Line data Source code
1 : //===-- Globals.cpp - Implement the GlobalValue & GlobalVariable class ----===//
2 : //
3 : // The LLVM Compiler Infrastructure
4 : //
5 : // This file is distributed under the University of Illinois Open Source
6 : // License. See LICENSE.TXT for details.
7 : //
8 : //===----------------------------------------------------------------------===//
9 : //
10 : // This file implements the GlobalValue & GlobalVariable classes for the IR
11 : // library.
12 : //
13 : //===----------------------------------------------------------------------===//
14 :
15 : #include "LLVMContextImpl.h"
16 : #include "llvm/ADT/SmallPtrSet.h"
17 : #include "llvm/ADT/Triple.h"
18 : #include "llvm/IR/ConstantRange.h"
19 : #include "llvm/IR/Constants.h"
20 : #include "llvm/IR/DerivedTypes.h"
21 : #include "llvm/IR/GlobalAlias.h"
22 : #include "llvm/IR/GlobalValue.h"
23 : #include "llvm/IR/GlobalVariable.h"
24 : #include "llvm/IR/Module.h"
25 : #include "llvm/IR/Operator.h"
26 : #include "llvm/Support/Error.h"
27 : #include "llvm/Support/ErrorHandling.h"
28 : using namespace llvm;
29 :
30 : //===----------------------------------------------------------------------===//
31 : // GlobalValue Class
32 : //===----------------------------------------------------------------------===//
33 :
34 : // GlobalValue should be a Constant, plus a type, a module, some flags, and an
35 : // intrinsic ID. Add an assert to prevent people from accidentally growing
36 : // GlobalValue while adding flags.
37 : static_assert(sizeof(GlobalValue) ==
38 : sizeof(Constant) + 2 * sizeof(void *) + 2 * sizeof(unsigned),
39 : "unexpected GlobalValue size growth");
40 :
41 : // GlobalObject adds a comdat.
42 : static_assert(sizeof(GlobalObject) == sizeof(GlobalValue) + sizeof(void *),
43 : "unexpected GlobalObject size growth");
44 :
45 86197 : bool GlobalValue::isMaterializable() const {
46 : if (const Function *F = dyn_cast<Function>(this))
47 0 : return F->isMaterializable();
48 : return false;
49 : }
50 834913 : Error GlobalValue::materialize() {
51 834913 : return getParent()->materialize(this);
52 : }
53 :
54 : /// Override destroyConstantImpl to make sure it doesn't get called on
55 : /// GlobalValue's because they shouldn't be treated like other constants.
56 0 : void GlobalValue::destroyConstantImpl() {
57 0 : llvm_unreachable("You can't GV->destroyConstantImpl()!");
58 : }
59 :
60 0 : Value *GlobalValue::handleOperandChangeImpl(Value *From, Value *To) {
61 0 : llvm_unreachable("Unsupported class for handleOperandChange()!");
62 : }
63 :
64 : /// copyAttributesFrom - copy all additional attributes (those not needed to
65 : /// create a GlobalValue) from the GlobalValue Src to this one.
66 4451 : void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
67 : setVisibility(Src->getVisibility());
68 : setUnnamedAddr(Src->getUnnamedAddr());
69 : setDLLStorageClass(Src->getDLLStorageClass());
70 : setDSOLocal(Src->isDSOLocal());
71 4451 : }
72 :
73 0 : void GlobalValue::removeFromParent() {
74 0 : switch (getValueID()) {
75 : #define HANDLE_GLOBAL_VALUE(NAME) \
76 : case Value::NAME##Val: \
77 : return static_cast<NAME *>(this)->removeFromParent();
78 : #include "llvm/IR/Value.def"
79 : default:
80 : break;
81 : }
82 0 : llvm_unreachable("not a global");
83 : }
84 :
85 5376 : void GlobalValue::eraseFromParent() {
86 10752 : switch (getValueID()) {
87 : #define HANDLE_GLOBAL_VALUE(NAME) \
88 : case Value::NAME##Val: \
89 : return static_cast<NAME *>(this)->eraseFromParent();
90 : #include "llvm/IR/Value.def"
91 : default:
92 : break;
93 : }
94 0 : llvm_unreachable("not a global");
95 : }
96 :
97 2902963 : unsigned GlobalValue::getAlignment() const {
98 : if (auto *GA = dyn_cast<GlobalAlias>(this)) {
99 : // In general we cannot compute this at the IR level, but we try.
100 3113 : if (const GlobalObject *GO = GA->getBaseObject())
101 3006 : return GO->getAlignment();
102 :
103 : // FIXME: we should also be able to handle:
104 : // Alias = Global + Offset
105 : // Alias = Absolute
106 : return 0;
107 : }
108 2899850 : return cast<GlobalObject>(this)->getAlignment();
109 : }
110 :
111 3065816 : unsigned GlobalValue::getAddressSpace() const {
112 : PointerType *PtrTy = getType();
113 3065816 : return PtrTy->getAddressSpace();
114 : }
115 :
116 1295490 : void GlobalObject::setAlignment(unsigned Align) {
117 : assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
118 : assert(Align <= MaximumAlignment &&
119 : "Alignment is greater than MaximumAlignment!");
120 1295490 : unsigned AlignmentData = Log2_32(Align) + 1;
121 : unsigned OldData = getGlobalValueSubClassData();
122 1295490 : setGlobalValueSubClassData((OldData & ~AlignmentMask) | AlignmentData);
123 : assert(getAlignment() == Align && "Alignment representation error!");
124 1295490 : }
125 :
126 4337 : void GlobalObject::copyAttributesFrom(const GlobalObject *Src) {
127 4337 : GlobalValue::copyAttributesFrom(Src);
128 4337 : setAlignment(Src->getAlignment());
129 4337 : setSection(Src->getSection());
130 4337 : }
131 :
132 11805 : std::string GlobalValue::getGlobalIdentifier(StringRef Name,
133 : GlobalValue::LinkageTypes Linkage,
134 : StringRef FileName) {
135 :
136 : // Value names may be prefixed with a binary '1' to indicate
137 : // that the backend should not modify the symbols due to any platform
138 : // naming convention. Do not include that '1' in the PGO profile name.
139 23610 : if (Name[0] == '\1')
140 54 : Name = Name.substr(1);
141 :
142 : std::string NewName = Name;
143 : if (llvm::GlobalValue::isLocalLinkage(Linkage)) {
144 : // For local symbols, prepend the main file name to distinguish them.
145 : // Do not include the full path in the file name since there's no guarantee
146 : // that it will stay the same, e.g., if the files are checked out from
147 : // version control in different locations.
148 818 : if (FileName.empty())
149 1 : NewName = NewName.insert(0, "<unknown>:");
150 : else
151 2451 : NewName = NewName.insert(0, FileName.str() + ":");
152 : }
153 11805 : return NewName;
154 : }
155 :
156 7399 : std::string GlobalValue::getGlobalIdentifier() const {
157 : return getGlobalIdentifier(getName(), getLinkage(),
158 14798 : getParent()->getSourceFileName());
159 : }
160 :
161 687918 : StringRef GlobalValue::getSection() const {
162 : if (auto *GA = dyn_cast<GlobalAlias>(this)) {
163 : // In general we cannot compute this at the IR level, but we try.
164 135 : if (const GlobalObject *GO = GA->getBaseObject())
165 : return GO->getSection();
166 0 : return "";
167 : }
168 : return cast<GlobalObject>(this)->getSection();
169 : }
170 :
171 2171428 : const Comdat *GlobalValue::getComdat() const {
172 : if (auto *GA = dyn_cast<GlobalAlias>(this)) {
173 : // In general we cannot compute this at the IR level, but we try.
174 5019 : if (const GlobalObject *GO = GA->getBaseObject())
175 4981 : return const_cast<GlobalObject *>(GO)->getComdat();
176 : return nullptr;
177 : }
178 : // ifunc and its resolver are separate things so don't use resolver comdat.
179 2166409 : if (isa<GlobalIFunc>(this))
180 : return nullptr;
181 2166401 : return cast<GlobalObject>(this)->getComdat();
182 : }
183 :
184 30250 : StringRef GlobalObject::getSectionImpl() const {
185 : assert(hasSection());
186 30250 : return getContext().pImpl->GlobalObjectSections[this];
187 : }
188 :
189 352189 : void GlobalObject::setSection(StringRef S) {
190 : // Do nothing if we're clearing the section and it is already empty.
191 352189 : if (!hasSection() && S.empty())
192 : return;
193 :
194 : // Get or create a stable section name string and put it in the table in the
195 : // context.
196 24698 : if (!S.empty()) {
197 24697 : S = getContext().pImpl->SectionStrings.insert(S).first->first();
198 : }
199 24698 : getContext().pImpl->GlobalObjectSections[this] = S;
200 :
201 : // Update the HasSectionHashEntryBit. Setting the section to the empty string
202 : // means this global no longer has a section.
203 : setGlobalObjectFlag(HasSectionHashEntryBit, !S.empty());
204 : }
205 :
206 86156628 : bool GlobalValue::isDeclaration() const {
207 : // Globals are definitions if they have an initializer.
208 : if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
209 47316041 : return GV->getNumOperands() == 0;
210 :
211 : // Functions are definitions if they have a body.
212 : if (const Function *F = dyn_cast<Function>(this))
213 38831131 : return F->empty() && !F->isMaterializable();
214 :
215 : // Aliases and ifuncs are always definitions.
216 : assert(isa<GlobalIndirectSymbol>(this));
217 : return false;
218 : }
219 :
220 13997 : bool GlobalValue::canIncreaseAlignment() const {
221 : // Firstly, can only increase the alignment of a global if it
222 : // is a strong definition.
223 13997 : if (!isStrongDefinitionForLinker())
224 : return false;
225 :
226 : // It also has to either not have a section defined, or, not have
227 : // alignment specified. (If it is assigned a section, the global
228 : // could be densely packed with other objects in the section, and
229 : // increasing the alignment could cause padding issues.)
230 13833 : if (hasSection() && getAlignment() > 0)
231 : return false;
232 :
233 : // On ELF platforms, we're further restricted in that we can't
234 : // increase the alignment of any variable which might be emitted
235 : // into a shared library, and which is exported. If the main
236 : // executable accesses a variable found in a shared-lib, the main
237 : // exe actually allocates memory for and exports the symbol ITSELF,
238 : // overriding the symbol found in the library. That is, at link
239 : // time, the observed alignment of the variable is copied into the
240 : // executable binary. (A COPY relocation is also generated, to copy
241 : // the initial data from the shadowed variable in the shared-lib
242 : // into the location in the main binary, before running code.)
243 : //
244 : // And thus, even though you might think you are defining the
245 : // global, and allocating the memory for the global in your object
246 : // file, and thus should be able to set the alignment arbitrarily,
247 : // that's not actually true. Doing so can cause an ABI breakage; an
248 : // executable might have already been built with the previous
249 : // alignment of the variable, and then assuming an increased
250 : // alignment will be incorrect.
251 :
252 : // Conservatively assume ELF if there's no parent pointer.
253 : bool isELF =
254 13815 : (!Parent || Triple(Parent->getTargetTriple()).isOSBinFormatELF());
255 13815 : if (isELF && hasDefaultVisibility() && !hasLocalLinkage())
256 28 : return false;
257 :
258 : return true;
259 : }
260 :
261 47790 : const GlobalObject *GlobalValue::getBaseObject() const {
262 : if (auto *GO = dyn_cast<GlobalObject>(this))
263 : return GO;
264 : if (auto *GA = dyn_cast<GlobalIndirectSymbol>(this))
265 690 : return GA->getBaseObject();
266 : return nullptr;
267 : }
268 :
269 1143060 : bool GlobalValue::isAbsoluteSymbolRef() const {
270 : auto *GO = dyn_cast<GlobalObject>(this);
271 : if (!GO)
272 : return false;
273 :
274 1142942 : return GO->getMetadata(LLVMContext::MD_absolute_symbol);
275 : }
276 :
277 2752966 : Optional<ConstantRange> GlobalValue::getAbsoluteSymbolRange() const {
278 : auto *GO = dyn_cast<GlobalObject>(this);
279 : if (!GO)
280 : return None;
281 :
282 2752829 : MDNode *MD = GO->getMetadata(LLVMContext::MD_absolute_symbol);
283 2752829 : if (!MD)
284 : return None;
285 :
286 54 : return getConstantRangeFromMetadata(*MD);
287 : }
288 :
289 20290 : bool GlobalValue::canBeOmittedFromSymbolTable() const {
290 20290 : if (!hasLinkOnceODRLinkage())
291 : return false;
292 :
293 : // We assume that anyone who sets global unnamed_addr on a non-constant
294 : // knows what they're doing.
295 1918 : if (hasGlobalUnnamedAddr())
296 : return true;
297 :
298 : // If it is a non constant variable, it needs to be uniqued across shared
299 : // objects.
300 : if (auto *Var = dyn_cast<GlobalVariable>(this))
301 29 : if (!Var->isConstant())
302 : return false;
303 :
304 548 : return hasAtLeastLocalUnnamedAddr();
305 : }
306 :
307 : //===----------------------------------------------------------------------===//
308 : // GlobalVariable Implementation
309 : //===----------------------------------------------------------------------===//
310 :
311 1364 : GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link,
312 : Constant *InitVal, const Twine &Name,
313 : ThreadLocalMode TLMode, unsigned AddressSpace,
314 1364 : bool isExternallyInitialized)
315 : : GlobalObject(Ty, Value::GlobalVariableVal,
316 : OperandTraits<GlobalVariable>::op_begin(this),
317 : InitVal != nullptr, Link, Name, AddressSpace),
318 : isConstantGlobal(constant),
319 1364 : isExternallyInitializedConstant(isExternallyInitialized) {
320 : assert(!Ty->isFunctionTy() && PointerType::isValidElementType(Ty) &&
321 : "invalid type for global variable");
322 : setThreadLocalMode(TLMode);
323 1364 : if (InitVal) {
324 : assert(InitVal->getType() == Ty &&
325 : "Initializer should be the same type as the GlobalVariable!");
326 : Op<0>() = InitVal;
327 : }
328 1364 : }
329 :
330 403708 : GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
331 : LinkageTypes Link, Constant *InitVal,
332 : const Twine &Name, GlobalVariable *Before,
333 : ThreadLocalMode TLMode, unsigned AddressSpace,
334 403708 : bool isExternallyInitialized)
335 : : GlobalObject(Ty, Value::GlobalVariableVal,
336 : OperandTraits<GlobalVariable>::op_begin(this),
337 : InitVal != nullptr, Link, Name, AddressSpace),
338 : isConstantGlobal(constant),
339 403708 : isExternallyInitializedConstant(isExternallyInitialized) {
340 : assert(!Ty->isFunctionTy() && PointerType::isValidElementType(Ty) &&
341 : "invalid type for global variable");
342 : setThreadLocalMode(TLMode);
343 403708 : if (InitVal) {
344 : assert(InitVal->getType() == Ty &&
345 : "Initializer should be the same type as the GlobalVariable!");
346 : Op<0>() = InitVal;
347 : }
348 :
349 403708 : if (Before)
350 340 : Before->getParent()->getGlobalList().insert(Before->getIterator(), this);
351 : else
352 403368 : M.getGlobalList().push_back(this);
353 403708 : }
354 :
355 155 : void GlobalVariable::removeFromParent() {
356 155 : getParent()->getGlobalList().remove(getIterator());
357 155 : }
358 :
359 3163 : void GlobalVariable::eraseFromParent() {
360 3163 : getParent()->getGlobalList().erase(getIterator());
361 3163 : }
362 :
363 84904 : void GlobalVariable::setInitializer(Constant *InitVal) {
364 84904 : if (!InitVal) {
365 157 : if (hasInitializer()) {
366 : // Note, the num operands is used to compute the offset of the operand, so
367 : // the order here matters. Clearing the operand then clearing the num
368 : // operands ensures we have the correct offset to the operand.
369 : Op<0>().set(nullptr);
370 : setGlobalVariableNumOperands(0);
371 : }
372 : } else {
373 : assert(InitVal->getType() == getValueType() &&
374 : "Initializer type must match GlobalVariable type");
375 : // Note, the num operands is used to compute the offset of the operand, so
376 : // the order here matters. We need to set num operands to 1 first so that
377 : // we get the correct offset to the first operand when we set it.
378 84747 : if (!hasInitializer())
379 : setGlobalVariableNumOperands(1);
380 84747 : Op<0>().set(InitVal);
381 : }
382 84904 : }
383 :
384 : /// Copy all additional attributes (those not needed to create a GlobalVariable)
385 : /// from the GlobalVariable Src to this one.
386 1068 : void GlobalVariable::copyAttributesFrom(const GlobalVariable *Src) {
387 1068 : GlobalObject::copyAttributesFrom(Src);
388 : setThreadLocalMode(Src->getThreadLocalMode());
389 : setExternallyInitialized(Src->isExternallyInitialized());
390 : setAttributes(Src->getAttributes());
391 1068 : }
392 :
393 260083 : void GlobalVariable::dropAllReferences() {
394 260083 : User::dropAllReferences();
395 260083 : clearMetadata();
396 260083 : }
397 :
398 : //===----------------------------------------------------------------------===//
399 : // GlobalIndirectSymbol Implementation
400 : //===----------------------------------------------------------------------===//
401 :
402 3246 : GlobalIndirectSymbol::GlobalIndirectSymbol(Type *Ty, ValueTy VTy,
403 : unsigned AddressSpace, LinkageTypes Linkage, const Twine &Name,
404 3246 : Constant *Symbol)
405 6492 : : GlobalValue(Ty, VTy, &Op<0>(), 1, Linkage, Name, AddressSpace) {
406 : Op<0>() = Symbol;
407 3246 : }
408 :
409 :
410 : //===----------------------------------------------------------------------===//
411 : // GlobalAlias Implementation
412 : //===----------------------------------------------------------------------===//
413 :
414 3112 : GlobalAlias::GlobalAlias(Type *Ty, unsigned AddressSpace, LinkageTypes Link,
415 : const Twine &Name, Constant *Aliasee,
416 3112 : Module *ParentModule)
417 : : GlobalIndirectSymbol(Ty, Value::GlobalAliasVal, AddressSpace, Link, Name,
418 3112 : Aliasee) {
419 3112 : if (ParentModule)
420 2137 : ParentModule->getAliasList().push_back(this);
421 3112 : }
422 :
423 3112 : GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
424 : LinkageTypes Link, const Twine &Name,
425 : Constant *Aliasee, Module *ParentModule) {
426 3112 : return new GlobalAlias(Ty, AddressSpace, Link, Name, Aliasee, ParentModule);
427 : }
428 :
429 990 : GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
430 : LinkageTypes Linkage, const Twine &Name,
431 : Module *Parent) {
432 990 : return create(Ty, AddressSpace, Linkage, Name, nullptr, Parent);
433 : }
434 :
435 545 : GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
436 : LinkageTypes Linkage, const Twine &Name,
437 : GlobalValue *Aliasee) {
438 545 : return create(Ty, AddressSpace, Linkage, Name, Aliasee, Aliasee->getParent());
439 : }
440 :
441 545 : GlobalAlias *GlobalAlias::create(LinkageTypes Link, const Twine &Name,
442 : GlobalValue *Aliasee) {
443 : PointerType *PTy = Aliasee->getType();
444 545 : return create(PTy->getElementType(), PTy->getAddressSpace(), Link, Name,
445 545 : Aliasee);
446 : }
447 :
448 4 : GlobalAlias *GlobalAlias::create(const Twine &Name, GlobalValue *Aliasee) {
449 4 : return create(Aliasee->getLinkage(), Name, Aliasee);
450 : }
451 :
452 9 : void GlobalAlias::removeFromParent() {
453 9 : getParent()->getAliasList().remove(getIterator());
454 9 : }
455 :
456 120 : void GlobalAlias::eraseFromParent() {
457 120 : getParent()->getAliasList().erase(getIterator());
458 120 : }
459 :
460 122 : void GlobalAlias::setAliasee(Constant *Aliasee) {
461 : assert((!Aliasee || Aliasee->getType() == getType()) &&
462 : "Alias and aliasee types should match!");
463 : setIndirectSymbol(Aliasee);
464 122 : }
465 :
466 : //===----------------------------------------------------------------------===//
467 : // GlobalIFunc Implementation
468 : //===----------------------------------------------------------------------===//
469 :
470 134 : GlobalIFunc::GlobalIFunc(Type *Ty, unsigned AddressSpace, LinkageTypes Link,
471 : const Twine &Name, Constant *Resolver,
472 134 : Module *ParentModule)
473 : : GlobalIndirectSymbol(Ty, Value::GlobalIFuncVal, AddressSpace, Link, Name,
474 134 : Resolver) {
475 134 : if (ParentModule)
476 93 : ParentModule->getIFuncList().push_back(this);
477 134 : }
478 :
479 134 : GlobalIFunc *GlobalIFunc::create(Type *Ty, unsigned AddressSpace,
480 : LinkageTypes Link, const Twine &Name,
481 : Constant *Resolver, Module *ParentModule) {
482 134 : return new GlobalIFunc(Ty, AddressSpace, Link, Name, Resolver, ParentModule);
483 : }
484 :
485 0 : void GlobalIFunc::removeFromParent() {
486 0 : getParent()->getIFuncList().remove(getIterator());
487 0 : }
488 :
489 6 : void GlobalIFunc::eraseFromParent() {
490 6 : getParent()->getIFuncList().erase(getIterator());
491 6 : }
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