Avoid calling getNamedValue.

In lld we usually avoid hash lookups. In addition to that, IR names are
not fully mangled, so it is best to avoid using them whenever possible.

llvm-svn: 263248

lld/ELF/InputFiles.cpp

@@ -436,6 +436,50 @@ static uint8_t getGvVisibility(const GlobalValue *GV) {
   llvm_unreachable("Unknown visibility");
 }
 
+SymbolBody *
+BitcodeFile::createSymbolBody(const DenseSet<const Comdat *> &KeptComdats,
+                              const IRObjectFile &Obj,
+                              const BasicSymbolRef &Sym) {
+  const GlobalValue *GV = Obj.getSymbolGV(Sym.getRawDataRefImpl());
+  assert(GV);
+  if (const Comdat *C = GV->getComdat())
+    if (!KeptComdats.count(C))
+      return nullptr;
+
+  uint8_t Visibility = getGvVisibility(GV);
+
+  SmallString<64> Name;
+  raw_svector_ostream OS(Name);
+  Sym.printName(OS);
+  StringRef NameRef = Saver.save(StringRef(Name));
+
+  const Module &M = Obj.getModule();
+  SymbolBody *Body;
+  uint32_t Flags = Sym.getFlags();
+  bool IsWeak = Flags & BasicSymbolRef::SF_Weak;
+  if (Flags & BasicSymbolRef::SF_Undefined) {
+    Body = new (Alloc) Undefined(NameRef, IsWeak, Visibility, false);
+  } else if (Flags & BasicSymbolRef::SF_Common) {
+    const DataLayout &DL = M.getDataLayout();
+    uint64_t Size = DL.getTypeAllocSize(GV->getValueType());
+    Body = new (Alloc)
+        DefinedCommon(NameRef, Size, GV->getAlignment(), IsWeak, Visibility);
+  } else {
+    Body = new (Alloc) DefinedBitcode(NameRef, IsWeak, Visibility);
+  }
+  Body->IsTls = GV->isThreadLocal();
+  return Body;
+}
+
+bool BitcodeFile::shouldSkip(const BasicSymbolRef &Sym) {
+  uint32_t Flags = Sym.getFlags();
+  if (!(Flags & BasicSymbolRef::SF_Global))
+    return true;
+  if (Flags & BasicSymbolRef::SF_FormatSpecific)
+    return true;
+  return false;
+}
+
 void BitcodeFile::parse(DenseSet<StringRef> &ComdatGroups) {
   LLVMContext Context;
   std::unique_ptr<IRObjectFile> Obj = check(IRObjectFile::create(MB, Context));
@@ -448,43 +492,9 @@ void BitcodeFile::parse(DenseSet<StringRef> &ComdatGroups) {
       KeptComdats.insert(&P.second);
   }
 
-  for (const BasicSymbolRef &Sym : Obj->symbols()) {
-    const GlobalValue *GV = Obj->getSymbolGV(Sym.getRawDataRefImpl());
-    assert(GV);
-    uint32_t Flags = Sym.getFlags();
-    if (const Comdat *C = GV->getComdat())
-      if (!KeptComdats.count(C))
-        continue;
-    if (!(Flags & BasicSymbolRef::SF_Global))
-        continue;
-    if (GV->hasAppendingLinkage()) {
-      ExtraKeeps.push_back(GV->getName().copy(Alloc));
-      continue;
-    }
-    if (Flags & BasicSymbolRef::SF_FormatSpecific)
-      continue;
-    uint8_t Visibility = getGvVisibility(GV);
-
-    SmallString<64> Name;
-    raw_svector_ostream OS(Name);
-    Sym.printName(OS);
-    StringRef NameRef = Saver.save(StringRef(Name));
-
-    SymbolBody *Body;
-    bool IsWeak = Flags & BasicSymbolRef::SF_Weak;
-    if (Flags & BasicSymbolRef::SF_Undefined) {
-      Body = new (Alloc) Undefined(NameRef, IsWeak, Visibility, false);
-    } else if (Flags & BasicSymbolRef::SF_Common) {
-      const DataLayout &DL = M.getDataLayout();
-      uint64_t Size = DL.getTypeAllocSize(GV->getValueType());
-      Body = new (Alloc)
-          DefinedCommon(NameRef, Size, GV->getAlignment(), IsWeak, Visibility);
-    } else {
-      Body = new (Alloc) DefinedBitcode(NameRef, IsWeak, Visibility);
-    }
-    Body->IsTls = GV->isThreadLocal();
-    SymbolBodies.push_back(Body);
-  }
+  for (const BasicSymbolRef &Sym : Obj->symbols())
+    if (!shouldSkip(Sym))
+      SymbolBodies.push_back(createSymbolBody(KeptComdats, *Obj, Sym));
 }
 
 template <typename T>

lld/ELF/InputFiles.h

@@ -18,8 +18,10 @@
 #include "lld/Core/LLVM.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/IR/Comdat.h"
 #include "llvm/Object/Archive.h"
 #include "llvm/Object/ELF.h"
+#include "llvm/Object/IRObjectFile.h"
 #include "llvm/Support/StringSaver.h"
 
 namespace lld {
@@ -180,19 +182,16 @@ public:
   static bool classof(const InputFile *F);
   void parse(llvm::DenseSet<StringRef> &ComdatGroups);
   ArrayRef<SymbolBody *> getSymbols() { return SymbolBodies; }
-  ArrayRef<StringRef> getExtraKeeps() { return ExtraKeeps; }
+  static bool shouldSkip(const llvm::object::BasicSymbolRef &Sym);
 
 private:
   std::vector<SymbolBody *> SymbolBodies;
-  // Some symbols like llvm.global_ctors are internal to the IR and so
-  // don't show up in SymbolBodies, but must be kept when creating the
-  // combined LTO module. We track them here.
-  // We currently use a different Module for creating SymbolBody's vs when
-  // we are creating the combined LTO module, and so we can't store IR
-  // pointers directly and must rely on the IR names.
-  std::vector<StringRef> ExtraKeeps;
   llvm::BumpPtrAllocator Alloc;
   llvm::StringSaver Saver{Alloc};
+  SymbolBody *
+  createSymbolBody(const llvm::DenseSet<const llvm::Comdat *> &KeptComdats,
+                   const llvm::object::IRObjectFile &Obj,
+                   const llvm::object::BasicSymbolRef &Sym);
 };
 
 // .so file.

lld/ELF/SymbolTable.cpp

@@ -84,7 +84,8 @@ void SymbolTable<ELFT>::addFile(std::unique_ptr<InputFile> File) {
     BitcodeFiles.emplace_back(cast<BitcodeFile>(File.release()));
     F->parse(ComdatGroups);
     for (SymbolBody *B : F->getSymbols())
-      resolve(B);
+      if (B)
+        resolve(B);
     return;
   }
 
@@ -139,28 +140,33 @@ std::unique_ptr<InputFile> SymbolTable<ELFT>::codegen(Module &M) {
 
 static void addBitcodeFile(IRMover &Mover, BitcodeFile &F,
                            LLVMContext &Context) {
-  std::unique_ptr<MemoryBuffer> Buffer =
-      MemoryBuffer::getMemBuffer(F.MB, false);
-  std::unique_ptr<Module> M =
-      check(getLazyBitcodeModule(std::move(Buffer), Context,
-                                 /*ShouldLazyLoadMetadata*/ false));
+
+  std::unique_ptr<IRObjectFile> Obj =
+      check(IRObjectFile::create(F.MB, Context));
   std::vector<GlobalValue *> Keep;
-  for (SymbolBody *B : F.getSymbols()) {
-    if (&B->repl() != B)
+  unsigned BodyIndex = 0;
+  ArrayRef<SymbolBody *> Bodies = F.getSymbols();
+
+  for (const BasicSymbolRef &Sym : Obj->symbols()) {
+    GlobalValue *GV = Obj->getSymbolGV(Sym.getRawDataRefImpl());
+    assert(GV);
+    if (GV->hasAppendingLinkage()) {
+      Keep.push_back(GV);
+      continue;
+    }
+    if (BitcodeFile::shouldSkip(Sym))
+      continue;
+    SymbolBody *B = Bodies[BodyIndex++];
+    if (!B || &B->repl() != B)
       continue;
     auto *DB = dyn_cast<DefinedBitcode>(B);
     if (!DB)
       continue;
-    GlobalValue *GV = M->getNamedValue(B->getName());
-    assert(GV);
     Keep.push_back(GV);
   }
-  for (StringRef S : F.getExtraKeeps()) {
-    GlobalValue *GV = M->getNamedValue(S);
-    assert(GV);
-    Keep.push_back(GV);
-  }
-  Mover.move(std::move(M), Keep, [](GlobalValue &, IRMover::ValueAdder) {});
+
+  Mover.move(Obj->takeModule(), Keep,
+             [](GlobalValue &, IRMover::ValueAdder) {});
 }
 
 // This is for use when debugging LTO.