Object: Simplify the IRObjectFile symbol iterator implementation.

Change the IRObjectFile symbol iterator to be a pointer into a vector of
PointerUnions representing either IR symbols or asm symbols.

This change is in preparation for a future change for supporting multiple
modules in an IRObjectFile. Although it causes an increase in memory
consumption, we can deal with that issue separately by introducing a bitcode
symbol table.

Differential Revision: https://reviews.llvm.org/D26928

llvm-svn: 287845

1 files changed, 25 insertions, 89 deletions

diff --git a/llvm/lib/Object/IRObjectFile.cpp b/llvm/lib/Object/IRObjectFile.cpp
index bf55398f922..4fd5e64fb7c 100644
--- a/llvm/lib/Object/IRObjectFile.cpp
+++ b/llvm/lib/Object/IRObjectFile.cpp
@@ -38,9 +38,18 @@ using namespace object;
 IRObjectFile::IRObjectFile(MemoryBufferRef Object, std::unique_ptr<Module> Mod)
     : SymbolicFile(Binary::ID_IR, Object), M(std::move(Mod)) {
   Mang.reset(new Mangler());
+
+  for (Function &F : *M)
+    SymTab.push_back(&F);
+  for (GlobalVariable &GV : M->globals())
+    SymTab.push_back(&GV);
+  for (GlobalAlias &GA : M->aliases())
+    SymTab.push_back(&GA);
+
   CollectAsmUndefinedRefs(Triple(M->getTargetTriple()), M->getModuleInlineAsm(),
                           [this](StringRef Name, BasicSymbolRef::Flags Flags) {
-                            AsmSymbols.emplace_back(Name, std::move(Flags));
+                            SymTab.push_back(new (AsmSymbols.Allocate())
+                                                 AsmSymbol(Name, Flags));
                           });
 }
 
@@ -124,91 +133,21 @@ void IRObjectFile::CollectAsmUndefinedRefs(
   }
 }
 
-IRObjectFile::~IRObjectFile() {
- }
-
-static GlobalValue *getGV(DataRefImpl &Symb) {
-  if ((Symb.p & 3) == 3)
-    return nullptr;
-
-  return reinterpret_cast<GlobalValue*>(Symb.p & ~uintptr_t(3));
-}
-
-static uintptr_t skipEmpty(Module::const_alias_iterator I, const Module &M) {
-  if (I == M.alias_end())
-    return 3;
-  const GlobalValue *GV = &*I;
-  return reinterpret_cast<uintptr_t>(GV) | 2;
-}
-
-static uintptr_t skipEmpty(Module::const_global_iterator I, const Module &M) {
-  if (I == M.global_end())
-    return skipEmpty(M.alias_begin(), M);
-  const GlobalValue *GV = &*I;
-  return reinterpret_cast<uintptr_t>(GV) | 1;
-}
-
-static uintptr_t skipEmpty(Module::const_iterator I, const Module &M) {
-  if (I == M.end())
-    return skipEmpty(M.global_begin(), M);
-  const GlobalValue *GV = &*I;
-  return reinterpret_cast<uintptr_t>(GV) | 0;
-}
-
-static unsigned getAsmSymIndex(DataRefImpl Symb) {
-  assert((Symb.p & uintptr_t(3)) == 3);
-  uintptr_t Index = Symb.p & ~uintptr_t(3);
-  Index >>= 2;
-  return Index;
-}
+IRObjectFile::~IRObjectFile() {}
 
 void IRObjectFile::moveSymbolNext(DataRefImpl &Symb) const {
-  const GlobalValue *GV = getGV(Symb);
-  uintptr_t Res;
-
-  switch (Symb.p & 3) {
-  case 0: {
-    Module::const_iterator Iter(static_cast<const Function*>(GV));
-    ++Iter;
-    Res = skipEmpty(Iter, *M);
-    break;
-  }
-  case 1: {
-    Module::const_global_iterator Iter(static_cast<const GlobalVariable*>(GV));
-    ++Iter;
-    Res = skipEmpty(Iter, *M);
-    break;
-  }
-  case 2: {
-    Module::const_alias_iterator Iter(static_cast<const GlobalAlias*>(GV));
-    ++Iter;
-    Res = skipEmpty(Iter, *M);
-    break;
-  }
-  case 3: {
-    unsigned Index = getAsmSymIndex(Symb);
-    assert(Index < AsmSymbols.size());
-    ++Index;
-    Res = (Index << 2) | 3;
-    break;
-  }
-  default:
-    llvm_unreachable("unreachable case");
-  }
-
-  Symb.p = Res;
+  Symb.p += sizeof(Sym);
 }
 
 std::error_code IRObjectFile::printSymbolName(raw_ostream &OS,
                                               DataRefImpl Symb) const {
-  const GlobalValue *GV = getGV(Symb);
-  if (!GV) {
-    unsigned Index = getAsmSymIndex(Symb);
-    assert(Index <= AsmSymbols.size());
-    OS << AsmSymbols[Index].first;
+  Sym S = getSym(Symb);
+  if (S.is<AsmSymbol *>()) {
+    OS << S.get<AsmSymbol *>()->first;
     return std::error_code();
   }
 
+  auto *GV = S.get<GlobalValue *>();
   if (GV->hasDLLImportStorageClass())
     OS << "__imp_";
 
@@ -221,13 +160,11 @@ std::error_code IRObjectFile::printSymbolName(raw_ostream &OS,
 }
 
 uint32_t IRObjectFile::getSymbolFlags(DataRefImpl Symb) const {
-  const GlobalValue *GV = getGV(Symb);
+  Sym S = getSym(Symb);
+  if (S.is<AsmSymbol *>())
+    return S.get<AsmSymbol *>()->second;
 
-  if (!GV) {
-    unsigned Index = getAsmSymIndex(Symb);
-    assert(Index <= AsmSymbols.size());
-    return AsmSymbols[Index].second;
-  }
+  auto *GV = S.get<GlobalValue *>();
 
   uint32_t Res = BasicSymbolRef::SF_None;
   if (GV->isDeclarationForLinker())
@@ -258,22 +195,21 @@ uint32_t IRObjectFile::getSymbolFlags(DataRefImpl Symb) const {
   return Res;
 }
 
-GlobalValue *IRObjectFile::getSymbolGV(DataRefImpl Symb) { return getGV(Symb); }
+GlobalValue *IRObjectFile::getSymbolGV(DataRefImpl Symb) {
+  return getSym(Symb).dyn_cast<GlobalValue *>();
+}
 
 std::unique_ptr<Module> IRObjectFile::takeModule() { return std::move(M); }
 
 basic_symbol_iterator IRObjectFile::symbol_begin() const {
-  Module::const_iterator I = M->begin();
   DataRefImpl Ret;
-  Ret.p = skipEmpty(I, *M);
+  Ret.p = reinterpret_cast<uintptr_t>(SymTab.data());
   return basic_symbol_iterator(BasicSymbolRef(Ret, this));
 }
 
 basic_symbol_iterator IRObjectFile::symbol_end() const {
   DataRefImpl Ret;
-  uint64_t NumAsm = AsmSymbols.size();
-  NumAsm <<= 2;
-  Ret.p = 3 | NumAsm;
+  Ret.p = reinterpret_cast<uintptr_t>(SymTab.data() + SymTab.size());
   return basic_symbol_iterator(BasicSymbolRef(Ret, this));
 }