[ELF] Move whyExtract/backwardReferences from LinkerDriver to Ctx. NFC

Ctx was recently added as a more suitable place for such singletons.

lld/ELF/Config.h

@@ -380,6 +380,14 @@ struct Ctx {
   SmallVector<std::pair<Symbol *, unsigned>, 0> nonPrevailingSyms;
   // True if SHT_LLVM_SYMPART is used.
   std::atomic<bool> hasSympart{false};
+  // A tuple of (reference, extractedFile, sym). Used by --why-extract=.
+  SmallVector<std::tuple<std::string, const InputFile *, const Symbol &>, 0>
+      whyExtractRecords;
+  // A mapping from a symbol to an InputFile referencing it backward. Used by
+  // --warn-backrefs.
+  llvm::DenseMap<const Symbol *,
+                 std::pair<const InputFile *, const InputFile *>>
+      backwardReferences;
 };
 
 // The only instance of Ctx struct.

lld/ELF/Driver.cpp

@@ -1774,7 +1774,7 @@ static void handleUndefined(Symbol *sym, const char *option) {
     return;
   sym->extract();
   if (!config->whyExtract.empty())
-    driver->whyExtract.emplace_back(option, sym->file, *sym);
+    ctx->whyExtractRecords.emplace_back(option, sym->file, *sym);
 }
 
 // As an extension to GNU linkers, lld supports a variant of `-u`
@@ -1810,7 +1810,7 @@ static void handleLibcall(StringRef name) {
     sym->extract();
 }
 
-void LinkerDriver::writeArchiveStats() const {
+static void writeArchiveStats() {
   if (config->printArchiveStats.empty())
     return;
 
@@ -1832,7 +1832,7 @@ void LinkerDriver::writeArchiveStats() const {
   for (BitcodeFile *file : bitcodeFiles)
     if (file->archiveName.size())
       ++extracted[CachedHashStringRef(file->archiveName)];
-  for (std::pair<StringRef, unsigned> f : archiveFiles) {
+  for (std::pair<StringRef, unsigned> f : driver->archiveFiles) {
     unsigned &v = extracted[CachedHashString(f.first)];
     os << f.second << '\t' << v << '\t' << f.first << '\n';
     // If the archive occurs multiple times, other instances have a count of 0.
@@ -1840,7 +1840,7 @@ void LinkerDriver::writeArchiveStats() const {
   }
 }
 
-void LinkerDriver::writeWhyExtract() const {
+static void writeWhyExtract() {
   if (config->whyExtract.empty())
     return;
 
@@ -1853,14 +1853,14 @@ void LinkerDriver::writeWhyExtract() const {
   }
 
   os << "reference\textracted\tsymbol\n";
-  for (auto &entry : whyExtract) {
+  for (auto &entry : ctx->whyExtractRecords) {
     os << std::get<0>(entry) << '\t' << toString(std::get<1>(entry)) << '\t'
        << toString(std::get<2>(entry)) << '\n';
   }
 }
 
-void LinkerDriver::reportBackrefs() const {
-  for (auto &ref : backwardReferences) {
+static void reportBackrefs() {
+  for (auto &ref : ctx->backwardReferences) {
     const Symbol &sym = *ref.first;
     std::string to = toString(ref.second.second);
     // Some libraries have known problems and can cause noise. Filter them out

lld/ELF/Driver.h

@@ -33,9 +33,6 @@ private:
   void inferMachineType();
   void link(llvm::opt::InputArgList &args);
   template <class ELFT> void compileBitcodeFiles(bool skipLinkedOutput);
-  void writeArchiveStats() const;
-  void writeWhyExtract() const;
-  void reportBackrefs() const;
 
   // True if we are in --whole-archive and --no-whole-archive.
   bool inWholeArchive = false;
@@ -47,17 +44,9 @@ private:
   std::unique_ptr<BitcodeCompiler> lto;
 
   std::vector<InputFile *> files;
-  SmallVector<std::pair<StringRef, unsigned>, 0> archiveFiles;
 
 public:
-  // A tuple of (reference, extractedFile, sym). Used by --why-extract=.
-  SmallVector<std::tuple<std::string, const InputFile *, const Symbol &>, 0>
-      whyExtract;
-  // A mapping from a symbol to an InputFile referencing it backward. Used by
-  // --warn-backrefs.
-  llvm::DenseMap<const Symbol *,
-                 std::pair<const InputFile *, const InputFile *>>
-      backwardReferences;
+  SmallVector<std::pair<StringRef, unsigned>, 0> archiveFiles;
 };
 
 // Parses command line options.

lld/ELF/Symbols.cpp

@@ -304,7 +304,7 @@ void elf::printTraceSymbol(const Symbol &sym, StringRef name) {
 
 static void recordWhyExtract(const InputFile *reference,
                              const InputFile &extracted, const Symbol &sym) {
-  driver->whyExtract.emplace_back(toString(reference), &extracted, sym);
+  ctx->whyExtractRecords.emplace_back(toString(reference), &extracted, sym);
 }
 
 void elf::maybeWarnUnorderableSymbol(const Symbol *sym) {
@@ -508,8 +508,8 @@ void Symbol::resolveUndefined(const Undefined &other) {
     // definition. this->file needs to be saved because in the case of LTO it
     // may be reset to nullptr or be replaced with a file named lto.tmp.
     if (backref && !isWeak())
-      driver->backwardReferences.try_emplace(this,
-                                             std::make_pair(other.file, file));
+      ctx->backwardReferences.try_emplace(this,
+                                          std::make_pair(other.file, file));
     return;
   }
 
@@ -647,7 +647,7 @@ void Symbol::resolveLazy(const LazyObject &other) {
   // should be extracted as the canonical definition instead.
   if (LLVM_UNLIKELY(isCommon()) && elf::config->fortranCommon &&
       other.file->shouldExtractForCommon(getName())) {
-    driver->backwardReferences.erase(this);
+    ctx->backwardReferences.erase(this);
     replace(other);
     other.extract();
     return;
@@ -656,7 +656,7 @@ void Symbol::resolveLazy(const LazyObject &other) {
   if (!isUndefined()) {
     // See the comment in resolveUndefined().
     if (isDefined())
-      driver->backwardReferences.erase(this);
+      ctx->backwardReferences.erase(this);
     return;
   }
 

lld/ELF/Symbols.h

@@ -554,7 +554,6 @@ void reportDuplicate(const Symbol &sym, const InputFile *newFile,
                      InputSectionBase *errSec, uint64_t errOffset);
 void maybeWarnUnorderableSymbol(const Symbol *sym);
 bool computeIsPreemptible(const Symbol &sym);
-void reportBackrefs();
 
 } // namespace elf
 } // namespace lld