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/Function.h"
  20 #include "llvm/IR/GlobalAlias.h"
  21 #include "llvm/IR/GlobalValue.h"
  22 #include "llvm/IR/GlobalVariable.h"
  23 #include "llvm/IR/InlineAsm.h"
  24 #include "llvm/IR/Module.h"
  25 #include "llvm/MC/MCAsmInfo.h"
  26 #include "llvm/MC/MCContext.h"
  27 #include "llvm/MC/MCInstrInfo.h"
  28 #include "llvm/MC/MCObjectFileInfo.h"
  29 #include "llvm/MC/MCParser/MCAsmParser.h"
  30 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
  31 #include "llvm/MC/MCRegisterInfo.h"
  32 #include "llvm/MC/MCSubtargetInfo.h"
  33 #include "llvm/MC/MCSymbol.h"
  34 #include "llvm/MC/MCTargetOptions.h"
  35 #include "llvm/MC/TargetRegistry.h"
  36 #include "llvm/Object/SymbolicFile.h"
  37 #include "llvm/Support/Casting.h"
  38 #include "llvm/Support/ErrorHandling.h"
  39 #include "llvm/Support/MemoryBuffer.h"
  40 #include "llvm/Support/SMLoc.h"
  41 #include "llvm/Support/SourceMgr.h"
  42 #include "llvm/Support/raw_ostream.h"
  43 #include "llvm/TargetParser/Triple.h"
  44 #include <algorithm>
  45 #include <cassert>
  46 #include <cstdint>
  47 #include <memory>
  48 #include <string>
  49
  50 using namespace llvm;
  51 using namespace object;
  52
  53 void ModuleSymbolTable::addModule(Module *M) {
  54   if (FirstMod)
  55     assert(FirstMod->getTargetTriple() == M->getTargetTriple());
  56   else
  57     FirstMod = M;
  58
  59   for (GlobalValue &GV : M->global_values())
  60     SymTab.push_back(&GV);
  61
  62   CollectAsmSymbols(*M, [this](StringRef Name, BasicSymbolRef::Flags Flags) {
  63     SymTab.push_back(new (AsmSymbols.Allocate())
  64                          AsmSymbol(std::string(Name), Flags));
  65   });
  66 }
  67
  68 static void
  69 initializeRecordStreamer(const Module &M,
  70                          function_ref<void(RecordStreamer &)> Init) {
  71   StringRef InlineAsm = M.getModuleInlineAsm();
  72   if (InlineAsm.empty())
  73     return;
  74
  75   std::string Err;
  76   const Triple TT(M.getTargetTriple());
  77   const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
  78   assert(T && T->hasMCAsmParser());
  79
  80   std::unique_ptr<MCRegisterInfo> MRI(T->createMCRegInfo(TT.str()));
  81   if (!MRI)
  82     return;
  83
  84   MCTargetOptions MCOptions;
  85   std::unique_ptr<MCAsmInfo> MAI(T->createMCAsmInfo(*MRI, TT.str(), MCOptions));
  86   if (!MAI)
  87     return;
  88
  89   std::unique_ptr<MCSubtargetInfo> STI(
  90       T->createMCSubtargetInfo(TT.str(), "", ""));
  91   if (!STI)
  92     return;
  93
  94   std::unique_ptr<MCInstrInfo> MCII(T->createMCInstrInfo());
  95   if (!MCII)
  96     return;
  97
  98   std::unique_ptr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer(InlineAsm));
  99   SourceMgr SrcMgr;
 100   SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
 101
 102   MCContext MCCtx(TT, MAI.get(), MRI.get(), STI.get(), &SrcMgr);
 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<MCAsmParser> Parser(
 111       createMCAsmParser(SrcMgr, MCCtx, Streamer, *MAI));
 112
 113   std::unique_ptr<MCTargetAsmParser> TAP(
 114       T->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
 115   if (!TAP)
 116     return;
 117
 118   // Module-level inline asm is assumed to use At&t syntax (see
 119   // AsmPrinter::doInitialization()).
 120   Parser->setAssemblerDialect(InlineAsm::AD_ATT);
 121
 122   Parser->setTargetParser(*TAP);
 123   if (Parser->Run(false))
 124     return;
 125
 126   Init(Streamer);
 127 }
 128
 129 void ModuleSymbolTable::CollectAsmSymbols(
 130     const Module &M,
 131     function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) {
 132   initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
 133     Streamer.flushSymverDirectives();
 134
 135     for (auto &KV : Streamer) {
 136       StringRef Key = KV.first();
 137       RecordStreamer::State Value = KV.second;
 138       // FIXME: For now we just assume that all asm symbols are executable.
 139       uint32_t Res = BasicSymbolRef::SF_Executable;
 140       switch (Value) {
 141       case RecordStreamer::NeverSeen:
 142         llvm_unreachable("NeverSeen should have been replaced earlier");
 143       case RecordStreamer::DefinedGlobal:
 144         Res |= BasicSymbolRef::SF_Global;
 145         break;
 146       case RecordStreamer::Defined:
 147         break;
 148       case RecordStreamer::Global:
 149       case RecordStreamer::Used:
 150         Res |= BasicSymbolRef::SF_Undefined;
 151         Res |= BasicSymbolRef::SF_Global;
 152         break;
 153       case RecordStreamer::DefinedWeak:
 154         Res |= BasicSymbolRef::SF_Weak;
 155         Res |= BasicSymbolRef::SF_Global;
 156         break;
 157       case RecordStreamer::UndefinedWeak:
 158         Res |= BasicSymbolRef::SF_Weak;
 159         Res |= BasicSymbolRef::SF_Undefined;
 160       }
 161       AsmSymbol(Key, BasicSymbolRef::Flags(Res));
 162     }
 163   });
 164 }
 165
 166 void ModuleSymbolTable::CollectAsmSymvers(
 167     const Module &M, function_ref<void(StringRef, StringRef)> AsmSymver) {
 168   initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
 169     for (auto &KV : Streamer.symverAliases())
 170       for (auto &Alias : KV.second)
 171         AsmSymver(KV.first->getName(), Alias);
 172   });
 173 }
 174
 175 void ModuleSymbolTable::printSymbolName(raw_ostream &OS, Symbol S) const {
 176   if (isa<AsmSymbol *>(S)) {
 177     OS << cast<AsmSymbol *>(S)->first;
 178     return;
 179   }
 180
 181   auto *GV = cast<GlobalValue *>(S);
 182   if (GV->hasDLLImportStorageClass())
 183     OS << "__imp_";
 184
 185   Mang.getNameWithPrefix(OS, GV, false);
 186 }
 187
 188 uint32_t ModuleSymbolTable::getSymbolFlags(Symbol S) const {
 189   if (isa<AsmSymbol *>(S))
 190     return cast<AsmSymbol *>(S)->second;
 191
 192   auto *GV = cast<GlobalValue *>(S);
 193
 194   uint32_t Res = BasicSymbolRef::SF_None;
 195   if (GV->isDeclarationForLinker())
 196     Res |= BasicSymbolRef::SF_Undefined;
 197   else if (GV->hasHiddenVisibility() && !GV->hasLocalLinkage())
 198     Res |= BasicSymbolRef::SF_Hidden;
 199   if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
 200     if (GVar->isConstant())
 201       Res |= BasicSymbolRef::SF_Const;
 202   }
 203   if (const GlobalObject *GO = GV->getAliaseeObject())
 204     if (isa<Function>(GO) || isa<GlobalIFunc>(GO))
 205       Res |= BasicSymbolRef::SF_Executable;
 206   if (isa<GlobalAlias>(GV))
 207     Res |= BasicSymbolRef::SF_Indirect;
 208   if (GV->hasPrivateLinkage())
 209     Res |= BasicSymbolRef::SF_FormatSpecific;
 210   if (!GV->hasLocalLinkage())
 211     Res |= BasicSymbolRef::SF_Global;
 212   if (GV->hasCommonLinkage())
 213     Res |= BasicSymbolRef::SF_Common;
 214   if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
 215       GV->hasExternalWeakLinkage())
 216     Res |= BasicSymbolRef::SF_Weak;
 217
 218   if (GV->getName().startswith("llvm."))
 219     Res |= BasicSymbolRef::SF_FormatSpecific;
 220   else if (auto *Var = dyn_cast<GlobalVariable>(GV)) {
 221     if (Var->getSection() == "llvm.metadata")
 222       Res |= BasicSymbolRef::SF_FormatSpecific;
 223   }
 224
 225   return Res;
 226 }