COFF: New symbol table design.

This ports the ELF linker's symbol table design, introduced in r268178,
to the COFF linker.

Differential Revision: http://reviews.llvm.org/D21166

llvm-svn: 289280

lld/COFF/Chunks.cpp

@@ -150,7 +150,7 @@ void SectionChunk::writeTo(uint8_t *Buf) const {
   // Apply relocations.
   for (const coff_relocation &Rel : Relocs) {
     uint8_t *Off = Buf + OutputSectionOff + Rel.VirtualAddress;
-    SymbolBody *Body = File->getSymbolBody(Rel.SymbolTableIndex)->repl();
+    SymbolBody *Body = File->getSymbolBody(Rel.SymbolTableIndex);
     Defined *Sym = cast<Defined>(Body);
     uint64_t P = RVA + Rel.VirtualAddress;
     switch (Config->Machine) {
@@ -203,7 +203,7 @@ void SectionChunk::getBaserels(std::vector<Baserel> *Res) {
     uint8_t Ty = getBaserelType(Rel);
     if (Ty == IMAGE_REL_BASED_ABSOLUTE)
       continue;
-    SymbolBody *Body = File->getSymbolBody(Rel.SymbolTableIndex)->repl();
+    SymbolBody *Body = File->getSymbolBody(Rel.SymbolTableIndex);
     if (isa<DefinedAbsolute>(Body))
       continue;
     Res->emplace_back(RVA + Rel.VirtualAddress, Ty);

lld/COFF/Chunks.h

@@ -28,7 +28,6 @@ using llvm::object::COFFSymbolRef;
 using llvm::object::SectionRef;
 using llvm::object::coff_relocation;
 using llvm::object::coff_section;
-using llvm::sys::fs::file_magic;
 
 class Baserel;
 class Defined;

lld/COFF/Config.h

@@ -26,7 +26,8 @@ using llvm::StringRef;
 class DefinedAbsolute;
 class DefinedRelative;
 class StringChunk;
-class Undefined;
+struct Symbol;
+class SymbolBody;
 
 // Short aliases.
 static const auto AMD64 = llvm::COFF::IMAGE_FILE_MACHINE_AMD64;
@@ -37,7 +38,7 @@ static const auto I386 = llvm::COFF::IMAGE_FILE_MACHINE_I386;
 struct Export {
   StringRef Name;       // N in /export:N or /export:E=N
   StringRef ExtName;    // E in /export:E=N
-  Undefined *Sym = nullptr;
+  SymbolBody *Sym = nullptr;
   uint16_t Ordinal = 0;
   bool Noname = false;
   bool Data = false;
@@ -76,7 +77,7 @@ struct Configuration {
   llvm::COFF::MachineTypes Machine = IMAGE_FILE_MACHINE_UNKNOWN;
   bool Verbose = false;
   WindowsSubsystem Subsystem = llvm::COFF::IMAGE_SUBSYSTEM_UNKNOWN;
-  Undefined *Entry = nullptr;
+  SymbolBody *Entry = nullptr;
   bool NoEntry = false;
   std::string OutputFile;
   bool DoGC = true;
@@ -89,7 +90,7 @@ struct Configuration {
   StringRef PDBPath;
 
   // Symbols in this set are considered as live by the garbage collector.
-  std::set<Undefined *> GCRoot;
+  std::set<SymbolBody *> GCRoot;
 
   std::set<StringRef> NoDefaultLibs;
   bool NoDefaultLibAll = false;
@@ -100,11 +101,11 @@ struct Configuration {
   std::vector<Export> Exports;
   std::set<std::string> DelayLoads;
   std::map<std::string, int> DLLOrder;
-  Undefined *DelayLoadHelper = nullptr;
+  SymbolBody *DelayLoadHelper = nullptr;
 
   // Used for SafeSEH.
-  DefinedRelative *SEHTable = nullptr;
-  DefinedAbsolute *SEHCount = nullptr;
+  Symbol *SEHTable = nullptr;
+  Symbol *SEHCount = nullptr;
 
   // Used for /opt:lldlto=N
   unsigned LTOOptLevel = 2;

lld/COFF/DLL.cpp

@@ -324,7 +324,7 @@ class AddressTableChunk : public Chunk {
       if (E.ForwardChunk) {
         write32le(P, E.ForwardChunk->getRVA());
       } else {
-        write32le(P, cast<Defined>(E.Sym->repl())->getRVA());
+        write32le(P, cast<Defined>(E.Sym)->getRVA());
       }
     }
   }

lld/COFF/Driver.cpp

@@ -207,10 +207,10 @@ void LinkerDriver::addLibSearchPaths() {
   }
 }
 
-Undefined *LinkerDriver::addUndefined(StringRef Name) {
-  Undefined *U = Symtab.addUndefined(Name);
-  Config->GCRoot.insert(U);
-  return U;
+SymbolBody *LinkerDriver::addUndefined(StringRef Name) {
+  SymbolBody *B = Symtab.addUndefined(Name);
+  Config->GCRoot.insert(B);
+  return B;
 }
 
 // Symbol names are mangled by appending "_" prefix on x86.
@@ -232,7 +232,7 @@ StringRef LinkerDriver::findDefaultEntry() {
   };
   for (auto E : Entries) {
     StringRef Entry = Symtab.findMangle(mangle(E[0]));
-    if (!Entry.empty() && !isa<Undefined>(Symtab.find(Entry)->Body))
+    if (!Entry.empty() && !isa<Undefined>(Symtab.find(Entry)->body()))
       return mangle(E[1]);
   }
   return "";
@@ -715,7 +715,7 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
       Symbol *Sym = Symtab.find(From);
       if (!Sym)
         continue;
-      if (auto *U = dyn_cast<Undefined>(Sym->Body))
+      if (auto *U = dyn_cast<Undefined>(Sym->body()))
         if (!U->WeakAlias)
           U->WeakAlias = Symtab.addUndefined(To);
     }
@@ -734,7 +734,7 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   Symtab.addCombinedLTOObjects();
 
   // Make sure we have resolved all symbols.
-  Symtab.reportRemainingUndefines(/*Resolve=*/true);
+  Symtab.reportRemainingUndefines();
 
   // Windows specific -- if no /subsystem is given, we need to infer
   // that from entry point name.

lld/COFF/Driver.h

@@ -59,6 +59,7 @@ class ArgParser {
 
 class LinkerDriver {
 public:
+  LinkerDriver() { coff::Symtab = &Symtab; }
   void link(llvm::ArrayRef<const char *> Args);
 
   // Used by the resolver to parse .drectve section contents.
@@ -86,7 +87,7 @@ class LinkerDriver {
   std::vector<StringRef> SearchPaths;
   std::set<std::string> VisitedFiles;
 
-  Undefined *addUndefined(StringRef Sym);
+  SymbolBody *addUndefined(StringRef Sym);
   StringRef mangle(StringRef Sym);
 
   // Windows specific -- "main" is not the only main function in Windows.

lld/COFF/DriverUtils.cpp

@@ -510,13 +510,13 @@ void fixupExports() {
   }
 
   for (Export &E : Config->Exports) {
+    SymbolBody *Sym = E.Sym;
     if (!E.ForwardTo.empty()) {
       E.SymbolName = E.Name;
-    } else if (Undefined *U = cast_or_null<Undefined>(E.Sym->WeakAlias)) {
-      E.SymbolName = U->getName();
-    } else {
-      E.SymbolName = E.Sym->getName();
-    }
+    } else if (auto *U = dyn_cast<Undefined>(Sym))
+      if (U->WeakAlias)
+        Sym = U->WeakAlias;
+    E.SymbolName = Sym->getName();
   }
 
   for (Export &E : Config->Exports) {

lld/COFF/ICF.cpp

@@ -115,8 +115,8 @@ bool ICF::equalsConstant(const SectionChunk *A, const SectionChunk *B) {
         R1.VirtualAddress != R2.VirtualAddress) {
       return false;
     }
-    SymbolBody *B1 = A->File->getSymbolBody(R1.SymbolTableIndex)->repl();
-    SymbolBody *B2 = B->File->getSymbolBody(R2.SymbolTableIndex)->repl();
+    SymbolBody *B1 = A->File->getSymbolBody(R1.SymbolTableIndex);
+    SymbolBody *B2 = B->File->getSymbolBody(R2.SymbolTableIndex);
     if (B1 == B2)
       return true;
     if (auto *D1 = dyn_cast<DefinedRegular>(B1))
@@ -141,8 +141,8 @@ bool ICF::equalsConstant(const SectionChunk *A, const SectionChunk *B) {
 bool ICF::equalsVariable(const SectionChunk *A, const SectionChunk *B) {
   // Compare relocations.
   auto Eq = [&](const coff_relocation &R1, const coff_relocation &R2) {
-    SymbolBody *B1 = A->File->getSymbolBody(R1.SymbolTableIndex)->repl();
-    SymbolBody *B2 = B->File->getSymbolBody(R2.SymbolTableIndex)->repl();
+    SymbolBody *B1 = A->File->getSymbolBody(R1.SymbolTableIndex);
+    SymbolBody *B2 = B->File->getSymbolBody(R2.SymbolTableIndex);
     if (B1 == B2)
       return true;
     if (auto *D1 = dyn_cast<DefinedRegular>(B1))