Revert "Use tbb::concurrent_unordered_set"

This reverts commit e88e662854.

input_sections.cc

@@ -460,7 +460,7 @@ MergeableSection::MergeableSection(InputSection *isec, std::string_view data)
     std::string_view substr = data.substr(0, end + 1);
     data = data.substr(end + 1);
 
-    SectionFragment *frag = parent.insert(substr);
+    SectionFragment *frag = parent.map.insert(substr, SectionFragment(substr));
     fragments.push_back(frag);
     frag_offsets.push_back(offset);
     offset += substr.size();

main.cc

@@ -217,7 +217,7 @@ static void handle_mergeable_strings() {
       for (SectionFragment *frag : m->fragments) {
         if (frag->isec == m && frag->output_offset == -1) {
           frag->output_offset = offset;
-          offset += frag->data.size();
+          offset += frag->size;
         }
       }
       m->size = offset;
@@ -981,6 +981,10 @@ static void show_stats() {
   for (ObjectFile *file : out::objs)
     num_input_sections.inc(file->sections.size());
 
+  static Counter merged_strings("merged_strings");
+  for (MergedSection *osec : MergedSection::instances)
+    merged_strings.inc(osec->map.size());
+
   Counter num_output_chunks("output_out::chunks", out::chunks.size());
   Counter num_objs("num_objs", out::objs.size());
   Counter num_dsos("num_dsos", out::dsos.size());

mold.h

@@ -19,7 +19,6 @@
 #include <string>
 #include <string_view>
 #include <tbb/concurrent_hash_map.h>
-#include <tbb/concurrent_unordered_set.h>
 #include <tbb/spin_mutex.h>
 #include <tbb/spin_rw_mutex.h>
 #include <vector>
@@ -158,11 +157,11 @@ std::ostream &operator<<(std::ostream &out, const InputFile &file);
 namespace tbb {
 template<>
 struct tbb_hash_compare<std::string_view> {
-  static size_t hash(const std::string_view &k) {
+  static size_t hash(const std::string_view& k) {
     return std::hash<std::string_view>()(k);
   }
 
-  static bool equal(const std::string_view &k1, const std::string_view &k2) {
+  static bool equal(const std::string_view& k1, const std::string_view& k2) {
     return k1 == k2;
   }
 };
@@ -197,16 +196,18 @@ private:
 //
 
 struct SectionFragment {
-  SectionFragment(std::string_view data) : data(data) {}
+  SectionFragment(std::string_view view)
+    : data((const char *)view.data()), size(view.size()) {}
 
   SectionFragment(const SectionFragment &other)
-    : isec(other.isec.load()), data(other.data),
+    : isec(other.isec.load()), data(other.data), size(other.size),
       output_offset(other.output_offset) {}
 
   inline u64 get_addr() const;
 
   std::atomic<MergeableSection *> isec = nullptr;
-  std::string_view data;
+  const char *data;
+  u32 size;
   u32 output_offset = -1;
 };
 
@@ -228,10 +229,14 @@ enum {
 class Symbol {
 public:
   Symbol() {}
-  Symbol(std::string_view name) : name(name) {}
   Symbol(const Symbol &other) : name(other.name) {}
 
-  static inline Symbol *intern(std::string_view name);
+  static Symbol *intern(std::string_view name) {
+    static ConcurrentMap<Symbol> map;
+    Symbol sym;
+    sym.name = name;
+    return map.insert(name, sym);
+  }
 
   inline u64 get_addr() const;
   inline u64 get_got_addr() const;
@@ -277,38 +282,6 @@ public:
   u8 has_copyrel : 1 = false;
 };
 
-namespace tbb {
-template<> struct tbb_hash<SectionFragment> {
-  size_t operator()(const SectionFragment &frag) const {
-    return std::hash<std::string_view>()(frag.data);
-  }
-};
-
-template<> struct tbb_hash<Symbol> {
-  size_t operator()(const Symbol &sym) const {
-    return std::hash<std::string_view>()(sym.name);
-  }
-};
-}
-
-template<> struct std::equal_to<SectionFragment> {
-  bool operator()(const SectionFragment &lhs, const SectionFragment &rhs) const {
-    return lhs.data == rhs.data;
-  }
-};
-
-template<> struct std::equal_to<Symbol> {
-  bool operator()(const Symbol &lhs, const Symbol &rhs) const {
-    return lhs.name == rhs.name;
-  }
-};
-
-inline Symbol *Symbol::intern(std::string_view name) {
-  static tbb::concurrent_unordered_set<Symbol> set;
-  auto [it, inserted] = set.emplace(name);
-  return &*it;
-}
-
 //
 // input_sections.cc
 //
@@ -662,8 +635,7 @@ public:
   static MergedSection *get_instance(std::string_view name, u32 type, u64 flags);
 
   static inline std::vector<MergedSection *> instances;
-
+  ConcurrentMap<SectionFragment> map;
-  inline SectionFragment *insert(std::string_view data);
 
   void copy_buf() override;
 
@@ -675,8 +647,6 @@ private:
     shdr.sh_type = type;
     shdr.sh_addralign = 1;
   }
-
-  tbb::concurrent_unordered_set<SectionFragment> set;
 };
 
 struct EhReloc {
@@ -1248,8 +1218,3 @@ template <typename T, typename U>
 inline void sort(T &vec, U less) {
   std::stable_sort(vec.begin(), vec.end(), less);
 }
-
-inline SectionFragment *MergedSection::insert(std::string_view data) {
-  auto [it, inserted] = set.emplace(data);
-  return &*it;
-}

output_chunks.cc

@@ -700,13 +700,10 @@ MergedSection::get_instance(std::string_view name, u32 type, u64 flags) {
 void MergedSection::copy_buf() {
   u8 *base = out::buf + shdr.sh_offset;
 
-  for (const SectionFragment &frag : set)
+  map.for_each_value([&](const SectionFragment &frag) {
     if (MergeableSection *m = frag.isec)
-      memcpy(base + m->offset + frag.output_offset,
+      memcpy(base + m->offset + frag.output_offset, frag.data, frag.size);
-             frag.data.data(), frag.data.size());
+  });
-
-  static Counter merged_strings("merged_strings");
-  merged_strings.inc(set.size());
 }
 
 void EhFrameSection::construct() {