1*1db9f3b2SDimitry Andric //===- DWARFLinkerDeclContext.cpp -----------------------------------------===//
2*1db9f3b2SDimitry Andric //
3*1db9f3b2SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*1db9f3b2SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5*1db9f3b2SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*1db9f3b2SDimitry Andric //
7*1db9f3b2SDimitry Andric //===----------------------------------------------------------------------===//
8*1db9f3b2SDimitry Andric 
9*1db9f3b2SDimitry Andric #include "llvm/DWARFLinker/Classic/DWARFLinkerDeclContext.h"
10*1db9f3b2SDimitry Andric #include "llvm/DWARFLinker/Classic/DWARFLinkerCompileUnit.h"
11*1db9f3b2SDimitry Andric #include "llvm/DebugInfo/DWARF/DWARFContext.h"
12*1db9f3b2SDimitry Andric #include "llvm/DebugInfo/DWARF/DWARFDie.h"
13*1db9f3b2SDimitry Andric #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
14*1db9f3b2SDimitry Andric 
15*1db9f3b2SDimitry Andric namespace llvm {
16*1db9f3b2SDimitry Andric 
17*1db9f3b2SDimitry Andric using namespace dwarf_linker;
18*1db9f3b2SDimitry Andric using namespace dwarf_linker::classic;
19*1db9f3b2SDimitry Andric 
20*1db9f3b2SDimitry Andric /// Set the last DIE/CU a context was seen in and, possibly invalidate the
21*1db9f3b2SDimitry Andric /// context if it is ambiguous.
22*1db9f3b2SDimitry Andric ///
23*1db9f3b2SDimitry Andric /// In the current implementation, we don't handle overloaded functions well,
24*1db9f3b2SDimitry Andric /// because the argument types are not taken into account when computing the
25*1db9f3b2SDimitry Andric /// DeclContext tree.
26*1db9f3b2SDimitry Andric ///
27*1db9f3b2SDimitry Andric /// Some of this is mitigated byt using mangled names that do contain the
28*1db9f3b2SDimitry Andric /// arguments types, but sometimes (e.g. with function templates) we don't have
29*1db9f3b2SDimitry Andric /// that. In that case, just do not unique anything that refers to the contexts
30*1db9f3b2SDimitry Andric /// we are not able to distinguish.
31*1db9f3b2SDimitry Andric ///
32*1db9f3b2SDimitry Andric /// If a context that is not a namespace appears twice in the same CU, we know
33*1db9f3b2SDimitry Andric /// it is ambiguous. Make it invalid.
setLastSeenDIE(CompileUnit & U,const DWARFDie & Die)34*1db9f3b2SDimitry Andric bool DeclContext::setLastSeenDIE(CompileUnit &U, const DWARFDie &Die) {
35*1db9f3b2SDimitry Andric   if (LastSeenCompileUnitID == U.getUniqueID()) {
36*1db9f3b2SDimitry Andric     DWARFUnit &OrigUnit = U.getOrigUnit();
37*1db9f3b2SDimitry Andric     uint32_t FirstIdx = OrigUnit.getDIEIndex(LastSeenDIE);
38*1db9f3b2SDimitry Andric     U.getInfo(FirstIdx).Ctxt = nullptr;
39*1db9f3b2SDimitry Andric     return false;
40*1db9f3b2SDimitry Andric   }
41*1db9f3b2SDimitry Andric 
42*1db9f3b2SDimitry Andric   LastSeenCompileUnitID = U.getUniqueID();
43*1db9f3b2SDimitry Andric   LastSeenDIE = Die;
44*1db9f3b2SDimitry Andric   return true;
45*1db9f3b2SDimitry Andric }
46*1db9f3b2SDimitry Andric 
47*1db9f3b2SDimitry Andric PointerIntPair<DeclContext *, 1>
getChildDeclContext(DeclContext & Context,const DWARFDie & DIE,CompileUnit & U,bool InClangModule)48*1db9f3b2SDimitry Andric DeclContextTree::getChildDeclContext(DeclContext &Context, const DWARFDie &DIE,
49*1db9f3b2SDimitry Andric                                      CompileUnit &U, bool InClangModule) {
50*1db9f3b2SDimitry Andric   unsigned Tag = DIE.getTag();
51*1db9f3b2SDimitry Andric 
52*1db9f3b2SDimitry Andric   // FIXME: dsymutil-classic compat: We should bail out here if we
53*1db9f3b2SDimitry Andric   // have a specification or an abstract_origin. We will get the
54*1db9f3b2SDimitry Andric   // parent context wrong here.
55*1db9f3b2SDimitry Andric 
56*1db9f3b2SDimitry Andric   switch (Tag) {
57*1db9f3b2SDimitry Andric   default:
58*1db9f3b2SDimitry Andric     // By default stop gathering child contexts.
59*1db9f3b2SDimitry Andric     return PointerIntPair<DeclContext *, 1>(nullptr);
60*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_module:
61*1db9f3b2SDimitry Andric     break;
62*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_compile_unit:
63*1db9f3b2SDimitry Andric     return PointerIntPair<DeclContext *, 1>(&Context);
64*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_subprogram:
65*1db9f3b2SDimitry Andric     // Do not unique anything inside CU local functions.
66*1db9f3b2SDimitry Andric     if ((Context.getTag() == dwarf::DW_TAG_namespace ||
67*1db9f3b2SDimitry Andric          Context.getTag() == dwarf::DW_TAG_compile_unit) &&
68*1db9f3b2SDimitry Andric         !dwarf::toUnsigned(DIE.find(dwarf::DW_AT_external), 0))
69*1db9f3b2SDimitry Andric       return PointerIntPair<DeclContext *, 1>(nullptr);
70*1db9f3b2SDimitry Andric     [[fallthrough]];
71*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_member:
72*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_namespace:
73*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_structure_type:
74*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_class_type:
75*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_union_type:
76*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_enumeration_type:
77*1db9f3b2SDimitry Andric   case dwarf::DW_TAG_typedef:
78*1db9f3b2SDimitry Andric     // Artificial things might be ambiguous, because they might be created on
79*1db9f3b2SDimitry Andric     // demand. For example implicitly defined constructors are ambiguous
80*1db9f3b2SDimitry Andric     // because of the way we identify contexts, and they won't be generated
81*1db9f3b2SDimitry Andric     // every time everywhere.
82*1db9f3b2SDimitry Andric     if (dwarf::toUnsigned(DIE.find(dwarf::DW_AT_artificial), 0))
83*1db9f3b2SDimitry Andric       return PointerIntPair<DeclContext *, 1>(nullptr);
84*1db9f3b2SDimitry Andric     break;
85*1db9f3b2SDimitry Andric   }
86*1db9f3b2SDimitry Andric 
87*1db9f3b2SDimitry Andric   StringRef NameRef;
88*1db9f3b2SDimitry Andric   StringRef FileRef;
89*1db9f3b2SDimitry Andric 
90*1db9f3b2SDimitry Andric   if (const char *LinkageName = DIE.getLinkageName())
91*1db9f3b2SDimitry Andric     NameRef = StringPool.internString(LinkageName);
92*1db9f3b2SDimitry Andric   else if (const char *ShortName = DIE.getShortName())
93*1db9f3b2SDimitry Andric     NameRef = StringPool.internString(ShortName);
94*1db9f3b2SDimitry Andric 
95*1db9f3b2SDimitry Andric   bool IsAnonymousNamespace = NameRef.empty() && Tag == dwarf::DW_TAG_namespace;
96*1db9f3b2SDimitry Andric   if (IsAnonymousNamespace) {
97*1db9f3b2SDimitry Andric     // FIXME: For dsymutil-classic compatibility. I think uniquing within
98*1db9f3b2SDimitry Andric     // anonymous namespaces is wrong. There is no ODR guarantee there.
99*1db9f3b2SDimitry Andric     NameRef = "(anonymous namespace)";
100*1db9f3b2SDimitry Andric   }
101*1db9f3b2SDimitry Andric 
102*1db9f3b2SDimitry Andric   if (Tag != dwarf::DW_TAG_class_type && Tag != dwarf::DW_TAG_structure_type &&
103*1db9f3b2SDimitry Andric       Tag != dwarf::DW_TAG_union_type &&
104*1db9f3b2SDimitry Andric       Tag != dwarf::DW_TAG_enumeration_type && NameRef.empty())
105*1db9f3b2SDimitry Andric     return PointerIntPair<DeclContext *, 1>(nullptr);
106*1db9f3b2SDimitry Andric 
107*1db9f3b2SDimitry Andric   unsigned Line = 0;
108*1db9f3b2SDimitry Andric   unsigned ByteSize = std::numeric_limits<uint32_t>::max();
109*1db9f3b2SDimitry Andric 
110*1db9f3b2SDimitry Andric   if (!InClangModule) {
111*1db9f3b2SDimitry Andric     // Gather some discriminating data about the DeclContext we will be
112*1db9f3b2SDimitry Andric     // creating: File, line number and byte size. This shouldn't be necessary,
113*1db9f3b2SDimitry Andric     // because the ODR is just about names, but given that we do some
114*1db9f3b2SDimitry Andric     // approximations with overloaded functions and anonymous namespaces, use
115*1db9f3b2SDimitry Andric     // these additional data points to make the process safer.
116*1db9f3b2SDimitry Andric     //
117*1db9f3b2SDimitry Andric     // This is disabled for clang modules, because forward declarations of
118*1db9f3b2SDimitry Andric     // module-defined types do not have a file and line.
119*1db9f3b2SDimitry Andric     ByteSize = dwarf::toUnsigned(DIE.find(dwarf::DW_AT_byte_size),
120*1db9f3b2SDimitry Andric                                  std::numeric_limits<uint64_t>::max());
121*1db9f3b2SDimitry Andric     if (Tag != dwarf::DW_TAG_namespace || IsAnonymousNamespace) {
122*1db9f3b2SDimitry Andric       if (unsigned FileNum =
123*1db9f3b2SDimitry Andric               dwarf::toUnsigned(DIE.find(dwarf::DW_AT_decl_file), 0)) {
124*1db9f3b2SDimitry Andric         if (const auto *LT = U.getOrigUnit().getContext().getLineTableForUnit(
125*1db9f3b2SDimitry Andric                 &U.getOrigUnit())) {
126*1db9f3b2SDimitry Andric           // FIXME: dsymutil-classic compatibility. I'd rather not
127*1db9f3b2SDimitry Andric           // unique anything in anonymous namespaces, but if we do, then
128*1db9f3b2SDimitry Andric           // verify that the file and line correspond.
129*1db9f3b2SDimitry Andric           if (IsAnonymousNamespace)
130*1db9f3b2SDimitry Andric             FileNum = 1;
131*1db9f3b2SDimitry Andric 
132*1db9f3b2SDimitry Andric           if (LT->hasFileAtIndex(FileNum)) {
133*1db9f3b2SDimitry Andric             Line = dwarf::toUnsigned(DIE.find(dwarf::DW_AT_decl_line), 0);
134*1db9f3b2SDimitry Andric             // Cache the resolved paths based on the index in the line table,
135*1db9f3b2SDimitry Andric             // because calling realpath is expensive.
136*1db9f3b2SDimitry Andric             FileRef = getResolvedPath(U, FileNum, *LT);
137*1db9f3b2SDimitry Andric           }
138*1db9f3b2SDimitry Andric         }
139*1db9f3b2SDimitry Andric       }
140*1db9f3b2SDimitry Andric     }
141*1db9f3b2SDimitry Andric   }
142*1db9f3b2SDimitry Andric 
143*1db9f3b2SDimitry Andric   if (!Line && NameRef.empty())
144*1db9f3b2SDimitry Andric     return PointerIntPair<DeclContext *, 1>(nullptr);
145*1db9f3b2SDimitry Andric 
146*1db9f3b2SDimitry Andric   // We hash NameRef, which is the mangled name, in order to get most
147*1db9f3b2SDimitry Andric   // overloaded functions resolve correctly.
148*1db9f3b2SDimitry Andric   //
149*1db9f3b2SDimitry Andric   // Strictly speaking, hashing the Tag is only necessary for a
150*1db9f3b2SDimitry Andric   // DW_TAG_module, to prevent uniquing of a module and a namespace
151*1db9f3b2SDimitry Andric   // with the same name.
152*1db9f3b2SDimitry Andric   //
153*1db9f3b2SDimitry Andric   // FIXME: dsymutil-classic won't unique the same type presented
154*1db9f3b2SDimitry Andric   // once as a struct and once as a class. Using the Tag in the fully
155*1db9f3b2SDimitry Andric   // qualified name hash to get the same effect.
156*1db9f3b2SDimitry Andric   unsigned Hash = hash_combine(Context.getQualifiedNameHash(), Tag, NameRef);
157*1db9f3b2SDimitry Andric 
158*1db9f3b2SDimitry Andric   // FIXME: dsymutil-classic compatibility: when we don't have a name,
159*1db9f3b2SDimitry Andric   // use the filename.
160*1db9f3b2SDimitry Andric   if (IsAnonymousNamespace)
161*1db9f3b2SDimitry Andric     Hash = hash_combine(Hash, FileRef);
162*1db9f3b2SDimitry Andric 
163*1db9f3b2SDimitry Andric   // Now look if this context already exists.
164*1db9f3b2SDimitry Andric   DeclContext Key(Hash, Line, ByteSize, Tag, NameRef, FileRef, Context);
165*1db9f3b2SDimitry Andric   auto ContextIter = Contexts.find(&Key);
166*1db9f3b2SDimitry Andric 
167*1db9f3b2SDimitry Andric   if (ContextIter == Contexts.end()) {
168*1db9f3b2SDimitry Andric     // The context wasn't found.
169*1db9f3b2SDimitry Andric     bool Inserted;
170*1db9f3b2SDimitry Andric     DeclContext *NewContext =
171*1db9f3b2SDimitry Andric         new (Allocator) DeclContext(Hash, Line, ByteSize, Tag, NameRef, FileRef,
172*1db9f3b2SDimitry Andric                                     Context, DIE, U.getUniqueID());
173*1db9f3b2SDimitry Andric     std::tie(ContextIter, Inserted) = Contexts.insert(NewContext);
174*1db9f3b2SDimitry Andric     assert(Inserted && "Failed to insert DeclContext");
175*1db9f3b2SDimitry Andric     (void)Inserted;
176*1db9f3b2SDimitry Andric   } else if (Tag != dwarf::DW_TAG_namespace &&
177*1db9f3b2SDimitry Andric              !(*ContextIter)->setLastSeenDIE(U, DIE)) {
178*1db9f3b2SDimitry Andric     // The context was found, but it is ambiguous with another context
179*1db9f3b2SDimitry Andric     // in the same file. Mark it invalid.
180*1db9f3b2SDimitry Andric     return PointerIntPair<DeclContext *, 1>(*ContextIter, /* IntVal= */ 1);
181*1db9f3b2SDimitry Andric   }
182*1db9f3b2SDimitry Andric 
183*1db9f3b2SDimitry Andric   assert(ContextIter != Contexts.end());
184*1db9f3b2SDimitry Andric   // FIXME: dsymutil-classic compatibility. Union types aren't
185*1db9f3b2SDimitry Andric   // uniques, but their children might be.
186*1db9f3b2SDimitry Andric   if ((Tag == dwarf::DW_TAG_subprogram &&
187*1db9f3b2SDimitry Andric        Context.getTag() != dwarf::DW_TAG_structure_type &&
188*1db9f3b2SDimitry Andric        Context.getTag() != dwarf::DW_TAG_class_type) ||
189*1db9f3b2SDimitry Andric       (Tag == dwarf::DW_TAG_union_type))
190*1db9f3b2SDimitry Andric     return PointerIntPair<DeclContext *, 1>(*ContextIter, /* IntVal= */ 1);
191*1db9f3b2SDimitry Andric 
192*1db9f3b2SDimitry Andric   return PointerIntPair<DeclContext *, 1>(*ContextIter);
193*1db9f3b2SDimitry Andric }
194*1db9f3b2SDimitry Andric 
195*1db9f3b2SDimitry Andric StringRef
getResolvedPath(CompileUnit & CU,unsigned FileNum,const DWARFDebugLine::LineTable & LineTable)196*1db9f3b2SDimitry Andric DeclContextTree::getResolvedPath(CompileUnit &CU, unsigned FileNum,
197*1db9f3b2SDimitry Andric                                  const DWARFDebugLine::LineTable &LineTable) {
198*1db9f3b2SDimitry Andric   std::pair<unsigned, unsigned> Key = {CU.getUniqueID(), FileNum};
199*1db9f3b2SDimitry Andric 
200*1db9f3b2SDimitry Andric   ResolvedPathsMap::const_iterator It = ResolvedPaths.find(Key);
201*1db9f3b2SDimitry Andric   if (It == ResolvedPaths.end()) {
202*1db9f3b2SDimitry Andric     std::string FileName;
203*1db9f3b2SDimitry Andric     bool FoundFileName = LineTable.getFileNameByIndex(
204*1db9f3b2SDimitry Andric         FileNum, CU.getOrigUnit().getCompilationDir(),
205*1db9f3b2SDimitry Andric         DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, FileName);
206*1db9f3b2SDimitry Andric     (void)FoundFileName;
207*1db9f3b2SDimitry Andric     assert(FoundFileName && "Must get file name from line table");
208*1db9f3b2SDimitry Andric 
209*1db9f3b2SDimitry Andric     // Second level of caching, this time based on the file's parent
210*1db9f3b2SDimitry Andric     // path.
211*1db9f3b2SDimitry Andric     StringRef ResolvedPath = PathResolver.resolve(FileName, StringPool);
212*1db9f3b2SDimitry Andric 
213*1db9f3b2SDimitry Andric     It = ResolvedPaths.insert(std::make_pair(Key, ResolvedPath)).first;
214*1db9f3b2SDimitry Andric   }
215*1db9f3b2SDimitry Andric 
216*1db9f3b2SDimitry Andric   return It->second;
217*1db9f3b2SDimitry Andric }
218*1db9f3b2SDimitry Andric 
219*1db9f3b2SDimitry Andric } // namespace llvm
220