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/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 }