xref: /llvm-project/llvm/lib/IR/Module.cpp (revision 6bcf2ba2f0fff179602fd60b5e0127cd20fc907e)
1 //===- Module.cpp - Implement the Module 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 Module class for the IR library.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/IR/Module.h"
15 #include "SymbolTableListTraitsImpl.h"
16 #include "llvm/ADT/SmallPtrSet.h"
17 #include "llvm/ADT/SmallString.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/ADT/Twine.h"
22 #include "llvm/IR/Attributes.h"
23 #include "llvm/IR/Comdat.h"
24 #include "llvm/IR/Constants.h"
25 #include "llvm/IR/DataLayout.h"
26 #include "llvm/IR/DebugInfoMetadata.h"
27 #include "llvm/IR/DerivedTypes.h"
28 #include "llvm/IR/Function.h"
29 #include "llvm/IR/GVMaterializer.h"
30 #include "llvm/IR/GlobalAlias.h"
31 #include "llvm/IR/GlobalIFunc.h"
32 #include "llvm/IR/GlobalValue.h"
33 #include "llvm/IR/GlobalVariable.h"
34 #include "llvm/IR/LLVMContext.h"
35 #include "llvm/IR/Metadata.h"
36 #include "llvm/IR/SymbolTableListTraits.h"
37 #include "llvm/IR/Type.h"
38 #include "llvm/IR/TypeFinder.h"
39 #include "llvm/IR/Value.h"
40 #include "llvm/IR/ValueSymbolTable.h"
41 #include "llvm/Pass.h"
42 #include "llvm/Support/Casting.h"
43 #include "llvm/Support/CodeGen.h"
44 #include "llvm/Support/Error.h"
45 #include "llvm/Support/MemoryBuffer.h"
46 #include "llvm/Support/Path.h"
47 #include "llvm/Support/RandomNumberGenerator.h"
48 #include <algorithm>
49 #include <cassert>
50 #include <cstdint>
51 #include <memory>
52 #include <utility>
53 #include <vector>
54 
55 using namespace llvm;
56 
57 //===----------------------------------------------------------------------===//
58 // Methods to implement the globals and functions lists.
59 //
60 
61 // Explicit instantiations of SymbolTableListTraits since some of the methods
62 // are not in the public header file.
63 template class llvm::SymbolTableListTraits<Function>;
64 template class llvm::SymbolTableListTraits<GlobalVariable>;
65 template class llvm::SymbolTableListTraits<GlobalAlias>;
66 template class llvm::SymbolTableListTraits<GlobalIFunc>;
67 
68 //===----------------------------------------------------------------------===//
69 // Primitive Module methods.
70 //
71 
72 Module::Module(StringRef MID, LLVMContext &C)
73     : Context(C), Materializer(), ModuleID(MID), SourceFileName(MID), DL("") {
74   ValSymTab = new ValueSymbolTable();
75   NamedMDSymTab = new StringMap<NamedMDNode *>();
76   Context.addModule(this);
77 }
78 
79 Module::~Module() {
80   Context.removeModule(this);
81   dropAllReferences();
82   GlobalList.clear();
83   FunctionList.clear();
84   AliasList.clear();
85   IFuncList.clear();
86   NamedMDList.clear();
87   delete ValSymTab;
88   delete static_cast<StringMap<NamedMDNode *> *>(NamedMDSymTab);
89 }
90 
91 std::unique_ptr<RandomNumberGenerator> Module::createRNG(const Pass* P) const {
92   SmallString<32> Salt(P->getPassName());
93 
94   // This RNG is guaranteed to produce the same random stream only
95   // when the Module ID and thus the input filename is the same. This
96   // might be problematic if the input filename extension changes
97   // (e.g. from .c to .bc or .ll).
98   //
99   // We could store this salt in NamedMetadata, but this would make
100   // the parameter non-const. This would unfortunately make this
101   // interface unusable by any Machine passes, since they only have a
102   // const reference to their IR Module. Alternatively we can always
103   // store salt metadata from the Module constructor.
104   Salt += sys::path::filename(getModuleIdentifier());
105 
106   return std::unique_ptr<RandomNumberGenerator>(new RandomNumberGenerator(Salt));
107 }
108 
109 /// getNamedValue - Return the first global value in the module with
110 /// the specified name, of arbitrary type.  This method returns null
111 /// if a global with the specified name is not found.
112 GlobalValue *Module::getNamedValue(StringRef Name) const {
113   return cast_or_null<GlobalValue>(getValueSymbolTable().lookup(Name));
114 }
115 
116 /// getMDKindID - Return a unique non-zero ID for the specified metadata kind.
117 /// This ID is uniqued across modules in the current LLVMContext.
118 unsigned Module::getMDKindID(StringRef Name) const {
119   return Context.getMDKindID(Name);
120 }
121 
122 /// getMDKindNames - Populate client supplied SmallVector with the name for
123 /// custom metadata IDs registered in this LLVMContext.   ID #0 is not used,
124 /// so it is filled in as an empty string.
125 void Module::getMDKindNames(SmallVectorImpl<StringRef> &Result) const {
126   return Context.getMDKindNames(Result);
127 }
128 
129 void Module::getOperandBundleTags(SmallVectorImpl<StringRef> &Result) const {
130   return Context.getOperandBundleTags(Result);
131 }
132 
133 //===----------------------------------------------------------------------===//
134 // Methods for easy access to the functions in the module.
135 //
136 
137 // getOrInsertFunction - Look up the specified function in the module symbol
138 // table.  If it does not exist, add a prototype for the function and return
139 // it.  This is nice because it allows most passes to get away with not handling
140 // the symbol table directly for this common task.
141 //
142 Constant *Module::getOrInsertFunction(StringRef Name, FunctionType *Ty,
143                                       AttributeList AttributeList) {
144   // See if we have a definition for the specified function already.
145   GlobalValue *F = getNamedValue(Name);
146   if (!F) {
147     // Nope, add it
148     Function *New = Function::Create(Ty, GlobalVariable::ExternalLinkage,
149                                      DL.getProgramAddressSpace(), Name);
150     if (!New->isIntrinsic())       // Intrinsics get attrs set on construction
151       New->setAttributes(AttributeList);
152     FunctionList.push_back(New);
153     return New;                    // Return the new prototype.
154   }
155 
156   // If the function exists but has the wrong type, return a bitcast to the
157   // right type.
158   auto *PTy = PointerType::get(Ty, F->getAddressSpace());
159   if (F->getType() != PTy)
160     return ConstantExpr::getBitCast(F, PTy);
161 
162   // Otherwise, we just found the existing function or a prototype.
163   return F;
164 }
165 
166 Constant *Module::getOrInsertFunction(StringRef Name,
167                                       FunctionType *Ty) {
168   return getOrInsertFunction(Name, Ty, AttributeList());
169 }
170 
171 // getFunction - Look up the specified function in the module symbol table.
172 // If it does not exist, return null.
173 //
174 Function *Module::getFunction(StringRef Name) const {
175   return dyn_cast_or_null<Function>(getNamedValue(Name));
176 }
177 
178 //===----------------------------------------------------------------------===//
179 // Methods for easy access to the global variables in the module.
180 //
181 
182 /// getGlobalVariable - Look up the specified global variable in the module
183 /// symbol table.  If it does not exist, return null.  The type argument
184 /// should be the underlying type of the global, i.e., it should not have
185 /// the top-level PointerType, which represents the address of the global.
186 /// If AllowLocal is set to true, this function will return types that
187 /// have an local. By default, these types are not returned.
188 ///
189 GlobalVariable *Module::getGlobalVariable(StringRef Name,
190                                           bool AllowLocal) const {
191   if (GlobalVariable *Result =
192       dyn_cast_or_null<GlobalVariable>(getNamedValue(Name)))
193     if (AllowLocal || !Result->hasLocalLinkage())
194       return Result;
195   return nullptr;
196 }
197 
198 /// getOrInsertGlobal - Look up the specified global in the module symbol table.
199 ///   1. If it does not exist, add a declaration of the global and return it.
200 ///   2. Else, the global exists but has the wrong type: return the function
201 ///      with a constantexpr cast to the right type.
202 ///   3. Finally, if the existing global is the correct declaration, return the
203 ///      existing global.
204 Constant *Module::getOrInsertGlobal(StringRef Name, Type *Ty) {
205   // See if we have a definition for the specified global already.
206   GlobalVariable *GV = dyn_cast_or_null<GlobalVariable>(getNamedValue(Name));
207   if (!GV) {
208     // Nope, add it
209     GlobalVariable *New =
210       new GlobalVariable(*this, Ty, false, GlobalVariable::ExternalLinkage,
211                          nullptr, Name);
212      return New;                    // Return the new declaration.
213   }
214 
215   // If the variable exists but has the wrong type, return a bitcast to the
216   // right type.
217   Type *GVTy = GV->getType();
218   PointerType *PTy = PointerType::get(Ty, GVTy->getPointerAddressSpace());
219   if (GVTy != PTy)
220     return ConstantExpr::getBitCast(GV, PTy);
221 
222   // Otherwise, we just found the existing function or a prototype.
223   return GV;
224 }
225 
226 //===----------------------------------------------------------------------===//
227 // Methods for easy access to the global variables in the module.
228 //
229 
230 // getNamedAlias - Look up the specified global in the module symbol table.
231 // If it does not exist, return null.
232 //
233 GlobalAlias *Module::getNamedAlias(StringRef Name) const {
234   return dyn_cast_or_null<GlobalAlias>(getNamedValue(Name));
235 }
236 
237 GlobalIFunc *Module::getNamedIFunc(StringRef Name) const {
238   return dyn_cast_or_null<GlobalIFunc>(getNamedValue(Name));
239 }
240 
241 /// getNamedMetadata - Return the first NamedMDNode in the module with the
242 /// specified name. This method returns null if a NamedMDNode with the
243 /// specified name is not found.
244 NamedMDNode *Module::getNamedMetadata(const Twine &Name) const {
245   SmallString<256> NameData;
246   StringRef NameRef = Name.toStringRef(NameData);
247   return static_cast<StringMap<NamedMDNode*> *>(NamedMDSymTab)->lookup(NameRef);
248 }
249 
250 /// getOrInsertNamedMetadata - Return the first named MDNode in the module
251 /// with the specified name. This method returns a new NamedMDNode if a
252 /// NamedMDNode with the specified name is not found.
253 NamedMDNode *Module::getOrInsertNamedMetadata(StringRef Name) {
254   NamedMDNode *&NMD =
255     (*static_cast<StringMap<NamedMDNode *> *>(NamedMDSymTab))[Name];
256   if (!NMD) {
257     NMD = new NamedMDNode(Name);
258     NMD->setParent(this);
259     NamedMDList.push_back(NMD);
260   }
261   return NMD;
262 }
263 
264 /// eraseNamedMetadata - Remove the given NamedMDNode from this module and
265 /// delete it.
266 void Module::eraseNamedMetadata(NamedMDNode *NMD) {
267   static_cast<StringMap<NamedMDNode *> *>(NamedMDSymTab)->erase(NMD->getName());
268   NamedMDList.erase(NMD->getIterator());
269 }
270 
271 bool Module::isValidModFlagBehavior(Metadata *MD, ModFlagBehavior &MFB) {
272   if (ConstantInt *Behavior = mdconst::dyn_extract_or_null<ConstantInt>(MD)) {
273     uint64_t Val = Behavior->getLimitedValue();
274     if (Val >= ModFlagBehaviorFirstVal && Val <= ModFlagBehaviorLastVal) {
275       MFB = static_cast<ModFlagBehavior>(Val);
276       return true;
277     }
278   }
279   return false;
280 }
281 
282 /// getModuleFlagsMetadata - Returns the module flags in the provided vector.
283 void Module::
284 getModuleFlagsMetadata(SmallVectorImpl<ModuleFlagEntry> &Flags) const {
285   const NamedMDNode *ModFlags = getModuleFlagsMetadata();
286   if (!ModFlags) return;
287 
288   for (const MDNode *Flag : ModFlags->operands()) {
289     ModFlagBehavior MFB;
290     if (Flag->getNumOperands() >= 3 &&
291         isValidModFlagBehavior(Flag->getOperand(0), MFB) &&
292         dyn_cast_or_null<MDString>(Flag->getOperand(1))) {
293       // Check the operands of the MDNode before accessing the operands.
294       // The verifier will actually catch these failures.
295       MDString *Key = cast<MDString>(Flag->getOperand(1));
296       Metadata *Val = Flag->getOperand(2);
297       Flags.push_back(ModuleFlagEntry(MFB, Key, Val));
298     }
299   }
300 }
301 
302 /// Return the corresponding value if Key appears in module flags, otherwise
303 /// return null.
304 Metadata *Module::getModuleFlag(StringRef Key) const {
305   SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
306   getModuleFlagsMetadata(ModuleFlags);
307   for (const ModuleFlagEntry &MFE : ModuleFlags) {
308     if (Key == MFE.Key->getString())
309       return MFE.Val;
310   }
311   return nullptr;
312 }
313 
314 /// getModuleFlagsMetadata - Returns the NamedMDNode in the module that
315 /// represents module-level flags. This method returns null if there are no
316 /// module-level flags.
317 NamedMDNode *Module::getModuleFlagsMetadata() const {
318   return getNamedMetadata("llvm.module.flags");
319 }
320 
321 /// getOrInsertModuleFlagsMetadata - Returns the NamedMDNode in the module that
322 /// represents module-level flags. If module-level flags aren't found, it
323 /// creates the named metadata that contains them.
324 NamedMDNode *Module::getOrInsertModuleFlagsMetadata() {
325   return getOrInsertNamedMetadata("llvm.module.flags");
326 }
327 
328 /// addModuleFlag - Add a module-level flag to the module-level flags
329 /// metadata. It will create the module-level flags named metadata if it doesn't
330 /// already exist.
331 void Module::addModuleFlag(ModFlagBehavior Behavior, StringRef Key,
332                            Metadata *Val) {
333   Type *Int32Ty = Type::getInt32Ty(Context);
334   Metadata *Ops[3] = {
335       ConstantAsMetadata::get(ConstantInt::get(Int32Ty, Behavior)),
336       MDString::get(Context, Key), Val};
337   getOrInsertModuleFlagsMetadata()->addOperand(MDNode::get(Context, Ops));
338 }
339 void Module::addModuleFlag(ModFlagBehavior Behavior, StringRef Key,
340                            Constant *Val) {
341   addModuleFlag(Behavior, Key, ConstantAsMetadata::get(Val));
342 }
343 void Module::addModuleFlag(ModFlagBehavior Behavior, StringRef Key,
344                            uint32_t Val) {
345   Type *Int32Ty = Type::getInt32Ty(Context);
346   addModuleFlag(Behavior, Key, ConstantInt::get(Int32Ty, Val));
347 }
348 void Module::addModuleFlag(MDNode *Node) {
349   assert(Node->getNumOperands() == 3 &&
350          "Invalid number of operands for module flag!");
351   assert(mdconst::hasa<ConstantInt>(Node->getOperand(0)) &&
352          isa<MDString>(Node->getOperand(1)) &&
353          "Invalid operand types for module flag!");
354   getOrInsertModuleFlagsMetadata()->addOperand(Node);
355 }
356 
357 void Module::setDataLayout(StringRef Desc) {
358   DL.reset(Desc);
359 }
360 
361 void Module::setDataLayout(const DataLayout &Other) { DL = Other; }
362 
363 const DataLayout &Module::getDataLayout() const { return DL; }
364 
365 DICompileUnit *Module::debug_compile_units_iterator::operator*() const {
366   return cast<DICompileUnit>(CUs->getOperand(Idx));
367 }
368 DICompileUnit *Module::debug_compile_units_iterator::operator->() const {
369   return cast<DICompileUnit>(CUs->getOperand(Idx));
370 }
371 
372 void Module::debug_compile_units_iterator::SkipNoDebugCUs() {
373   while (CUs && (Idx < CUs->getNumOperands()) &&
374          ((*this)->getEmissionKind() == DICompileUnit::NoDebug))
375     ++Idx;
376 }
377 
378 //===----------------------------------------------------------------------===//
379 // Methods to control the materialization of GlobalValues in the Module.
380 //
381 void Module::setMaterializer(GVMaterializer *GVM) {
382   assert(!Materializer &&
383          "Module already has a GVMaterializer.  Call materializeAll"
384          " to clear it out before setting another one.");
385   Materializer.reset(GVM);
386 }
387 
388 Error Module::materialize(GlobalValue *GV) {
389   if (!Materializer)
390     return Error::success();
391 
392   return Materializer->materialize(GV);
393 }
394 
395 Error Module::materializeAll() {
396   if (!Materializer)
397     return Error::success();
398   std::unique_ptr<GVMaterializer> M = std::move(Materializer);
399   return M->materializeModule();
400 }
401 
402 Error Module::materializeMetadata() {
403   if (!Materializer)
404     return Error::success();
405   return Materializer->materializeMetadata();
406 }
407 
408 //===----------------------------------------------------------------------===//
409 // Other module related stuff.
410 //
411 
412 std::vector<StructType *> Module::getIdentifiedStructTypes() const {
413   // If we have a materializer, it is possible that some unread function
414   // uses a type that is currently not visible to a TypeFinder, so ask
415   // the materializer which types it created.
416   if (Materializer)
417     return Materializer->getIdentifiedStructTypes();
418 
419   std::vector<StructType *> Ret;
420   TypeFinder SrcStructTypes;
421   SrcStructTypes.run(*this, true);
422   Ret.assign(SrcStructTypes.begin(), SrcStructTypes.end());
423   return Ret;
424 }
425 
426 // dropAllReferences() - This function causes all the subelements to "let go"
427 // of all references that they are maintaining.  This allows one to 'delete' a
428 // whole module at a time, even though there may be circular references... first
429 // all references are dropped, and all use counts go to zero.  Then everything
430 // is deleted for real.  Note that no operations are valid on an object that
431 // has "dropped all references", except operator delete.
432 //
433 void Module::dropAllReferences() {
434   for (Function &F : *this)
435     F.dropAllReferences();
436 
437   for (GlobalVariable &GV : globals())
438     GV.dropAllReferences();
439 
440   for (GlobalAlias &GA : aliases())
441     GA.dropAllReferences();
442 
443   for (GlobalIFunc &GIF : ifuncs())
444     GIF.dropAllReferences();
445 }
446 
447 unsigned Module::getNumberRegisterParameters() const {
448   auto *Val =
449       cast_or_null<ConstantAsMetadata>(getModuleFlag("NumRegisterParameters"));
450   if (!Val)
451     return 0;
452   return cast<ConstantInt>(Val->getValue())->getZExtValue();
453 }
454 
455 unsigned Module::getDwarfVersion() const {
456   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("Dwarf Version"));
457   if (!Val)
458     return 0;
459   return cast<ConstantInt>(Val->getValue())->getZExtValue();
460 }
461 
462 unsigned Module::getCodeViewFlag() const {
463   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("CodeView"));
464   if (!Val)
465     return 0;
466   return cast<ConstantInt>(Val->getValue())->getZExtValue();
467 }
468 
469 unsigned Module::getInstructionCount() {
470   unsigned NumInstrs = 0;
471   for (Function &F : FunctionList)
472     NumInstrs += F.getInstructionCount();
473   return NumInstrs;
474 }
475 
476 Comdat *Module::getOrInsertComdat(StringRef Name) {
477   auto &Entry = *ComdatSymTab.insert(std::make_pair(Name, Comdat())).first;
478   Entry.second.Name = &Entry;
479   return &Entry.second;
480 }
481 
482 PICLevel::Level Module::getPICLevel() const {
483   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("PIC Level"));
484 
485   if (!Val)
486     return PICLevel::NotPIC;
487 
488   return static_cast<PICLevel::Level>(
489       cast<ConstantInt>(Val->getValue())->getZExtValue());
490 }
491 
492 void Module::setPICLevel(PICLevel::Level PL) {
493   addModuleFlag(ModFlagBehavior::Max, "PIC Level", PL);
494 }
495 
496 PIELevel::Level Module::getPIELevel() const {
497   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("PIE Level"));
498 
499   if (!Val)
500     return PIELevel::Default;
501 
502   return static_cast<PIELevel::Level>(
503       cast<ConstantInt>(Val->getValue())->getZExtValue());
504 }
505 
506 void Module::setPIELevel(PIELevel::Level PL) {
507   addModuleFlag(ModFlagBehavior::Max, "PIE Level", PL);
508 }
509 
510 void Module::setProfileSummary(Metadata *M) {
511   addModuleFlag(ModFlagBehavior::Error, "ProfileSummary", M);
512 }
513 
514 Metadata *Module::getProfileSummary() {
515   return getModuleFlag("ProfileSummary");
516 }
517 
518 void Module::setOwnedMemoryBuffer(std::unique_ptr<MemoryBuffer> MB) {
519   OwnedMemoryBuffer = std::move(MB);
520 }
521 
522 bool Module::getRtLibUseGOT() const {
523   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("RtLibUseGOT"));
524   return Val && (cast<ConstantInt>(Val->getValue())->getZExtValue() > 0);
525 }
526 
527 void Module::setRtLibUseGOT() {
528   addModuleFlag(ModFlagBehavior::Max, "RtLibUseGOT", 1);
529 }
530 
531 GlobalVariable *llvm::collectUsedGlobalVariables(
532     const Module &M, SmallPtrSetImpl<GlobalValue *> &Set, bool CompilerUsed) {
533   const char *Name = CompilerUsed ? "llvm.compiler.used" : "llvm.used";
534   GlobalVariable *GV = M.getGlobalVariable(Name);
535   if (!GV || !GV->hasInitializer())
536     return GV;
537 
538   const ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
539   for (Value *Op : Init->operands()) {
540     GlobalValue *G = cast<GlobalValue>(Op->stripPointerCastsNoFollowAliases());
541     Set.insert(G);
542   }
543   return GV;
544 }
545