LCOV - code coverage report
Current view: top level - lib/Object - IRSymtab.cpp (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 124 159 78.0 %
Date: 2018-09-23 13:06:45 Functions: 8 13 61.5 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- IRSymtab.cpp - implementation of IR symbol tables ------------------===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : 
      10             : #include "llvm/Object/IRSymtab.h"
      11             : #include "llvm/ADT/ArrayRef.h"
      12             : #include "llvm/ADT/DenseMap.h"
      13             : #include "llvm/ADT/SmallPtrSet.h"
      14             : #include "llvm/ADT/SmallString.h"
      15             : #include "llvm/ADT/SmallVector.h"
      16             : #include "llvm/ADT/StringRef.h"
      17             : #include "llvm/ADT/Triple.h"
      18             : #include "llvm/Config/llvm-config.h"
      19             : #include "llvm/IR/Comdat.h"
      20             : #include "llvm/IR/DataLayout.h"
      21             : #include "llvm/IR/GlobalAlias.h"
      22             : #include "llvm/IR/GlobalObject.h"
      23             : #include "llvm/IR/Mangler.h"
      24             : #include "llvm/IR/Metadata.h"
      25             : #include "llvm/IR/Module.h"
      26             : #include "llvm/Bitcode/BitcodeReader.h"
      27             : #include "llvm/MC/StringTableBuilder.h"
      28             : #include "llvm/Object/IRObjectFile.h"
      29             : #include "llvm/Object/ModuleSymbolTable.h"
      30             : #include "llvm/Object/SymbolicFile.h"
      31             : #include "llvm/Support/Allocator.h"
      32             : #include "llvm/Support/Casting.h"
      33             : #include "llvm/Support/Error.h"
      34             : #include "llvm/Support/StringSaver.h"
      35             : #include "llvm/Support/VCSRevision.h"
      36             : #include "llvm/Support/raw_ostream.h"
      37             : #include <cassert>
      38             : #include <string>
      39             : #include <utility>
      40             : #include <vector>
      41             : 
      42             : using namespace llvm;
      43             : using namespace irsymtab;
      44             : 
      45             : static const char *LibcallRoutineNames[] = {
      46             : #define HANDLE_LIBCALL(code, name) name,
      47             : #include "llvm/IR/RuntimeLibcalls.def"
      48             : #undef HANDLE_LIBCALL
      49             : };
      50             : 
      51             : namespace {
      52             : 
      53             : const char *getExpectedProducerName() {
      54             :   static char DefaultName[] = LLVM_VERSION_STRING
      55             : #ifdef LLVM_REVISION
      56             :       " " LLVM_REVISION
      57             : #endif
      58             :       ;
      59             :   // Allows for testing of the irsymtab writer and upgrade mechanism. This
      60             :   // environment variable should not be set by users.
      61             :   if (char *OverrideName = getenv("LLVM_OVERRIDE_PRODUCER"))
      62             :     return OverrideName;
      63             :   return DefaultName;
      64             : }
      65             : 
      66             : const char *kExpectedProducerName = getExpectedProducerName();
      67             : 
      68             : /// Stores the temporary state that is required to build an IR symbol table.
      69             : struct Builder {
      70             :   SmallVector<char, 0> &Symtab;
      71             :   StringTableBuilder &StrtabBuilder;
      72             :   StringSaver Saver;
      73             : 
      74             :   // This ctor initializes a StringSaver using the passed in BumpPtrAllocator.
      75             :   // The StringTableBuilder does not create a copy of any strings added to it,
      76             :   // so this provides somewhere to store any strings that we create.
      77        4637 :   Builder(SmallVector<char, 0> &Symtab, StringTableBuilder &StrtabBuilder,
      78             :           BumpPtrAllocator &Alloc)
      79        9274 :       : Symtab(Symtab), StrtabBuilder(StrtabBuilder), Saver(Alloc) {}
      80             : 
      81             :   DenseMap<const Comdat *, int> ComdatMap;
      82             :   Mangler Mang;
      83             :   Triple TT;
      84             : 
      85             :   std::vector<storage::Comdat> Comdats;
      86             :   std::vector<storage::Module> Mods;
      87             :   std::vector<storage::Symbol> Syms;
      88             :   std::vector<storage::Uncommon> Uncommons;
      89             : 
      90             :   std::string COFFLinkerOpts;
      91             :   raw_string_ostream COFFLinkerOptsOS{COFFLinkerOpts};
      92             : 
      93           0 :   void setStr(storage::Str &S, StringRef Value) {
      94       50544 :     S.Offset = StrtabBuilder.add(Value);
      95       50342 :     S.Size = Value.size();
      96           0 :   }
      97             : 
      98             :   template <typename T>
      99           0 :   void writeRange(storage::Range<T> &R, const std::vector<T> &Objs) {
     100           0 :     R.Offset = Symtab.size();
     101           0 :     R.Size = Objs.size();
     102           0 :     Symtab.insert(Symtab.end(), reinterpret_cast<const char *>(Objs.data()),
     103           0 :                   reinterpret_cast<const char *>(Objs.data() + Objs.size()));
     104           0 :   }
     105           0 : 
     106           0 :   Expected<int> getComdatIndex(const Comdat *C, const Module *M);
     107           0 : 
     108           0 :   Error addModule(Module *M);
     109           0 :   Error addSymbol(const ModuleSymbolTable &Msymtab,
     110           0 :                   const SmallPtrSet<GlobalValue *, 8> &Used,
     111           0 :                   ModuleSymbolTable::Symbol Sym);
     112           0 : 
     113           0 :   Error build(ArrayRef<Module *> Mods);
     114           0 : };
     115           0 : 
     116           0 : Error Builder::addModule(Module *M) {
     117           0 :   if (M->getDataLayoutStr().empty())
     118           0 :     return make_error<StringError>("input module has no datalayout",
     119           0 :                                    inconvertibleErrorCode());
     120           0 : 
     121           0 :   SmallPtrSet<GlobalValue *, 8> Used;
     122           0 :   collectUsedGlobalVariables(*M, Used, /*CompilerUsed*/ false);
     123           0 : 
     124           0 :   ModuleSymbolTable Msymtab;
     125           0 :   Msymtab.addModule(M);
     126           0 : 
     127           0 :   storage::Module Mod;
     128           0 :   Mod.Begin = Syms.size();
     129             :   Mod.End = Syms.size() + Msymtab.symbols().size();
     130             :   Mod.UncBegin = Uncommons.size();
     131             :   Mods.push_back(Mod);
     132             : 
     133             :   if (TT.isOSBinFormatCOFF()) {
     134             :     if (auto E = M->materializeMetadata())
     135             :       return E;
     136             :     if (NamedMDNode *LinkerOptions =
     137             :             M->getNamedMetadata("llvm.linker.options")) {
     138             :       for (MDNode *MDOptions : LinkerOptions->operands())
     139             :         for (const MDOperand &MDOption : cast<MDNode>(MDOptions)->operands())
     140        4654 :           COFFLinkerOptsOS << " " << cast<MDString>(MDOption)->getString();
     141        4654 :     }
     142             :   }
     143        4376 : 
     144             :   for (ModuleSymbolTable::Symbol Msym : Msymtab.symbols())
     145             :     if (Error Err = addSymbol(Msymtab, Used, Msym))
     146        2466 :       return Err;
     147             : 
     148        4932 :   return Error::success();
     149        2466 : }
     150             : 
     151             : Expected<int> Builder::getComdatIndex(const Comdat *C, const Module *M) {
     152        4930 :   auto P = ComdatMap.insert(std::make_pair(C, Comdats.size()));
     153        2465 :   if (P.second) {
     154        4930 :     std::string Name;
     155        2465 :     if (TT.isOSBinFormatCOFF()) {
     156             :       const GlobalValue *GV = M->getNamedValue(C->getName());
     157        2465 :       if (!GV)
     158         228 :         return make_error<StringError>("Could not find leader",
     159             :                                        inconvertibleErrorCode());
     160         114 :       // Internal leaders do not affect symbol resolution, therefore they do not
     161         114 :       // appear in the symbol table.
     162           6 :       if (GV->hasLocalLinkage()) {
     163           6 :         P.first->second = -1;
     164           3 :         return -1;
     165             :       }
     166             :       llvm::raw_string_ostream OS(Name);
     167             :       Mang.getNameWithPrefix(OS, GV, false);
     168       22607 :     } else {
     169       40323 :       Name = C->getName();
     170             :     }
     171             : 
     172             :     storage::Comdat Comdat;
     173             :     setStr(Comdat.Name, Saver.save(Name));
     174             :     Comdats.push_back(Comdat);
     175        2697 :   }
     176        2697 : 
     177        2697 :   return P.first->second;
     178             : }
     179        2043 : 
     180          20 : Error Builder::addSymbol(const ModuleSymbolTable &Msymtab,
     181          20 :                          const SmallPtrSet<GlobalValue *, 8> &Used,
     182           0 :                          ModuleSymbolTable::Symbol Msym) {
     183           0 :   Syms.emplace_back();
     184             :   storage::Symbol &Sym = Syms.back();
     185             :   Sym = {};
     186             : 
     187           3 :   storage::Uncommon *Unc = nullptr;
     188             :   auto Uncommon = [&]() -> storage::Uncommon & {
     189             :     if (Unc)
     190          17 :       return *Unc;
     191          17 :     Sym.Flags |= 1 << storage::Symbol::FB_has_uncommon;
     192             :     Uncommons.emplace_back();
     193        6069 :     Unc = &Uncommons.back();
     194             :     *Unc = {};
     195             :     setStr(Unc->COFFWeakExternFallbackName, "");
     196             :     setStr(Unc->SectionName, "");
     197        2040 :     return *Unc;
     198        2040 :   };
     199             : 
     200             :   SmallString<64> Name;
     201             :   {
     202             :     raw_svector_ostream OS(Name);
     203             :     Msymtab.printSymbolName(OS, Msym);
     204       20159 :   }
     205             :   setStr(Sym.Name, Saver.save(StringRef(Name)));
     206             : 
     207       20159 :   auto Flags = Msymtab.getSymbolFlags(Msym);
     208             :   if (Flags & object::BasicSymbolRef::SF_Undefined)
     209       20163 :     Sym.Flags |= 1 << storage::Symbol::FB_undefined;
     210             :   if (Flags & object::BasicSymbolRef::SF_Weak)
     211       20163 :     Sym.Flags |= 1 << storage::Symbol::FB_weak;
     212             :   if (Flags & object::BasicSymbolRef::SF_Common)
     213             :     Sym.Flags |= 1 << storage::Symbol::FB_common;
     214             :   if (Flags & object::BasicSymbolRef::SF_Indirect)
     215             :     Sym.Flags |= 1 << storage::Symbol::FB_indirect;
     216             :   if (Flags & object::BasicSymbolRef::SF_Global)
     217             :     Sym.Flags |= 1 << storage::Symbol::FB_global;
     218             :   if (Flags & object::BasicSymbolRef::SF_FormatSpecific)
     219             :     Sym.Flags |= 1 << storage::Symbol::FB_format_specific;
     220             :   if (Flags & object::BasicSymbolRef::SF_Executable)
     221             :     Sym.Flags |= 1 << storage::Symbol::FB_executable;
     222       20163 : 
     223             :   Sym.ComdatIndex = -1;
     224             :   auto *GV = Msym.dyn_cast<GlobalValue *>();
     225             :   if (!GV) {
     226             :     // Undefined module asm symbols act as GC roots and are implicitly used.
     227       20163 :     if (Flags & object::BasicSymbolRef::SF_Undefined)
     228             :       Sym.Flags |= 1 << storage::Symbol::FB_used;
     229       40326 :     setStr(Sym.IRName, "");
     230             :     return Error::success();
     231       20163 :   }
     232       20162 : 
     233             :   setStr(Sym.IRName, GV->getName());
     234       20162 : 
     235             :   bool IsBuiltinFunc = false;
     236       20162 : 
     237             :   for (const char *LibcallName : LibcallRoutineNames)
     238       20162 :     if (GV->getName() == LibcallName)
     239             :       IsBuiltinFunc = true;
     240       20162 : 
     241             :   if (Used.count(GV) || IsBuiltinFunc)
     242       20162 :     Sym.Flags |= 1 << storage::Symbol::FB_used;
     243             :   if (GV->isThreadLocal())
     244       20162 :     Sym.Flags |= 1 << storage::Symbol::FB_tls;
     245             :   if (GV->hasGlobalUnnamedAddr())
     246             :     Sym.Flags |= 1 << storage::Symbol::FB_unnamed_addr;
     247             :   if (GV->canBeOmittedFromSymbolTable())
     248             :     Sym.Flags |= 1 << storage::Symbol::FB_may_omit;
     249       19960 :   Sym.Flags |= unsigned(GV->getVisibility()) << storage::Symbol::FB_visibility;
     250             : 
     251         202 :   if (Flags & object::BasicSymbolRef::SF_Common) {
     252             :     Uncommon().CommonSize = GV->getParent()->getDataLayout().getTypeAllocSize(
     253         202 :         GV->getType()->getElementType());
     254             :     Uncommon().CommonAlign = GV->getAlignment();
     255             :   }
     256             : 
     257       19960 :   const GlobalObject *Base = GV->getBaseObject();
     258             :   if (!Base)
     259             :     return make_error<StringError>("Unable to determine comdat of alias!",
     260             :                                    inconvertibleErrorCode());
     261     9420123 :   if (const Comdat *C = Base->getComdat()) {
     262     9400162 :     Expected<int> ComdatIndexOrErr = getComdatIndex(C, GV->getParent());
     263             :     if (!ComdatIndexOrErr)
     264             :       return ComdatIndexOrErr.takeError();
     265       19961 :     Sym.ComdatIndex = *ComdatIndexOrErr;
     266             :   }
     267       19961 : 
     268             :   if (TT.isOSBinFormatCOFF()) {
     269       19961 :     emitLinkerFlagsForGlobalCOFF(COFFLinkerOptsOS, GV, TT, Mang);
     270             : 
     271       19961 :     if ((Flags & object::BasicSymbolRef::SF_Weak) &&
     272             :         (Flags & object::BasicSymbolRef::SF_Indirect)) {
     273             :       auto *Fallback = dyn_cast<GlobalValue>(
     274             :           cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts());
     275       19961 :       if (!Fallback)
     276         100 :         return make_error<StringError>("Invalid weak external",
     277             :                                        inconvertibleErrorCode());
     278         100 :       std::string FallbackName;
     279             :       raw_string_ostream OS(FallbackName);
     280             :       Msymtab.printSymbolName(OS, Fallback);
     281             :       OS.flush();
     282       19960 :       setStr(Uncommon().COFFWeakExternFallbackName, Saver.save(FallbackName));
     283             :     }
     284          36 :   }
     285       19942 : 
     286        2697 :   if (!Base->getSection().empty())
     287        2697 :     setStr(Uncommon().SectionName, Saver.save(Base->getSection()));
     288             : 
     289        2697 :   return Error::success();
     290             : }
     291             : 
     292       19942 : Error Builder::build(ArrayRef<Module *> IRMods) {
     293         221 :   storage::Header Hdr;
     294             : 
     295         221 :   assert(!IRMods.empty());
     296             :   Hdr.Version = storage::Header::kCurrentVersion;
     297             :   setStr(Hdr.Producer, kExpectedProducerName);
     298             :   setStr(Hdr.TargetTriple, IRMods[0]->getTargetTriple());
     299             :   setStr(Hdr.SourceFileName, IRMods[0]->getSourceFileName());
     300             :   TT = Triple(IRMods[0]->getTargetTriple());
     301           4 : 
     302             :   for (auto *M : IRMods)
     303           2 :     if (Error Err = addModule(M))
     304           2 :       return Err;
     305             : 
     306           2 :   COFFLinkerOptsOS.flush();
     307             :   setStr(Hdr.COFFLinkerOpts, Saver.save(COFFLinkerOpts));
     308             : 
     309             :   // We are about to fill in the header's range fields, so reserve space for it
     310       19940 :   // and copy it in afterwards.
     311        1110 :   Symtab.resize(sizeof(storage::Header));
     312             :   writeRange(Hdr.Modules, Mods);
     313             :   writeRange(Hdr.Comdats, Comdats);
     314             :   writeRange(Hdr.Symbols, Syms);
     315             :   writeRange(Hdr.Uncommons, Uncommons);
     316        4637 : 
     317             :   *reinterpret_cast<storage::Header *>(Symtab.data()) = Hdr;
     318             :   return Error::success();
     319             : }
     320             : 
     321        9274 : } // end anonymous namespace
     322        9274 : 
     323        9274 : Error irsymtab::build(ArrayRef<Module *> Mods, SmallVector<char, 0> &Symtab,
     324        9274 :                       StringTableBuilder &StrtabBuilder,
     325             :                       BumpPtrAllocator &Alloc) {
     326        7083 :   return Builder(Symtab, StrtabBuilder, Alloc).build(Mods);
     327        9308 : }
     328             : 
     329             : // Upgrade a vector of bitcode modules created by an old version of LLVM by
     330        2429 : // creating an irsymtab for them in the current format.
     331        2429 : static Expected<FileContents> upgrade(ArrayRef<BitcodeModule> BMs) {
     332             :   FileContents FC;
     333             : 
     334             :   LLVMContext Ctx;
     335        2429 :   std::vector<Module *> Mods;
     336        2429 :   std::vector<std::unique_ptr<Module>> OwnedMods;
     337        2429 :   for (auto BM : BMs) {
     338        2429 :     Expected<std::unique_ptr<Module>> MOrErr =
     339        2428 :         BM.getLazyModule(Ctx, /*ShouldLazyLoadMetadata*/ true,
     340             :                          /*IsImporting*/ false);
     341        2429 :     if (!MOrErr)
     342             :       return MOrErr.takeError();
     343             : 
     344             :     Mods.push_back(MOrErr->get());
     345             :     OwnedMods.push_back(std::move(*MOrErr));
     346             :   }
     347        4637 : 
     348             :   StringTableBuilder StrtabBuilder(StringTableBuilder::RAW);
     349             :   BumpPtrAllocator Alloc;
     350        4637 :   if (Error E = build(Mods, FC.Symtab, StrtabBuilder, Alloc))
     351             :     return std::move(E);
     352             : 
     353             :   StrtabBuilder.finalizeInOrder();
     354             :   FC.Strtab.resize(StrtabBuilder.getSize());
     355          22 :   StrtabBuilder.write((uint8_t *)FC.Strtab.data());
     356          22 : 
     357             :   FC.TheReader = {{FC.Symtab.data(), FC.Symtab.size()},
     358          44 :                   {FC.Strtab.data(), FC.Strtab.size()}};
     359             :   return std::move(FC);
     360          22 : }
     361          46 : 
     362             : Expected<FileContents> irsymtab::readBitcode(const BitcodeFileContents &BFC) {
     363             :   if (BFC.Mods.empty())
     364          48 :     return make_error<StringError>("Bitcode file does not contain any modules",
     365          24 :                                    inconvertibleErrorCode());
     366             : 
     367             :   if (BFC.StrtabForSymtab.empty() ||
     368          24 :       BFC.Symtab.size() < sizeof(storage::Header))
     369             :     return upgrade(BFC.Mods);
     370             : 
     371             :   // We cannot use the regular reader to read the version and producer, because
     372          44 :   // it will expect the header to be in the current format. The only thing we
     373          22 :   // can rely on is that the version and producer will be present as the first
     374          26 :   // struct elements.
     375             :   auto *Hdr = reinterpret_cast<const storage::Header *>(BFC.Symtab.data());
     376             :   unsigned Version = Hdr->Version;
     377          18 :   StringRef Producer = Hdr->Producer.get(BFC.StrtabForSymtab);
     378          18 :   if (Version != storage::Header::kCurrentVersion ||
     379          18 :       Producer != kExpectedProducerName)
     380             :     return upgrade(BFC.Mods);
     381          36 : 
     382          18 :   FileContents FC;
     383             :   FC.TheReader = {{BFC.Symtab.data(), BFC.Symtab.size()},
     384             :                   {BFC.StrtabForSymtab.data(), BFC.StrtabForSymtab.size()}};
     385             : 
     386         907 :   // Finally, make sure that the number of modules in the symbol table matches
     387         907 :   // the number of modules in the bitcode file. If they differ, it may mean that
     388           1 :   // the bitcode file was created by binary concatenation, so we need to create
     389           2 :   // a new symbol table from scratch.
     390             :   if (FC.TheReader.getNumModules() != BFC.Mods.size())
     391         906 :     return upgrade(std::move(BFC.Mods));
     392             : 
     393          21 :   return std::move(FC);
     394             : }

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