[ELF] Move elf::symtab into Ctx

Remove the global variable `symtab` and add a member variable
(`std::unique_ptr<SymbolTable>`) to `Ctx` instead.

This is one step toward eliminating global states.

Pull Request: llvm#109612

Author: MaskRay

lld/ELF/Arch/ARM.cpp

@@ -1215,7 +1215,7 @@ template <class ELFT> void ObjFile<ELFT>::importCmseSymbols() {
       continue;
     }
 
-    if (symtab.cmseImportLib.count(sym->getName())) {
+    if (ctx.symtab->cmseImportLib.count(sym->getName())) {
       error("CMSE symbol '" + sym->getName() +
             "' is multiply defined in import library '" + toString(this) + "'");
       continue;
@@ -1227,7 +1227,7 @@ template <class ELFT> void ObjFile<ELFT>::importCmseSymbols() {
            Twine(ACLESESYM_SIZE) + " bytes");
     }
 
-    symtab.cmseImportLib[sym->getName()] = sym;
+    ctx.symtab->cmseImportLib[sym->getName()] = sym;
   }
 }
 
@@ -1263,9 +1263,9 @@ static std::string checkCmseSymAttributes(Symbol *acleSeSym, Symbol *sym) {
 void elf::processArmCmseSymbols() {
   if (!ctx.arg.cmseImplib)
     return;
-  // Only symbols with external linkage end up in symtab, so no need to do
+  // Only symbols with external linkage end up in ctx.symtab, so no need to do
   // linkage checks. Only check symbol type.
-  for (Symbol *acleSeSym : symtab.getSymbols()) {
+  for (Symbol *acleSeSym : ctx.symtab->getSymbols()) {
     if (!acleSeSym->getName().starts_with(ACLESESYM_PREFIX))
       continue;
     // If input object build attributes do not support CMSE, error and disable
@@ -1279,7 +1279,7 @@ void elf::processArmCmseSymbols() {
     // Try to find the associated symbol definition.
     // Symbol must have external linkage.
     StringRef name = acleSeSym->getName().substr(std::strlen(ACLESESYM_PREFIX));
-    Symbol *sym = symtab.find(name);
+    Symbol *sym = ctx.symtab->find(name);
     if (!sym) {
       error(toString(acleSeSym->file) + ": cmse special symbol '" +
             acleSeSym->getName() +
@@ -1295,7 +1295,7 @@ void elf::processArmCmseSymbols() {
     }
 
     // <sym> may be redefined later in the link in .gnu.sgstubs
-    symtab.cmseSymMap[name] = {acleSeSym, sym};
+    ctx.symtab->cmseSymMap[name] = {acleSeSym, sym};
   }
 
   // If this is an Arm CMSE secure app, replace references to entry symbol <sym>
@@ -1304,8 +1304,8 @@ void elf::processArmCmseSymbols() {
     MutableArrayRef<Symbol *> syms = file->getMutableSymbols();
     for (size_t i = 0, e = syms.size(); i != e; ++i) {
       StringRef symName = syms[i]->getName();
-      if (symtab.cmseSymMap.count(symName))
-        syms[i] = symtab.cmseSymMap[symName].acleSeSym;
+      if (ctx.symtab->cmseSymMap.count(symName))
+        syms[i] = ctx.symtab->cmseSymMap[symName].acleSeSym;
     }
   });
 }
@@ -1332,26 +1332,26 @@ ArmCmseSGSection::ArmCmseSGSection()
                        /*alignment=*/32, ".gnu.sgstubs") {
   entsize = ACLESESYM_SIZE;
   // The range of addresses used in the CMSE import library should be fixed.
-  for (auto &[_, sym] : symtab.cmseImportLib) {
+  for (auto &[_, sym] : ctx.symtab->cmseImportLib) {
     if (impLibMaxAddr <= sym->value)
       impLibMaxAddr = sym->value + sym->size;
   }
-  if (symtab.cmseSymMap.empty())
+  if (ctx.symtab->cmseSymMap.empty())
     return;
   addMappingSymbol();
-  for (auto &[_, entryFunc] : symtab.cmseSymMap)
+  for (auto &[_, entryFunc] : ctx.symtab->cmseSymMap)
     addSGVeneer(cast<Defined>(entryFunc.acleSeSym),
                 cast<Defined>(entryFunc.sym));
-  for (auto &[_, sym] : symtab.cmseImportLib) {
-    if (!symtab.inCMSEOutImpLib.count(sym->getName()))
+  for (auto &[_, sym] : ctx.symtab->cmseImportLib) {
+    if (!ctx.symtab->inCMSEOutImpLib.count(sym->getName()))
       warn("entry function '" + sym->getName() +
            "' from CMSE import library is not present in secure application");
   }
 
-  if (!symtab.cmseImportLib.empty() && ctx.arg.cmseOutputLib.empty()) {
-    for (auto &[_, entryFunc] : symtab.cmseSymMap) {
+  if (!ctx.symtab->cmseImportLib.empty() && ctx.arg.cmseOutputLib.empty()) {
+    for (auto &[_, entryFunc] : ctx.symtab->cmseSymMap) {
       Symbol *sym = entryFunc.sym;
-      if (!symtab.inCMSEOutImpLib.count(sym->getName()))
+      if (!ctx.symtab->inCMSEOutImpLib.count(sym->getName()))
         warn("new entry function '" + sym->getName() +
              "' introduced but no output import library specified");
     }
@@ -1360,17 +1360,17 @@ ArmCmseSGSection::ArmCmseSGSection()
 
 void ArmCmseSGSection::addSGVeneer(Symbol *acleSeSym, Symbol *sym) {
   entries.emplace_back(acleSeSym, sym);
-  if (symtab.cmseImportLib.count(sym->getName()))
-    symtab.inCMSEOutImpLib[sym->getName()] = true;
+  if (ctx.symtab->cmseImportLib.count(sym->getName()))
+    ctx.symtab->inCMSEOutImpLib[sym->getName()] = true;
   // Symbol addresses different, nothing to do.
   if (acleSeSym->file != sym->file ||
       cast<Defined>(*acleSeSym).value != cast<Defined>(*sym).value)
     return;
   // Only secure symbols with values equal to that of it's non-secure
   // counterpart needs to be in the .gnu.sgstubs section.
   ArmCmseSGVeneer *ss = nullptr;
-  if (symtab.cmseImportLib.count(sym->getName())) {
-    Defined *impSym = symtab.cmseImportLib[sym->getName()];
+  if (ctx.symtab->cmseImportLib.count(sym->getName())) {
+    Defined *impSym = ctx.symtab->cmseImportLib[sym->getName()];
     ss = make<ArmCmseSGVeneer>(sym, acleSeSym, impSym->value);
   } else {
     ss = make<ArmCmseSGVeneer>(sym, acleSeSym);
@@ -1451,12 +1451,12 @@ template <typename ELFT> void elf::writeARMCmseImportLib() {
   osIsPairs.emplace_back(make<OutputSection>(impSymTab->name, 0, 0), impSymTab);
   osIsPairs.emplace_back(make<OutputSection>(shstrtab->name, 0, 0), shstrtab);
 
-  std::sort(symtab.cmseSymMap.begin(), symtab.cmseSymMap.end(),
+  std::sort(ctx.symtab->cmseSymMap.begin(), ctx.symtab->cmseSymMap.end(),
             [](const auto &a, const auto &b) -> bool {
               return a.second.sym->getVA() < b.second.sym->getVA();
             });
   // Copy the secure gateway entry symbols to the import library symbol table.
-  for (auto &p : symtab.cmseSymMap) {
+  for (auto &p : ctx.symtab->cmseSymMap) {
     Defined *d = cast<Defined>(p.second.sym);
     impSymTab->addSymbol(makeDefined(
         ctx.internalFile, d->getName(), d->computeBinding(),

lld/ELF/Arch/PPC64.cpp

@@ -251,7 +251,7 @@ void elf::writePrefixedInstruction(uint8_t *loc, uint64_t insn) {
 
 static bool addOptional(StringRef name, uint64_t value,
                         std::vector<Defined *> &defined) {
-  Symbol *sym = symtab.find(name);
+  Symbol *sym = ctx.symtab->find(name);
   if (!sym || sym->isDefined())
     return false;
   sym->resolve(Defined{ctx.internalFile, StringRef(), STB_GLOBAL, STV_HIDDEN,

lld/ELF/Config.h

@@ -44,6 +44,7 @@ class InputSectionBase;
 class EhInputSection;
 class Defined;
 class Symbol;
+class SymbolTable;
 class BitcodeCompiler;
 class OutputSection;
 class LinkerScript;
@@ -600,6 +601,7 @@ struct Ctx {
     Defined *tlsModuleBase;
   };
   ElfSym sym;
+  std::unique_ptr<SymbolTable> symtab;
 
   SmallVector<std::unique_ptr<MemoryBuffer>> memoryBuffers;
   SmallVector<ELFFileBase *, 0> objectFiles;

lld/ELF/Driver.cpp

@@ -109,6 +109,7 @@ void Ctx::reset() {
 
   in.reset();
   sym = ElfSym{};
+  symtab = std::make_unique<SymbolTable>();
 
   memoryBuffers.clear();
   objectFiles.clear();
@@ -155,7 +156,6 @@ bool link(ArrayRef<const char *> args, llvm::raw_ostream &stdoutOS,
   context->e.cleanupCallback = []() {
     elf::ctx.reset();
     elf::ctx.partitions.emplace_back();
-    symtab = SymbolTable();
 
     SharedFile::vernauxNum = 0;
   };
@@ -167,6 +167,7 @@ bool link(ArrayRef<const char *> args, llvm::raw_ostream &stdoutOS,
   LinkerScript script(ctx);
   ctx.script = &script;
   ctx.symAux.emplace_back();
+  ctx.symtab = std::make_unique<SymbolTable>();
 
   ctx.partitions.clear();
   ctx.partitions.emplace_back();
@@ -2194,7 +2195,7 @@ static void handleUndefinedGlob(Ctx &ctx, StringRef arg) {
   // Calling sym->extract() in the loop is not safe because it may add new
   // symbols to the symbol table, invalidating the current iterator.
   SmallVector<Symbol *, 0> syms;
-  for (Symbol *sym : symtab.getSymbols())
+  for (Symbol *sym : ctx.symtab->getSymbols())
     if (!sym->isPlaceholder() && pat->match(sym->getName()))
       syms.push_back(sym);
 
@@ -2203,7 +2204,7 @@ static void handleUndefinedGlob(Ctx &ctx, StringRef arg) {
 }
 
 static void handleLibcall(Ctx &ctx, StringRef name) {
-  Symbol *sym = symtab.find(name);
+  Symbol *sym = ctx.symtab->find(name);
   if (sym && sym->isLazy() && isa<BitcodeFile>(sym->file)) {
     if (!ctx.arg.whyExtract.empty())
       ctx.whyExtractRecords.emplace_back("<libcall>", sym->file, *sym);
@@ -2390,7 +2391,7 @@ template <class ELFT>
 static void findKeepUniqueSections(Ctx &ctx, opt::InputArgList &args) {
   for (auto *arg : args.filtered(OPT_keep_unique)) {
     StringRef name = arg->getValue();
-    auto *d = dyn_cast_or_null<Defined>(symtab.find(name));
+    auto *d = dyn_cast_or_null<Defined>(ctx.symtab->find(name));
     if (!d || !d->section) {
       warn("could not find symbol " + name + " to keep unique");
       continue;
@@ -2405,7 +2406,7 @@ static void findKeepUniqueSections(Ctx &ctx, opt::InputArgList &args) {
 
   // Symbols in the dynsym could be address-significant in other executables
   // or DSOs, so we conservatively mark them as address-significant.
-  for (Symbol *sym : symtab.getSymbols())
+  for (Symbol *sym : ctx.symtab->getSymbols())
     if (sym->includeInDynsym())
       markAddrsig(sym);
 
@@ -2574,24 +2575,24 @@ static std::vector<WrappedSymbol> addWrappedSymbols(opt::InputArgList &args) {
     if (!seen.insert(name).second)
       continue;
 
-    Symbol *sym = symtab.find(name);
+    Symbol *sym = ctx.symtab->find(name);
     if (!sym)
       continue;
 
-    Symbol *wrap =
-        symtab.addUnusedUndefined(saver().save("__wrap_" + name), sym->binding);
+    Symbol *wrap = ctx.symtab->addUnusedUndefined(
+        saver().save("__wrap_" + name), sym->binding);
 
     // If __real_ is referenced, pull in the symbol if it is lazy. Do this after
     // processing __wrap_ as that may have referenced __real_.
     StringRef realName = saver().save("__real_" + name);
-    if (Symbol *real = symtab.find(realName)) {
-      symtab.addUnusedUndefined(name, sym->binding);
+    if (Symbol *real = ctx.symtab->find(realName)) {
+      ctx.symtab->addUnusedUndefined(name, sym->binding);
       // Update sym's binding, which will replace real's later in
       // SymbolTable::wrap.
       sym->binding = real->binding;
     }
 
-    Symbol *real = symtab.addUnusedUndefined(realName);
+    Symbol *real = ctx.symtab->addUnusedUndefined(realName);
     v.push_back({sym, real, wrap});
 
     // We want to tell LTO not to inline symbols to be overwritten
@@ -2626,7 +2627,7 @@ static void combineVersionedSymbol(Symbol &sym,
   //
   // * There is a definition of foo@v1 and foo@@v1.
   // * There is a definition of foo@v1 and foo.
-  Defined *sym2 = dyn_cast_or_null<Defined>(symtab.find(sym.getName()));
+  Defined *sym2 = dyn_cast_or_null<Defined>(ctx.symtab->find(sym.getName()));
   if (!sym2)
     return;
   const char *suffix2 = sym2->getVersionSuffix();
@@ -2681,7 +2682,7 @@ static void redirectSymbols(Ctx &ctx, ArrayRef<WrappedSymbol> wrapped) {
   // symbols with a non-default version (foo@v1) and check whether it should be
   // combined with foo or foo@@v1.
   if (ctx.arg.versionDefinitions.size() > 2)
-    for (Symbol *sym : symtab.getSymbols())
+    for (Symbol *sym : ctx.symtab->getSymbols())
       if (sym->hasVersionSuffix)
         combineVersionedSymbol(*sym, map);
 
@@ -2697,7 +2698,7 @@ static void redirectSymbols(Ctx &ctx, ArrayRef<WrappedSymbol> wrapped) {
 
   // Update pointers in the symbol table.
   for (const WrappedSymbol &w : wrapped)
-    symtab.wrap(w.sym, w.real, w.wrap);
+    ctx.symtab->wrap(w.sym, w.real, w.wrap);
 }
 
 static void reportMissingFeature(StringRef config, const Twine &report) {
@@ -2861,22 +2862,22 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &args) {
 
   // Handle --trace-symbol.
   for (auto *arg : args.filtered(OPT_trace_symbol))
-    symtab.insert(arg->getValue())->traced = true;
+    ctx.symtab->insert(arg->getValue())->traced = true;
 
   ctx.internalFile = createInternalFile("<internal>");
 
   // Handle -u/--undefined before input files. If both a.a and b.so define foo,
   // -u foo a.a b.so will extract a.a.
   for (StringRef name : ctx.arg.undefined)
-    symtab.addUnusedUndefined(name)->referenced = true;
+    ctx.symtab->addUnusedUndefined(name)->referenced = true;
 
   parseFiles(files, armCmseImpLib);
 
   // Create dynamic sections for dynamic linking and static PIE.
   ctx.arg.hasDynSymTab = !ctx.sharedFiles.empty() || ctx.arg.isPic;
 
   // If an entry symbol is in a static archive, pull out that file now.
-  if (Symbol *sym = symtab.find(ctx.arg.entry))
+  if (Symbol *sym = ctx.symtab->find(ctx.arg.entry))
     handleUndefined(ctx, sym, "--entry");
 
   // Handle the `--undefined-glob <pattern>` options.
@@ -2890,13 +2891,13 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &args) {
 
   // Prevent LTO from removing any definition referenced by -u.
   for (StringRef name : ctx.arg.undefined)
-    if (Defined *sym = dyn_cast_or_null<Defined>(symtab.find(name)))
+    if (Defined *sym = dyn_cast_or_null<Defined>(ctx.symtab->find(name)))
       sym->isUsedInRegularObj = true;
 
   // Mark -init and -fini symbols so that the LTO doesn't eliminate them.
-  if (Symbol *sym = dyn_cast_or_null<Defined>(symtab.find(ctx.arg.init)))
+  if (Symbol *sym = dyn_cast_or_null<Defined>(ctx.symtab->find(ctx.arg.init)))
     sym->isUsedInRegularObj = true;
-  if (Symbol *sym = dyn_cast_or_null<Defined>(symtab.find(ctx.arg.fini)))
+  if (Symbol *sym = dyn_cast_or_null<Defined>(ctx.symtab->find(ctx.arg.fini)))
     sym->isUsedInRegularObj = true;
 
   // If any of our inputs are bitcode files, the LTO code generator may create
@@ -2977,7 +2978,7 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &args) {
   // name "foo@ver1") rather do harm, so we don't call this if -r is given.
   if (!ctx.arg.relocatable) {
     llvm::TimeTraceScope timeScope("Process symbol versions");
-    symtab.scanVersionScript();
+    ctx.symtab->scanVersionScript();
   }
 
   // Skip the normal linked output if some LTO options are specified.

lld/ELF/ICF.cpp

@@ -468,7 +468,7 @@ template <class ELFT> void ICF<ELFT>::run() {
   // cannot be merged with the later computeIsPreemptible() pass which is used
   // by scanRelocations().
   if (ctx.arg.hasDynSymTab)
-    for (Symbol *sym : symtab.getSymbols())
+    for (Symbol *sym : ctx.symtab->getSymbols())
       sym->isPreemptible = computeIsPreemptible(*sym);
 
   // Two text sections may have identical content and relocations but different
@@ -568,7 +568,7 @@ template <class ELFT> void ICF<ELFT>::run() {
           d->folded = true;
         }
   };
-  for (Symbol *sym : symtab.getSymbols())
+  for (Symbol *sym : ctx.symtab->getSymbols())
     fold(sym);
   parallelForEach(ctx.objectFiles, [&](ELFFileBase *file) {
     for (Symbol *sym : file->getLocalSymbols())