6 files changed, 52 insertions, 0 deletions
diff --git a/lldb/source/Core/Module.cpp b/lldb/source/Core/Module.cpp
index ddc9fca8067..d168474c347 100644
--- a/lldb/source/Core/Module.cpp
+++ b/lldb/source/Core/Module.cpp
@@ -1432,6 +1432,22 @@ size_t Module::FindSymbolsMatchingRegExAndType(const RegularExpression &regex,
   return sc_list.GetSize() - initial_size;
 }
 
+void Module::PreloadSymbols() {
+  std::lock_guard<std::recursive_mutex> guard(m_mutex);
+  SymbolVendor * sym_vendor = GetSymbolVendor();
+  if (!sym_vendor) {
+    return;
+  }
+  // Prime the symbol file first, since it adds symbols to the symbol table.
+  if (SymbolFile *symbol_file = sym_vendor->GetSymbolFile()) {
+    symbol_file->PreloadSymbols();
+  }
+  // Now we can prime the symbol table.
+  if (Symtab * symtab = sym_vendor->GetSymtab()) {
+    symtab->PreloadSymbols();
+  }
+}
+
 void Module::SetSymbolFileFileSpec(const FileSpec &file) {
   if (!file.Exists())
     return;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 973b5ef9fb4..8c2fc3d3aa4 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -1917,6 +1917,12 @@ uint32_t SymbolFileDWARF::ResolveSymbolContext(const FileSpec &file_spec,
   return sc_list.GetSize() - prev_size;
 }
 
+void SymbolFileDWARF::PreloadSymbols() {
+  std::lock_guard<std::recursive_mutex> guard(
+      GetObjectFile()->GetModule()->GetMutex());
+  Index();
+}
+
 void SymbolFileDWARF::Index() {
   if (m_indexed)
     return;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
index 14b29fa44fa..9b1eb1d76fe 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -226,6 +226,8 @@ public:
       const lldb_private::ConstString &name,
       const lldb_private::CompilerDeclContext *parent_decl_ctx) override;
 
+  void PreloadSymbols() override;
+
   //------------------------------------------------------------------
   // PluginInterface protocol
   //------------------------------------------------------------------
diff --git a/lldb/source/Symbol/SymbolFile.cpp b/lldb/source/Symbol/SymbolFile.cpp
index d7898919f45..eb20b80f491 100644
--- a/lldb/source/Symbol/SymbolFile.cpp
+++ b/lldb/source/Symbol/SymbolFile.cpp
@@ -21,6 +21,10 @@
 
 using namespace lldb_private;
 
+void SymbolFile::PreloadSymbols() {
+  // No-op for most implementations.
+}
+
 SymbolFile *SymbolFile::FindPlugin(ObjectFile *obj_file) {
   std::unique_ptr<SymbolFile> best_symfile_ap;
   if (obj_file != nullptr) {
diff --git a/lldb/source/Symbol/Symtab.cpp b/lldb/source/Symbol/Symtab.cpp
index 42702980263..f4cb49ce3e8 100644
--- a/lldb/source/Symbol/Symtab.cpp
+++ b/lldb/source/Symbol/Symtab.cpp
@@ -427,6 +427,11 @@ void Symtab::InitNameIndexes() {
   }
 }
 
+void Symtab::PreloadSymbols() {
+  std::lock_guard<std::recursive_mutex> guard(m_mutex);
+  InitNameIndexes();
+}
+
 void Symtab::AppendSymbolNamesToMap(const IndexCollection &indexes,
                                     bool add_demangled, bool add_mangled,
                                     NameToIndexMap &name_to_index_map) const {
diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
index df021e3953b..5c9e92aaaa2 100644
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -1870,6 +1870,11 @@ ModuleSP Target::GetSharedModule(const ModuleSpec &module_spec,
           }
         }
 
+        // Preload symbols outside of any lock, so hopefully we can do this for
+        // each library in parallel.
+        if (GetPreloadSymbols())
+          module_sp->PreloadSymbols();
+
         if (old_module_sp &&
             m_images.GetIndexForModule(old_module_sp.get()) !=
                 LLDB_INVALID_INDEX32) {
@@ -3277,6 +3282,8 @@ static PropertyDefinition g_properties[] = {
     {"detach-on-error", OptionValue::eTypeBoolean, false, true, nullptr,
      nullptr, "debugserver will detach (rather than killing) a process if it "
               "loses connection with lldb."},
+    {"preload-symbols", OptionValue::eTypeBoolean, false, true, nullptr, nullptr,
+     "Enable loading of symbol tables before they are needed."},
     {"disable-aslr", OptionValue::eTypeBoolean, false, true, nullptr, nullptr,
      "Disable Address Space Layout Randomization (ASLR)"},
     {"disable-stdio", OptionValue::eTypeBoolean, false, false, nullptr, nullptr,
@@ -3379,6 +3386,7 @@ enum {
   ePropertyOutputPath,
   ePropertyErrorPath,
   ePropertyDetachOnError,
+  ePropertyPreloadSymbols,
   ePropertyDisableASLR,
   ePropertyDisableSTDIO,
   ePropertyInlineStrategy,
@@ -3641,6 +3649,17 @@ bool TargetProperties::SetPreferDynamicValue(lldb::DynamicValueType d) {
   return m_collection_sp->SetPropertyAtIndexAsEnumeration(nullptr, idx, d);
 }
 
+bool TargetProperties::GetPreloadSymbols() const {
+  const uint32_t idx = ePropertyPreloadSymbols;
+  return m_collection_sp->GetPropertyAtIndexAsBoolean(
+      nullptr, idx, g_properties[idx].default_uint_value != 0);
+}
+
+void TargetProperties::SetPreloadSymbols(bool b) {
+  const uint32_t idx = ePropertyPreloadSymbols;
+  m_collection_sp->SetPropertyAtIndexAsBoolean(nullptr, idx, b);
+}
+
 bool TargetProperties::GetDisableASLR() const {
   const uint32_t idx = ePropertyDisableASLR;
   return m_collection_sp->GetPropertyAtIndexAsBoolean(