[Target] Introduce Process::GetLanguageRuntimes

[xiaobai]

Summary

Currently there's not really a good way to iterate over the language runtimes a
process has. This is sometimes desirable (as seen in my change to Thread).
Additionally, there's not really a good reason to iterate over every available
language, but rather only over languages for which we have a plugin loaded.

[JDevlieghere]

source/Target/Thread.cpp

2216

if for (LanguageRuntime *runtime : GetProcess()->GetLanguageRuntimes()) { fits on one line I would get rid of the temporary.

[labath]

source/Target/Process.cpp

1565

Use auto * to make it clear that this is a pointer (or even LanguageRuntime *, as the type is not that long). Then drop std::move below, as it's useless for pointers.

source/Target/Thread.cpp

2217–2218

It looks like the code already makes sure null pointers don't make it into the list. We should make that a part of the contract and not check it twice.

[xiaobai]

Address review feedback

[jingham]

LGTM

include/lldb/Target/Language.h

public:
   static bool LanguageIsCFamily(lldb::LanguageType language);
 
   static bool LanguageIsPascal(lldb::LanguageType language);
 
   // return the primary language, so if LanguageIsC(l), return eLanguageTypeC,
   // etc.
   static lldb::LanguageType GetPrimaryLanguage(lldb::LanguageType language);
 
+  static std::set<lldb::LanguageType> GetSupportedLanguages();
+
   static void GetLanguagesSupportingTypeSystems(
       std::set<lldb::LanguageType> &languages,
       std::set<lldb::LanguageType> &languages_for_expressions);
 
   static void
   GetLanguagesSupportingREPLs(std::set<lldb::LanguageType> &languages);
 
 protected:

include/lldb/Target/Process.h

public:
   bool StateChangedIsHijackedForSynchronousResume();
 
   bool StateChangedIsExternallyHijacked();
 
   const lldb::ABISP &GetABI();
 
   OperatingSystem *GetOperatingSystem() { return m_os_up.get(); }
 
+  std::vector<LanguageRuntime *>
+  GetLanguageRuntimes(bool retry_if_null = true);
+
   LanguageRuntime *GetLanguageRuntime(lldb::LanguageType language,
                                       bool retry_if_null = true);
 
   CPPLanguageRuntime *GetCPPLanguageRuntime(bool retry_if_null = true);
 
   ObjCLanguageRuntime *GetObjCLanguageRuntime(bool retry_if_null = true);
 
   bool IsPossibleDynamicValue(ValueObject &in_value);

source/Target/Language.cpp

LanguageType Language::GetPrimaryLanguage(LanguageType language) {
   case eLanguageTypeMipsAssembler:
   case eLanguageTypeExtRenderScript:
   case eLanguageTypeUnknown:
   default:
     return language;
   }
 }
 
+std::set<lldb::LanguageType> Language::GetSupportedLanguages() {
+  std::set<lldb::LanguageType> supported_languages;
+  ForEach([&](Language *lang) {
+    supported_languages.emplace(lang->GetLanguageType());
+    return true;
+  });
+  return supported_languages;
+}
+
 void Language::GetLanguagesSupportingTypeSystems(
     std::set<lldb::LanguageType> &languages,
     std::set<lldb::LanguageType> &languages_for_expressions) {
   uint32_t idx = 0;
 
   while (TypeSystemEnumerateSupportedLanguages enumerate = PluginManager::
              GetTypeSystemEnumerateSupportedLanguagesCallbackAtIndex(idx++)) {
     (*enumerate)(languages, languages_for_expressions);

source/Target/Process.cpp

 #include "lldb/Symbol/Function.h"
 #include "lldb/Symbol/Symbol.h"
 #include "lldb/Target/ABI.h"
 #include "lldb/Target/CPPLanguageRuntime.h"
 #include "lldb/Target/DynamicLoader.h"
 #include "lldb/Target/InstrumentationRuntime.h"
 #include "lldb/Target/JITLoader.h"
 #include "lldb/Target/JITLoaderList.h"
+#include "lldb/Target/Language.h"
 #include "lldb/Target/LanguageRuntime.h"
 #include "lldb/Target/MemoryHistory.h"
 #include "lldb/Target/MemoryRegionInfo.h"
 #include "lldb/Target/ObjCLanguageRuntime.h"
 #include "lldb/Target/OperatingSystem.h"
 #include "lldb/Target/Platform.h"
 #include "lldb/Target/Process.h"
 #include "lldb/Target/RegisterContext.h"

 addr_t Process::GetImageInfoAddress() { return LLDB_INVALID_ADDRESS; }
 
 const lldb::ABISP &Process::GetABI() {
   if (!m_abi_sp)
     m_abi_sp = ABI::FindPlugin(shared_from_this(), GetTarget().GetArchitecture());
   return m_abi_sp;
 }
 
+std::vector<LanguageRuntime *>
+Process::GetLanguageRuntimes(bool retry_if_null) {
+  std::vector<LanguageRuntime *> language_runtimes;
+
+  if (m_finalizing)
+    return language_runtimes;
+
+  std::lock_guard<std::recursive_mutex> guard(m_language_runtimes_mutex);
+  // Before we pass off a copy of the language runtimes, we must make sure that
+  // our collection is properly populated. It's possible that some of the
+  // language runtimes were not loaded yet, either because nobody requested it
+  // yet or the proper condition for loading wasn't yet met (e.g. libc++.so
+  // hadn't been loaded).
+  for (const lldb::LanguageType lang_type : Language::GetSupportedLanguages()) {
+    if (LanguageRuntime *runtime = GetLanguageRuntime(lang_type, retry_if_null))
+      language_runtimes.emplace_back(runtime);
+  }
+
+  return language_runtimes;
+}
+
 LanguageRuntime *Process::GetLanguageRuntime(lldb::LanguageType language,
                                              bool retry_if_null) {
   if (m_finalizing)
     return nullptr;
 
   std::lock_guard<std::recursive_mutex> guard(m_language_runtimes_mutex);
   LanguageRuntimeCollection::iterator pos;
   pos = m_language_runtimes.find(language);

source/Target/Thread.cpp

 ValueObjectSP Thread::GetCurrentException() {
   if (auto frame_sp = GetStackFrameAtIndex(0))
     if (auto recognized_frame = frame_sp->GetRecognizedFrame())
       if (auto e = recognized_frame->GetExceptionObject())
         return e;
 
   // NOTE: Even though this behavior is generalized, only ObjC is actually
   // supported at the moment.
-  for (unsigned lang = eLanguageTypeUnknown; lang < eNumLanguageTypes; lang++) {
-    if (auto runtime = GetProcess()->GetLanguageRuntime(
-            static_cast<lldb::LanguageType>(lang)))
-      if (auto e = runtime->GetExceptionObjectForThread(shared_from_this()))
-        return e;
+  for (LanguageRuntime *runtime : GetProcess()->GetLanguageRuntimes()) {
   }
 
   return ValueObjectSP();
 }
 
 ThreadSP Thread::GetCurrentExceptionBacktrace() {
   ValueObjectSP exception = GetCurrentException();
   if (!exception)
     return ThreadSP();
 
   // NOTE: Even though this behavior is generalized, only ObjC is actually
   // supported at the moment.
-  for (unsigned lang = eLanguageTypeUnknown; lang < eNumLanguageTypes; lang++) {
-    if (auto runtime = GetProcess()->GetLanguageRuntime(
-            static_cast<lldb::LanguageType>(lang)))
-      if (auto bt = runtime->GetBacktraceThreadFromException(exception))
-        return bt;
+  for (LanguageRuntime *runtime : GetProcess()->GetLanguageRuntimes()) {
   }
 
   return ThreadSP();
 }