";
260 
261  std::vector<Block *> SortedBlocks;
262  llvm::copy(Sec.blocks(), std::back_inserter(SortedBlocks));
263  llvm::sort(SortedBlocks, [](const Block *LHS, const Block *RHS) {
264  return LHS->getAddress() < RHS->getAddress();
265  });
266 
267  for (auto *B : SortedBlocks) {
268  OS << " block " << formatv("{0:x16}", B->getAddress())
269  << " size = " << formatv("{0:x8}", B->getSize())
270  << ", align = " << B->getAlignment()
271  << ", alignment-offset = " << B->getAlignmentOffset();
272  if (B->isZeroFill())
273  OS << ", zero-fill";
274  OS << "\n";
275 
276  auto BlockSymsI = BlockSymbols.find(B);
277  if (BlockSymsI != BlockSymbols.end()) {
278  OS << " symbols:\n";
279  auto &Syms = BlockSymsI->second;
280  for (auto *Sym : Syms)
281  OS << " " << *Sym << "\n";
282  } else
283  OS << " no symbols\n";
284 
285  if (!B->edges_empty()) {
286  OS << " edges:\n";
287  std::vector<Edge> SortedEdges;
288  llvm::copy(B->edges(), std::back_inserter(SortedEdges));
289  llvm::sort(SortedEdges, [](const Edge &LHS, const Edge &RHS) {
290  return LHS.getOffset() < RHS.getOffset();
291  });
292  for (auto &E : SortedEdges) {
293  OS << " " << formatv("{0:x16}", B->getFixupAddress(E))
294  << " (block + " << formatv("{0:x8}", E.getOffset())
295  << "), addend = ";
296  if (E.getAddend() >= 0)
297  OS << formatv("+{0:x8}", E.getAddend());
298  else
299  OS << formatv("-{0:x8}", -E.getAddend());
300  OS << ", kind = " << getEdgeKindName(E.getKind()) << ", target = ";
301  if (E.getTarget().hasName())
302  OS << E.getTarget().getName();
303  else
304  OS << "addressable@"
305  << formatv("{0:x16}", E.getTarget().getAddress()) << "+"
306  << formatv("{0:x8}", E.getTarget().getOffset());
307  OS << "\n";
308  }
309  } else
310  OS << " no edges\n";
311  OS << "\n";
312  }
313  }
314 
315  OS << "Absolute symbols:\n";
316  if (!llvm::empty(absolute_symbols())) {
317  for (auto *Sym : absolute_symbols())
318  OS << " " << format("0x%016" PRIx64, Sym->getAddress()) << ": " << *Sym
319  << "\n";
320  } else
321  OS << " none\n";
322 
323  OS << "\nExternal symbols:\n";
324  if (!llvm::empty(external_symbols())) {
325  for (auto *Sym : external_symbols())
326  OS << " " << format("0x%016" PRIx64, Sym->getAddress()) << ": " << *Sym
327  << "\n";
328  } else
329  OS << " none\n";
330 }
331 
333  switch (LF) {
334  case SymbolLookupFlags::RequiredSymbol:
335  return OS << "RequiredSymbol";
336  case SymbolLookupFlags::WeaklyReferencedSymbol:
337  return OS << "WeaklyReferencedSymbol";
338  }
339  llvm_unreachable("Unrecognized lookup flags");
340 }
341 
342 void JITLinkAsyncLookupContinuation::anchor() {}
343 
344 JITLinkContext::~JITLinkContext() {}
345 
346 bool JITLinkContext::shouldAddDefaultTargetPasses(const Triple &TT) const {
347  return true;
348 }
349 
350 LinkGraphPassFunction JITLinkContext::getMarkLivePass(const Triple &TT) const {
351  return LinkGraphPassFunction();
352 }
353 
354 Error JITLinkContext::modifyPassConfig(LinkGraph &G,
355  PassConfiguration &Config) {
356  return Error::success();
357 }
358 
360  for (auto *Sym : G.defined_symbols())
361  Sym->setLive(true);
362  return Error::success();
363 }
364 
366  const Edge &E) {
367  std::string ErrMsg;
368  {
369  raw_string_ostream ErrStream(ErrMsg);
370  Section &Sec = B.getSection();
371  ErrStream << "In graph " << G.getName() << ", section " << Sec.getName()
372  << ": relocation target ";
373  if (E.getTarget().hasName())
374  ErrStream << "\"" << E.getTarget().getName() << "\" ";
375  ErrStream << "at address " << formatv("{0:x}", E.getTarget().getAddress());
376  ErrStream << " is out of range of " << G.getEdgeKindName(E.getKind())
377  << " fixup at " << formatv("{0:x}", B.getFixupAddress(E)) << " (";
378 
379  Symbol *BestSymbolForBlock = nullptr;
380  for (auto *Sym : Sec.symbols())
381  if (&Sym->getBlock() == &B && Sym->hasName() && Sym->getOffset() == 0 &&
382  (!BestSymbolForBlock ||
383  Sym->getScope() < BestSymbolForBlock->getScope() ||
384  Sym->getLinkage() < BestSymbolForBlock->getLinkage()))
385  BestSymbolForBlock = Sym;
386 
387  if (BestSymbolForBlock)
388  ErrStream << BestSymbolForBlock->getName() << ", ";
389  else
390  ErrStream << "<anonymous block> @ ";
391 
392  ErrStream << formatv("{0:x}", B.getAddress()) << " + "
393  << formatv("{0:x}", E.getOffset()) << ")";
394  }
395  return make_error<JITLinkError>(std::move(ErrMsg));
396 }
397 
400  auto Magic = identify_magic(ObjectBuffer.getBuffer());
401  switch (Magic) {
403  return createLinkGraphFromMachOObject(ObjectBuffer);
405  return createLinkGraphFromELFObject(ObjectBuffer);
406  default:
407  return make_error<JITLinkError>("Unsupported file format");
408  };
409 }
410 
411 void link(std::unique_ptr<LinkGraph> G, std::unique_ptr<JITLinkContext> Ctx) {
412  switch (G->getTargetTriple().getObjectFormat()) {
413  case Triple::MachO:
414  return link_MachO(std::move(G), std::move(Ctx));
415  case Triple::ELF:
416  return link_ELF(std::move(G), std::move(Ctx));
417  default:
418  Ctx->notifyFailed(make_error<JITLinkError>("Unsupported object format"));
419  };
420 }
421 
422 } // end namespace jitlink
423 } // end namespace llvm
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