1 //===- ModuleSymbolTable.cpp - symbol table for in-memory IR --------------===//
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 class represents a symbol table built from in-memory IR. It provides
11 // access to GlobalValues and should only be used if such access is required
12 // (e.g. in the LTO implementation).
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "llvm/Object/ModuleSymbolTable.h"
17 #include "RecordStreamer.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/StringMap.h"
21 #include "llvm/ADT/StringRef.h"
22 #include "llvm/ADT/Triple.h"
23 #include "llvm/IR/Function.h"
24 #include "llvm/IR/GlobalAlias.h"
25 #include "llvm/IR/GlobalValue.h"
26 #include "llvm/IR/GlobalVariable.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/MC/MCAsmInfo.h"
29 #include "llvm/MC/MCContext.h"
30 #include "llvm/MC/MCDirectives.h"
31 #include "llvm/MC/MCInstrInfo.h"
32 #include "llvm/MC/MCObjectFileInfo.h"
33 #include "llvm/MC/MCParser/MCAsmParser.h"
34 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
35 #include "llvm/MC/MCRegisterInfo.h"
36 #include "llvm/MC/MCSubtargetInfo.h"
37 #include "llvm/MC/MCSymbol.h"
38 #include "llvm/MC/MCTargetOptions.h"
39 #include "llvm/Object/SymbolicFile.h"
40 #include "llvm/Support/Casting.h"
41 #include "llvm/Support/CodeGen.h"
42 #include "llvm/Support/ErrorHandling.h"
43 #include "llvm/Support/MemoryBuffer.h"
44 #include "llvm/Support/SMLoc.h"
45 #include "llvm/Support/SourceMgr.h"
46 #include "llvm/Support/TargetRegistry.h"
47 #include "llvm/Support/raw_ostream.h"
48 #include <algorithm>
49 #include <cassert>
50 #include <cstdint>
51 #include <memory>
52 #include <string>
53 
54 using namespace llvm;
55 using namespace object;
56 
addModule(Module * M)57 void ModuleSymbolTable::addModule(Module *M) {
58   if (FirstMod)
59     assert(FirstMod->getTargetTriple() == M->getTargetTriple());
60   else
61     FirstMod = M;
62 
63   for (GlobalValue &GV : M->global_values())
64     SymTab.push_back(&GV);
65 
66   CollectAsmSymbols(*M, [this](StringRef Name, BasicSymbolRef::Flags Flags) {
67     SymTab.push_back(new (AsmSymbols.Allocate()) AsmSymbol(Name, Flags));
68   });
69 }
70 
71 static void
initializeRecordStreamer(const Module & M,function_ref<void (RecordStreamer &)> Init)72 initializeRecordStreamer(const Module &M,
73                          function_ref<void(RecordStreamer &)> Init) {
74   StringRef InlineAsm = M.getModuleInlineAsm();
75   if (InlineAsm.empty())
76     return;
77 
78   std::string Err;
79   const Triple TT(M.getTargetTriple());
80   const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
81   assert(T && T->hasMCAsmParser());
82 
83   std::unique_ptr<MCRegisterInfo> MRI(T->createMCRegInfo(TT.str()));
84   if (!MRI)
85     return;
86 
87   std::unique_ptr<MCAsmInfo> MAI(T->createMCAsmInfo(*MRI, TT.str()));
88   if (!MAI)
89     return;
90 
91   std::unique_ptr<MCSubtargetInfo> STI(
92       T->createMCSubtargetInfo(TT.str(), "", ""));
93   if (!STI)
94     return;
95 
96   std::unique_ptr<MCInstrInfo> MCII(T->createMCInstrInfo());
97   if (!MCII)
98     return;
99 
100   MCObjectFileInfo MOFI;
101   MCContext MCCtx(MAI.get(), MRI.get(), &MOFI);
102   MOFI.InitMCObjectFileInfo(TT, /*PIC*/ false, MCCtx);
103   MOFI.setSDKVersion(M.getSDKVersion());
104   RecordStreamer Streamer(MCCtx, M);
105   T->createNullTargetStreamer(Streamer);
106 
107   std::unique_ptr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer(InlineAsm));
108   SourceMgr SrcMgr;
109   SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
110   std::unique_ptr<MCAsmParser> Parser(
111       createMCAsmParser(SrcMgr, MCCtx, Streamer, *MAI));
112 
113   MCTargetOptions MCOptions;
114   std::unique_ptr<MCTargetAsmParser> TAP(
115       T->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
116   if (!TAP)
117     return;
118 
119   Parser->setTargetParser(*TAP);
120   if (Parser->Run(false))
121     return;
122 
123   Init(Streamer);
124 }
125 
CollectAsmSymbols(const Module & M,function_ref<void (StringRef,BasicSymbolRef::Flags)> AsmSymbol)126 void ModuleSymbolTable::CollectAsmSymbols(
127     const Module &M,
128     function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) {
129   initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
130     Streamer.flushSymverDirectives();
131 
132     for (auto &KV : Streamer) {
133       StringRef Key = KV.first();
134       RecordStreamer::State Value = KV.second;
135       // FIXME: For now we just assume that all asm symbols are executable.
136       uint32_t Res = BasicSymbolRef::SF_Executable;
137       switch (Value) {
138       case RecordStreamer::NeverSeen:
139         llvm_unreachable("NeverSeen should have been replaced earlier");
140       case RecordStreamer::DefinedGlobal:
141         Res |= BasicSymbolRef::SF_Global;
142         break;
143       case RecordStreamer::Defined:
144         break;
145       case RecordStreamer::Global:
146       case RecordStreamer::Used:
147         Res |= BasicSymbolRef::SF_Undefined;
148         Res |= BasicSymbolRef::SF_Global;
149         break;
150       case RecordStreamer::DefinedWeak:
151         Res |= BasicSymbolRef::SF_Weak;
152         Res |= BasicSymbolRef::SF_Global;
153         break;
154       case RecordStreamer::UndefinedWeak:
155         Res |= BasicSymbolRef::SF_Weak;
156         Res |= BasicSymbolRef::SF_Undefined;
157       }
158       AsmSymbol(Key, BasicSymbolRef::Flags(Res));
159     }
160   });
161 }
162 
CollectAsmSymvers(const Module & M,function_ref<void (StringRef,StringRef)> AsmSymver)163 void ModuleSymbolTable::CollectAsmSymvers(
164     const Module &M, function_ref<void(StringRef, StringRef)> AsmSymver) {
165   initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
166     for (auto &KV : Streamer.symverAliases())
167       for (auto &Alias : KV.second)
168         AsmSymver(KV.first->getName(), Alias);
169   });
170 }
171 
printSymbolName(raw_ostream & OS,Symbol S) const172 void ModuleSymbolTable::printSymbolName(raw_ostream &OS, Symbol S) const {
173   if (S.is<AsmSymbol *>()) {
174     OS << S.get<AsmSymbol *>()->first;
175     return;
176   }
177 
178   auto *GV = S.get<GlobalValue *>();
179   if (GV->hasDLLImportStorageClass())
180     OS << "__imp_";
181 
182   Mang.getNameWithPrefix(OS, GV, false);
183 }
184 
getSymbolFlags(Symbol S) const185 uint32_t ModuleSymbolTable::getSymbolFlags(Symbol S) const {
186   if (S.is<AsmSymbol *>())
187     return S.get<AsmSymbol *>()->second;
188 
189   auto *GV = S.get<GlobalValue *>();
190 
191   uint32_t Res = BasicSymbolRef::SF_None;
192   if (GV->isDeclarationForLinker())
193     Res |= BasicSymbolRef::SF_Undefined;
194   else if (GV->hasHiddenVisibility() && !GV->hasLocalLinkage())
195     Res |= BasicSymbolRef::SF_Hidden;
196   if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
197     if (GVar->isConstant())
198       Res |= BasicSymbolRef::SF_Const;
199   }
200   if (dyn_cast_or_null<Function>(GV->getBaseObject()))
201     Res |= BasicSymbolRef::SF_Executable;
202   if (isa<GlobalAlias>(GV))
203     Res |= BasicSymbolRef::SF_Indirect;
204   if (GV->hasPrivateLinkage())
205     Res |= BasicSymbolRef::SF_FormatSpecific;
206   if (!GV->hasLocalLinkage())
207     Res |= BasicSymbolRef::SF_Global;
208   if (GV->hasCommonLinkage())
209     Res |= BasicSymbolRef::SF_Common;
210   if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
211       GV->hasExternalWeakLinkage())
212     Res |= BasicSymbolRef::SF_Weak;
213 
214   if (GV->getName().startswith("llvm."))
215     Res |= BasicSymbolRef::SF_FormatSpecific;
216   else if (auto *Var = dyn_cast<GlobalVariable>(GV)) {
217     if (Var->getSection() == "llvm.metadata")
218       Res |= BasicSymbolRef::SF_FormatSpecific;
219   }
220 
221   return Res;
222 }
223