1 files changed, 136 insertions, 49 deletions
diff --git a/COFF/SymbolTable.cpp b/COFF/SymbolTable.cpp
index b286d865caaf..1a9e0455dc1d 100644
--- a/COFF/SymbolTable.cpp
+++ b/COFF/SymbolTable.cpp
@@ -60,16 +60,16 @@ void SymbolTable::addFile(InputFile *File) {
 }
 
 static void errorOrWarn(const Twine &S) {
-  if (Config->Force)
+  if (Config->ForceUnresolved)
     warn(S);
   else
     error(S);
 }
 
-// Returns the name of the symbol in SC whose value is <= Addr that is closest
-// to Addr. This is generally the name of the global variable or function whose
-// definition contains Addr.
-static StringRef getSymbolName(SectionChunk *SC, uint32_t Addr) {
+// Returns the symbol in SC whose value is <= Addr that is closest to Addr.
+// This is generally the global variable or function whose definition contains
+// Addr.
+static Symbol *getSymbol(SectionChunk *SC, uint32_t Addr) {
   DefinedRegular *Candidate = nullptr;
 
   for (Symbol *S : SC->File->getSymbols()) {
@@ -81,14 +81,12 @@ static StringRef getSymbolName(SectionChunk *SC, uint32_t Addr) {
     Candidate = D;
   }
 
-  if (!Candidate)
-    return "";
-  return Candidate->getName();
+  return Candidate;
 }
 
-static std::string getSymbolLocations(ObjFile *File, uint32_t SymIndex) {
+std::string getSymbolLocations(ObjFile *File, uint32_t SymIndex) {
   struct Location {
-    StringRef SymName;
+    Symbol *Sym;
     std::pair<StringRef, uint32_t> FileLine;
   };
   std::vector<Location> Locations;
@@ -102,14 +100,14 @@ static std::string getSymbolLocations(ObjFile *File, uint32_t SymIndex) {
         continue;
       std::pair<StringRef, uint32_t> FileLine =
           getFileLine(SC, R.VirtualAddress);
-      StringRef SymName = getSymbolName(SC, R.VirtualAddress);
-      if (!FileLine.first.empty() || !SymName.empty())
-        Locations.push_back({SymName, FileLine});
+      Symbol *Sym = getSymbol(SC, R.VirtualAddress);
+      if (!FileLine.first.empty() || Sym)
+        Locations.push_back({Sym, FileLine});
     }
   }
 
   if (Locations.empty())
-    return "\n>>> referenced by " + toString(File) + "\n";
+    return "\n>>> referenced by " + toString(File);
 
   std::string Out;
   llvm::raw_string_ostream OS(Out);
@@ -119,13 +117,87 @@ static std::string getSymbolLocations(ObjFile *File, uint32_t SymIndex) {
       OS << Loc.FileLine.first << ":" << Loc.FileLine.second
          << "\n>>>               ";
     OS << toString(File);
-    if (!Loc.SymName.empty())
-      OS << ":(" << Loc.SymName << ')';
+    if (Loc.Sym)
+      OS << ":(" << toString(*Loc.Sym) << ')';
   }
-  OS << '\n';
   return OS.str();
 }
 
+void SymbolTable::loadMinGWAutomaticImports() {
+  for (auto &I : SymMap) {
+    Symbol *Sym = I.second;
+    auto *Undef = dyn_cast<Undefined>(Sym);
+    if (!Undef)
+      continue;
+    if (!Sym->IsUsedInRegularObj)
+      continue;
+
+    StringRef Name = Undef->getName();
+
+    if (Name.startswith("__imp_"))
+      continue;
+    // If we have an undefined symbol, but we have a Lazy representing a
+    // symbol we could load from file, make sure to load that.
+    Lazy *L = dyn_cast_or_null<Lazy>(find(("__imp_" + Name).str()));
+    if (!L || L->PendingArchiveLoad)
+      continue;
+
+    log("Loading lazy " + L->getName() + " from " + L->File->getName() +
+        " for automatic import");
+    L->PendingArchiveLoad = true;
+    L->File->addMember(&L->Sym);
+  }
+}
+
+bool SymbolTable::handleMinGWAutomaticImport(Symbol *Sym, StringRef Name) {
+  if (Name.startswith("__imp_"))
+    return false;
+  Defined *Imp = dyn_cast_or_null<Defined>(find(("__imp_" + Name).str()));
+  if (!Imp)
+    return false;
+
+  // Replace the reference directly to a variable with a reference
+  // to the import address table instead. This obviously isn't right,
+  // but we mark the symbol as IsRuntimePseudoReloc, and a later pass
+  // will add runtime pseudo relocations for every relocation against
+  // this Symbol. The runtime pseudo relocation framework expects the
+  // reference itself to point at the IAT entry.
+  size_t ImpSize = 0;
+  if (isa<DefinedImportData>(Imp)) {
+    log("Automatically importing " + Name + " from " +
+        cast<DefinedImportData>(Imp)->getDLLName());
+    ImpSize = sizeof(DefinedImportData);
+  } else if (isa<DefinedRegular>(Imp)) {
+    log("Automatically importing " + Name + " from " +
+        toString(cast<DefinedRegular>(Imp)->File));
+    ImpSize = sizeof(DefinedRegular);
+  } else {
+    warn("unable to automatically import " + Name + " from " + Imp->getName() +
+         " from " + toString(cast<DefinedRegular>(Imp)->File) +
+         "; unexpected symbol type");
+    return false;
+  }
+  Sym->replaceKeepingName(Imp, ImpSize);
+  Sym->IsRuntimePseudoReloc = true;
+
+  // There may exist symbols named .refptr.<name> which only consist
+  // of a single pointer to <name>. If it turns out <name> is
+  // automatically imported, we don't need to keep the .refptr.<name>
+  // pointer at all, but redirect all accesses to it to the IAT entry
+  // for __imp_<name> instead, and drop the whole .refptr.<name> chunk.
+  DefinedRegular *Refptr =
+      dyn_cast_or_null<DefinedRegular>(find((".refptr." + Name).str()));
+  if (Refptr && Refptr->getChunk()->getSize() == Config->Wordsize) {
+    SectionChunk *SC = dyn_cast_or_null<SectionChunk>(Refptr->getChunk());
+    if (SC && SC->Relocs.size() == 1 && *SC->symbols().begin() == Sym) {
+      log("Replacing .refptr." + Name + " with " + Imp->getName());
+      Refptr->getChunk()->Live = false;
+      Refptr->replaceKeepingName(Imp, ImpSize);
+    }
+  }
+  return true;
+}
+
 void SymbolTable::reportRemainingUndefines() {
   SmallPtrSet<Symbol *, 8> Undefs;
   DenseMap<Symbol *, Symbol *> LocalImports;
@@ -169,9 +241,17 @@ void SymbolTable::reportRemainingUndefines() {
       }
     }
 
+    // We don't want to report missing Microsoft precompiled headers symbols.
+    // A proper message will be emitted instead in PDBLinker::aquirePrecompObj
+    if (Name.contains("_PchSym_"))
+      continue;
+
+    if (Config->MinGW && handleMinGWAutomaticImport(Sym, Name))
+      continue;
+
     // Remaining undefined symbols are not fatal if /force is specified.
     // They are replaced with dummy defined symbols.
-    if (Config->Force)
+    if (Config->ForceUnresolved)
       replaceSymbol<DefinedAbsolute>(Sym, Name, 0);
     Undefs.insert(Sym);
   }
@@ -181,10 +261,10 @@ void SymbolTable::reportRemainingUndefines() {
 
   for (Symbol *B : Config->GCRoot) {
     if (Undefs.count(B))
-      errorOrWarn("<root>: undefined symbol: " + B->getName());
+      errorOrWarn("<root>: undefined symbol: " + toString(*B));
     if (Config->WarnLocallyDefinedImported)
       if (Symbol *Imp = LocalImports.lookup(B))
-        warn("<root>: locally defined symbol imported: " + Imp->getName() +
+        warn("<root>: locally defined symbol imported: " + toString(*Imp) +
              " (defined in " + toString(Imp->getFile()) + ") [LNK4217]");
   }
 
@@ -195,34 +275,41 @@ void SymbolTable::reportRemainingUndefines() {
       if (!Sym)
         continue;
       if (Undefs.count(Sym))
-        errorOrWarn("undefined symbol: " + Sym->getName() +
+        errorOrWarn("undefined symbol: " + toString(*Sym) +
                     getSymbolLocations(File, SymIndex));
       if (Config->WarnLocallyDefinedImported)
         if (Symbol *Imp = LocalImports.lookup(Sym))
-          warn(toString(File) + ": locally defined symbol imported: " +
-               Imp->getName() + " (defined in " + toString(Imp->getFile()) +
-               ") [LNK4217]");
+          warn(toString(File) +
+               ": locally defined symbol imported: " + toString(*Imp) +
+               " (defined in " + toString(Imp->getFile()) + ") [LNK4217]");
     }
   }
 }
 
 std::pair<Symbol *, bool> SymbolTable::insert(StringRef Name) {
+  bool Inserted = false;
   Symbol *&Sym = SymMap[CachedHashStringRef(Name)];
-  if (Sym)
-    return {Sym, false};
-  Sym = reinterpret_cast<Symbol *>(make<SymbolUnion>());
-  Sym->IsUsedInRegularObj = false;
-  Sym->PendingArchiveLoad = false;
-  return {Sym, true};
+  if (!Sym) {
+    Sym = reinterpret_cast<Symbol *>(make<SymbolUnion>());
+    Sym->IsUsedInRegularObj = false;
+    Sym->PendingArchiveLoad = false;
+    Inserted = true;
+  }
+  return {Sym, Inserted};
+}
+
+std::pair<Symbol *, bool> SymbolTable::insert(StringRef Name, InputFile *File) {
+  std::pair<Symbol *, bool> Result = insert(Name);
+  if (!File || !isa<BitcodeFile>(File))
+    Result.first->IsUsedInRegularObj = true;
+  return Result;
 }
 
 Symbol *SymbolTable::addUndefined(StringRef Name, InputFile *F,
                                   bool IsWeakAlias) {
   Symbol *S;
   bool WasInserted;
-  std::tie(S, WasInserted) = insert(Name);
-  if (!F || !isa<BitcodeFile>(F))
-    S->IsUsedInRegularObj = true;
+  std::tie(S, WasInserted) = insert(Name, F);
   if (WasInserted || (isa<Lazy>(S) && IsWeakAlias)) {
     replaceSymbol<Undefined>(S, Name);
     return S;
@@ -253,14 +340,20 @@ void SymbolTable::addLazy(ArchiveFile *F, const Archive::Symbol Sym) {
 }
 
 void SymbolTable::reportDuplicate(Symbol *Existing, InputFile *NewFile) {
-  error("duplicate symbol: " + toString(*Existing) + " in " +
-        toString(Existing->getFile()) + " and in " + toString(NewFile));
+  std::string Msg = "duplicate symbol: " + toString(*Existing) + " in " +
+                    toString(Existing->getFile()) + " and in " +
+                    toString(NewFile);
+
+  if (Config->ForceMultiple)
+    warn(Msg);
+  else
+    error(Msg);
 }
 
 Symbol *SymbolTable::addAbsolute(StringRef N, COFFSymbolRef Sym) {
   Symbol *S;
   bool WasInserted;
-  std::tie(S, WasInserted) = insert(N);
+  std::tie(S, WasInserted) = insert(N, nullptr);
   S->IsUsedInRegularObj = true;
   if (WasInserted || isa<Undefined>(S) || isa<Lazy>(S))
     replaceSymbol<DefinedAbsolute>(S, N, Sym);
@@ -272,7 +365,7 @@ Symbol *SymbolTable::addAbsolute(StringRef N, COFFSymbolRef Sym) {
 Symbol *SymbolTable::addAbsolute(StringRef N, uint64_t VA) {
   Symbol *S;
   bool WasInserted;
-  std::tie(S, WasInserted) = insert(N);
+  std::tie(S, WasInserted) = insert(N, nullptr);
   S->IsUsedInRegularObj = true;
   if (WasInserted || isa<Undefined>(S) || isa<Lazy>(S))
     replaceSymbol<DefinedAbsolute>(S, N, VA);
@@ -284,7 +377,7 @@ Symbol *SymbolTable::addAbsolute(StringRef N, uint64_t VA) {
 Symbol *SymbolTable::addSynthetic(StringRef N, Chunk *C) {
   Symbol *S;
   bool WasInserted;
-  std::tie(S, WasInserted) = insert(N);
+  std::tie(S, WasInserted) = insert(N, nullptr);
   S->IsUsedInRegularObj = true;
   if (WasInserted || isa<Undefined>(S) || isa<Lazy>(S))
     replaceSymbol<DefinedSynthetic>(S, N, C);
@@ -298,9 +391,7 @@ Symbol *SymbolTable::addRegular(InputFile *F, StringRef N,
                                 SectionChunk *C) {
   Symbol *S;
   bool WasInserted;
-  std::tie(S, WasInserted) = insert(N);
-  if (!isa<BitcodeFile>(F))
-    S->IsUsedInRegularObj = true;
+  std::tie(S, WasInserted) = insert(N, F);
   if (WasInserted || !isa<DefinedRegular>(S))
     replaceSymbol<DefinedRegular>(S, F, N, /*IsCOMDAT*/ false,
                                   /*IsExternal*/ true, Sym, C);
@@ -314,9 +405,7 @@ SymbolTable::addComdat(InputFile *F, StringRef N,
                        const coff_symbol_generic *Sym) {
   Symbol *S;
   bool WasInserted;
-  std::tie(S, WasInserted) = insert(N);
-  if (!isa<BitcodeFile>(F))
-    S->IsUsedInRegularObj = true;
+  std::tie(S, WasInserted) = insert(N, F);
   if (WasInserted || !isa<DefinedRegular>(S)) {
     replaceSymbol<DefinedRegular>(S, F, N, /*IsCOMDAT*/ true,
                                   /*IsExternal*/ true, Sym, nullptr);
@@ -331,9 +420,7 @@ Symbol *SymbolTable::addCommon(InputFile *F, StringRef N, uint64_t Size,
                                const coff_symbol_generic *Sym, CommonChunk *C) {
   Symbol *S;
   bool WasInserted;
-  std::tie(S, WasInserted) = insert(N);
-  if (!isa<BitcodeFile>(F))
-    S->IsUsedInRegularObj = true;
+  std::tie(S, WasInserted) = insert(N, F);
   if (WasInserted || !isa<DefinedCOFF>(S))
     replaceSymbol<DefinedCommon>(S, F, N, Size, Sym, C);
   else if (auto *DC = dyn_cast<DefinedCommon>(S))
@@ -345,7 +432,7 @@ Symbol *SymbolTable::addCommon(InputFile *F, StringRef N, uint64_t Size,
 Symbol *SymbolTable::addImportData(StringRef N, ImportFile *F) {
   Symbol *S;
   bool WasInserted;
-  std::tie(S, WasInserted) = insert(N);
+  std::tie(S, WasInserted) = insert(N, nullptr);
   S->IsUsedInRegularObj = true;
   if (WasInserted || isa<Undefined>(S) || isa<Lazy>(S)) {
     replaceSymbol<DefinedImportData>(S, N, F);
@@ -360,7 +447,7 @@ Symbol *SymbolTable::addImportThunk(StringRef Name, DefinedImportData *ID,
                                     uint16_t Machine) {
   Symbol *S;
   bool WasInserted;
-  std::tie(S, WasInserted) = insert(Name);
+  std::tie(S, WasInserted) = insert(Name, nullptr);
   S->IsUsedInRegularObj = true;
   if (WasInserted || isa<Undefined>(S) || isa<Lazy>(S)) {
     replaceSymbol<DefinedImportThunk>(S, Name, ID, Machine);