1 //===------------ JITLink.h - JIT linker functionality ----------*- C++ -*-===//
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 // Contains generic JIT-linker types.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #ifndef LLVM_EXECUTIONENGINE_JITLINK_JITLINK_H
14 #define LLVM_EXECUTIONENGINE_JITLINK_JITLINK_H
15
16 #include "JITLinkMemoryManager.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/DenseSet.h"
19 #include "llvm/ADT/Optional.h"
20 #include "llvm/ADT/STLExtras.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/ExecutionEngine/JITSymbol.h"
23 #include "llvm/Support/Allocator.h"
24 #include "llvm/Support/Endian.h"
25 #include "llvm/Support/Error.h"
26 #include "llvm/Support/FormatVariadic.h"
27 #include "llvm/Support/MathExtras.h"
28 #include "llvm/Support/Memory.h"
29 #include "llvm/Support/MemoryBuffer.h"
30
31 #include <map>
32 #include <string>
33 #include <system_error>
34
35 namespace llvm {
36 namespace jitlink {
37
38 class LinkGraph;
39 class Symbol;
40 class Section;
41
42 /// Base class for errors originating in JIT linker, e.g. missing relocation
43 /// support.
44 class JITLinkError : public ErrorInfo<JITLinkError> {
45 public:
46 static char ID;
47
JITLinkError(Twine ErrMsg)48 JITLinkError(Twine ErrMsg) : ErrMsg(ErrMsg.str()) {}
49
50 void log(raw_ostream &OS) const override;
getErrorMessage()51 const std::string &getErrorMessage() const { return ErrMsg; }
52 std::error_code convertToErrorCode() const override;
53
54 private:
55 std::string ErrMsg;
56 };
57
58 /// Represents fixups and constraints in the LinkGraph.
59 class Edge {
60 public:
61 using Kind = uint8_t;
62
63 enum GenericEdgeKind : Kind {
64 Invalid, // Invalid edge value.
65 FirstKeepAlive, // Keeps target alive. Offset/addend zero.
66 KeepAlive = FirstKeepAlive, // Tag first edge kind that preserves liveness.
67 FirstRelocation // First architecture specific relocation.
68 };
69
70 using OffsetT = uint32_t;
71 using AddendT = int64_t;
72
Edge(Kind K,OffsetT Offset,Symbol & Target,AddendT Addend)73 Edge(Kind K, OffsetT Offset, Symbol &Target, AddendT Addend)
74 : Target(&Target), Offset(Offset), Addend(Addend), K(K) {}
75
getOffset()76 OffsetT getOffset() const { return Offset; }
setOffset(OffsetT Offset)77 void setOffset(OffsetT Offset) { this->Offset = Offset; }
getKind()78 Kind getKind() const { return K; }
setKind(Kind K)79 void setKind(Kind K) { this->K = K; }
isRelocation()80 bool isRelocation() const { return K >= FirstRelocation; }
getRelocation()81 Kind getRelocation() const {
82 assert(isRelocation() && "Not a relocation edge");
83 return K - FirstRelocation;
84 }
isKeepAlive()85 bool isKeepAlive() const { return K >= FirstKeepAlive; }
getTarget()86 Symbol &getTarget() const { return *Target; }
setTarget(Symbol & Target)87 void setTarget(Symbol &Target) { this->Target = &Target; }
getAddend()88 AddendT getAddend() const { return Addend; }
setAddend(AddendT Addend)89 void setAddend(AddendT Addend) { this->Addend = Addend; }
90
91 private:
92 Symbol *Target = nullptr;
93 OffsetT Offset = 0;
94 AddendT Addend = 0;
95 Kind K = 0;
96 };
97
98 /// Returns the string name of the given generic edge kind, or "unknown"
99 /// otherwise. Useful for debugging.
100 const char *getGenericEdgeKindName(Edge::Kind K);
101
102 /// Base class for Addressable entities (externals, absolutes, blocks).
103 class Addressable {
104 friend class LinkGraph;
105
106 protected:
Addressable(JITTargetAddress Address,bool IsDefined)107 Addressable(JITTargetAddress Address, bool IsDefined)
108 : Address(Address), IsDefined(IsDefined), IsAbsolute(false) {}
109
Addressable(JITTargetAddress Address)110 Addressable(JITTargetAddress Address)
111 : Address(Address), IsDefined(false), IsAbsolute(true) {
112 assert(!(IsDefined && IsAbsolute) &&
113 "Block cannot be both defined and absolute");
114 }
115
116 public:
117 Addressable(const Addressable &) = delete;
118 Addressable &operator=(const Addressable &) = default;
119 Addressable(Addressable &&) = delete;
120 Addressable &operator=(Addressable &&) = default;
121
getAddress()122 JITTargetAddress getAddress() const { return Address; }
setAddress(JITTargetAddress Address)123 void setAddress(JITTargetAddress Address) { this->Address = Address; }
124
125 /// Returns true if this is a defined addressable, in which case you
126 /// can downcast this to a Block.
isDefined()127 bool isDefined() const { return static_cast<bool>(IsDefined); }
isAbsolute()128 bool isAbsolute() const { return static_cast<bool>(IsAbsolute); }
129
130 private:
setAbsolute(bool IsAbsolute)131 void setAbsolute(bool IsAbsolute) {
132 assert(!IsDefined && "Cannot change the Absolute flag on a defined block");
133 this->IsAbsolute = IsAbsolute;
134 }
135
136 JITTargetAddress Address = 0;
137 uint64_t IsDefined : 1;
138 uint64_t IsAbsolute : 1;
139
140 protected:
141 // bitfields for Block, allocated here to improve packing.
142 uint64_t ContentMutable : 1;
143 uint64_t P2Align : 5;
144 uint64_t AlignmentOffset : 56;
145 };
146
147 using SectionOrdinal = unsigned;
148
149 /// An Addressable with content and edges.
150 class Block : public Addressable {
151 friend class LinkGraph;
152
153 private:
154 /// Create a zero-fill defined addressable.
Block(Section & Parent,JITTargetAddress Size,JITTargetAddress Address,uint64_t Alignment,uint64_t AlignmentOffset)155 Block(Section &Parent, JITTargetAddress Size, JITTargetAddress Address,
156 uint64_t Alignment, uint64_t AlignmentOffset)
157 : Addressable(Address, true), Parent(&Parent), Size(Size) {
158 assert(isPowerOf2_64(Alignment) && "Alignment must be power of 2");
159 assert(AlignmentOffset < Alignment &&
160 "Alignment offset cannot exceed alignment");
161 assert(AlignmentOffset <= MaxAlignmentOffset &&
162 "Alignment offset exceeds maximum");
163 ContentMutable = false;
164 P2Align = Alignment ? countTrailingZeros(Alignment) : 0;
165 this->AlignmentOffset = AlignmentOffset;
166 }
167
168 /// Create a defined addressable for the given content.
169 /// The Content is assumed to be non-writable, and will be copied when
170 /// mutations are required.
Block(Section & Parent,ArrayRef<char> Content,JITTargetAddress Address,uint64_t Alignment,uint64_t AlignmentOffset)171 Block(Section &Parent, ArrayRef<char> Content, JITTargetAddress Address,
172 uint64_t Alignment, uint64_t AlignmentOffset)
173 : Addressable(Address, true), Parent(&Parent), Data(Content.data()),
174 Size(Content.size()) {
175 assert(isPowerOf2_64(Alignment) && "Alignment must be power of 2");
176 assert(AlignmentOffset < Alignment &&
177 "Alignment offset cannot exceed alignment");
178 assert(AlignmentOffset <= MaxAlignmentOffset &&
179 "Alignment offset exceeds maximum");
180 ContentMutable = false;
181 P2Align = Alignment ? countTrailingZeros(Alignment) : 0;
182 this->AlignmentOffset = AlignmentOffset;
183 }
184
185 /// Create a defined addressable for the given content.
186 /// The content is assumed to be writable, and the caller is responsible
187 /// for ensuring that it lives for the duration of the Block's lifetime.
188 /// The standard way to achieve this is to allocate it on the Graph's
189 /// allocator.
Block(Section & Parent,MutableArrayRef<char> Content,JITTargetAddress Address,uint64_t Alignment,uint64_t AlignmentOffset)190 Block(Section &Parent, MutableArrayRef<char> Content,
191 JITTargetAddress Address, uint64_t Alignment, uint64_t AlignmentOffset)
192 : Addressable(Address, true), Parent(&Parent), Data(Content.data()),
193 Size(Content.size()) {
194 assert(isPowerOf2_64(Alignment) && "Alignment must be power of 2");
195 assert(AlignmentOffset < Alignment &&
196 "Alignment offset cannot exceed alignment");
197 assert(AlignmentOffset <= MaxAlignmentOffset &&
198 "Alignment offset exceeds maximum");
199 ContentMutable = true;
200 P2Align = Alignment ? countTrailingZeros(Alignment) : 0;
201 this->AlignmentOffset = AlignmentOffset;
202 }
203
204 public:
205 using EdgeVector = std::vector<Edge>;
206 using edge_iterator = EdgeVector::iterator;
207 using const_edge_iterator = EdgeVector::const_iterator;
208
209 Block(const Block &) = delete;
210 Block &operator=(const Block &) = delete;
211 Block(Block &&) = delete;
212 Block &operator=(Block &&) = delete;
213
214 /// Return the parent section for this block.
getSection()215 Section &getSection() const { return *Parent; }
216
217 /// Returns true if this is a zero-fill block.
218 ///
219 /// If true, getSize is callable but getContent is not (the content is
220 /// defined to be a sequence of zero bytes of length Size).
isZeroFill()221 bool isZeroFill() const { return !Data; }
222
223 /// Returns the size of this defined addressable.
getSize()224 size_t getSize() const { return Size; }
225
226 /// Get the content for this block. Block must not be a zero-fill block.
getContent()227 ArrayRef<char> getContent() const {
228 assert(Data && "Section does not contain content");
229 return ArrayRef<char>(Data, Size);
230 }
231
232 /// Set the content for this block.
233 /// Caller is responsible for ensuring the underlying bytes are not
234 /// deallocated while pointed to by this block.
setContent(ArrayRef<char> Content)235 void setContent(ArrayRef<char> Content) {
236 Data = Content.data();
237 Size = Content.size();
238 ContentMutable = false;
239 }
240
241 /// Get mutable content for this block.
242 ///
243 /// If this Block's content is not already mutable this will trigger a copy
244 /// of the existing immutable content to a new, mutable buffer allocated using
245 /// LinkGraph::allocateContent.
246 MutableArrayRef<char> getMutableContent(LinkGraph &G);
247
248 /// Get mutable content for this block.
249 ///
250 /// This block's content must already be mutable. It is a programmatic error
251 /// to call this on a block with immutable content -- consider using
252 /// getMutableContent instead.
getAlreadyMutableContent()253 MutableArrayRef<char> getAlreadyMutableContent() {
254 assert(ContentMutable && "Content is not mutable");
255 return MutableArrayRef<char>(const_cast<char *>(Data), Size);
256 }
257
258 /// Set mutable content for this block.
259 ///
260 /// The caller is responsible for ensuring that the memory pointed to by
261 /// MutableContent is not deallocated while pointed to by this block.
setMutableContent(MutableArrayRef<char> MutableContent)262 void setMutableContent(MutableArrayRef<char> MutableContent) {
263 Data = MutableContent.data();
264 Size = MutableContent.size();
265 ContentMutable = true;
266 }
267
268 /// Returns true if this block's content is mutable.
269 ///
270 /// This is primarily useful for asserting that a block is already in a
271 /// mutable state prior to modifying the content. E.g. when applying
272 /// fixups we expect the block to already be mutable as it should have been
273 /// copied to working memory.
isContentMutable()274 bool isContentMutable() const { return ContentMutable; }
275
276 /// Get the alignment for this content.
getAlignment()277 uint64_t getAlignment() const { return 1ull << P2Align; }
278
279 /// Set the alignment for this content.
setAlignment(uint64_t Alignment)280 void setAlignment(uint64_t Alignment) {
281 assert(isPowerOf2_64(Alignment) && "Alignment must be a power of two");
282 P2Align = Alignment ? countTrailingZeros(Alignment) : 0;
283 }
284
285 /// Get the alignment offset for this content.
getAlignmentOffset()286 uint64_t getAlignmentOffset() const { return AlignmentOffset; }
287
288 /// Set the alignment offset for this content.
setAlignmentOffset(uint64_t AlignmentOffset)289 void setAlignmentOffset(uint64_t AlignmentOffset) {
290 assert(AlignmentOffset < (1ull << P2Align) &&
291 "Alignment offset can't exceed alignment");
292 this->AlignmentOffset = AlignmentOffset;
293 }
294
295 /// Add an edge to this block.
addEdge(Edge::Kind K,Edge::OffsetT Offset,Symbol & Target,Edge::AddendT Addend)296 void addEdge(Edge::Kind K, Edge::OffsetT Offset, Symbol &Target,
297 Edge::AddendT Addend) {
298 Edges.push_back(Edge(K, Offset, Target, Addend));
299 }
300
301 /// Add an edge by copying an existing one. This is typically used when
302 /// moving edges between blocks.
addEdge(const Edge & E)303 void addEdge(const Edge &E) { Edges.push_back(E); }
304
305 /// Return the list of edges attached to this content.
edges()306 iterator_range<edge_iterator> edges() {
307 return make_range(Edges.begin(), Edges.end());
308 }
309
310 /// Returns the list of edges attached to this content.
edges()311 iterator_range<const_edge_iterator> edges() const {
312 return make_range(Edges.begin(), Edges.end());
313 }
314
315 /// Return the size of the edges list.
edges_size()316 size_t edges_size() const { return Edges.size(); }
317
318 /// Returns true if the list of edges is empty.
edges_empty()319 bool edges_empty() const { return Edges.empty(); }
320
321 /// Remove the edge pointed to by the given iterator.
322 /// Returns an iterator to the new next element.
removeEdge(edge_iterator I)323 edge_iterator removeEdge(edge_iterator I) { return Edges.erase(I); }
324
325 /// Returns the address of the fixup for the given edge, which is equal to
326 /// this block's address plus the edge's offset.
getFixupAddress(const Edge & E)327 JITTargetAddress getFixupAddress(const Edge &E) const {
328 return getAddress() + E.getOffset();
329 }
330
331 private:
332 static constexpr uint64_t MaxAlignmentOffset = (1ULL << 56) - 1;
333
setSection(Section & Parent)334 void setSection(Section &Parent) { this->Parent = &Parent; }
335
336 Section *Parent;
337 const char *Data = nullptr;
338 size_t Size = 0;
339 std::vector<Edge> Edges;
340 };
341
342 /// Describes symbol linkage. This can be used to make resolve definition
343 /// clashes.
344 enum class Linkage : uint8_t {
345 Strong,
346 Weak,
347 };
348
349 /// For errors and debugging output.
350 const char *getLinkageName(Linkage L);
351
352 /// Defines the scope in which this symbol should be visible:
353 /// Default -- Visible in the public interface of the linkage unit.
354 /// Hidden -- Visible within the linkage unit, but not exported from it.
355 /// Local -- Visible only within the LinkGraph.
356 enum class Scope : uint8_t {
357 Default,
358 Hidden,
359 Local
360 };
361
362 /// For debugging output.
363 const char *getScopeName(Scope S);
364
365 raw_ostream &operator<<(raw_ostream &OS, const Block &B);
366
367 /// Symbol representation.
368 ///
369 /// Symbols represent locations within Addressable objects.
370 /// They can be either Named or Anonymous.
371 /// Anonymous symbols have neither linkage nor visibility, and must point at
372 /// ContentBlocks.
373 /// Named symbols may be in one of four states:
374 /// - Null: Default initialized. Assignable, but otherwise unusable.
375 /// - Defined: Has both linkage and visibility and points to a ContentBlock
376 /// - Common: Has both linkage and visibility, points to a null Addressable.
377 /// - External: Has neither linkage nor visibility, points to an external
378 /// Addressable.
379 ///
380 class Symbol {
381 friend class LinkGraph;
382
383 private:
Symbol(Addressable & Base,JITTargetAddress Offset,StringRef Name,JITTargetAddress Size,Linkage L,Scope S,bool IsLive,bool IsCallable)384 Symbol(Addressable &Base, JITTargetAddress Offset, StringRef Name,
385 JITTargetAddress Size, Linkage L, Scope S, bool IsLive,
386 bool IsCallable)
387 : Name(Name), Base(&Base), Offset(Offset), Size(Size) {
388 assert(Offset <= MaxOffset && "Offset out of range");
389 setLinkage(L);
390 setScope(S);
391 setLive(IsLive);
392 setCallable(IsCallable);
393 }
394
constructCommon(void * SymStorage,Block & Base,StringRef Name,JITTargetAddress Size,Scope S,bool IsLive)395 static Symbol &constructCommon(void *SymStorage, Block &Base, StringRef Name,
396 JITTargetAddress Size, Scope S, bool IsLive) {
397 assert(SymStorage && "Storage cannot be null");
398 assert(!Name.empty() && "Common symbol name cannot be empty");
399 assert(Base.isDefined() &&
400 "Cannot create common symbol from undefined block");
401 assert(static_cast<Block &>(Base).getSize() == Size &&
402 "Common symbol size should match underlying block size");
403 auto *Sym = reinterpret_cast<Symbol *>(SymStorage);
404 new (Sym) Symbol(Base, 0, Name, Size, Linkage::Weak, S, IsLive, false);
405 return *Sym;
406 }
407
constructExternal(void * SymStorage,Addressable & Base,StringRef Name,JITTargetAddress Size,Linkage L)408 static Symbol &constructExternal(void *SymStorage, Addressable &Base,
409 StringRef Name, JITTargetAddress Size,
410 Linkage L) {
411 assert(SymStorage && "Storage cannot be null");
412 assert(!Base.isDefined() &&
413 "Cannot create external symbol from defined block");
414 assert(!Name.empty() && "External symbol name cannot be empty");
415 auto *Sym = reinterpret_cast<Symbol *>(SymStorage);
416 new (Sym) Symbol(Base, 0, Name, Size, L, Scope::Default, false, false);
417 return *Sym;
418 }
419
constructAbsolute(void * SymStorage,Addressable & Base,StringRef Name,JITTargetAddress Size,Linkage L,Scope S,bool IsLive)420 static Symbol &constructAbsolute(void *SymStorage, Addressable &Base,
421 StringRef Name, JITTargetAddress Size,
422 Linkage L, Scope S, bool IsLive) {
423 assert(SymStorage && "Storage cannot be null");
424 assert(!Base.isDefined() &&
425 "Cannot create absolute symbol from a defined block");
426 auto *Sym = reinterpret_cast<Symbol *>(SymStorage);
427 new (Sym) Symbol(Base, 0, Name, Size, L, S, IsLive, false);
428 return *Sym;
429 }
430
constructAnonDef(void * SymStorage,Block & Base,JITTargetAddress Offset,JITTargetAddress Size,bool IsCallable,bool IsLive)431 static Symbol &constructAnonDef(void *SymStorage, Block &Base,
432 JITTargetAddress Offset,
433 JITTargetAddress Size, bool IsCallable,
434 bool IsLive) {
435 assert(SymStorage && "Storage cannot be null");
436 assert((Offset + Size) <= Base.getSize() &&
437 "Symbol extends past end of block");
438 auto *Sym = reinterpret_cast<Symbol *>(SymStorage);
439 new (Sym) Symbol(Base, Offset, StringRef(), Size, Linkage::Strong,
440 Scope::Local, IsLive, IsCallable);
441 return *Sym;
442 }
443
constructNamedDef(void * SymStorage,Block & Base,JITTargetAddress Offset,StringRef Name,JITTargetAddress Size,Linkage L,Scope S,bool IsLive,bool IsCallable)444 static Symbol &constructNamedDef(void *SymStorage, Block &Base,
445 JITTargetAddress Offset, StringRef Name,
446 JITTargetAddress Size, Linkage L, Scope S,
447 bool IsLive, bool IsCallable) {
448 assert(SymStorage && "Storage cannot be null");
449 assert((Offset + Size) <= Base.getSize() &&
450 "Symbol extends past end of block");
451 assert(!Name.empty() && "Name cannot be empty");
452 auto *Sym = reinterpret_cast<Symbol *>(SymStorage);
453 new (Sym) Symbol(Base, Offset, Name, Size, L, S, IsLive, IsCallable);
454 return *Sym;
455 }
456
457 public:
458 /// Create a null Symbol. This allows Symbols to be default initialized for
459 /// use in containers (e.g. as map values). Null symbols are only useful for
460 /// assigning to.
461 Symbol() = default;
462
463 // Symbols are not movable or copyable.
464 Symbol(const Symbol &) = delete;
465 Symbol &operator=(const Symbol &) = delete;
466 Symbol(Symbol &&) = delete;
467 Symbol &operator=(Symbol &&) = delete;
468
469 /// Returns true if this symbol has a name.
hasName()470 bool hasName() const { return !Name.empty(); }
471
472 /// Returns the name of this symbol (empty if the symbol is anonymous).
getName()473 StringRef getName() const {
474 assert((!Name.empty() || getScope() == Scope::Local) &&
475 "Anonymous symbol has non-local scope");
476 return Name;
477 }
478
479 /// Rename this symbol. The client is responsible for updating scope and
480 /// linkage if this name-change requires it.
setName(StringRef Name)481 void setName(StringRef Name) { this->Name = Name; }
482
483 /// Returns true if this Symbol has content (potentially) defined within this
484 /// object file (i.e. is anything but an external or absolute symbol).
isDefined()485 bool isDefined() const {
486 assert(Base && "Attempt to access null symbol");
487 return Base->isDefined();
488 }
489
490 /// Returns true if this symbol is live (i.e. should be treated as a root for
491 /// dead stripping).
isLive()492 bool isLive() const {
493 assert(Base && "Attempting to access null symbol");
494 return IsLive;
495 }
496
497 /// Set this symbol's live bit.
setLive(bool IsLive)498 void setLive(bool IsLive) { this->IsLive = IsLive; }
499
500 /// Returns true is this symbol is callable.
isCallable()501 bool isCallable() const { return IsCallable; }
502
503 /// Set this symbol's callable bit.
setCallable(bool IsCallable)504 void setCallable(bool IsCallable) { this->IsCallable = IsCallable; }
505
506 /// Returns true if the underlying addressable is an unresolved external.
isExternal()507 bool isExternal() const {
508 assert(Base && "Attempt to access null symbol");
509 return !Base->isDefined() && !Base->isAbsolute();
510 }
511
512 /// Returns true if the underlying addressable is an absolute symbol.
isAbsolute()513 bool isAbsolute() const {
514 assert(Base && "Attempt to access null symbol");
515 return Base->isAbsolute();
516 }
517
518 /// Return the addressable that this symbol points to.
getAddressable()519 Addressable &getAddressable() {
520 assert(Base && "Cannot get underlying addressable for null symbol");
521 return *Base;
522 }
523
524 /// Return the addressable that thsi symbol points to.
getAddressable()525 const Addressable &getAddressable() const {
526 assert(Base && "Cannot get underlying addressable for null symbol");
527 return *Base;
528 }
529
530 /// Return the Block for this Symbol (Symbol must be defined).
getBlock()531 Block &getBlock() {
532 assert(Base && "Cannot get block for null symbol");
533 assert(Base->isDefined() && "Not a defined symbol");
534 return static_cast<Block &>(*Base);
535 }
536
537 /// Return the Block for this Symbol (Symbol must be defined).
getBlock()538 const Block &getBlock() const {
539 assert(Base && "Cannot get block for null symbol");
540 assert(Base->isDefined() && "Not a defined symbol");
541 return static_cast<const Block &>(*Base);
542 }
543
544 /// Returns the offset for this symbol within the underlying addressable.
getOffset()545 JITTargetAddress getOffset() const { return Offset; }
546
547 /// Returns the address of this symbol.
getAddress()548 JITTargetAddress getAddress() const { return Base->getAddress() + Offset; }
549
550 /// Returns the size of this symbol.
getSize()551 JITTargetAddress getSize() const { return Size; }
552
553 /// Set the size of this symbol.
setSize(JITTargetAddress Size)554 void setSize(JITTargetAddress Size) {
555 assert(Base && "Cannot set size for null Symbol");
556 assert((Size == 0 || Base->isDefined()) &&
557 "Non-zero size can only be set for defined symbols");
558 assert((Offset + Size <= static_cast<const Block &>(*Base).getSize()) &&
559 "Symbol size cannot extend past the end of its containing block");
560 this->Size = Size;
561 }
562
563 /// Returns true if this symbol is backed by a zero-fill block.
564 /// This method may only be called on defined symbols.
isSymbolZeroFill()565 bool isSymbolZeroFill() const { return getBlock().isZeroFill(); }
566
567 /// Returns the content in the underlying block covered by this symbol.
568 /// This method may only be called on defined non-zero-fill symbols.
getSymbolContent()569 ArrayRef<char> getSymbolContent() const {
570 return getBlock().getContent().slice(Offset, Size);
571 }
572
573 /// Get the linkage for this Symbol.
getLinkage()574 Linkage getLinkage() const { return static_cast<Linkage>(L); }
575
576 /// Set the linkage for this Symbol.
setLinkage(Linkage L)577 void setLinkage(Linkage L) {
578 assert((L == Linkage::Strong || (!Base->isAbsolute() && !Name.empty())) &&
579 "Linkage can only be applied to defined named symbols");
580 this->L = static_cast<uint8_t>(L);
581 }
582
583 /// Get the visibility for this Symbol.
getScope()584 Scope getScope() const { return static_cast<Scope>(S); }
585
586 /// Set the visibility for this Symbol.
setScope(Scope S)587 void setScope(Scope S) {
588 assert((!Name.empty() || S == Scope::Local) &&
589 "Can not set anonymous symbol to non-local scope");
590 assert((S == Scope::Default || Base->isDefined() || Base->isAbsolute()) &&
591 "Invalid visibility for symbol type");
592 this->S = static_cast<uint8_t>(S);
593 }
594
595 private:
makeExternal(Addressable & A)596 void makeExternal(Addressable &A) {
597 assert(!A.isDefined() && !A.isAbsolute() &&
598 "Attempting to make external with defined or absolute block");
599 Base = &A;
600 Offset = 0;
601 setScope(Scope::Default);
602 IsLive = 0;
603 // note: Size, Linkage and IsCallable fields left unchanged.
604 }
605
makeAbsolute(Addressable & A)606 void makeAbsolute(Addressable &A) {
607 assert(!A.isDefined() && A.isAbsolute() &&
608 "Attempting to make absolute with defined or external block");
609 Base = &A;
610 Offset = 0;
611 }
612
setBlock(Block & B)613 void setBlock(Block &B) { Base = &B; }
614
setOffset(uint64_t NewOffset)615 void setOffset(uint64_t NewOffset) {
616 assert(NewOffset <= MaxOffset && "Offset out of range");
617 Offset = NewOffset;
618 }
619
620 static constexpr uint64_t MaxOffset = (1ULL << 59) - 1;
621
622 // FIXME: A char* or SymbolStringPtr may pack better.
623 StringRef Name;
624 Addressable *Base = nullptr;
625 uint64_t Offset : 59;
626 uint64_t L : 1;
627 uint64_t S : 2;
628 uint64_t IsLive : 1;
629 uint64_t IsCallable : 1;
630 JITTargetAddress Size = 0;
631 };
632
633 raw_ostream &operator<<(raw_ostream &OS, const Symbol &A);
634
635 void printEdge(raw_ostream &OS, const Block &B, const Edge &E,
636 StringRef EdgeKindName);
637
638 /// Represents an object file section.
639 class Section {
640 friend class LinkGraph;
641
642 private:
Section(StringRef Name,sys::Memory::ProtectionFlags Prot,SectionOrdinal SecOrdinal)643 Section(StringRef Name, sys::Memory::ProtectionFlags Prot,
644 SectionOrdinal SecOrdinal)
645 : Name(Name), Prot(Prot), SecOrdinal(SecOrdinal) {}
646
647 using SymbolSet = DenseSet<Symbol *>;
648 using BlockSet = DenseSet<Block *>;
649
650 public:
651 using symbol_iterator = SymbolSet::iterator;
652 using const_symbol_iterator = SymbolSet::const_iterator;
653
654 using block_iterator = BlockSet::iterator;
655 using const_block_iterator = BlockSet::const_iterator;
656
657 ~Section();
658
659 // Sections are not movable or copyable.
660 Section(const Section &) = delete;
661 Section &operator=(const Section &) = delete;
662 Section(Section &&) = delete;
663 Section &operator=(Section &&) = delete;
664
665 /// Returns the name of this section.
getName()666 StringRef getName() const { return Name; }
667
668 /// Returns the protection flags for this section.
getProtectionFlags()669 sys::Memory::ProtectionFlags getProtectionFlags() const { return Prot; }
670
671 /// Set the protection flags for this section.
setProtectionFlags(sys::Memory::ProtectionFlags Prot)672 void setProtectionFlags(sys::Memory::ProtectionFlags Prot) {
673 this->Prot = Prot;
674 }
675
676 /// Returns the ordinal for this section.
getOrdinal()677 SectionOrdinal getOrdinal() const { return SecOrdinal; }
678
679 /// Returns an iterator over the blocks defined in this section.
blocks()680 iterator_range<block_iterator> blocks() {
681 return make_range(Blocks.begin(), Blocks.end());
682 }
683
684 /// Returns an iterator over the blocks defined in this section.
blocks()685 iterator_range<const_block_iterator> blocks() const {
686 return make_range(Blocks.begin(), Blocks.end());
687 }
688
blocks_size()689 BlockSet::size_type blocks_size() const { return Blocks.size(); }
690
691 /// Returns an iterator over the symbols defined in this section.
symbols()692 iterator_range<symbol_iterator> symbols() {
693 return make_range(Symbols.begin(), Symbols.end());
694 }
695
696 /// Returns an iterator over the symbols defined in this section.
symbols()697 iterator_range<const_symbol_iterator> symbols() const {
698 return make_range(Symbols.begin(), Symbols.end());
699 }
700
701 /// Return the number of symbols in this section.
symbols_size()702 SymbolSet::size_type symbols_size() const { return Symbols.size(); }
703
704 private:
addSymbol(Symbol & Sym)705 void addSymbol(Symbol &Sym) {
706 assert(!Symbols.count(&Sym) && "Symbol is already in this section");
707 Symbols.insert(&Sym);
708 }
709
removeSymbol(Symbol & Sym)710 void removeSymbol(Symbol &Sym) {
711 assert(Symbols.count(&Sym) && "symbol is not in this section");
712 Symbols.erase(&Sym);
713 }
714
addBlock(Block & B)715 void addBlock(Block &B) {
716 assert(!Blocks.count(&B) && "Block is already in this section");
717 Blocks.insert(&B);
718 }
719
removeBlock(Block & B)720 void removeBlock(Block &B) {
721 assert(Blocks.count(&B) && "Block is not in this section");
722 Blocks.erase(&B);
723 }
724
transferContentTo(Section & DstSection)725 void transferContentTo(Section &DstSection) {
726 if (&DstSection == this)
727 return;
728 for (auto *S : Symbols)
729 DstSection.addSymbol(*S);
730 for (auto *B : Blocks)
731 DstSection.addBlock(*B);
732 Symbols.clear();
733 Blocks.clear();
734 }
735
736 StringRef Name;
737 sys::Memory::ProtectionFlags Prot;
738 SectionOrdinal SecOrdinal = 0;
739 BlockSet Blocks;
740 SymbolSet Symbols;
741 };
742
743 /// Represents a section address range via a pair of Block pointers
744 /// to the first and last Blocks in the section.
745 class SectionRange {
746 public:
747 SectionRange() = default;
SectionRange(const Section & Sec)748 SectionRange(const Section &Sec) {
749 if (llvm::empty(Sec.blocks()))
750 return;
751 First = Last = *Sec.blocks().begin();
752 for (auto *B : Sec.blocks()) {
753 if (B->getAddress() < First->getAddress())
754 First = B;
755 if (B->getAddress() > Last->getAddress())
756 Last = B;
757 }
758 }
getFirstBlock()759 Block *getFirstBlock() const {
760 assert((!Last || First) && "First can not be null if end is non-null");
761 return First;
762 }
getLastBlock()763 Block *getLastBlock() const {
764 assert((First || !Last) && "Last can not be null if start is non-null");
765 return Last;
766 }
empty()767 bool empty() const {
768 assert((First || !Last) && "Last can not be null if start is non-null");
769 return !First;
770 }
getStart()771 JITTargetAddress getStart() const {
772 return First ? First->getAddress() : 0;
773 }
getEnd()774 JITTargetAddress getEnd() const {
775 return Last ? Last->getAddress() + Last->getSize() : 0;
776 }
getSize()777 uint64_t getSize() const { return getEnd() - getStart(); }
778
779 private:
780 Block *First = nullptr;
781 Block *Last = nullptr;
782 };
783
784 class LinkGraph {
785 private:
786 using SectionList = std::vector<std::unique_ptr<Section>>;
787 using ExternalSymbolSet = DenseSet<Symbol *>;
788 using BlockSet = DenseSet<Block *>;
789
790 template <typename... ArgTs>
createAddressable(ArgTs &&...Args)791 Addressable &createAddressable(ArgTs &&... Args) {
792 Addressable *A =
793 reinterpret_cast<Addressable *>(Allocator.Allocate<Addressable>());
794 new (A) Addressable(std::forward<ArgTs>(Args)...);
795 return *A;
796 }
797
destroyAddressable(Addressable & A)798 void destroyAddressable(Addressable &A) {
799 A.~Addressable();
800 Allocator.Deallocate(&A);
801 }
802
createBlock(ArgTs &&...Args)803 template <typename... ArgTs> Block &createBlock(ArgTs &&... Args) {
804 Block *B = reinterpret_cast<Block *>(Allocator.Allocate<Block>());
805 new (B) Block(std::forward<ArgTs>(Args)...);
806 B->getSection().addBlock(*B);
807 return *B;
808 }
809
destroyBlock(Block & B)810 void destroyBlock(Block &B) {
811 B.~Block();
812 Allocator.Deallocate(&B);
813 }
814
destroySymbol(Symbol & S)815 void destroySymbol(Symbol &S) {
816 S.~Symbol();
817 Allocator.Deallocate(&S);
818 }
819
getSectionBlocks(Section & S)820 static iterator_range<Section::block_iterator> getSectionBlocks(Section &S) {
821 return S.blocks();
822 }
823
824 static iterator_range<Section::const_block_iterator>
getSectionConstBlocks(Section & S)825 getSectionConstBlocks(Section &S) {
826 return S.blocks();
827 }
828
829 static iterator_range<Section::symbol_iterator>
getSectionSymbols(Section & S)830 getSectionSymbols(Section &S) {
831 return S.symbols();
832 }
833
834 static iterator_range<Section::const_symbol_iterator>
getSectionConstSymbols(Section & S)835 getSectionConstSymbols(Section &S) {
836 return S.symbols();
837 }
838
839 public:
840 using external_symbol_iterator = ExternalSymbolSet::iterator;
841
842 using section_iterator = pointee_iterator<SectionList::iterator>;
843 using const_section_iterator = pointee_iterator<SectionList::const_iterator>;
844
845 template <typename OuterItrT, typename InnerItrT, typename T,
846 iterator_range<InnerItrT> getInnerRange(
847 typename OuterItrT::reference)>
848 class nested_collection_iterator
849 : public iterator_facade_base<
850 nested_collection_iterator<OuterItrT, InnerItrT, T, getInnerRange>,
851 std::forward_iterator_tag, T> {
852 public:
853 nested_collection_iterator() = default;
854
nested_collection_iterator(OuterItrT OuterI,OuterItrT OuterE)855 nested_collection_iterator(OuterItrT OuterI, OuterItrT OuterE)
856 : OuterI(OuterI), OuterE(OuterE),
857 InnerI(getInnerBegin(OuterI, OuterE)) {
858 moveToNonEmptyInnerOrEnd();
859 }
860
861 bool operator==(const nested_collection_iterator &RHS) const {
862 return (OuterI == RHS.OuterI) && (InnerI == RHS.InnerI);
863 }
864
865 T operator*() const {
866 assert(InnerI != getInnerRange(*OuterI).end() && "Dereferencing end?");
867 return *InnerI;
868 }
869
870 nested_collection_iterator operator++() {
871 ++InnerI;
872 moveToNonEmptyInnerOrEnd();
873 return *this;
874 }
875
876 private:
getInnerBegin(OuterItrT OuterI,OuterItrT OuterE)877 static InnerItrT getInnerBegin(OuterItrT OuterI, OuterItrT OuterE) {
878 return OuterI != OuterE ? getInnerRange(*OuterI).begin() : InnerItrT();
879 }
880
moveToNonEmptyInnerOrEnd()881 void moveToNonEmptyInnerOrEnd() {
882 while (OuterI != OuterE && InnerI == getInnerRange(*OuterI).end()) {
883 ++OuterI;
884 InnerI = getInnerBegin(OuterI, OuterE);
885 }
886 }
887
888 OuterItrT OuterI, OuterE;
889 InnerItrT InnerI;
890 };
891
892 using defined_symbol_iterator =
893 nested_collection_iterator<const_section_iterator,
894 Section::symbol_iterator, Symbol *,
895 getSectionSymbols>;
896
897 using const_defined_symbol_iterator =
898 nested_collection_iterator<const_section_iterator,
899 Section::const_symbol_iterator, const Symbol *,
900 getSectionConstSymbols>;
901
902 using block_iterator = nested_collection_iterator<const_section_iterator,
903 Section::block_iterator,
904 Block *, getSectionBlocks>;
905
906 using const_block_iterator =
907 nested_collection_iterator<const_section_iterator,
908 Section::const_block_iterator, const Block *,
909 getSectionConstBlocks>;
910
911 using GetEdgeKindNameFunction = const char *(*)(Edge::Kind);
912
LinkGraph(std::string Name,const Triple & TT,unsigned PointerSize,support::endianness Endianness,GetEdgeKindNameFunction GetEdgeKindName)913 LinkGraph(std::string Name, const Triple &TT, unsigned PointerSize,
914 support::endianness Endianness,
915 GetEdgeKindNameFunction GetEdgeKindName)
916 : Name(std::move(Name)), TT(TT), PointerSize(PointerSize),
917 Endianness(Endianness), GetEdgeKindName(std::move(GetEdgeKindName)) {}
918
919 /// Returns the name of this graph (usually the name of the original
920 /// underlying MemoryBuffer).
getName()921 const std::string &getName() const { return Name; }
922
923 /// Returns the target triple for this Graph.
getTargetTriple()924 const Triple &getTargetTriple() const { return TT; }
925
926 /// Returns the pointer size for use in this graph.
getPointerSize()927 unsigned getPointerSize() const { return PointerSize; }
928
929 /// Returns the endianness of content in this graph.
getEndianness()930 support::endianness getEndianness() const { return Endianness; }
931
getEdgeKindName(Edge::Kind K)932 const char *getEdgeKindName(Edge::Kind K) const { return GetEdgeKindName(K); }
933
934 /// Allocate a mutable buffer of the given size using the LinkGraph's
935 /// allocator.
allocateBuffer(size_t Size)936 MutableArrayRef<char> allocateBuffer(size_t Size) {
937 return {Allocator.Allocate<char>(Size), Size};
938 }
939
940 /// Allocate a copy of the given string using the LinkGraph's allocator.
941 /// This can be useful when renaming symbols or adding new content to the
942 /// graph.
allocateContent(ArrayRef<char> Source)943 MutableArrayRef<char> allocateContent(ArrayRef<char> Source) {
944 auto *AllocatedBuffer = Allocator.Allocate<char>(Source.size());
945 llvm::copy(Source, AllocatedBuffer);
946 return MutableArrayRef<char>(AllocatedBuffer, Source.size());
947 }
948
949 /// Allocate a copy of the given string using the LinkGraph's allocator.
950 /// This can be useful when renaming symbols or adding new content to the
951 /// graph.
952 ///
953 /// Note: This Twine-based overload requires an extra string copy and an
954 /// extra heap allocation for large strings. The ArrayRef<char> overload
955 /// should be preferred where possible.
allocateString(Twine Source)956 MutableArrayRef<char> allocateString(Twine Source) {
957 SmallString<256> TmpBuffer;
958 auto SourceStr = Source.toStringRef(TmpBuffer);
959 auto *AllocatedBuffer = Allocator.Allocate<char>(SourceStr.size());
960 llvm::copy(SourceStr, AllocatedBuffer);
961 return MutableArrayRef<char>(AllocatedBuffer, SourceStr.size());
962 }
963
964 /// Create a section with the given name, protection flags, and alignment.
createSection(StringRef Name,sys::Memory::ProtectionFlags Prot)965 Section &createSection(StringRef Name, sys::Memory::ProtectionFlags Prot) {
966 assert(llvm::find_if(Sections,
967 [&](std::unique_ptr<Section> &Sec) {
968 return Sec->getName() == Name;
969 }) == Sections.end() &&
970 "Duplicate section name");
971 std::unique_ptr<Section> Sec(new Section(Name, Prot, Sections.size()));
972 Sections.push_back(std::move(Sec));
973 return *Sections.back();
974 }
975
976 /// Create a content block.
createContentBlock(Section & Parent,ArrayRef<char> Content,uint64_t Address,uint64_t Alignment,uint64_t AlignmentOffset)977 Block &createContentBlock(Section &Parent, ArrayRef<char> Content,
978 uint64_t Address, uint64_t Alignment,
979 uint64_t AlignmentOffset) {
980 return createBlock(Parent, Content, Address, Alignment, AlignmentOffset);
981 }
982
983 /// Create a content block with initially mutable data.
createMutableContentBlock(Section & Parent,MutableArrayRef<char> MutableContent,uint64_t Address,uint64_t Alignment,uint64_t AlignmentOffset)984 Block &createMutableContentBlock(Section &Parent,
985 MutableArrayRef<char> MutableContent,
986 uint64_t Address, uint64_t Alignment,
987 uint64_t AlignmentOffset) {
988 return createBlock(Parent, MutableContent, Address, Alignment,
989 AlignmentOffset);
990 }
991
992 /// Create a zero-fill block.
createZeroFillBlock(Section & Parent,uint64_t Size,uint64_t Address,uint64_t Alignment,uint64_t AlignmentOffset)993 Block &createZeroFillBlock(Section &Parent, uint64_t Size, uint64_t Address,
994 uint64_t Alignment, uint64_t AlignmentOffset) {
995 return createBlock(Parent, Size, Address, Alignment, AlignmentOffset);
996 }
997
998 /// Cache type for the splitBlock function.
999 using SplitBlockCache = Optional<SmallVector<Symbol *, 8>>;
1000
1001 /// Splits block B at the given index which must be greater than zero.
1002 /// If SplitIndex == B.getSize() then this function is a no-op and returns B.
1003 /// If SplitIndex < B.getSize() then this function returns a new block
1004 /// covering the range [ 0, SplitIndex ), and B is modified to cover the range
1005 /// [ SplitIndex, B.size() ).
1006 ///
1007 /// The optional Cache parameter can be used to speed up repeated calls to
1008 /// splitBlock for a single block. If the value is None the cache will be
1009 /// treated as uninitialized and splitBlock will populate it. Otherwise it
1010 /// is assumed to contain the list of Symbols pointing at B, sorted in
1011 /// descending order of offset.
1012 ///
1013 /// Notes:
1014 ///
1015 /// 1. splitBlock must be used with care. Splitting a block may cause
1016 /// incoming edges to become invalid if the edge target subexpression
1017 /// points outside the bounds of the newly split target block (E.g. an
1018 /// edge 'S + 10 : Pointer64' where S points to a newly split block
1019 /// whose size is less than 10). No attempt is made to detect invalidation
1020 /// of incoming edges, as in general this requires context that the
1021 /// LinkGraph does not have. Clients are responsible for ensuring that
1022 /// splitBlock is not used in a way that invalidates edges.
1023 ///
1024 /// 2. The newly introduced block will have a new ordinal which will be
1025 /// higher than any other ordinals in the section. Clients are responsible
1026 /// for re-assigning block ordinals to restore a compatible order if
1027 /// needed.
1028 ///
1029 /// 3. The cache is not automatically updated if new symbols are introduced
1030 /// between calls to splitBlock. Any newly introduced symbols may be
1031 /// added to the cache manually (descending offset order must be
1032 /// preserved), or the cache can be set to None and rebuilt by
1033 /// splitBlock on the next call.
1034 Block &splitBlock(Block &B, size_t SplitIndex,
1035 SplitBlockCache *Cache = nullptr);
1036
1037 /// Add an external symbol.
1038 /// Some formats (e.g. ELF) allow Symbols to have sizes. For Symbols whose
1039 /// size is not known, you should substitute '0'.
1040 /// For external symbols Linkage determines whether the symbol must be
1041 /// present during lookup: Externals with strong linkage must be found or
1042 /// an error will be emitted. Externals with weak linkage are permitted to
1043 /// be undefined, in which case they are assigned a value of 0.
addExternalSymbol(StringRef Name,uint64_t Size,Linkage L)1044 Symbol &addExternalSymbol(StringRef Name, uint64_t Size, Linkage L) {
1045 assert(llvm::count_if(ExternalSymbols,
1046 [&](const Symbol *Sym) {
1047 return Sym->getName() == Name;
1048 }) == 0 &&
1049 "Duplicate external symbol");
1050 auto &Sym =
1051 Symbol::constructExternal(Allocator.Allocate<Symbol>(),
1052 createAddressable(0, false), Name, Size, L);
1053 ExternalSymbols.insert(&Sym);
1054 return Sym;
1055 }
1056
1057 /// Add an absolute symbol.
addAbsoluteSymbol(StringRef Name,JITTargetAddress Address,uint64_t Size,Linkage L,Scope S,bool IsLive)1058 Symbol &addAbsoluteSymbol(StringRef Name, JITTargetAddress Address,
1059 uint64_t Size, Linkage L, Scope S, bool IsLive) {
1060 assert(llvm::count_if(AbsoluteSymbols,
1061 [&](const Symbol *Sym) {
1062 return Sym->getName() == Name;
1063 }) == 0 &&
1064 "Duplicate absolute symbol");
1065 auto &Sym = Symbol::constructAbsolute(Allocator.Allocate<Symbol>(),
1066 createAddressable(Address), Name,
1067 Size, L, S, IsLive);
1068 AbsoluteSymbols.insert(&Sym);
1069 return Sym;
1070 }
1071
1072 /// Convenience method for adding a weak zero-fill symbol.
addCommonSymbol(StringRef Name,Scope S,Section & Section,JITTargetAddress Address,uint64_t Size,uint64_t Alignment,bool IsLive)1073 Symbol &addCommonSymbol(StringRef Name, Scope S, Section &Section,
1074 JITTargetAddress Address, uint64_t Size,
1075 uint64_t Alignment, bool IsLive) {
1076 assert(llvm::count_if(defined_symbols(),
1077 [&](const Symbol *Sym) {
1078 return Sym->getName() == Name;
1079 }) == 0 &&
1080 "Duplicate defined symbol");
1081 auto &Sym = Symbol::constructCommon(
1082 Allocator.Allocate<Symbol>(),
1083 createBlock(Section, Size, Address, Alignment, 0), Name, Size, S,
1084 IsLive);
1085 Section.addSymbol(Sym);
1086 return Sym;
1087 }
1088
1089 /// Add an anonymous symbol.
addAnonymousSymbol(Block & Content,JITTargetAddress Offset,JITTargetAddress Size,bool IsCallable,bool IsLive)1090 Symbol &addAnonymousSymbol(Block &Content, JITTargetAddress Offset,
1091 JITTargetAddress Size, bool IsCallable,
1092 bool IsLive) {
1093 auto &Sym = Symbol::constructAnonDef(Allocator.Allocate<Symbol>(), Content,
1094 Offset, Size, IsCallable, IsLive);
1095 Content.getSection().addSymbol(Sym);
1096 return Sym;
1097 }
1098
1099 /// Add a named symbol.
addDefinedSymbol(Block & Content,JITTargetAddress Offset,StringRef Name,JITTargetAddress Size,Linkage L,Scope S,bool IsCallable,bool IsLive)1100 Symbol &addDefinedSymbol(Block &Content, JITTargetAddress Offset,
1101 StringRef Name, JITTargetAddress Size, Linkage L,
1102 Scope S, bool IsCallable, bool IsLive) {
1103 assert(llvm::count_if(defined_symbols(),
1104 [&](const Symbol *Sym) {
1105 return Sym->getName() == Name;
1106 }) == 0 &&
1107 "Duplicate defined symbol");
1108 auto &Sym =
1109 Symbol::constructNamedDef(Allocator.Allocate<Symbol>(), Content, Offset,
1110 Name, Size, L, S, IsLive, IsCallable);
1111 Content.getSection().addSymbol(Sym);
1112 return Sym;
1113 }
1114
sections()1115 iterator_range<section_iterator> sections() {
1116 return make_range(section_iterator(Sections.begin()),
1117 section_iterator(Sections.end()));
1118 }
1119
sections_size()1120 SectionList::size_type sections_size() const { return Sections.size(); }
1121
1122 /// Returns the section with the given name if it exists, otherwise returns
1123 /// null.
findSectionByName(StringRef Name)1124 Section *findSectionByName(StringRef Name) {
1125 for (auto &S : sections())
1126 if (S.getName() == Name)
1127 return &S;
1128 return nullptr;
1129 }
1130
blocks()1131 iterator_range<block_iterator> blocks() {
1132 return make_range(block_iterator(Sections.begin(), Sections.end()),
1133 block_iterator(Sections.end(), Sections.end()));
1134 }
1135
blocks()1136 iterator_range<const_block_iterator> blocks() const {
1137 return make_range(const_block_iterator(Sections.begin(), Sections.end()),
1138 const_block_iterator(Sections.end(), Sections.end()));
1139 }
1140
external_symbols()1141 iterator_range<external_symbol_iterator> external_symbols() {
1142 return make_range(ExternalSymbols.begin(), ExternalSymbols.end());
1143 }
1144
absolute_symbols()1145 iterator_range<external_symbol_iterator> absolute_symbols() {
1146 return make_range(AbsoluteSymbols.begin(), AbsoluteSymbols.end());
1147 }
1148
defined_symbols()1149 iterator_range<defined_symbol_iterator> defined_symbols() {
1150 return make_range(defined_symbol_iterator(Sections.begin(), Sections.end()),
1151 defined_symbol_iterator(Sections.end(), Sections.end()));
1152 }
1153
defined_symbols()1154 iterator_range<const_defined_symbol_iterator> defined_symbols() const {
1155 return make_range(
1156 const_defined_symbol_iterator(Sections.begin(), Sections.end()),
1157 const_defined_symbol_iterator(Sections.end(), Sections.end()));
1158 }
1159
1160 /// Make the given symbol external (must not already be external).
1161 ///
1162 /// Symbol size, linkage and callability will be left unchanged. Symbol scope
1163 /// will be set to Default, and offset will be reset to 0.
makeExternal(Symbol & Sym)1164 void makeExternal(Symbol &Sym) {
1165 assert(!Sym.isExternal() && "Symbol is already external");
1166 if (Sym.isAbsolute()) {
1167 assert(AbsoluteSymbols.count(&Sym) &&
1168 "Sym is not in the absolute symbols set");
1169 assert(Sym.getOffset() == 0 && "Absolute not at offset 0");
1170 AbsoluteSymbols.erase(&Sym);
1171 Sym.getAddressable().setAbsolute(false);
1172 } else {
1173 assert(Sym.isDefined() && "Sym is not a defined symbol");
1174 Section &Sec = Sym.getBlock().getSection();
1175 Sec.removeSymbol(Sym);
1176 Sym.makeExternal(createAddressable(0, false));
1177 }
1178 ExternalSymbols.insert(&Sym);
1179 }
1180
1181 /// Make the given symbol an absolute with the given address (must not already
1182 /// be absolute).
1183 ///
1184 /// Symbol size, linkage, scope, and callability, and liveness will be left
1185 /// unchanged. Symbol offset will be reset to 0.
makeAbsolute(Symbol & Sym,JITTargetAddress Address)1186 void makeAbsolute(Symbol &Sym, JITTargetAddress Address) {
1187 assert(!Sym.isAbsolute() && "Symbol is already absolute");
1188 if (Sym.isExternal()) {
1189 assert(ExternalSymbols.count(&Sym) &&
1190 "Sym is not in the absolute symbols set");
1191 assert(Sym.getOffset() == 0 && "External is not at offset 0");
1192 ExternalSymbols.erase(&Sym);
1193 Sym.getAddressable().setAbsolute(true);
1194 } else {
1195 assert(Sym.isDefined() && "Sym is not a defined symbol");
1196 Section &Sec = Sym.getBlock().getSection();
1197 Sec.removeSymbol(Sym);
1198 Sym.makeAbsolute(createAddressable(Address));
1199 }
1200 AbsoluteSymbols.insert(&Sym);
1201 }
1202
1203 /// Turn an absolute or external symbol into a defined one by attaching it to
1204 /// a block. Symbol must not already be defined.
makeDefined(Symbol & Sym,Block & Content,JITTargetAddress Offset,JITTargetAddress Size,Linkage L,Scope S,bool IsLive)1205 void makeDefined(Symbol &Sym, Block &Content, JITTargetAddress Offset,
1206 JITTargetAddress Size, Linkage L, Scope S, bool IsLive) {
1207 assert(!Sym.isDefined() && "Sym is already a defined symbol");
1208 if (Sym.isAbsolute()) {
1209 assert(AbsoluteSymbols.count(&Sym) &&
1210 "Symbol is not in the absolutes set");
1211 AbsoluteSymbols.erase(&Sym);
1212 } else {
1213 assert(ExternalSymbols.count(&Sym) &&
1214 "Symbol is not in the externals set");
1215 ExternalSymbols.erase(&Sym);
1216 }
1217 Addressable &OldBase = *Sym.Base;
1218 Sym.setBlock(Content);
1219 Sym.setOffset(Offset);
1220 Sym.setSize(Size);
1221 Sym.setLinkage(L);
1222 Sym.setScope(S);
1223 Sym.setLive(IsLive);
1224 Content.getSection().addSymbol(Sym);
1225 destroyAddressable(OldBase);
1226 }
1227
1228 /// Transfer a defined symbol from one block to another.
1229 ///
1230 /// The symbol's offset within DestBlock is set to NewOffset.
1231 ///
1232 /// If ExplicitNewSize is given as None then the size of the symbol will be
1233 /// checked and auto-truncated to at most the size of the remainder (from the
1234 /// given offset) of the size of the new block.
1235 ///
1236 /// All other symbol attributes are unchanged.
transferDefinedSymbol(Symbol & Sym,Block & DestBlock,JITTargetAddress NewOffset,Optional<JITTargetAddress> ExplicitNewSize)1237 void transferDefinedSymbol(Symbol &Sym, Block &DestBlock,
1238 JITTargetAddress NewOffset,
1239 Optional<JITTargetAddress> ExplicitNewSize) {
1240 Sym.setBlock(DestBlock);
1241 Sym.setOffset(NewOffset);
1242 if (ExplicitNewSize)
1243 Sym.setSize(*ExplicitNewSize);
1244 else {
1245 JITTargetAddress RemainingBlockSize = DestBlock.getSize() - NewOffset;
1246 if (Sym.getSize() > RemainingBlockSize)
1247 Sym.setSize(RemainingBlockSize);
1248 }
1249 }
1250
1251 /// Transfers the given Block and all Symbols pointing to it to the given
1252 /// Section.
1253 ///
1254 /// No attempt is made to check compatibility of the source and destination
1255 /// sections. Blocks may be moved between sections with incompatible
1256 /// permissions (e.g. from data to text). The client is responsible for
1257 /// ensuring that this is safe.
transferBlock(Block & B,Section & NewSection)1258 void transferBlock(Block &B, Section &NewSection) {
1259 auto &OldSection = B.getSection();
1260 if (&OldSection == &NewSection)
1261 return;
1262 SmallVector<Symbol *> AttachedSymbols;
1263 for (auto *S : OldSection.symbols())
1264 if (&S->getBlock() == &B)
1265 AttachedSymbols.push_back(S);
1266 for (auto *S : AttachedSymbols) {
1267 OldSection.removeSymbol(*S);
1268 NewSection.addSymbol(*S);
1269 }
1270 OldSection.removeBlock(B);
1271 NewSection.addBlock(B);
1272 }
1273
1274 /// Move all blocks and symbols from the source section to the destination
1275 /// section.
1276 ///
1277 /// If PreserveSrcSection is true (or SrcSection and DstSection are the same)
1278 /// then SrcSection is preserved, otherwise it is removed (the default).
1279 void mergeSections(Section &DstSection, Section &SrcSection,
1280 bool PreserveSrcSection = false) {
1281 if (&DstSection == &SrcSection)
1282 return;
1283 SrcSection.transferContentTo(DstSection);
1284 if (!PreserveSrcSection)
1285 removeSection(SrcSection);
1286 }
1287
1288 /// Removes an external symbol. Also removes the underlying Addressable.
removeExternalSymbol(Symbol & Sym)1289 void removeExternalSymbol(Symbol &Sym) {
1290 assert(!Sym.isDefined() && !Sym.isAbsolute() &&
1291 "Sym is not an external symbol");
1292 assert(ExternalSymbols.count(&Sym) && "Symbol is not in the externals set");
1293 ExternalSymbols.erase(&Sym);
1294 Addressable &Base = *Sym.Base;
1295 assert(llvm::find_if(ExternalSymbols,
1296 [&](Symbol *AS) { return AS->Base == &Base; }) ==
1297 ExternalSymbols.end() &&
1298 "Base addressable still in use");
1299 destroySymbol(Sym);
1300 destroyAddressable(Base);
1301 }
1302
1303 /// Remove an absolute symbol. Also removes the underlying Addressable.
removeAbsoluteSymbol(Symbol & Sym)1304 void removeAbsoluteSymbol(Symbol &Sym) {
1305 assert(!Sym.isDefined() && Sym.isAbsolute() &&
1306 "Sym is not an absolute symbol");
1307 assert(AbsoluteSymbols.count(&Sym) &&
1308 "Symbol is not in the absolute symbols set");
1309 AbsoluteSymbols.erase(&Sym);
1310 Addressable &Base = *Sym.Base;
1311 assert(llvm::find_if(ExternalSymbols,
1312 [&](Symbol *AS) { return AS->Base == &Base; }) ==
1313 ExternalSymbols.end() &&
1314 "Base addressable still in use");
1315 destroySymbol(Sym);
1316 destroyAddressable(Base);
1317 }
1318
1319 /// Removes defined symbols. Does not remove the underlying block.
removeDefinedSymbol(Symbol & Sym)1320 void removeDefinedSymbol(Symbol &Sym) {
1321 assert(Sym.isDefined() && "Sym is not a defined symbol");
1322 Sym.getBlock().getSection().removeSymbol(Sym);
1323 destroySymbol(Sym);
1324 }
1325
1326 /// Remove a block. The block reference is defunct after calling this
1327 /// function and should no longer be used.
removeBlock(Block & B)1328 void removeBlock(Block &B) {
1329 assert(llvm::none_of(B.getSection().symbols(),
1330 [&](const Symbol *Sym) {
1331 return &Sym->getBlock() == &B;
1332 }) &&
1333 "Block still has symbols attached");
1334 B.getSection().removeBlock(B);
1335 destroyBlock(B);
1336 }
1337
1338 /// Remove a section. The section reference is defunct after calling this
1339 /// function and should no longer be used.
removeSection(Section & Sec)1340 void removeSection(Section &Sec) {
1341 auto I = llvm::find_if(Sections, [&Sec](const std::unique_ptr<Section> &S) {
1342 return S.get() == &Sec;
1343 });
1344 assert(I != Sections.end() && "Section does not appear in this graph");
1345 Sections.erase(I);
1346 }
1347
1348 /// Dump the graph.
1349 void dump(raw_ostream &OS);
1350
1351 private:
1352 // Put the BumpPtrAllocator first so that we don't free any of the underlying
1353 // memory until the Symbol/Addressable destructors have been run.
1354 BumpPtrAllocator Allocator;
1355
1356 std::string Name;
1357 Triple TT;
1358 unsigned PointerSize;
1359 support::endianness Endianness;
1360 GetEdgeKindNameFunction GetEdgeKindName = nullptr;
1361 SectionList Sections;
1362 ExternalSymbolSet ExternalSymbols;
1363 ExternalSymbolSet AbsoluteSymbols;
1364 };
1365
getMutableContent(LinkGraph & G)1366 inline MutableArrayRef<char> Block::getMutableContent(LinkGraph &G) {
1367 if (!ContentMutable)
1368 setMutableContent(G.allocateContent({Data, Size}));
1369 return MutableArrayRef<char>(const_cast<char *>(Data), Size);
1370 }
1371
1372 /// Enables easy lookup of blocks by addresses.
1373 class BlockAddressMap {
1374 public:
1375 using AddrToBlockMap = std::map<JITTargetAddress, Block *>;
1376 using const_iterator = AddrToBlockMap::const_iterator;
1377
1378 /// A block predicate that always adds all blocks.
includeAllBlocks(const Block & B)1379 static bool includeAllBlocks(const Block &B) { return true; }
1380
1381 /// A block predicate that always includes blocks with non-null addresses.
includeNonNull(const Block & B)1382 static bool includeNonNull(const Block &B) { return B.getAddress(); }
1383
1384 BlockAddressMap() = default;
1385
1386 /// Add a block to the map. Returns an error if the block overlaps with any
1387 /// existing block.
1388 template <typename PredFn = decltype(includeAllBlocks)>
1389 Error addBlock(Block &B, PredFn Pred = includeAllBlocks) {
1390 if (!Pred(B))
1391 return Error::success();
1392
1393 auto I = AddrToBlock.upper_bound(B.getAddress());
1394
1395 // If we're not at the end of the map, check for overlap with the next
1396 // element.
1397 if (I != AddrToBlock.end()) {
1398 if (B.getAddress() + B.getSize() > I->second->getAddress())
1399 return overlapError(B, *I->second);
1400 }
1401
1402 // If we're not at the start of the map, check for overlap with the previous
1403 // element.
1404 if (I != AddrToBlock.begin()) {
1405 auto &PrevBlock = *std::prev(I)->second;
1406 if (PrevBlock.getAddress() + PrevBlock.getSize() > B.getAddress())
1407 return overlapError(B, PrevBlock);
1408 }
1409
1410 AddrToBlock.insert(I, std::make_pair(B.getAddress(), &B));
1411 return Error::success();
1412 }
1413
1414 /// Add a block to the map without checking for overlap with existing blocks.
1415 /// The client is responsible for ensuring that the block added does not
1416 /// overlap with any existing block.
addBlockWithoutChecking(Block & B)1417 void addBlockWithoutChecking(Block &B) { AddrToBlock[B.getAddress()] = &B; }
1418
1419 /// Add a range of blocks to the map. Returns an error if any block in the
1420 /// range overlaps with any other block in the range, or with any existing
1421 /// block in the map.
1422 template <typename BlockPtrRange,
1423 typename PredFn = decltype(includeAllBlocks)>
1424 Error addBlocks(BlockPtrRange &&Blocks, PredFn Pred = includeAllBlocks) {
1425 for (auto *B : Blocks)
1426 if (auto Err = addBlock(*B, Pred))
1427 return Err;
1428 return Error::success();
1429 }
1430
1431 /// Add a range of blocks to the map without checking for overlap with
1432 /// existing blocks. The client is responsible for ensuring that the block
1433 /// added does not overlap with any existing block.
1434 template <typename BlockPtrRange>
addBlocksWithoutChecking(BlockPtrRange && Blocks)1435 void addBlocksWithoutChecking(BlockPtrRange &&Blocks) {
1436 for (auto *B : Blocks)
1437 addBlockWithoutChecking(*B);
1438 }
1439
1440 /// Iterates over (Address, Block*) pairs in ascending order of address.
begin()1441 const_iterator begin() const { return AddrToBlock.begin(); }
end()1442 const_iterator end() const { return AddrToBlock.end(); }
1443
1444 /// Returns the block starting at the given address, or nullptr if no such
1445 /// block exists.
getBlockAt(JITTargetAddress Addr)1446 Block *getBlockAt(JITTargetAddress Addr) const {
1447 auto I = AddrToBlock.find(Addr);
1448 if (I == AddrToBlock.end())
1449 return nullptr;
1450 return I->second;
1451 }
1452
1453 /// Returns the block covering the given address, or nullptr if no such block
1454 /// exists.
getBlockCovering(JITTargetAddress Addr)1455 Block *getBlockCovering(JITTargetAddress Addr) const {
1456 auto I = AddrToBlock.upper_bound(Addr);
1457 if (I == AddrToBlock.begin())
1458 return nullptr;
1459 auto *B = std::prev(I)->second;
1460 if (Addr < B->getAddress() + B->getSize())
1461 return B;
1462 return nullptr;
1463 }
1464
1465 private:
overlapError(Block & NewBlock,Block & ExistingBlock)1466 Error overlapError(Block &NewBlock, Block &ExistingBlock) {
1467 auto NewBlockEnd = NewBlock.getAddress() + NewBlock.getSize();
1468 auto ExistingBlockEnd =
1469 ExistingBlock.getAddress() + ExistingBlock.getSize();
1470 return make_error<JITLinkError>(
1471 "Block at " +
1472 formatv("{0:x16} -- {1:x16}", NewBlock.getAddress(), NewBlockEnd) +
1473 " overlaps " +
1474 formatv("{0:x16} -- {1:x16}", ExistingBlock.getAddress(),
1475 ExistingBlockEnd));
1476 }
1477
1478 AddrToBlockMap AddrToBlock;
1479 };
1480
1481 /// A map of addresses to Symbols.
1482 class SymbolAddressMap {
1483 public:
1484 using SymbolVector = SmallVector<Symbol *, 1>;
1485
1486 /// Add a symbol to the SymbolAddressMap.
addSymbol(Symbol & Sym)1487 void addSymbol(Symbol &Sym) {
1488 AddrToSymbols[Sym.getAddress()].push_back(&Sym);
1489 }
1490
1491 /// Add all symbols in a given range to the SymbolAddressMap.
1492 template <typename SymbolPtrCollection>
addSymbols(SymbolPtrCollection && Symbols)1493 void addSymbols(SymbolPtrCollection &&Symbols) {
1494 for (auto *Sym : Symbols)
1495 addSymbol(*Sym);
1496 }
1497
1498 /// Returns the list of symbols that start at the given address, or nullptr if
1499 /// no such symbols exist.
getSymbolsAt(JITTargetAddress Addr)1500 const SymbolVector *getSymbolsAt(JITTargetAddress Addr) const {
1501 auto I = AddrToSymbols.find(Addr);
1502 if (I == AddrToSymbols.end())
1503 return nullptr;
1504 return &I->second;
1505 }
1506
1507 private:
1508 std::map<JITTargetAddress, SymbolVector> AddrToSymbols;
1509 };
1510
1511 /// A function for mutating LinkGraphs.
1512 using LinkGraphPassFunction = std::function<Error(LinkGraph &)>;
1513
1514 /// A list of LinkGraph passes.
1515 using LinkGraphPassList = std::vector<LinkGraphPassFunction>;
1516
1517 /// An LinkGraph pass configuration, consisting of a list of pre-prune,
1518 /// post-prune, and post-fixup passes.
1519 struct PassConfiguration {
1520
1521 /// Pre-prune passes.
1522 ///
1523 /// These passes are called on the graph after it is built, and before any
1524 /// symbols have been pruned. Graph nodes still have their original vmaddrs.
1525 ///
1526 /// Notable use cases: Marking symbols live or should-discard.
1527 LinkGraphPassList PrePrunePasses;
1528
1529 /// Post-prune passes.
1530 ///
1531 /// These passes are called on the graph after dead stripping, but before
1532 /// memory is allocated or nodes assigned their final addresses.
1533 ///
1534 /// Notable use cases: Building GOT, stub, and TLV symbols.
1535 LinkGraphPassList PostPrunePasses;
1536
1537 /// Post-allocation passes.
1538 ///
1539 /// These passes are called on the graph after memory has been allocated and
1540 /// defined nodes have been assigned their final addresses, but before the
1541 /// context has been notified of these addresses. At this point externals
1542 /// have not been resolved, and symbol content has not yet been copied into
1543 /// working memory.
1544 ///
1545 /// Notable use cases: Setting up data structures associated with addresses
1546 /// of defined symbols (e.g. a mapping of __dso_handle to JITDylib* for the
1547 /// JIT runtime) -- using a PostAllocationPass for this ensures that the
1548 /// data structures are in-place before any query for resolved symbols
1549 /// can complete.
1550 LinkGraphPassList PostAllocationPasses;
1551
1552 /// Pre-fixup passes.
1553 ///
1554 /// These passes are called on the graph after memory has been allocated,
1555 /// content copied into working memory, and all nodes (including externals)
1556 /// have been assigned their final addresses, but before any fixups have been
1557 /// applied.
1558 ///
1559 /// Notable use cases: Late link-time optimizations like GOT and stub
1560 /// elimination.
1561 LinkGraphPassList PreFixupPasses;
1562
1563 /// Post-fixup passes.
1564 ///
1565 /// These passes are called on the graph after block contents has been copied
1566 /// to working memory, and fixups applied. Blocks have been updated to point
1567 /// to their fixed up content.
1568 ///
1569 /// Notable use cases: Testing and validation.
1570 LinkGraphPassList PostFixupPasses;
1571 };
1572
1573 /// Flags for symbol lookup.
1574 ///
1575 /// FIXME: These basically duplicate orc::SymbolLookupFlags -- We should merge
1576 /// the two types once we have an OrcSupport library.
1577 enum class SymbolLookupFlags { RequiredSymbol, WeaklyReferencedSymbol };
1578
1579 raw_ostream &operator<<(raw_ostream &OS, const SymbolLookupFlags &LF);
1580
1581 /// A map of symbol names to resolved addresses.
1582 using AsyncLookupResult = DenseMap<StringRef, JITEvaluatedSymbol>;
1583
1584 /// A function object to call with a resolved symbol map (See AsyncLookupResult)
1585 /// or an error if resolution failed.
1586 class JITLinkAsyncLookupContinuation {
1587 public:
~JITLinkAsyncLookupContinuation()1588 virtual ~JITLinkAsyncLookupContinuation() {}
1589 virtual void run(Expected<AsyncLookupResult> LR) = 0;
1590
1591 private:
1592 virtual void anchor();
1593 };
1594
1595 /// Create a lookup continuation from a function object.
1596 template <typename Continuation>
1597 std::unique_ptr<JITLinkAsyncLookupContinuation>
createLookupContinuation(Continuation Cont)1598 createLookupContinuation(Continuation Cont) {
1599
1600 class Impl final : public JITLinkAsyncLookupContinuation {
1601 public:
1602 Impl(Continuation C) : C(std::move(C)) {}
1603 void run(Expected<AsyncLookupResult> LR) override { C(std::move(LR)); }
1604
1605 private:
1606 Continuation C;
1607 };
1608
1609 return std::make_unique<Impl>(std::move(Cont));
1610 }
1611
1612 /// Holds context for a single jitLink invocation.
1613 class JITLinkContext {
1614 public:
1615 using LookupMap = DenseMap<StringRef, SymbolLookupFlags>;
1616
1617 /// Create a JITLinkContext.
JITLinkContext(const JITLinkDylib * JD)1618 JITLinkContext(const JITLinkDylib *JD) : JD(JD) {}
1619
1620 /// Destroy a JITLinkContext.
1621 virtual ~JITLinkContext();
1622
1623 /// Return the JITLinkDylib that this link is targeting, if any.
getJITLinkDylib()1624 const JITLinkDylib *getJITLinkDylib() const { return JD; }
1625
1626 /// Return the MemoryManager to be used for this link.
1627 virtual JITLinkMemoryManager &getMemoryManager() = 0;
1628
1629 /// Notify this context that linking failed.
1630 /// Called by JITLink if linking cannot be completed.
1631 virtual void notifyFailed(Error Err) = 0;
1632
1633 /// Called by JITLink to resolve external symbols. This method is passed a
1634 /// lookup continutation which it must call with a result to continue the
1635 /// linking process.
1636 virtual void lookup(const LookupMap &Symbols,
1637 std::unique_ptr<JITLinkAsyncLookupContinuation> LC) = 0;
1638
1639 /// Called by JITLink once all defined symbols in the graph have been assigned
1640 /// their final memory locations in the target process. At this point the
1641 /// LinkGraph can be inspected to build a symbol table, however the block
1642 /// content will not generally have been copied to the target location yet.
1643 ///
1644 /// If the client detects an error in the LinkGraph state (e.g. unexpected or
1645 /// missing symbols) they may return an error here. The error will be
1646 /// propagated to notifyFailed and the linker will bail out.
1647 virtual Error notifyResolved(LinkGraph &G) = 0;
1648
1649 /// Called by JITLink to notify the context that the object has been
1650 /// finalized (i.e. emitted to memory and memory permissions set). If all of
1651 /// this objects dependencies have also been finalized then the code is ready
1652 /// to run.
1653 virtual void
1654 notifyFinalized(std::unique_ptr<JITLinkMemoryManager::Allocation> A) = 0;
1655
1656 /// Called by JITLink prior to linking to determine whether default passes for
1657 /// the target should be added. The default implementation returns true.
1658 /// If subclasses override this method to return false for any target then
1659 /// they are required to fully configure the pass pipeline for that target.
1660 virtual bool shouldAddDefaultTargetPasses(const Triple &TT) const;
1661
1662 /// Returns the mark-live pass to be used for this link. If no pass is
1663 /// returned (the default) then the target-specific linker implementation will
1664 /// choose a conservative default (usually marking all symbols live).
1665 /// This function is only called if shouldAddDefaultTargetPasses returns true,
1666 /// otherwise the JITContext is responsible for adding a mark-live pass in
1667 /// modifyPassConfig.
1668 virtual LinkGraphPassFunction getMarkLivePass(const Triple &TT) const;
1669
1670 /// Called by JITLink to modify the pass pipeline prior to linking.
1671 /// The default version performs no modification.
1672 virtual Error modifyPassConfig(LinkGraph &G, PassConfiguration &Config);
1673
1674 private:
1675 const JITLinkDylib *JD = nullptr;
1676 };
1677
1678 /// Marks all symbols in a graph live. This can be used as a default,
1679 /// conservative mark-live implementation.
1680 Error markAllSymbolsLive(LinkGraph &G);
1681
1682 /// Create an out of range error for the given edge in the given block.
1683 Error makeTargetOutOfRangeError(const LinkGraph &G, const Block &B,
1684 const Edge &E);
1685
1686 /// Create a LinkGraph from the given object buffer.
1687 ///
1688 /// Note: The graph does not take ownership of the underlying buffer, nor copy
1689 /// its contents. The caller is responsible for ensuring that the object buffer
1690 /// outlives the graph.
1691 Expected<std::unique_ptr<LinkGraph>>
1692 createLinkGraphFromObject(MemoryBufferRef ObjectBuffer);
1693
1694 /// Link the given graph.
1695 void link(std::unique_ptr<LinkGraph> G, std::unique_ptr<JITLinkContext> Ctx);
1696
1697 } // end namespace jitlink
1698 } // end namespace llvm
1699
1700 #endif // LLVM_EXECUTIONENGINE_JITLINK_JITLINK_H
1701