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/SmallString.h" 19 #include "llvm/ADT/StringMap.h" 20 #include "llvm/ADT/StringRef.h" 21 #include "llvm/ADT/Triple.h" 22 #include "llvm/IR/Function.h" 23 #include "llvm/IR/GlobalAlias.h" 24 #include "llvm/IR/GlobalValue.h" 25 #include "llvm/IR/GlobalVariable.h" 26 #include "llvm/IR/InlineAsm.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 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()) 68 AsmSymbol(std::string(Name), Flags)); 69 }); 70 } 71 72 static void 73 initializeRecordStreamer(const Module &M, 74 function_ref<void(RecordStreamer &)> Init) { 75 StringRef InlineAsm = M.getModuleInlineAsm(); 76 if (InlineAsm.empty()) 77 return; 78 79 std::string Err; 80 const Triple TT(M.getTargetTriple()); 81 const Target *T = TargetRegistry::lookupTarget(TT.str(), Err); 82 assert(T && T->hasMCAsmParser()); 83 84 std::unique_ptr<MCRegisterInfo> MRI(T->createMCRegInfo(TT.str())); 85 if (!MRI) 86 return; 87 88 MCTargetOptions MCOptions; 89 std::unique_ptr<MCAsmInfo> MAI(T->createMCAsmInfo(*MRI, TT.str(), MCOptions)); 90 if (!MAI) 91 return; 92 93 std::unique_ptr<MCSubtargetInfo> STI( 94 T->createMCSubtargetInfo(TT.str(), "", "")); 95 if (!STI) 96 return; 97 98 std::unique_ptr<MCInstrInfo> MCII(T->createMCInstrInfo()); 99 if (!MCII) 100 return; 101 102 std::unique_ptr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer(InlineAsm)); 103 SourceMgr SrcMgr; 104 SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc()); 105 106 MCContext MCCtx(TT, MAI.get(), MRI.get(), STI.get(), &SrcMgr); 107 std::unique_ptr<MCObjectFileInfo> MOFI( 108 T->createMCObjectFileInfo(MCCtx, /*PIC=*/false)); 109 MOFI->setSDKVersion(M.getSDKVersion()); 110 MCCtx.setObjectFileInfo(MOFI.get()); 111 RecordStreamer Streamer(MCCtx, M); 112 T->createNullTargetStreamer(Streamer); 113 114 std::unique_ptr<MCAsmParser> Parser( 115 createMCAsmParser(SrcMgr, MCCtx, Streamer, *MAI)); 116 117 std::unique_ptr<MCTargetAsmParser> TAP( 118 T->createMCAsmParser(*STI, *Parser, *MCII, MCOptions)); 119 if (!TAP) 120 return; 121 122 // Module-level inline asm is assumed to use At&t syntax (see 123 // AsmPrinter::doInitialization()). 124 Parser->setAssemblerDialect(InlineAsm::AD_ATT); 125 126 Parser->setTargetParser(*TAP); 127 if (Parser->Run(false)) 128 return; 129 130 Init(Streamer); 131 } 132 133 void ModuleSymbolTable::CollectAsmSymbols( 134 const Module &M, 135 function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) { 136 initializeRecordStreamer(M, [&](RecordStreamer &Streamer) { 137 Streamer.flushSymverDirectives(); 138 139 for (auto &KV : Streamer) { 140 StringRef Key = KV.first(); 141 RecordStreamer::State Value = KV.second; 142 // FIXME: For now we just assume that all asm symbols are executable. 143 uint32_t Res = BasicSymbolRef::SF_Executable; 144 switch (Value) { 145 case RecordStreamer::NeverSeen: 146 llvm_unreachable("NeverSeen should have been replaced earlier"); 147 case RecordStreamer::DefinedGlobal: 148 Res |= BasicSymbolRef::SF_Global; 149 break; 150 case RecordStreamer::Defined: 151 break; 152 case RecordStreamer::Global: 153 case RecordStreamer::Used: 154 Res |= BasicSymbolRef::SF_Undefined; 155 Res |= BasicSymbolRef::SF_Global; 156 break; 157 case RecordStreamer::DefinedWeak: 158 Res |= BasicSymbolRef::SF_Weak; 159 Res |= BasicSymbolRef::SF_Global; 160 break; 161 case RecordStreamer::UndefinedWeak: 162 Res |= BasicSymbolRef::SF_Weak; 163 Res |= BasicSymbolRef::SF_Undefined; 164 } 165 AsmSymbol(Key, BasicSymbolRef::Flags(Res)); 166 } 167 }); 168 } 169 170 void ModuleSymbolTable::CollectAsmSymvers( 171 const Module &M, function_ref<void(StringRef, StringRef)> AsmSymver) { 172 initializeRecordStreamer(M, [&](RecordStreamer &Streamer) { 173 for (auto &KV : Streamer.symverAliases()) 174 for (auto &Alias : KV.second) 175 AsmSymver(KV.first->getName(), Alias); 176 }); 177 } 178 179 void ModuleSymbolTable::printSymbolName(raw_ostream &OS, Symbol S) const { 180 if (S.is<AsmSymbol *>()) { 181 OS << S.get<AsmSymbol *>()->first; 182 return; 183 } 184 185 auto *GV = S.get<GlobalValue *>(); 186 if (GV->hasDLLImportStorageClass()) 187 OS << "__imp_"; 188 189 Mang.getNameWithPrefix(OS, GV, false); 190 } 191 192 uint32_t ModuleSymbolTable::getSymbolFlags(Symbol S) const { 193 if (S.is<AsmSymbol *>()) 194 return S.get<AsmSymbol *>()->second; 195 196 auto *GV = S.get<GlobalValue *>(); 197 198 uint32_t Res = BasicSymbolRef::SF_None; 199 if (GV->isDeclarationForLinker()) 200 Res |= BasicSymbolRef::SF_Undefined; 201 else if (GV->hasHiddenVisibility() && !GV->hasLocalLinkage()) 202 Res |= BasicSymbolRef::SF_Hidden; 203 if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) { 204 if (GVar->isConstant()) 205 Res |= BasicSymbolRef::SF_Const; 206 } 207 if (dyn_cast_or_null<Function>(GV->getBaseObject())) 208 Res |= BasicSymbolRef::SF_Executable; 209 if (isa<GlobalAlias>(GV)) 210 Res |= BasicSymbolRef::SF_Indirect; 211 if (GV->hasPrivateLinkage()) 212 Res |= BasicSymbolRef::SF_FormatSpecific; 213 if (!GV->hasLocalLinkage()) 214 Res |= BasicSymbolRef::SF_Global; 215 if (GV->hasCommonLinkage()) 216 Res |= BasicSymbolRef::SF_Common; 217 if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() || 218 GV->hasExternalWeakLinkage()) 219 Res |= BasicSymbolRef::SF_Weak; 220 221 if (GV->getName().startswith("llvm.")) 222 Res |= BasicSymbolRef::SF_FormatSpecific; 223 else if (auto *Var = dyn_cast<GlobalVariable>(GV)) { 224 if (Var->getSection() == "llvm.metadata") 225 Res |= BasicSymbolRef::SF_FormatSpecific; 226 } 227 228 return Res; 229 } 230