1 //===----------- Mangling.cpp -- Name Mangling Utilities for ORC ----------===//
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 #include "llvm/ExecutionEngine/Orc/Mangling.h"
10 #include "llvm/IR/Constants.h"
11 #include "llvm/IR/Mangler.h"
12 #include "llvm/Object/MachO.h"
13 #include "llvm/Object/ObjectFile.h"
14 #include "llvm/Support/Debug.h"
15 
16 #define DEBUG_TYPE "orc"
17 
18 namespace llvm {
19 namespace orc {
20 
21 MangleAndInterner::MangleAndInterner(ExecutionSession &ES, const DataLayout &DL)
22     : ES(ES), DL(DL) {}
23 
24 SymbolStringPtr MangleAndInterner::operator()(StringRef Name) {
25   std::string MangledName;
26   {
27     raw_string_ostream MangledNameStream(MangledName);
28     Mangler::getNameWithPrefix(MangledNameStream, Name, DL);
29   }
30   return ES.intern(MangledName);
31 }
32 
33 void IRSymbolMapper::add(ExecutionSession &ES, const ManglingOptions &MO,
34                          ArrayRef<GlobalValue *> GVs,
35                          SymbolFlagsMap &SymbolFlags,
36                          SymbolNameToDefinitionMap *SymbolToDefinition) {
37   if (GVs.empty())
38     return;
39 
40   MangleAndInterner Mangle(ES, GVs[0]->getParent()->getDataLayout());
41   for (auto *G : GVs) {
42     assert(G && "GVs cannot contain null elements");
43     if (!G->hasName() || G->isDeclaration() || G->hasLocalLinkage() ||
44         G->hasAvailableExternallyLinkage() || G->hasAppendingLinkage())
45       continue;
46 
47     if (G->isThreadLocal() && MO.EmulatedTLS) {
48       auto *GV = cast<GlobalVariable>(G);
49 
50       auto Flags = JITSymbolFlags::fromGlobalValue(*GV);
51 
52       auto EmuTLSV = Mangle(("__emutls_v." + GV->getName()).str());
53       SymbolFlags[EmuTLSV] = Flags;
54       if (SymbolToDefinition)
55         (*SymbolToDefinition)[EmuTLSV] = GV;
56 
57       // If this GV has a non-zero initializer we'll need to emit an
58       // __emutls.t symbol too.
59       if (GV->hasInitializer()) {
60         const auto *InitVal = GV->getInitializer();
61 
62         // Skip zero-initializers.
63         if (isa<ConstantAggregateZero>(InitVal))
64           continue;
65         const auto *InitIntValue = dyn_cast<ConstantInt>(InitVal);
66         if (InitIntValue && InitIntValue->isZero())
67           continue;
68 
69         auto EmuTLST = Mangle(("__emutls_t." + GV->getName()).str());
70         SymbolFlags[EmuTLST] = Flags;
71         if (SymbolToDefinition)
72           (*SymbolToDefinition)[EmuTLST] = GV;
73       }
74       continue;
75     }
76 
77     // Otherwise we just need a normal linker mangling.
78     auto MangledName = Mangle(G->getName());
79     SymbolFlags[MangledName] = JITSymbolFlags::fromGlobalValue(*G);
80     if (SymbolToDefinition)
81       (*SymbolToDefinition)[MangledName] = G;
82   }
83 }
84 
85 Expected<std::pair<SymbolFlagsMap, SymbolStringPtr>>
86 getObjectSymbolInfo(ExecutionSession &ES, MemoryBufferRef ObjBuffer) {
87   auto Obj = object::ObjectFile::createObjectFile(ObjBuffer);
88 
89   if (!Obj)
90     return Obj.takeError();
91 
92   SymbolFlagsMap SymbolFlags;
93   for (auto &Sym : (*Obj)->symbols()) {
94     // Skip symbols not defined in this object file.
95     if (Sym.getFlags() & object::BasicSymbolRef::SF_Undefined)
96       continue;
97 
98     // Skip symbols that are not global.
99     if (!(Sym.getFlags() & object::BasicSymbolRef::SF_Global))
100       continue;
101 
102     auto Name = Sym.getName();
103     if (!Name)
104       return Name.takeError();
105     auto InternedName = ES.intern(*Name);
106     auto SymFlags = JITSymbolFlags::fromObjectSymbol(Sym);
107     if (!SymFlags)
108       return SymFlags.takeError();
109     SymbolFlags[InternedName] = std::move(*SymFlags);
110   }
111 
112   SymbolStringPtr InitSymbol;
113 
114   if (auto *MachOObj = dyn_cast<object::MachOObjectFile>(Obj->get())) {
115     for (auto &Sec : MachOObj->sections()) {
116       auto SecType = MachOObj->getSectionType(Sec);
117       if ((SecType & MachO::SECTION_TYPE) == MachO::S_MOD_INIT_FUNC_POINTERS) {
118         std::string InitSymString;
119         raw_string_ostream(InitSymString)
120             << "$." << ObjBuffer.getBufferIdentifier() << ".__inits";
121         InitSymbol = ES.intern(InitSymString);
122         break;
123       }
124     }
125   }
126 
127   return std::make_pair(std::move(SymbolFlags), std::move(InitSymbol));
128 }
129 
130 } // End namespace orc.
131 } // End namespace llvm.
132