Imported Upstream version 5.18.0.179

Former-commit-id: 67aa10e65b237e1c4537630979ee99ebe1374215

external/llvm/lib/Object/IRSymtab.cpp

@@ -0,0 +1,382 @@
+//===- IRSymtab.cpp - implementation of IR symbol tables ------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Object/IRSymtab.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/Analysis/ObjectUtils.h"
+#include "llvm/IR/Comdat.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/GlobalAlias.h"
+#include "llvm/IR/GlobalObject.h"
+#include "llvm/IR/Mangler.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Bitcode/BitcodeReader.h"
+#include "llvm/MC/StringTableBuilder.h"
+#include "llvm/Object/IRObjectFile.h"
+#include "llvm/Object/ModuleSymbolTable.h"
+#include "llvm/Object/SymbolicFile.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/StringSaver.h"
+#include "llvm/Support/VCSRevision.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cassert>
+#include <string>
+#include <utility>
+#include <vector>
+
+using namespace llvm;
+using namespace irsymtab;
+
+namespace {
+
+const char *getExpectedProducerName() {
+  static char DefaultName[] = LLVM_VERSION_STRING
+#ifdef LLVM_REVISION
+      " " LLVM_REVISION
+#endif
+      ;
+  // Allows for testing of the irsymtab writer and upgrade mechanism. This
+  // environment variable should not be set by users.
+  if (char *OverrideName = getenv("LLVM_OVERRIDE_PRODUCER"))
+    return OverrideName;
+  return DefaultName;
+}
+
+const char *kExpectedProducerName = getExpectedProducerName();
+
+/// Stores the temporary state that is required to build an IR symbol table.
+struct Builder {
+  SmallVector<char, 0> &Symtab;
+  StringTableBuilder &StrtabBuilder;
+  StringSaver Saver;
+
+  // This ctor initializes a StringSaver using the passed in BumpPtrAllocator.
+  // The StringTableBuilder does not create a copy of any strings added to it,
+  // so this provides somewhere to store any strings that we create.
+  Builder(SmallVector<char, 0> &Symtab, StringTableBuilder &StrtabBuilder,
+          BumpPtrAllocator &Alloc)
+      : Symtab(Symtab), StrtabBuilder(StrtabBuilder), Saver(Alloc) {}
+
+  DenseMap<const Comdat *, int> ComdatMap;
+  Mangler Mang;
+  Triple TT;
+
+  std::vector<storage::Comdat> Comdats;
+  std::vector<storage::Module> Mods;
+  std::vector<storage::Symbol> Syms;
+  std::vector<storage::Uncommon> Uncommons;
+
+  std::string COFFLinkerOpts;
+  raw_string_ostream COFFLinkerOptsOS{COFFLinkerOpts};
+
+  void setStr(storage::Str &S, StringRef Value) {
+    S.Offset = StrtabBuilder.add(Value);
+    S.Size = Value.size();
+  }
+
+  template <typename T>
+  void writeRange(storage::Range<T> &R, const std::vector<T> &Objs) {
+    R.Offset = Symtab.size();
+    R.Size = Objs.size();
+    Symtab.insert(Symtab.end(), reinterpret_cast<const char *>(Objs.data()),
+                  reinterpret_cast<const char *>(Objs.data() + Objs.size()));
+  }
+
+  Expected<int> getComdatIndex(const Comdat *C, const Module *M);
+
+  Error addModule(Module *M);
+  Error addSymbol(const ModuleSymbolTable &Msymtab,
+                  const SmallPtrSet<GlobalValue *, 8> &Used,
+                  ModuleSymbolTable::Symbol Sym);
+
+  Error build(ArrayRef<Module *> Mods);
+};
+
+Error Builder::addModule(Module *M) {
+  if (M->getDataLayoutStr().empty())
+    return make_error<StringError>("input module has no datalayout",
+                                   inconvertibleErrorCode());
+
+  SmallPtrSet<GlobalValue *, 8> Used;
+  collectUsedGlobalVariables(*M, Used, /*CompilerUsed*/ false);
+
+  ModuleSymbolTable Msymtab;
+  Msymtab.addModule(M);
+
+  storage::Module Mod;
+  Mod.Begin = Syms.size();
+  Mod.End = Syms.size() + Msymtab.symbols().size();
+  Mod.UncBegin = Uncommons.size();
+  Mods.push_back(Mod);
+
+  if (TT.isOSBinFormatCOFF()) {
+    if (auto E = M->materializeMetadata())
+      return E;
+    if (NamedMDNode *LinkerOptions =
+            M->getNamedMetadata("llvm.linker.options")) {
+      for (MDNode *MDOptions : LinkerOptions->operands())
+        for (const MDOperand &MDOption : cast<MDNode>(MDOptions)->operands())
+          COFFLinkerOptsOS << " " << cast<MDString>(MDOption)->getString();
+    }
+  }
+
+  for (ModuleSymbolTable::Symbol Msym : Msymtab.symbols())
+    if (Error Err = addSymbol(Msymtab, Used, Msym))
+      return Err;
+
+  return Error::success();
+}
+
+Expected<int> Builder::getComdatIndex(const Comdat *C, const Module *M) {
+  auto P = ComdatMap.insert(std::make_pair(C, Comdats.size()));
+  if (P.second) {
+    std::string Name;
+    if (TT.isOSBinFormatCOFF()) {
+      const GlobalValue *GV = M->getNamedValue(C->getName());
+      if (!GV)
+        return make_error<StringError>("Could not find leader",
+                                       inconvertibleErrorCode());
+      // Internal leaders do not affect symbol resolution, therefore they do not
+      // appear in the symbol table.
+      if (GV->hasLocalLinkage()) {
+        P.first->second = -1;
+        return -1;
+      }
+      llvm::raw_string_ostream OS(Name);
+      Mang.getNameWithPrefix(OS, GV, false);
+    } else {
+      Name = C->getName();
+    }
+
+    storage::Comdat Comdat;
+    setStr(Comdat.Name, Saver.save(Name));
+    Comdats.push_back(Comdat);
+  }
+
+  return P.first->second;
+}
+
+Error Builder::addSymbol(const ModuleSymbolTable &Msymtab,
+                         const SmallPtrSet<GlobalValue *, 8> &Used,
+                         ModuleSymbolTable::Symbol Msym) {
+  Syms.emplace_back();
+  storage::Symbol &Sym = Syms.back();
+  Sym = {};
+
+  storage::Uncommon *Unc = nullptr;
+  auto Uncommon = [&]() -> storage::Uncommon & {
+    if (Unc)
+      return *Unc;
+    Sym.Flags |= 1 << storage::Symbol::FB_has_uncommon;
+    Uncommons.emplace_back();
+    Unc = &Uncommons.back();
+    *Unc = {};
+    setStr(Unc->COFFWeakExternFallbackName, "");
+    setStr(Unc->SectionName, "");
+    return *Unc;
+  };
+
+  SmallString<64> Name;
+  {
+    raw_svector_ostream OS(Name);
+    Msymtab.printSymbolName(OS, Msym);
+  }
+  setStr(Sym.Name, Saver.save(StringRef(Name)));
+
+  auto Flags = Msymtab.getSymbolFlags(Msym);
+  if (Flags & object::BasicSymbolRef::SF_Undefined)
+    Sym.Flags |= 1 << storage::Symbol::FB_undefined;
+  if (Flags & object::BasicSymbolRef::SF_Weak)
+    Sym.Flags |= 1 << storage::Symbol::FB_weak;
+  if (Flags & object::BasicSymbolRef::SF_Common)
+    Sym.Flags |= 1 << storage::Symbol::FB_common;
+  if (Flags & object::BasicSymbolRef::SF_Indirect)
+    Sym.Flags |= 1 << storage::Symbol::FB_indirect;
+  if (Flags & object::BasicSymbolRef::SF_Global)
+    Sym.Flags |= 1 << storage::Symbol::FB_global;
+  if (Flags & object::BasicSymbolRef::SF_FormatSpecific)
+    Sym.Flags |= 1 << storage::Symbol::FB_format_specific;
+  if (Flags & object::BasicSymbolRef::SF_Executable)
+    Sym.Flags |= 1 << storage::Symbol::FB_executable;
+
+  Sym.ComdatIndex = -1;
+  auto *GV = Msym.dyn_cast<GlobalValue *>();
+  if (!GV) {
+    // Undefined module asm symbols act as GC roots and are implicitly used.
+    if (Flags & object::BasicSymbolRef::SF_Undefined)
+      Sym.Flags |= 1 << storage::Symbol::FB_used;
+    setStr(Sym.IRName, "");
+    return Error::success();
+  }
+
+  setStr(Sym.IRName, GV->getName());
+
+  if (Used.count(GV))
+    Sym.Flags |= 1 << storage::Symbol::FB_used;
+  if (GV->isThreadLocal())
+    Sym.Flags |= 1 << storage::Symbol::FB_tls;
+  if (GV->hasGlobalUnnamedAddr())
+    Sym.Flags |= 1 << storage::Symbol::FB_unnamed_addr;
+  if (canBeOmittedFromSymbolTable(GV))
+    Sym.Flags |= 1 << storage::Symbol::FB_may_omit;
+  Sym.Flags |= unsigned(GV->getVisibility()) << storage::Symbol::FB_visibility;
+
+  if (Flags & object::BasicSymbolRef::SF_Common) {
+    Uncommon().CommonSize = GV->getParent()->getDataLayout().getTypeAllocSize(
+        GV->getType()->getElementType());
+    Uncommon().CommonAlign = GV->getAlignment();
+  }
+
+  const GlobalObject *Base = GV->getBaseObject();
+  if (!Base)
+    return make_error<StringError>("Unable to determine comdat of alias!",
+                                   inconvertibleErrorCode());
+  if (const Comdat *C = Base->getComdat()) {
+    Expected<int> ComdatIndexOrErr = getComdatIndex(C, GV->getParent());
+    if (!ComdatIndexOrErr)
+      return ComdatIndexOrErr.takeError();
+    Sym.ComdatIndex = *ComdatIndexOrErr;
+  }
+
+  if (TT.isOSBinFormatCOFF()) {
+    emitLinkerFlagsForGlobalCOFF(COFFLinkerOptsOS, GV, TT, Mang);
+
+    if ((Flags & object::BasicSymbolRef::SF_Weak) &&
+        (Flags & object::BasicSymbolRef::SF_Indirect)) {
+      auto *Fallback = dyn_cast<GlobalValue>(
+          cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts());
+      if (!Fallback)
+        return make_error<StringError>("Invalid weak external",
+                                       inconvertibleErrorCode());
+      std::string FallbackName;
+      raw_string_ostream OS(FallbackName);
+      Msymtab.printSymbolName(OS, Fallback);
+      OS.flush();
+      setStr(Uncommon().COFFWeakExternFallbackName, Saver.save(FallbackName));
+    }
+  }
+
+  if (!Base->getSection().empty())
+    setStr(Uncommon().SectionName, Saver.save(Base->getSection()));
+
+  return Error::success();
+}
+
+Error Builder::build(ArrayRef<Module *> IRMods) {
+  storage::Header Hdr;
+
+  assert(!IRMods.empty());
+  Hdr.Version = storage::Header::kCurrentVersion;
+  setStr(Hdr.Producer, kExpectedProducerName);
+  setStr(Hdr.TargetTriple, IRMods[0]->getTargetTriple());
+  setStr(Hdr.SourceFileName, IRMods[0]->getSourceFileName());
+  TT = Triple(IRMods[0]->getTargetTriple());
+
+  for (auto *M : IRMods)
+    if (Error Err = addModule(M))
+      return Err;
+
+  COFFLinkerOptsOS.flush();
+  setStr(Hdr.COFFLinkerOpts, Saver.save(COFFLinkerOpts));
+
+  // We are about to fill in the header's range fields, so reserve space for it
+  // and copy it in afterwards.
+  Symtab.resize(sizeof(storage::Header));
+  writeRange(Hdr.Modules, Mods);
+  writeRange(Hdr.Comdats, Comdats);
+  writeRange(Hdr.Symbols, Syms);
+  writeRange(Hdr.Uncommons, Uncommons);
+
+  *reinterpret_cast<storage::Header *>(Symtab.data()) = Hdr;
+  return Error::success();
+}
+
+} // end anonymous namespace
+
+Error irsymtab::build(ArrayRef<Module *> Mods, SmallVector<char, 0> &Symtab,
+                      StringTableBuilder &StrtabBuilder,
+                      BumpPtrAllocator &Alloc) {
+  return Builder(Symtab, StrtabBuilder, Alloc).build(Mods);
+}
+
+// Upgrade a vector of bitcode modules created by an old version of LLVM by
+// creating an irsymtab for them in the current format.
+static Expected<FileContents> upgrade(ArrayRef<BitcodeModule> BMs) {
+  FileContents FC;
+
+  LLVMContext Ctx;
+  std::vector<Module *> Mods;
+  std::vector<std::unique_ptr<Module>> OwnedMods;
+  for (auto BM : BMs) {
+    Expected<std::unique_ptr<Module>> MOrErr =
+        BM.getLazyModule(Ctx, /*ShouldLazyLoadMetadata*/ true,
+                         /*IsImporting*/ false);
+    if (!MOrErr)
+      return MOrErr.takeError();
+
+    Mods.push_back(MOrErr->get());
+    OwnedMods.push_back(std::move(*MOrErr));
+  }
+
+  StringTableBuilder StrtabBuilder(StringTableBuilder::RAW);
+  BumpPtrAllocator Alloc;
+  if (Error E = build(Mods, FC.Symtab, StrtabBuilder, Alloc))
+    return std::move(E);
+
+  StrtabBuilder.finalizeInOrder();
+  FC.Strtab.resize(StrtabBuilder.getSize());
+  StrtabBuilder.write((uint8_t *)FC.Strtab.data());
+
+  FC.TheReader = {{FC.Symtab.data(), FC.Symtab.size()},
+                  {FC.Strtab.data(), FC.Strtab.size()}};
+  return std::move(FC);
+}
+
+Expected<FileContents> irsymtab::readBitcode(const BitcodeFileContents &BFC) {
+  if (BFC.Mods.empty())
+    return make_error<StringError>("Bitcode file does not contain any modules",
+                                   inconvertibleErrorCode());
+
+  if (BFC.StrtabForSymtab.empty() ||
+      BFC.Symtab.size() < sizeof(storage::Header))
+    return upgrade(BFC.Mods);
+
+  // We cannot use the regular reader to read the version and producer, because
+  // it will expect the header to be in the current format. The only thing we
+  // can rely on is that the version and producer will be present as the first
+  // struct elements.
+  auto *Hdr = reinterpret_cast<const storage::Header *>(BFC.Symtab.data());
+  unsigned Version = Hdr->Version;
+  StringRef Producer = Hdr->Producer.get(BFC.StrtabForSymtab);
+  if (Version != storage::Header::kCurrentVersion ||
+      Producer != kExpectedProducerName)
+    return upgrade(BFC.Mods);
+
+  FileContents FC;
+  FC.TheReader = {{BFC.Symtab.data(), BFC.Symtab.size()},
+                  {BFC.StrtabForSymtab.data(), BFC.StrtabForSymtab.size()}};
+
+  // Finally, make sure that the number of modules in the symbol table matches
+  // the number of modules in the bitcode file. If they differ, it may mean that
+  // the bitcode file was created by binary concatenation, so we need to create
+  // a new symbol table from scratch.
+  if (FC.TheReader.getNumModules() != BFC.Mods.size())
+    return upgrade(std::move(BFC.Mods));
+
+  return std::move(FC);
+}