1 //===- ModuleSymbolTable.cpp - symbol table for in-memory IR --------------===// 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 // This class represents a symbol table built from in-memory IR. It provides 10 // access to GlobalValues and should only be used if such access is required 11 // (e.g. in the LTO implementation). 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/Object/ModuleSymbolTable.h" 16 #include "RecordStreamer.h" 17 #include "llvm/ADT/STLExtras.h" 18 #include "llvm/ADT/StringMap.h" 19 #include "llvm/ADT/StringRef.h" 20 #include "llvm/ADT/Triple.h" 21 #include "llvm/IR/Function.h" 22 #include "llvm/IR/GlobalAlias.h" 23 #include "llvm/IR/GlobalValue.h" 24 #include "llvm/IR/GlobalVariable.h" 25 #include "llvm/IR/InlineAsm.h" 26 #include "llvm/IR/Module.h" 27 #include "llvm/MC/MCAsmInfo.h" 28 #include "llvm/MC/MCContext.h" 29 #include "llvm/MC/MCInstrInfo.h" 30 #include "llvm/MC/MCObjectFileInfo.h" 31 #include "llvm/MC/MCParser/MCAsmParser.h" 32 #include "llvm/MC/MCParser/MCTargetAsmParser.h" 33 #include "llvm/MC/MCRegisterInfo.h" 34 #include "llvm/MC/MCSubtargetInfo.h" 35 #include "llvm/MC/MCSymbol.h" 36 #include "llvm/MC/MCTargetOptions.h" 37 #include "llvm/MC/TargetRegistry.h" 38 #include "llvm/Object/SymbolicFile.h" 39 #include "llvm/Support/Casting.h" 40 #include "llvm/Support/ErrorHandling.h" 41 #include "llvm/Support/MemoryBuffer.h" 42 #include "llvm/Support/SMLoc.h" 43 #include "llvm/Support/SourceMgr.h" 44 #include "llvm/Support/raw_ostream.h" 45 #include <algorithm> 46 #include <cassert> 47 #include <cstdint> 48 #include <memory> 49 #include <string> 50 51 using namespace llvm; 52 using namespace object; 53 54 void ModuleSymbolTable::addModule(Module *M) { 55 if (FirstMod) 56 assert(FirstMod->getTargetTriple() == M->getTargetTriple()); 57 else 58 FirstMod = M; 59 60 for (GlobalValue &GV : M->global_values()) 61 SymTab.push_back(&GV); 62 63 CollectAsmSymbols(*M, [this](StringRef Name, BasicSymbolRef::Flags Flags) { 64 SymTab.push_back(new (AsmSymbols.Allocate()) 65 AsmSymbol(std::string(Name), Flags)); 66 }); 67 } 68 69 static void 70 initializeRecordStreamer(const Module &M, 71 function_ref<void(RecordStreamer &)> Init) { 72 StringRef InlineAsm = M.getModuleInlineAsm(); 73 if (InlineAsm.empty()) 74 return; 75 76 std::string Err; 77 const Triple TT(M.getTargetTriple()); 78 const Target *T = TargetRegistry::lookupTarget(TT.str(), Err); 79 assert(T && T->hasMCAsmParser()); 80 81 std::unique_ptr<MCRegisterInfo> MRI(T->createMCRegInfo(TT.str())); 82 if (!MRI) 83 return; 84 85 MCTargetOptions MCOptions; 86 std::unique_ptr<MCAsmInfo> MAI(T->createMCAsmInfo(*MRI, TT.str(), MCOptions)); 87 if (!MAI) 88 return; 89 90 std::unique_ptr<MCSubtargetInfo> STI( 91 T->createMCSubtargetInfo(TT.str(), "", "")); 92 if (!STI) 93 return; 94 95 std::unique_ptr<MCInstrInfo> MCII(T->createMCInstrInfo()); 96 if (!MCII) 97 return; 98 99 std::unique_ptr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer(InlineAsm)); 100 SourceMgr SrcMgr; 101 SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc()); 102 103 MCContext MCCtx(TT, MAI.get(), MRI.get(), STI.get(), &SrcMgr); 104 std::unique_ptr<MCObjectFileInfo> MOFI( 105 T->createMCObjectFileInfo(MCCtx, /*PIC=*/false)); 106 MOFI->setSDKVersion(M.getSDKVersion()); 107 MCCtx.setObjectFileInfo(MOFI.get()); 108 RecordStreamer Streamer(MCCtx, M); 109 T->createNullTargetStreamer(Streamer); 110 111 std::unique_ptr<MCAsmParser> Parser( 112 createMCAsmParser(SrcMgr, MCCtx, Streamer, *MAI)); 113 114 std::unique_ptr<MCTargetAsmParser> TAP( 115 T->createMCAsmParser(*STI, *Parser, *MCII, MCOptions)); 116 if (!TAP) 117 return; 118 119 // Module-level inline asm is assumed to use At&t syntax (see 120 // AsmPrinter::doInitialization()). 121 Parser->setAssemblerDialect(InlineAsm::AD_ATT); 122 123 Parser->setTargetParser(*TAP); 124 if (Parser->Run(false)) 125 return; 126 127 Init(Streamer); 128 } 129 130 void ModuleSymbolTable::CollectAsmSymbols( 131 const Module &M, 132 function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) { 133 initializeRecordStreamer(M, [&](RecordStreamer &Streamer) { 134 Streamer.flushSymverDirectives(); 135 136 for (auto &KV : Streamer) { 137 StringRef Key = KV.first(); 138 RecordStreamer::State Value = KV.second; 139 // FIXME: For now we just assume that all asm symbols are executable. 140 uint32_t Res = BasicSymbolRef::SF_Executable; 141 switch (Value) { 142 case RecordStreamer::NeverSeen: 143 llvm_unreachable("NeverSeen should have been replaced earlier"); 144 case RecordStreamer::DefinedGlobal: 145 Res |= BasicSymbolRef::SF_Global; 146 break; 147 case RecordStreamer::Defined: 148 break; 149 case RecordStreamer::Global: 150 case RecordStreamer::Used: 151 Res |= BasicSymbolRef::SF_Undefined; 152 Res |= BasicSymbolRef::SF_Global; 153 break; 154 case RecordStreamer::DefinedWeak: 155 Res |= BasicSymbolRef::SF_Weak; 156 Res |= BasicSymbolRef::SF_Global; 157 break; 158 case RecordStreamer::UndefinedWeak: 159 Res |= BasicSymbolRef::SF_Weak; 160 Res |= BasicSymbolRef::SF_Undefined; 161 } 162 AsmSymbol(Key, BasicSymbolRef::Flags(Res)); 163 } 164 }); 165 } 166 167 void ModuleSymbolTable::CollectAsmSymvers( 168 const Module &M, function_ref<void(StringRef, StringRef)> AsmSymver) { 169 initializeRecordStreamer(M, [&](RecordStreamer &Streamer) { 170 for (auto &KV : Streamer.symverAliases()) 171 for (auto &Alias : KV.second) 172 AsmSymver(KV.first->getName(), Alias); 173 }); 174 } 175 176 void ModuleSymbolTable::printSymbolName(raw_ostream &OS, Symbol S) const { 177 if (S.is<AsmSymbol *>()) { 178 OS << S.get<AsmSymbol *>()->first; 179 return; 180 } 181 182 auto *GV = S.get<GlobalValue *>(); 183 if (GV->hasDLLImportStorageClass()) 184 OS << "__imp_"; 185 186 Mang.getNameWithPrefix(OS, GV, false); 187 } 188 189 uint32_t ModuleSymbolTable::getSymbolFlags(Symbol S) const { 190 if (S.is<AsmSymbol *>()) 191 return S.get<AsmSymbol *>()->second; 192 193 auto *GV = S.get<GlobalValue *>(); 194 195 uint32_t Res = BasicSymbolRef::SF_None; 196 if (GV->isDeclarationForLinker()) 197 Res |= BasicSymbolRef::SF_Undefined; 198 else if (GV->hasHiddenVisibility() && !GV->hasLocalLinkage()) 199 Res |= BasicSymbolRef::SF_Hidden; 200 if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) { 201 if (GVar->isConstant()) 202 Res |= BasicSymbolRef::SF_Const; 203 } 204 if (const GlobalObject *GO = GV->getAliaseeObject()) 205 if (isa<Function>(GO) || isa<GlobalIFunc>(GO)) 206 Res |= BasicSymbolRef::SF_Executable; 207 if (isa<GlobalAlias>(GV)) 208 Res |= BasicSymbolRef::SF_Indirect; 209 if (GV->hasPrivateLinkage()) 210 Res |= BasicSymbolRef::SF_FormatSpecific; 211 if (!GV->hasLocalLinkage()) 212 Res |= BasicSymbolRef::SF_Global; 213 if (GV->hasCommonLinkage()) 214 Res |= BasicSymbolRef::SF_Common; 215 if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() || 216 GV->hasExternalWeakLinkage()) 217 Res |= BasicSymbolRef::SF_Weak; 218 219 if (GV->getName().startswith("llvm.")) 220 Res |= BasicSymbolRef::SF_FormatSpecific; 221 else if (auto *Var = dyn_cast<GlobalVariable>(GV)) { 222 if (Var->getSection() == "llvm.metadata") 223 Res |= BasicSymbolRef::SF_FormatSpecific; 224 } 225 226 return Res; 227 } 228