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