llvm/lib/Object/ModuleSymbolTable.cpp

   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/StringRef.h"
  19 #include "llvm/IR/DiagnosticInfo.h"
  20 #include "llvm/IR/Function.h"
  21 #include "llvm/IR/GlobalAlias.h"
  22 #include "llvm/IR/GlobalValue.h"
  23 #include "llvm/IR/GlobalVariable.h"
  24 #include "llvm/IR/InlineAsm.h"
  25 #include "llvm/IR/Module.h"
  26 #include "llvm/MC/MCAsmInfo.h"
  27 #include "llvm/MC/MCContext.h"
  28 #include "llvm/MC/MCInstrInfo.h"
  29 #include "llvm/MC/MCObjectFileInfo.h"
  30 #include "llvm/MC/MCParser/MCAsmParser.h"
  31 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
  32 #include "llvm/MC/MCRegisterInfo.h"
  33 #include "llvm/MC/MCSubtargetInfo.h"
  34 #include "llvm/MC/MCSymbol.h"
  35 #include "llvm/MC/MCTargetOptions.h"
  36 #include "llvm/MC/TargetRegistry.h"
  37 #include "llvm/Object/SymbolicFile.h"
  38 #include "llvm/Support/Casting.h"
  39 #include "llvm/Support/ErrorHandling.h"
  40 #include "llvm/Support/MemoryBuffer.h"
  41 #include "llvm/Support/SMLoc.h"
  42 #include "llvm/Support/SourceMgr.h"
  43 #include "llvm/Support/raw_ostream.h"
  44 #include "llvm/TargetParser/Triple.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   // This function may be called twice, once for ModuleSummaryIndexAnalysis and
  73   // the other when writing the IR symbol table. If parsing inline assembly has
  74   // caused errors in the first run, suppress the second run.
  75   if (M.getContext().getDiagHandlerPtr()->HasErrors)
  76     return;
  77   StringRef InlineAsm = M.getModuleInlineAsm();
  78   if (InlineAsm.empty())
  79     return;
  80
  81   std::string Err;
  82   const Triple TT(M.getTargetTriple());
  83   const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
  84   assert(T && T->hasMCAsmParser());
  85
  86   std::unique_ptr<MCRegisterInfo> MRI(T->createMCRegInfo(TT.str()));
  87   if (!MRI)
  88     return;
  89
  90   MCTargetOptions MCOptions;
  91   std::unique_ptr<MCAsmInfo> MAI(T->createMCAsmInfo(*MRI, TT.str(), MCOptions));
  92   if (!MAI)
  93     return;
  94
  95   std::unique_ptr<MCSubtargetInfo> STI(
  96       T->createMCSubtargetInfo(TT.str(), "", ""));
  97   if (!STI)
  98     return;
  99
 100   std::unique_ptr<MCInstrInfo> MCII(T->createMCInstrInfo());
 101   if (!MCII)
 102     return;
 103
 104   std::unique_ptr<MemoryBuffer> Buffer(
 105       MemoryBuffer::getMemBuffer(InlineAsm, "<inline asm>"));
 106   SourceMgr SrcMgr;
 107   SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
 108
 109   MCContext MCCtx(TT, MAI.get(), MRI.get(), STI.get(), &SrcMgr);
 110   std::unique_ptr<MCObjectFileInfo> MOFI(
 111       T->createMCObjectFileInfo(MCCtx, /*PIC=*/false));
 112   MOFI->setSDKVersion(M.getSDKVersion());
 113   MCCtx.setObjectFileInfo(MOFI.get());
 114   RecordStreamer Streamer(MCCtx, M);
 115   T->createNullTargetStreamer(Streamer);
 116
 117   std::unique_ptr<MCAsmParser> Parser(
 118       createMCAsmParser(SrcMgr, MCCtx, Streamer, *MAI));
 119
 120   std::unique_ptr<MCTargetAsmParser> TAP(
 121       T->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
 122   if (!TAP)
 123     return;
 124
 125   MCCtx.setDiagnosticHandler([&](const SMDiagnostic &SMD, bool IsInlineAsm,
 126                                  const SourceMgr &SrcMgr,
 127                                  std::vector<const MDNode *> &LocInfos) {
 128     M.getContext().diagnose(
 129         DiagnosticInfoSrcMgr(SMD, M.getName(), IsInlineAsm, /*LocCookie=*/0));
 130   });
 131
 132   // Module-level inline asm is assumed to use At&t syntax (see
 133   // AsmPrinter::doInitialization()).
 134   Parser->setAssemblerDialect(InlineAsm::AD_ATT);
 135
 136   Parser->setTargetParser(*TAP);
 137   if (Parser->Run(false))
 138     return;
 139
 140   Init(Streamer);
 141 }
 142
 143 void ModuleSymbolTable::CollectAsmSymbols(
 144     const Module &M,
 145     function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) {
 146   initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
 147     Streamer.flushSymverDirectives();
 148
 149     for (auto &KV : Streamer) {
 150       StringRef Key = KV.first();
 151       RecordStreamer::State Value = KV.second;
 152       // FIXME: For now we just assume that all asm symbols are executable.
 153       uint32_t Res = BasicSymbolRef::SF_Executable;
 154       switch (Value) {
 155       case RecordStreamer::NeverSeen:
 156         llvm_unreachable("NeverSeen should have been replaced earlier");
 157       case RecordStreamer::DefinedGlobal:
 158         Res |= BasicSymbolRef::SF_Global;
 159         break;
 160       case RecordStreamer::Defined:
 161         break;
 162       case RecordStreamer::Global:
 163       case RecordStreamer::Used:
 164         Res |= BasicSymbolRef::SF_Undefined;
 165         Res |= BasicSymbolRef::SF_Global;
 166         break;
 167       case RecordStreamer::DefinedWeak:
 168         Res |= BasicSymbolRef::SF_Weak;
 169         Res |= BasicSymbolRef::SF_Global;
 170         break;
 171       case RecordStreamer::UndefinedWeak:
 172         Res |= BasicSymbolRef::SF_Weak;
 173         Res |= BasicSymbolRef::SF_Undefined;
 174       }
 175       AsmSymbol(Key, BasicSymbolRef::Flags(Res));
 176     }
 177   });
 178
 179   // In ELF, object code generated for x86-32 and some code models of x86-64 may
 180   // reference the special symbol _GLOBAL_OFFSET_TABLE_ that is not used in the
 181   // IR. Record it like inline asm symbols.
 182   Triple TT(M.getTargetTriple());
 183   if (!TT.isOSBinFormatELF() || !TT.isX86())
 184     return;
 185   auto CM = M.getCodeModel();
 186   if (TT.getArch() == Triple::x86 || CM == CodeModel::Medium ||
 187       CM == CodeModel::Large) {
 188     AsmSymbol("_GLOBAL_OFFSET_TABLE_",
 189               BasicSymbolRef::Flags(BasicSymbolRef::SF_Undefined |
 190                                     BasicSymbolRef::SF_Global));
 191   }
 192 }
 193
 194 void ModuleSymbolTable::CollectAsmSymvers(
 195     const Module &M, function_ref<void(StringRef, StringRef)> AsmSymver) {
 196   initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
 197     for (auto &KV : Streamer.symverAliases())
 198       for (auto &Alias : KV.second)
 199         AsmSymver(KV.first->getName(), Alias);
 200   });
 201 }
 202
 203 void ModuleSymbolTable::printSymbolName(raw_ostream &OS, Symbol S) const {
 204   if (isa<AsmSymbol *>(S)) {
 205     OS << cast<AsmSymbol *>(S)->first;
 206     return;
 207   }
 208
 209   auto *GV = cast<GlobalValue *>(S);
 210   if (GV->hasDLLImportStorageClass())
 211     OS << "__imp_";
 212
 213   Mang.getNameWithPrefix(OS, GV, false);
 214 }
 215
 216 uint32_t ModuleSymbolTable::getSymbolFlags(Symbol S) const {
 217   if (isa<AsmSymbol *>(S))
 218     return cast<AsmSymbol *>(S)->second;
 219
 220   auto *GV = cast<GlobalValue *>(S);
 221
 222   uint32_t Res = BasicSymbolRef::SF_None;
 223   if (GV->isDeclarationForLinker())
 224     Res |= BasicSymbolRef::SF_Undefined;
 225   else if (GV->hasHiddenVisibility() && !GV->hasLocalLinkage())
 226     Res |= BasicSymbolRef::SF_Hidden;
 227   if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
 228     if (GVar->isConstant())
 229       Res |= BasicSymbolRef::SF_Const;
 230   }
 231   if (const GlobalObject *GO = GV->getAliaseeObject())
 232     if (isa<Function>(GO) || isa<GlobalIFunc>(GO))
 233       Res |= BasicSymbolRef::SF_Executable;
 234   if (isa<GlobalAlias>(GV))
 235     Res |= BasicSymbolRef::SF_Indirect;
 236   if (GV->hasPrivateLinkage())
 237     Res |= BasicSymbolRef::SF_FormatSpecific;
 238   if (!GV->hasLocalLinkage())
 239     Res |= BasicSymbolRef::SF_Global;
 240   if (GV->hasCommonLinkage())
 241     Res |= BasicSymbolRef::SF_Common;
 242   if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
 243       GV->hasExternalWeakLinkage())
 244     Res |= BasicSymbolRef::SF_Weak;
 245
 246   if (GV->getName().starts_with("llvm."))
 247     Res |= BasicSymbolRef::SF_FormatSpecific;
 248   else if (auto *Var = dyn_cast<GlobalVariable>(GV)) {
 249     if (Var->getSection() == "llvm.metadata")
 250       Res |= BasicSymbolRef::SF_FormatSpecific;
 251   }
 252
 253   return Res;
 254 }