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