Fixing warnings for unused variables and copy ellision

[ravitheja]

Summary

The std::move was preventing copy ellision when compiled with
clang, the patch fixes the warning along with rearranging code
to remove unused variables warnings on Linux machines with
older perf_event interface.

[labath]

cool

source/Plugins/Process/Linux/ProcessorTrace.cpp

#else
   error = GetCPUType(config);
 
   return error;
 #endif
 }
 
 Status ProcessorTraceMonitor::StartTrace(lldb::pid_t pid, lldb::tid_t tid,
                                          const TraceOptions &config) {
-  Status error;
-  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
-  LLDB_LOG(log, "{0}", config.getThreadID());
-
 #ifndef PERF_ATTR_SIZE_VER5
   llvm_unreachable("perf event not supported");
 #else
+  Status error;
+  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
 
   LLDB_LOG(log, "called thread id {0}", tid);
   uint64_t page_size = getpagesize();
   uint64_t bufsize = config.getTraceBufferSize();
   uint64_t metabufsize = config.getMetaDataBufferSize();
 
   uint64_t numpages = static_cast<uint64_t>(
       llvm::PowerOf2Floor((bufsize + page_size - 1) / page_size));
   numpages = std::max(1ul, numpages);
   bufsize = page_size * numpages;
 
   numpages = static_cast<uint64_t>(
       llvm::PowerOf2Floor((metabufsize + page_size - 1) / page_size));
-  numpages = std::max(0ul, numpages);
   metabufsize = page_size * numpages;
 
   perf_event_attr attr;
   memset(&attr, 0, sizeof(attr));
   attr.size = sizeof(attr);
   attr.exclude_kernel = 1;
   attr.sample_type = PERF_SAMPLE_TIME;
   attr.sample_id_all = 1;
#else
   auto fd =
       syscall(SYS_perf_event_open, &attr, static_cast<::tid_t>(tid), -1, -1, 0);
   if (fd == -1) {
     LLDB_LOG(log, "syscall error {0}", errno);
     error.SetErrorString("perf event syscall Failed");
     return error;
   }
 
-  m_fd = std::move(std::unique_ptr<int, file_close>(new int(fd), file_close()));
+  m_fd = std::unique_ptr<int, file_close>(new int(fd), file_close());
 
   errno = 0;
   auto base =
       mmap(NULL, (metabufsize + page_size), PROT_WRITE, MAP_SHARED, fd, 0);
 
   if (base == MAP_FAILED) {
     LLDB_LOG(log, "mmap base error {0}", errno);
     error.SetErrorString("Meta buffer allocation failed");
     return error;
   }
 
-  m_mmap_meta = std::move(std::unique_ptr<perf_event_mmap_page, munmap_delete>(
+  m_mmap_meta = std::unique_ptr<perf_event_mmap_page, munmap_delete>(
       reinterpret_cast<perf_event_mmap_page *>(base),
-      munmap_delete(metabufsize + page_size)));
+      munmap_delete(metabufsize + page_size));
 
   m_mmap_meta->aux_offset = m_mmap_meta->data_offset + m_mmap_meta->data_size;
   m_mmap_meta->aux_size = bufsize;
 
   errno = 0;
   auto mmap_aux = mmap(NULL, bufsize, PROT_READ, MAP_SHARED, fd,
                        static_cast<long int>(m_mmap_meta->aux_offset));
 
   if (mmap_aux == MAP_FAILED) {
     LLDB_LOG(log, "second mmap done {0}", errno);
     error.SetErrorString("Trace buffer allocation failed");
     return error;
   }
-  m_mmap_aux = std::move(std::unique_ptr<uint8_t, munmap_delete>(
-      reinterpret_cast<uint8_t *>(mmap_aux), munmap_delete(bufsize)));
-#endif
+  m_mmap_aux = std::unique_ptr<uint8_t, munmap_delete>(
+      reinterpret_cast<uint8_t *>(mmap_aux), munmap_delete(bufsize));
   return error;
+#endif
 }
 
 llvm::MutableArrayRef<uint8_t> ProcessorTraceMonitor::GetDataBuffer() {
 #ifndef PERF_ATTR_SIZE_VER5
   llvm_unreachable("perf event not supported");
 #else
   return MutableArrayRef<uint8_t>(
       (reinterpret_cast<uint8_t *>(m_mmap_meta.get()) +
ProcessorTraceMonitor::Create(lldb::pid_t pid, lldb::tid_t tid,
                               const TraceOptions &config,
                               bool useProcessSettings) {
 
   Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
 
   Status error;
   if (tid == LLDB_INVALID_THREAD_ID) {
     error.SetErrorString("thread not specified");
-    return std::move(error.ToError());
+    return error.ToError();
   }
 
   ProcessorTraceMonitorUP pt_monitor_up(new ProcessorTraceMonitor);
 
   error = pt_monitor_up->StartTrace(pid, tid, config);
   if (error.Fail())
-    return std::move(error.ToError());
+    return error.ToError();
 
   pt_monitor_up->SetThreadID(tid);
 
   if (useProcessSettings) {
     pt_monitor_up->SetTraceID(0);
   } else {
     pt_monitor_up->SetTraceID(m_trace_num++);
     LLDB_LOG(log, "Trace ID {0}", m_trace_num);
   }
   return std::move(pt_monitor_up);
 }
 
 Status
 ProcessorTraceMonitor::ReadPerfTraceAux(llvm::MutableArrayRef<uint8_t> &buffer,
                                         size_t offset) {
-
-  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
-  Status error;
-
 #ifndef PERF_ATTR_SIZE_VER5
   llvm_unreachable("perf event not supported");
 #else
+  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
+  Status error;
   uint64_t head = m_mmap_meta->aux_head;
 
   LLDB_LOG(log, "Aux size -{0} , Head - {1}", m_mmap_meta->aux_size, head);
 
   /**
    * When configured as ring buffer, the aux buffer keeps wrapping around
    * the buffer and its not possible to detect how many times the buffer
    * wrapped. Initially the buffer is filled with zeros,as shown below
#else
   LLDB_LOG(log, "ReadCyclic BUffer Done");
   return error;
 #endif
 }
 
 Status
 ProcessorTraceMonitor::ReadPerfTraceData(llvm::MutableArrayRef<uint8_t> &buffer,
                                          size_t offset) {
-  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
-  uint64_t bytes_remaining = buffer.size();
-  Status error;
 #ifndef PERF_ATTR_SIZE_VER5
   llvm_unreachable("perf event not supported");
 #else
+  Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PTRACE));
+  uint64_t bytes_remaining = buffer.size();
+  Status error;
 
   uint64_t head = m_mmap_meta->data_head;
 
   /*
    * The data buffer and aux buffer have different implementations
    * with respect to their definition of head pointer. In the case
    * of Aux data buffer the head always wraps around the aux buffer
    * and we don't need to care about it, whereas the data_head keeps