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