[lldb] Nits on uses of llvm::raw_string_ostream (NFC) (llvm#108745)

As specified in the docs,
1) raw_string_ostream is always unbuffered and
2) the underlying buffer may be used directly

( 65b1361 for further reference )

* Don't call raw_string_ostream::flush(), which is essentially a no-op.
* Avoid unneeded calls to raw_string_ostream::str(), to avoid excess
indirection.

Author: JOE1994

lldb/include/lldb/Utility/Instrumentation.h

@@ -70,7 +70,7 @@ template <typename... Ts> inline std::string stringify_args(const Ts &...ts) {
   std::string buffer;
   llvm::raw_string_ostream ss(buffer);
   stringify_helper(ss, ts...);
-  return ss.str();
+  return buffer;
 }
 
 /// RAII object for instrumenting LLDB API functions.

lldb/source/Breakpoint/Breakpoint.cpp

@@ -1127,7 +1127,7 @@ json::Value Breakpoint::GetStatistics() {
     llvm::raw_string_ostream ss(buffer);
     json::OStream json_os(ss);
     bp_data_sp->Serialize(json_os);
-    if (auto expected_value = llvm::json::parse(ss.str())) {
+    if (auto expected_value = llvm::json::parse(buffer)) {
       bp.try_emplace("details", std::move(*expected_value));
     } else {
       std::string details_error = toString(expected_value.takeError());

lldb/source/Commands/CommandObjectLog.cpp

@@ -204,7 +204,7 @@ class CommandObjectLogEnable : public CommandObjectParsed {
         channel, args.GetArgumentArrayRef(), log_file, m_options.log_options,
         m_options.buffer_size.GetCurrentValue(), m_options.handler,
         error_stream);
-    result.GetErrorStream() << error_stream.str();
+    result.GetErrorStream() << error;
 
     if (success)
       result.SetStatus(eReturnStatusSuccessFinishNoResult);
@@ -273,7 +273,7 @@ class CommandObjectLogDisable : public CommandObjectParsed {
       if (Log::DisableLogChannel(channel, args.GetArgumentArrayRef(),
                                  error_stream))
         result.SetStatus(eReturnStatusSuccessFinishNoResult);
-      result.GetErrorStream() << error_stream.str();
+      result.GetErrorStream() << error;
     }
   }
 };
@@ -313,7 +313,7 @@ class CommandObjectLogList : public CommandObjectParsed {
       if (success)
         result.SetStatus(eReturnStatusSuccessFinishResult);
     }
-    result.GetOutputStream() << output_stream.str();
+    result.GetOutputStream() << output;
   }
 };
 class CommandObjectLogDump : public CommandObjectParsed {
@@ -404,7 +404,7 @@ class CommandObjectLogDump : public CommandObjectParsed {
       result.SetStatus(eReturnStatusSuccessFinishNoResult);
     } else {
       result.SetStatus(eReturnStatusFailed);
-      result.GetErrorStream() << error_stream.str();
+      result.GetErrorStream() << error;
     }
   }
 

lldb/source/Commands/CommandObjectRegexCommand.cpp

@@ -51,7 +51,7 @@ llvm::Expected<std::string> CommandObjectRegexCommand::SubstituteVariables(
     output << part;
   }
 
-  return output.str();
+  return buffer;
 }
 
 void CommandObjectRegexCommand::DoExecute(llvm::StringRef command,

lldb/source/Core/Module.cpp

@@ -1626,7 +1626,7 @@ uint32_t Module::Hash() {
   const auto mtime = llvm::sys::toTimeT(m_object_mod_time);
   if (mtime > 0)
     id_strm << mtime;
-  return llvm::djbHash(id_strm.str());
+  return llvm::djbHash(identifier);
 }
 
 std::string Module::GetCacheKey() {
@@ -1636,7 +1636,7 @@ std::string Module::GetCacheKey() {
   if (m_object_name)
     strm << '(' << m_object_name << ')';
   strm << '-' << llvm::format_hex(Hash(), 10);
-  return strm.str();
+  return key;
 }
 
 DataFileCache *Module::GetIndexCache() {

lldb/source/Expression/IRExecutionUnit.cpp

@@ -261,8 +261,6 @@ void IRExecutionUnit::GetRunnableInfo(Status &error, lldb::addr_t &func_addr,
 
     m_module->print(oss, nullptr);
 
-    oss.flush();
-
     LLDB_LOGF(log, "Module being sent to JIT: \n%s", s.c_str());
   }
 

lldb/source/Expression/IRInterpreter.cpp

@@ -49,7 +49,6 @@ static std::string PrintValue(const Value *value, bool truncate = false) {
   std::string s;
   raw_string_ostream rso(s);
   value->print(rso);
-  rso.flush();
   if (truncate)
     s.resize(s.length() - 1);
 
@@ -66,7 +65,6 @@ static std::string PrintType(const Type *type, bool truncate = false) {
   std::string s;
   raw_string_ostream rso(s);
   type->print(rso);
-  rso.flush();
   if (truncate)
     s.resize(s.length() - 1);
   return s;
@@ -698,8 +696,6 @@ bool IRInterpreter::Interpret(llvm::Module &module, llvm::Function &function,
 
     module.print(oss, nullptr);
 
-    oss.flush();
-
     LLDB_LOGF(log, "Module as passed in to IRInterpreter::Interpret: \n\"%s\"",
               s.c_str());
   }

lldb/source/Host/windows/PipeWindows.cpp

@@ -74,7 +74,6 @@ Status PipeWindows::CreateNew(bool child_process_inherit) {
   std::string pipe_name;
   llvm::raw_string_ostream pipe_name_stream(pipe_name);
   pipe_name_stream << "lldb.pipe." << ::GetCurrentProcessId() << "." << serial;
-  pipe_name_stream.flush();
 
   return CreateNew(pipe_name.c_str(), child_process_inherit);
 }

lldb/source/Interpreter/Options.cpp

@@ -923,7 +923,7 @@ static std::string BuildShortOptions(const Option *long_options) {
       }
     }
   }
-  return std::move(sstr.str());
+  return storage;
 }
 
 llvm::Expected<Args> Options::ParseAlias(const Args &args,

lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp

@@ -1366,8 +1366,6 @@ void DisassemblerLLVMC::MCDisasmInstance::PrintMCInst(
                                 *m_subtarget_info_up, inst_stream);
   m_instr_printer_up->setCommentStream(llvm::nulls());
 
-  comments_stream.flush();
-
   static std::string g_newlines("\r\n");
 
   for (size_t newline_pos = 0;