1 //===- DebugInfo.cpp - Debug Information Helper Classes -------------------===//
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 helper classes used to build and interpret debug
11 // information in LLVM IR form.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm-c/DebugInfo.h"
16 #include "llvm/ADT/DenseMap.h"
17 #include "llvm/ADT/DenseSet.h"
18 #include "llvm/ADT/None.h"
19 #include "llvm/ADT/STLExtras.h"
20 #include "llvm/ADT/SmallPtrSet.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/StringRef.h"
23 #include "llvm/IR/BasicBlock.h"
24 #include "llvm/IR/Constants.h"
25 #include "llvm/IR/DebugInfoMetadata.h"
26 #include "llvm/IR/DebugLoc.h"
27 #include "llvm/IR/DebugInfo.h"
28 #include "llvm/IR/DIBuilder.h"
29 #include "llvm/IR/Function.h"
30 #include "llvm/IR/GVMaterializer.h"
31 #include "llvm/IR/Instruction.h"
32 #include "llvm/IR/IntrinsicInst.h"
33 #include "llvm/IR/LLVMContext.h"
34 #include "llvm/IR/Metadata.h"
35 #include "llvm/IR/Module.h"
36 #include "llvm/Support/Casting.h"
37 #include <algorithm>
38 #include <cassert>
39 #include <utility>
40 
41 using namespace llvm;
42 using namespace llvm::dwarf;
43 
44 DISubprogram *llvm::getDISubprogram(const MDNode *Scope) {
45   if (auto *LocalScope = dyn_cast_or_null<DILocalScope>(Scope))
46     return LocalScope->getSubprogram();
47   return nullptr;
48 }
49 
50 //===----------------------------------------------------------------------===//
51 // DebugInfoFinder implementations.
52 //===----------------------------------------------------------------------===//
53 
54 void DebugInfoFinder::reset() {
55   CUs.clear();
56   SPs.clear();
57   GVs.clear();
58   TYs.clear();
59   Scopes.clear();
60   NodesSeen.clear();
61 }
62 
63 void DebugInfoFinder::processModule(const Module &M) {
64   for (auto *CU : M.debug_compile_units()) {
65     addCompileUnit(CU);
66     for (auto DIG : CU->getGlobalVariables()) {
67       if (!addGlobalVariable(DIG))
68         continue;
69       auto *GV = DIG->getVariable();
70       processScope(GV->getScope());
71       processType(GV->getType().resolve());
72     }
73     for (auto *ET : CU->getEnumTypes())
74       processType(ET);
75     for (auto *RT : CU->getRetainedTypes())
76       if (auto *T = dyn_cast<DIType>(RT))
77         processType(T);
78       else
79         processSubprogram(cast<DISubprogram>(RT));
80     for (auto *Import : CU->getImportedEntities()) {
81       auto *Entity = Import->getEntity().resolve();
82       if (auto *T = dyn_cast<DIType>(Entity))
83         processType(T);
84       else if (auto *SP = dyn_cast<DISubprogram>(Entity))
85         processSubprogram(SP);
86       else if (auto *NS = dyn_cast<DINamespace>(Entity))
87         processScope(NS->getScope());
88       else if (auto *M = dyn_cast<DIModule>(Entity))
89         processScope(M->getScope());
90     }
91   }
92   for (auto &F : M.functions()) {
93     if (auto *SP = cast_or_null<DISubprogram>(F.getSubprogram()))
94       processSubprogram(SP);
95     // There could be subprograms from inlined functions referenced from
96     // instructions only. Walk the function to find them.
97     for (const BasicBlock &BB : F) {
98       for (const Instruction &I : BB) {
99         if (!I.getDebugLoc())
100           continue;
101         processLocation(M, I.getDebugLoc().get());
102       }
103     }
104   }
105 }
106 
107 void DebugInfoFinder::processLocation(const Module &M, const DILocation *Loc) {
108   if (!Loc)
109     return;
110   processScope(Loc->getScope());
111   processLocation(M, Loc->getInlinedAt());
112 }
113 
114 void DebugInfoFinder::processType(DIType *DT) {
115   if (!addType(DT))
116     return;
117   processScope(DT->getScope().resolve());
118   if (auto *ST = dyn_cast<DISubroutineType>(DT)) {
119     for (DITypeRef Ref : ST->getTypeArray())
120       processType(Ref.resolve());
121     return;
122   }
123   if (auto *DCT = dyn_cast<DICompositeType>(DT)) {
124     processType(DCT->getBaseType().resolve());
125     for (Metadata *D : DCT->getElements()) {
126       if (auto *T = dyn_cast<DIType>(D))
127         processType(T);
128       else if (auto *SP = dyn_cast<DISubprogram>(D))
129         processSubprogram(SP);
130     }
131     return;
132   }
133   if (auto *DDT = dyn_cast<DIDerivedType>(DT)) {
134     processType(DDT->getBaseType().resolve());
135   }
136 }
137 
138 void DebugInfoFinder::processScope(DIScope *Scope) {
139   if (!Scope)
140     return;
141   if (auto *Ty = dyn_cast<DIType>(Scope)) {
142     processType(Ty);
143     return;
144   }
145   if (auto *CU = dyn_cast<DICompileUnit>(Scope)) {
146     addCompileUnit(CU);
147     return;
148   }
149   if (auto *SP = dyn_cast<DISubprogram>(Scope)) {
150     processSubprogram(SP);
151     return;
152   }
153   if (!addScope(Scope))
154     return;
155   if (auto *LB = dyn_cast<DILexicalBlockBase>(Scope)) {
156     processScope(LB->getScope());
157   } else if (auto *NS = dyn_cast<DINamespace>(Scope)) {
158     processScope(NS->getScope());
159   } else if (auto *M = dyn_cast<DIModule>(Scope)) {
160     processScope(M->getScope());
161   }
162 }
163 
164 void DebugInfoFinder::processSubprogram(DISubprogram *SP) {
165   if (!addSubprogram(SP))
166     return;
167   processScope(SP->getScope().resolve());
168   processType(SP->getType());
169   for (auto *Element : SP->getTemplateParams()) {
170     if (auto *TType = dyn_cast<DITemplateTypeParameter>(Element)) {
171       processType(TType->getType().resolve());
172     } else if (auto *TVal = dyn_cast<DITemplateValueParameter>(Element)) {
173       processType(TVal->getType().resolve());
174     }
175   }
176 }
177 
178 void DebugInfoFinder::processDeclare(const Module &M,
179                                      const DbgDeclareInst *DDI) {
180   auto *N = dyn_cast<MDNode>(DDI->getVariable());
181   if (!N)
182     return;
183 
184   auto *DV = dyn_cast<DILocalVariable>(N);
185   if (!DV)
186     return;
187 
188   if (!NodesSeen.insert(DV).second)
189     return;
190   processScope(DV->getScope());
191   processType(DV->getType().resolve());
192 }
193 
194 void DebugInfoFinder::processValue(const Module &M, const DbgValueInst *DVI) {
195   auto *N = dyn_cast<MDNode>(DVI->getVariable());
196   if (!N)
197     return;
198 
199   auto *DV = dyn_cast<DILocalVariable>(N);
200   if (!DV)
201     return;
202 
203   if (!NodesSeen.insert(DV).second)
204     return;
205   processScope(DV->getScope());
206   processType(DV->getType().resolve());
207 }
208 
209 bool DebugInfoFinder::addType(DIType *DT) {
210   if (!DT)
211     return false;
212 
213   if (!NodesSeen.insert(DT).second)
214     return false;
215 
216   TYs.push_back(const_cast<DIType *>(DT));
217   return true;
218 }
219 
220 bool DebugInfoFinder::addCompileUnit(DICompileUnit *CU) {
221   if (!CU)
222     return false;
223   if (!NodesSeen.insert(CU).second)
224     return false;
225 
226   CUs.push_back(CU);
227   return true;
228 }
229 
230 bool DebugInfoFinder::addGlobalVariable(DIGlobalVariableExpression *DIG) {
231   if (!NodesSeen.insert(DIG).second)
232     return false;
233 
234   GVs.push_back(DIG);
235   return true;
236 }
237 
238 bool DebugInfoFinder::addSubprogram(DISubprogram *SP) {
239   if (!SP)
240     return false;
241 
242   if (!NodesSeen.insert(SP).second)
243     return false;
244 
245   SPs.push_back(SP);
246   return true;
247 }
248 
249 bool DebugInfoFinder::addScope(DIScope *Scope) {
250   if (!Scope)
251     return false;
252   // FIXME: Ocaml binding generates a scope with no content, we treat it
253   // as null for now.
254   if (Scope->getNumOperands() == 0)
255     return false;
256   if (!NodesSeen.insert(Scope).second)
257     return false;
258   Scopes.push_back(Scope);
259   return true;
260 }
261 
262 static MDNode *stripDebugLocFromLoopID(MDNode *N) {
263   assert(N->op_begin() != N->op_end() && "Missing self reference?");
264 
265   // if there is no debug location, we do not have to rewrite this MDNode.
266   if (std::none_of(N->op_begin() + 1, N->op_end(), [](const MDOperand &Op) {
267         return isa<DILocation>(Op.get());
268       }))
269     return N;
270 
271   // If there is only the debug location without any actual loop metadata, we
272   // can remove the metadata.
273   if (std::none_of(N->op_begin() + 1, N->op_end(), [](const MDOperand &Op) {
274         return !isa<DILocation>(Op.get());
275       }))
276     return nullptr;
277 
278   SmallVector<Metadata *, 4> Args;
279   // Reserve operand 0 for loop id self reference.
280   auto TempNode = MDNode::getTemporary(N->getContext(), None);
281   Args.push_back(TempNode.get());
282   // Add all non-debug location operands back.
283   for (auto Op = N->op_begin() + 1; Op != N->op_end(); Op++) {
284     if (!isa<DILocation>(*Op))
285       Args.push_back(*Op);
286   }
287 
288   // Set the first operand to itself.
289   MDNode *LoopID = MDNode::get(N->getContext(), Args);
290   LoopID->replaceOperandWith(0, LoopID);
291   return LoopID;
292 }
293 
294 bool llvm::stripDebugInfo(Function &F) {
295   bool Changed = false;
296   if (F.getMetadata(LLVMContext::MD_dbg)) {
297     Changed = true;
298     F.setSubprogram(nullptr);
299   }
300 
301   DenseMap<MDNode*, MDNode*> LoopIDsMap;
302   for (BasicBlock &BB : F) {
303     for (auto II = BB.begin(), End = BB.end(); II != End;) {
304       Instruction &I = *II++; // We may delete the instruction, increment now.
305       if (isa<DbgInfoIntrinsic>(&I)) {
306         I.eraseFromParent();
307         Changed = true;
308         continue;
309       }
310       if (I.getDebugLoc()) {
311         Changed = true;
312         I.setDebugLoc(DebugLoc());
313       }
314     }
315 
316     auto *TermInst = BB.getTerminator();
317     if (!TermInst)
318       // This is invalid IR, but we may not have run the verifier yet
319       continue;
320     if (auto *LoopID = TermInst->getMetadata(LLVMContext::MD_loop)) {
321       auto *NewLoopID = LoopIDsMap.lookup(LoopID);
322       if (!NewLoopID)
323         NewLoopID = LoopIDsMap[LoopID] = stripDebugLocFromLoopID(LoopID);
324       if (NewLoopID != LoopID)
325         TermInst->setMetadata(LLVMContext::MD_loop, NewLoopID);
326     }
327   }
328   return Changed;
329 }
330 
331 bool llvm::StripDebugInfo(Module &M) {
332   bool Changed = false;
333 
334   for (Module::named_metadata_iterator NMI = M.named_metadata_begin(),
335          NME = M.named_metadata_end(); NMI != NME;) {
336     NamedMDNode *NMD = &*NMI;
337     ++NMI;
338 
339     // We're stripping debug info, and without them, coverage information
340     // doesn't quite make sense.
341     if (NMD->getName().startswith("llvm.dbg.") ||
342         NMD->getName() == "llvm.gcov") {
343       NMD->eraseFromParent();
344       Changed = true;
345     }
346   }
347 
348   for (Function &F : M)
349     Changed |= stripDebugInfo(F);
350 
351   for (auto &GV : M.globals()) {
352     SmallVector<MDNode *, 1> MDs;
353     GV.getMetadata(LLVMContext::MD_dbg, MDs);
354     if (!MDs.empty()) {
355       GV.eraseMetadata(LLVMContext::MD_dbg);
356       Changed = true;
357     }
358   }
359 
360   if (GVMaterializer *Materializer = M.getMaterializer())
361     Materializer->setStripDebugInfo();
362 
363   return Changed;
364 }
365 
366 namespace {
367 
368 /// Helper class to downgrade -g metadata to -gline-tables-only metadata.
369 class DebugTypeInfoRemoval {
370   DenseMap<Metadata *, Metadata *> Replacements;
371 
372 public:
373   /// The (void)() type.
374   MDNode *EmptySubroutineType;
375 
376 private:
377   /// Remember what linkage name we originally had before stripping. If we end
378   /// up making two subprograms identical who originally had different linkage
379   /// names, then we need to make one of them distinct, to avoid them getting
380   /// uniqued. Maps the new node to the old linkage name.
381   DenseMap<DISubprogram *, StringRef> NewToLinkageName;
382 
383   // TODO: Remember the distinct subprogram we created for a given linkage name,
384   // so that we can continue to unique whenever possible. Map <newly created
385   // node, old linkage name> to the first (possibly distinct) mdsubprogram
386   // created for that combination. This is not strictly needed for correctness,
387   // but can cut down on the number of MDNodes and let us diff cleanly with the
388   // output of -gline-tables-only.
389 
390 public:
391   DebugTypeInfoRemoval(LLVMContext &C)
392       : EmptySubroutineType(DISubroutineType::get(C, DINode::FlagZero, 0,
393                                                   MDNode::get(C, {}))) {}
394 
395   Metadata *map(Metadata *M) {
396     if (!M)
397       return nullptr;
398     auto Replacement = Replacements.find(M);
399     if (Replacement != Replacements.end())
400       return Replacement->second;
401 
402     return M;
403   }
404   MDNode *mapNode(Metadata *N) { return dyn_cast_or_null<MDNode>(map(N)); }
405 
406   /// Recursively remap N and all its referenced children. Does a DF post-order
407   /// traversal, so as to remap bottoms up.
408   void traverseAndRemap(MDNode *N) { traverse(N); }
409 
410 private:
411   // Create a new DISubprogram, to replace the one given.
412   DISubprogram *getReplacementSubprogram(DISubprogram *MDS) {
413     auto *FileAndScope = cast_or_null<DIFile>(map(MDS->getFile()));
414     StringRef LinkageName = MDS->getName().empty() ? MDS->getLinkageName() : "";
415     DISubprogram *Declaration = nullptr;
416     auto *Type = cast_or_null<DISubroutineType>(map(MDS->getType()));
417     DITypeRef ContainingType(map(MDS->getContainingType()));
418     auto *Unit = cast_or_null<DICompileUnit>(map(MDS->getUnit()));
419     auto Variables = nullptr;
420     auto TemplateParams = nullptr;
421 
422     // Make a distinct DISubprogram, for situations that warrent it.
423     auto distinctMDSubprogram = [&]() {
424       return DISubprogram::getDistinct(
425           MDS->getContext(), FileAndScope, MDS->getName(), LinkageName,
426           FileAndScope, MDS->getLine(), Type, MDS->isLocalToUnit(),
427           MDS->isDefinition(), MDS->getScopeLine(), ContainingType,
428           MDS->getVirtuality(), MDS->getVirtualIndex(),
429           MDS->getThisAdjustment(), MDS->getFlags(), MDS->isOptimized(), Unit,
430           TemplateParams, Declaration, Variables);
431     };
432 
433     if (MDS->isDistinct())
434       return distinctMDSubprogram();
435 
436     auto *NewMDS = DISubprogram::get(
437         MDS->getContext(), FileAndScope, MDS->getName(), LinkageName,
438         FileAndScope, MDS->getLine(), Type, MDS->isLocalToUnit(),
439         MDS->isDefinition(), MDS->getScopeLine(), ContainingType,
440         MDS->getVirtuality(), MDS->getVirtualIndex(), MDS->getThisAdjustment(),
441         MDS->getFlags(), MDS->isOptimized(), Unit, TemplateParams, Declaration,
442         Variables);
443 
444     StringRef OldLinkageName = MDS->getLinkageName();
445 
446     // See if we need to make a distinct one.
447     auto OrigLinkage = NewToLinkageName.find(NewMDS);
448     if (OrigLinkage != NewToLinkageName.end()) {
449       if (OrigLinkage->second == OldLinkageName)
450         // We're good.
451         return NewMDS;
452 
453       // Otherwise, need to make a distinct one.
454       // TODO: Query the map to see if we already have one.
455       return distinctMDSubprogram();
456     }
457 
458     NewToLinkageName.insert({NewMDS, MDS->getLinkageName()});
459     return NewMDS;
460   }
461 
462   /// Create a new compile unit, to replace the one given
463   DICompileUnit *getReplacementCU(DICompileUnit *CU) {
464     // Drop skeleton CUs.
465     if (CU->getDWOId())
466       return nullptr;
467 
468     auto *File = cast_or_null<DIFile>(map(CU->getFile()));
469     MDTuple *EnumTypes = nullptr;
470     MDTuple *RetainedTypes = nullptr;
471     MDTuple *GlobalVariables = nullptr;
472     MDTuple *ImportedEntities = nullptr;
473     return DICompileUnit::getDistinct(
474         CU->getContext(), CU->getSourceLanguage(), File, CU->getProducer(),
475         CU->isOptimized(), CU->getFlags(), CU->getRuntimeVersion(),
476         CU->getSplitDebugFilename(), DICompileUnit::LineTablesOnly, EnumTypes,
477         RetainedTypes, GlobalVariables, ImportedEntities, CU->getMacros(),
478         CU->getDWOId(), CU->getSplitDebugInlining(),
479         CU->getDebugInfoForProfiling(), CU->getGnuPubnames());
480   }
481 
482   DILocation *getReplacementMDLocation(DILocation *MLD) {
483     auto *Scope = map(MLD->getScope());
484     auto *InlinedAt = map(MLD->getInlinedAt());
485     if (MLD->isDistinct())
486       return DILocation::getDistinct(MLD->getContext(), MLD->getLine(),
487                                      MLD->getColumn(), Scope, InlinedAt);
488     return DILocation::get(MLD->getContext(), MLD->getLine(), MLD->getColumn(),
489                            Scope, InlinedAt);
490   }
491 
492   /// Create a new generic MDNode, to replace the one given
493   MDNode *getReplacementMDNode(MDNode *N) {
494     SmallVector<Metadata *, 8> Ops;
495     Ops.reserve(N->getNumOperands());
496     for (auto &I : N->operands())
497       if (I)
498         Ops.push_back(map(I));
499     auto *Ret = MDNode::get(N->getContext(), Ops);
500     return Ret;
501   }
502 
503   /// Attempt to re-map N to a newly created node.
504   void remap(MDNode *N) {
505     if (Replacements.count(N))
506       return;
507 
508     auto doRemap = [&](MDNode *N) -> MDNode * {
509       if (!N)
510         return nullptr;
511       if (auto *MDSub = dyn_cast<DISubprogram>(N)) {
512         remap(MDSub->getUnit());
513         return getReplacementSubprogram(MDSub);
514       }
515       if (isa<DISubroutineType>(N))
516         return EmptySubroutineType;
517       if (auto *CU = dyn_cast<DICompileUnit>(N))
518         return getReplacementCU(CU);
519       if (isa<DIFile>(N))
520         return N;
521       if (auto *MDLB = dyn_cast<DILexicalBlockBase>(N))
522         // Remap to our referenced scope (recursively).
523         return mapNode(MDLB->getScope());
524       if (auto *MLD = dyn_cast<DILocation>(N))
525         return getReplacementMDLocation(MLD);
526 
527       // Otherwise, if we see these, just drop them now. Not strictly necessary,
528       // but this speeds things up a little.
529       if (isa<DINode>(N))
530         return nullptr;
531 
532       return getReplacementMDNode(N);
533     };
534     Replacements[N] = doRemap(N);
535   }
536 
537   /// Do the remapping traversal.
538   void traverse(MDNode *);
539 };
540 
541 } // end anonymous namespace
542 
543 void DebugTypeInfoRemoval::traverse(MDNode *N) {
544   if (!N || Replacements.count(N))
545     return;
546 
547   // To avoid cycles, as well as for efficiency sake, we will sometimes prune
548   // parts of the graph.
549   auto prune = [](MDNode *Parent, MDNode *Child) {
550     if (auto *MDS = dyn_cast<DISubprogram>(Parent))
551       return Child == MDS->getVariables().get();
552     return false;
553   };
554 
555   SmallVector<MDNode *, 16> ToVisit;
556   DenseSet<MDNode *> Opened;
557 
558   // Visit each node starting at N in post order, and map them.
559   ToVisit.push_back(N);
560   while (!ToVisit.empty()) {
561     auto *N = ToVisit.back();
562     if (!Opened.insert(N).second) {
563       // Close it.
564       remap(N);
565       ToVisit.pop_back();
566       continue;
567     }
568     for (auto &I : N->operands())
569       if (auto *MDN = dyn_cast_or_null<MDNode>(I))
570         if (!Opened.count(MDN) && !Replacements.count(MDN) && !prune(N, MDN) &&
571             !isa<DICompileUnit>(MDN))
572           ToVisit.push_back(MDN);
573   }
574 }
575 
576 bool llvm::stripNonLineTableDebugInfo(Module &M) {
577   bool Changed = false;
578 
579   // First off, delete the debug intrinsics.
580   auto RemoveUses = [&](StringRef Name) {
581     if (auto *DbgVal = M.getFunction(Name)) {
582       while (!DbgVal->use_empty())
583         cast<Instruction>(DbgVal->user_back())->eraseFromParent();
584       DbgVal->eraseFromParent();
585       Changed = true;
586     }
587   };
588   RemoveUses("llvm.dbg.declare");
589   RemoveUses("llvm.dbg.value");
590 
591   // Delete non-CU debug info named metadata nodes.
592   for (auto NMI = M.named_metadata_begin(), NME = M.named_metadata_end();
593        NMI != NME;) {
594     NamedMDNode *NMD = &*NMI;
595     ++NMI;
596     // Specifically keep dbg.cu around.
597     if (NMD->getName() == "llvm.dbg.cu")
598       continue;
599   }
600 
601   // Drop all dbg attachments from global variables.
602   for (auto &GV : M.globals())
603     GV.eraseMetadata(LLVMContext::MD_dbg);
604 
605   DebugTypeInfoRemoval Mapper(M.getContext());
606   auto remap = [&](MDNode *Node) -> MDNode * {
607     if (!Node)
608       return nullptr;
609     Mapper.traverseAndRemap(Node);
610     auto *NewNode = Mapper.mapNode(Node);
611     Changed |= Node != NewNode;
612     Node = NewNode;
613     return NewNode;
614   };
615 
616   // Rewrite the DebugLocs to be equivalent to what
617   // -gline-tables-only would have created.
618   for (auto &F : M) {
619     if (auto *SP = F.getSubprogram()) {
620       Mapper.traverseAndRemap(SP);
621       auto *NewSP = cast<DISubprogram>(Mapper.mapNode(SP));
622       Changed |= SP != NewSP;
623       F.setSubprogram(NewSP);
624     }
625     for (auto &BB : F) {
626       for (auto &I : BB) {
627         auto remapDebugLoc = [&](DebugLoc DL) -> DebugLoc {
628           auto *Scope = DL.getScope();
629           MDNode *InlinedAt = DL.getInlinedAt();
630           Scope = remap(Scope);
631           InlinedAt = remap(InlinedAt);
632           return DebugLoc::get(DL.getLine(), DL.getCol(), Scope, InlinedAt);
633         };
634 
635         if (I.getDebugLoc() != DebugLoc())
636           I.setDebugLoc(remapDebugLoc(I.getDebugLoc()));
637 
638         // Remap DILocations in untyped MDNodes (e.g., llvm.loop).
639         SmallVector<std::pair<unsigned, MDNode *>, 2> MDs;
640         I.getAllMetadata(MDs);
641         for (auto Attachment : MDs)
642           if (auto *T = dyn_cast_or_null<MDTuple>(Attachment.second))
643             for (unsigned N = 0; N < T->getNumOperands(); ++N)
644               if (auto *Loc = dyn_cast_or_null<DILocation>(T->getOperand(N)))
645                 if (Loc != DebugLoc())
646                   T->replaceOperandWith(N, remapDebugLoc(Loc));
647       }
648     }
649   }
650 
651   // Create a new llvm.dbg.cu, which is equivalent to the one
652   // -gline-tables-only would have created.
653   for (auto &NMD : M.getNamedMDList()) {
654     SmallVector<MDNode *, 8> Ops;
655     for (MDNode *Op : NMD.operands())
656       Ops.push_back(remap(Op));
657 
658     if (!Changed)
659       continue;
660 
661     NMD.clearOperands();
662     for (auto *Op : Ops)
663       if (Op)
664         NMD.addOperand(Op);
665   }
666   return Changed;
667 }
668 
669 unsigned llvm::getDebugMetadataVersionFromModule(const Module &M) {
670   if (auto *Val = mdconst::dyn_extract_or_null<ConstantInt>(
671           M.getModuleFlag("Debug Info Version")))
672     return Val->getZExtValue();
673   return 0;
674 }
675 
676 void Instruction::applyMergedLocation(const DILocation *LocA,
677                                       const DILocation *LocB) {
678   setDebugLoc(DILocation::getMergedLocation(LocA, LocB, this));
679 }
680 
681 //===----------------------------------------------------------------------===//
682 // LLVM C API implementations.
683 //===----------------------------------------------------------------------===//
684 
685 static unsigned map_from_llvmDWARFsourcelanguage(LLVMDWARFSourceLanguage lang) {
686   switch (lang) {
687 #define HANDLE_DW_LANG(ID, NAME, VERSION, VENDOR) \
688 case LLVMDWARFSourceLanguage##NAME: return ID;
689 #include "llvm/BinaryFormat/Dwarf.def"
690 #undef HANDLE_DW_LANG
691   }
692   llvm_unreachable("Unhandled Tag");
693 }
694 
695 unsigned LLVMDebugMetadataVersion() {
696   return DEBUG_METADATA_VERSION;
697 }
698 
699 LLVMDIBuilderRef LLVMCreateDIBuilderDisallowUnresolved(LLVMModuleRef M) {
700   return wrap(new DIBuilder(*unwrap(M), false));
701 }
702 
703 LLVMDIBuilderRef LLVMCreateDIBuilder(LLVMModuleRef M) {
704   return wrap(new DIBuilder(*unwrap(M)));
705 }
706 
707 unsigned LLVMGetModuleDebugMetadataVersion(LLVMModuleRef M) {
708   return getDebugMetadataVersionFromModule(*unwrap(M));
709 }
710 
711 LLVMBool LLVMStripModuleDebugInfo(LLVMModuleRef M) {
712   return StripDebugInfo(*unwrap(M));
713 }
714 
715 void LLVMDisposeDIBuilder(LLVMDIBuilderRef Builder) {
716   delete unwrap(Builder);
717 }
718 
719 void LLVMDIBuilderFinalize(LLVMDIBuilderRef Builder) {
720   unwrap(Builder)->finalize();
721 }
722 
723 LLVMMetadataRef LLVMDIBuilderCreateCompileUnit(
724     LLVMDIBuilderRef Builder, LLVMDWARFSourceLanguage Lang,
725     LLVMMetadataRef FileRef, const char *Producer, size_t ProducerLen,
726     LLVMBool isOptimized, const char *Flags, size_t FlagsLen,
727     unsigned RuntimeVer, const char *SplitName, size_t SplitNameLen,
728     LLVMDWARFEmissionKind Kind, unsigned DWOId, LLVMBool SplitDebugInlining,
729     LLVMBool DebugInfoForProfiling) {
730   auto File = unwrap<DIFile>(FileRef);
731 
732   return wrap(unwrap(Builder)->createCompileUnit(
733                  map_from_llvmDWARFsourcelanguage(Lang), File,
734                  StringRef(Producer, ProducerLen), isOptimized,
735                  StringRef(Flags, FlagsLen), RuntimeVer,
736                  StringRef(SplitName, SplitNameLen),
737                  static_cast<DICompileUnit::DebugEmissionKind>(Kind), DWOId,
738                  SplitDebugInlining, DebugInfoForProfiling));
739 }
740 
741 LLVMMetadataRef
742 LLVMDIBuilderCreateFile(LLVMDIBuilderRef Builder, const char *Filename,
743                         size_t FilenameLen, const char *Directory,
744                         size_t DirectoryLen) {
745   return wrap(unwrap(Builder)->createFile(StringRef(Filename, FilenameLen),
746                                           StringRef(Directory, DirectoryLen)));
747 }
748 
749 LLVMMetadataRef
750 LLVMDIBuilderCreateDebugLocation(LLVMContextRef Ctx, unsigned Line,
751                                  unsigned Column, LLVMMetadataRef Scope,
752                                  LLVMMetadataRef InlinedAt) {
753   return wrap(DILocation::get(*unwrap(Ctx), Line, Column, unwrap(Scope),
754                               unwrap(InlinedAt)));
755 }
756